diff options
Diffstat (limited to 'gcc/ipa-strub.cc')
| -rw-r--r-- | gcc/ipa-strub.cc | 3573 |
1 files changed, 3573 insertions, 0 deletions
diff --git a/gcc/ipa-strub.cc b/gcc/ipa-strub.cc new file mode 100644 index 0000000..293bec1 --- /dev/null +++ b/gcc/ipa-strub.cc @@ -0,0 +1,3573 @@ +/* strub (stack scrubbing) support. + Copyright (C) 2021-2023 Free Software Foundation, Inc. + Contributed by Alexandre Oliva <oliva@adacore.com>. + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 3, or (at your option) any later +version. + +GCC is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING3. If not see +<http://www.gnu.org/licenses/>. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "tree.h" +#include "gimple.h" +#include "gimplify.h" +#include "tree-pass.h" +#include "ssa.h" +#include "gimple-iterator.h" +#include "gimplify-me.h" +#include "tree-into-ssa.h" +#include "tree-ssa.h" +#include "tree-cfg.h" +#include "cfghooks.h" +#include "cfgloop.h" +#include "cfgcleanup.h" +#include "tree-eh.h" +#include "except.h" +#include "builtins.h" +#include "attribs.h" +#include "tree-inline.h" +#include "cgraph.h" +#include "alloc-pool.h" +#include "symbol-summary.h" +#include "ipa-prop.h" +#include "ipa-fnsummary.h" +#include "gimple-fold.h" +#include "fold-const.h" +#include "gimple-walk.h" +#include "tree-dfa.h" +#include "langhooks.h" +#include "calls.h" +#include "vec.h" +#include "stor-layout.h" +#include "varasm.h" +#include "alias.h" +#include "diagnostic.h" +#include "intl.h" +#include "ipa-strub.h" +#include "symtab-thunks.h" +#include "attr-fnspec.h" + +/* This file introduces two passes that, together, implement + machine-independent stack scrubbing, strub for short. It arranges + for stack frames that have strub enabled to be zeroed-out after + relinquishing control to a caller, whether by returning or by + propagating an exception. This admittedly unusual design decision + was driven by exception support (one needs a stack frame to be + active to propagate exceptions out of it), and it enabled an + implementation that is entirely machine-independent (no custom + epilogue code is required). + + Strub modes can be selected for stack frames by attaching attribute + strub to functions or to variables (to their types, actually). + Different strub modes, with different implementation details, are + available, and they can be selected by an argument to the strub + attribute. When enabled by strub-enabled variables, whether by + accessing (as in reading from) statically-allocated ones, or by + introducing (as in declaring) automatically-allocated ones, a + suitable mode is selected automatically. + + At-calls mode modifies the interface of a function, adding a stack + watermark argument, that callers use to clean up the stack frame of + the called function. Because of the interface change, it can only + be used when explicitly selected, or when a function is internal to + a translation unit. Strub-at-calls function types are distinct + from their original types (they're not modified in-place), and they + are not interchangeable with other function types. + + Internal mode, in turn, does not modify the type or the interface + of a function. It is currently implemented by turning the function + into a wrapper, moving the function body to a separate wrapped + function, and scrubbing the wrapped body's stack in the wrapper. + Internal-strub function types are mostly interface-compatible with + other strub modes, namely callable (from strub functions, though + not strub-enabled) and disabled (not callable from strub + functions). + + Always_inline functions can be strub functions, but they can only + be called from other strub functions, because strub functions must + never be inlined into non-strub functions. Internal and at-calls + modes are indistinguishable when it comes to always_inline + functions: they will necessarily be inlined into another strub + function, and will thus be integrated into the caller's stack + frame, whatever the mode. (Contrast with non-always_inline strub + functions: an at-calls function can be called from other strub + functions, ensuring no discontinuity in stack erasing, whereas an + internal-strub function can only be called from other strub + functions if it happens to be inlined, or if -fstrub=relaxed mode + is in effect (that's the default). In -fstrub=strict mode, + internal-strub functions are not callable from strub functions, + because the wrapper itself is not strubbed. + + The implementation involves two simple-IPA passes. The earliest + one, strub-mode, assigns strub modes to functions. It needs to run + before any inlining, so that we can prevent inlining of strub + functions into non-strub functions. It notes explicit strub mode + requests, enables strub in response to strub variables and testing + options, and flags unsatisfiable requests. + + Three possibilities of unsatisfiable requests come to mind: (a) + when a strub mode is explicitly selected, but the function uses + features that make it ineligible for that mode (e.g. at-calls rules + out calling __builtin_apply_args, because of the interface changes, + and internal mode rules out noclone or otherwise non-versionable + functions, non-default varargs, non-local or forced labels, and + functions with far too many arguments); (b) when some strub mode + must be enabled because of a strub variable, but the function is + not eligible or not viable for any mode; and (c) when + -fstrub=strict is enabled, and calls are found in strub functions + to functions that are not callable from strub contexts. + compute_strub_mode implements (a) and (b), and verify_strub + implements (c). + + The second IPA pass modifies interfaces of at-calls-strub functions + and types, introduces strub calls in and around them. and splits + internal-strub functions. It is placed after early inlining, so + that even internal-strub functions get a chance of being inlined + into other strub functions, but before non-early inlining, so that + internal-strub wrapper functions still get a chance of inlining + after splitting. + + Wrappers avoid duplicating the copying of large arguments again by + passing them by reference to the wrapped bodies. This involves + occasional SSA rewriting of address computations, because of the + additional indirection. Besides these changes, and the + introduction of the stack watermark parameter, wrappers and wrapped + functions cooperate to handle variable argument lists (performing + va_start in the wrapper, passing the list as an argument, and + replacing va_start calls in the wrapped body with va_copy), and + __builtin_apply_args (also called in the wrapper and passed to the + wrapped body as an argument). + + Strub bodies (both internal-mode wrapped bodies, and at-calls + functions) always start by adjusting the watermark parameter, by + calling __builtin___strub_update. The compiler inserts them in the + main strub pass. Allocations of additional stack space for the + frame (__builtin_alloca) are also followed by watermark updates. + Stack space temporarily allocated to pass arguments to other + functions, released right after the call, is not regarded as part + of the frame. Around calls to them, i.e., in internal-mode + wrappers and at-calls callers (even calls through pointers), calls + to __builtin___strub_enter and __builtin___strub_leave are + inserted, the latter as a __finally block, so that it runs at + regular and exceptional exit paths. strub_enter only initializes + the stack watermark, and strub_leave is where the scrubbing takes + place, overwriting with zeros the stack space from the top of the + stack to the watermark. + + These calls can be optimized in various cases. In + pass_ipa_strub::adjust_at_calls_call, for example, we enable + tail-calling and other optimized calls from one strub body to + another by passing on the watermark parameter. The builtins + themselves may undergo inline substitution during expansion, + dependign on optimization levels. This involves dealing with stack + red zones (when the builtins are called out-of-line, the red zone + cannot be used) and other ugly details related with inlining strub + bodies into other strub bodies (see expand_builtin_strub_update). + expand_builtin_strub_leave may even perform partial inline + substitution. */ + +/* Const and pure functions that gain a watermark parameter for strub purposes + are still regarded as such, which may cause the inline expansions of the + __strub builtins to malfunction. Ideally, attribute "fn spec" would enable + us to inform the backend about requirements and side effects of the call, but + call_fusage building in calls.c:expand_call does not even look at + attr_fnspec, so we resort to asm loads and updates to attain an equivalent + effect. Once expand_call gains the ability to issue extra memory uses and + clobbers based on pure/const function's fnspec, we can define this to 1. */ +#define ATTR_FNSPEC_DECONST_WATERMARK 0 + +enum strub_mode { + /* This mode denotes a regular function, that does not require stack + scrubbing (strubbing). It may call any other functions, but if + it calls AT_CALLS (or WRAPPED) ones, strubbing logic is + automatically introduced around those calls (the latter, by + inlining INTERNAL wrappers). */ + STRUB_DISABLED = 0, + + /* This denotes a function whose signature is (to be) modified to + take an extra parameter, for stack use annotation, and its + callers must initialize and pass that argument, and perform the + strubbing. Functions that are explicitly marked with attribute + strub must have the mark visible wherever the function is, + including aliases, and overriders and overriding methods. + Functions that are implicitly marked for strubbing, for accessing + variables explicitly marked as such, will only select this + strubbing method if they are internal to a translation unit. It + can only be inlined into other strubbing functions, i.e., + STRUB_AT_CALLS or STRUB_WRAPPED. */ + STRUB_AT_CALLS = 1, + + /* This denotes a function that is to perform strubbing internally, + without any changes to its interface (the function is turned into + a strubbing wrapper, and its original body is moved to a separate + STRUB_WRAPPED function, with a modified interface). Functions + may be explicitly marked with attribute strub(2), and the + attribute must be visible at the point of definition. Functions + that are explicitly marked for strubbing, for accessing variables + explicitly marked as such, may select this strubbing mode if + their interface cannot change, e.g. because its interface is + visible to other translation units, directly, by indirection + (having its address taken), inheritance, etc. Functions that use + this method must not have the noclone attribute, nor the noipa + one. Functions marked as always_inline may select this mode, but + they are NOT wrapped, they remain unchanged, and are only inlined + into strubbed contexts. Once non-always_inline functions are + wrapped, the wrapper becomes STRUB_WRAPPER, and the wrapped becomes + STRUB_WRAPPED. */ + STRUB_INTERNAL = 2, + + /* This denotes a function whose stack is not strubbed, but that is + nevertheless explicitly or implicitly marked as callable from strubbing + functions. Normally, only STRUB_AT_CALLS (and STRUB_INTERNAL -> + STRUB_WRAPPED) functions can be called from strubbing contexts (bodies of + STRUB_AT_CALLS, STRUB_INTERNAL and STRUB_WRAPPED functions), but attribute + strub(3) enables other functions to be (indirectly) called from these + contexts. Some builtins and internal functions may be implicitly marked as + STRUB_CALLABLE. */ + STRUB_CALLABLE = 3, + + /* This denotes the function that took over the body of a + STRUB_INTERNAL function. At first, it's only called by its + wrapper, but the wrapper may be inlined. The wrapped function, + in turn, can only be inlined into other functions whose stack + frames are strubbed, i.e., that are STRUB_WRAPPED or + STRUB_AT_CALLS. */ + STRUB_WRAPPED = -1, + + /* This denotes the wrapper function that replaced the STRUB_INTERNAL + function. This mode overrides the STRUB_INTERNAL mode at the time the + internal to-be-wrapped function becomes a wrapper, so that inlining logic + can tell one from the other. */ + STRUB_WRAPPER = -2, + + /* This denotes an always_inline function that requires strubbing. It can + only be called from, and inlined into, other strubbing contexts. */ + STRUB_INLINABLE = -3, + + /* This denotes a function that accesses strub variables, so it would call for + internal strubbing (whether or not it's eligible for that), but since + at-calls strubbing is viable, that's selected as an optimization. This + mode addresses the inconvenience that such functions may have different + modes selected depending on optimization flags, and get a different + callable status depending on that choice: if we assigned them + STRUB_AT_CALLS mode, they would be callable when optimizing, whereas + STRUB_INTERNAL would not be callable. */ + STRUB_AT_CALLS_OPT = -4, + +}; + +/* Look up a strub attribute in TYPE, and return it. */ + +static tree +get_strub_attr_from_type (tree type) +{ + return lookup_attribute ("strub", TYPE_ATTRIBUTES (type)); +} + +/* Look up a strub attribute in DECL or in its type, and return it. */ + +static tree +get_strub_attr_from_decl (tree decl) +{ + tree ret = lookup_attribute ("strub", DECL_ATTRIBUTES (decl)); + if (ret) + return ret; + return get_strub_attr_from_type (TREE_TYPE (decl)); +} + +#define STRUB_ID_COUNT 8 +#define STRUB_IDENT_COUNT 3 +#define STRUB_TYPE_COUNT 5 + +#define STRUB_ID_BASE 0 +#define STRUB_IDENT_BASE (STRUB_ID_BASE + STRUB_ID_COUNT) +#define STRUB_TYPE_BASE (STRUB_IDENT_BASE + STRUB_IDENT_COUNT) +#define STRUB_CACHE_SIZE (STRUB_TYPE_BASE + STRUB_TYPE_COUNT) + +/* Keep the strub mode and temp identifiers and types from being GC'd. */ +static GTY((deletable)) tree strub_cache[STRUB_CACHE_SIZE]; + +/* Define a function to cache identifier ID, to be used as a strub attribute + parameter for a strub mode named after NAME. */ +#define DEF_STRUB_IDS(IDX, NAME, ID) \ +static inline tree get_strub_mode_id_ ## NAME () { \ + int idx = STRUB_ID_BASE + IDX; \ + tree identifier = strub_cache[idx]; \ + if (!identifier) \ + strub_cache[idx] = identifier = get_identifier (ID); \ + return identifier; \ +} +/* Same as DEF_STRUB_IDS, but use the string expansion of NAME as ID. */ +#define DEF_STRUB_ID(IDX, NAME) \ + DEF_STRUB_IDS (IDX, NAME, #NAME) + +/* Define functions for each of the strub mode identifiers. + Expose dashes rather than underscores. */ +DEF_STRUB_ID (0, disabled) +DEF_STRUB_IDS (1, at_calls, "at-calls") +DEF_STRUB_ID (2, internal) +DEF_STRUB_ID (3, callable) +DEF_STRUB_ID (4, wrapped) +DEF_STRUB_ID (5, wrapper) +DEF_STRUB_ID (6, inlinable) +DEF_STRUB_IDS (7, at_calls_opt, "at-calls-opt") + +/* Release the temporary macro names. */ +#undef DEF_STRUB_IDS +#undef DEF_STRUB_ID + +/* Return the identifier corresponding to strub MODE. */ + +static tree +get_strub_mode_attr_parm (enum strub_mode mode) +{ + switch (mode) + { + case STRUB_DISABLED: + return get_strub_mode_id_disabled (); + + case STRUB_AT_CALLS: + return get_strub_mode_id_at_calls (); + + case STRUB_INTERNAL: + return get_strub_mode_id_internal (); + + case STRUB_CALLABLE: + return get_strub_mode_id_callable (); + + case STRUB_WRAPPED: + return get_strub_mode_id_wrapped (); + + case STRUB_WRAPPER: + return get_strub_mode_id_wrapper (); + + case STRUB_INLINABLE: + return get_strub_mode_id_inlinable (); + + case STRUB_AT_CALLS_OPT: + return get_strub_mode_id_at_calls_opt (); + + default: + gcc_unreachable (); + } +} + +/* Return the parmeters (TREE_VALUE) for a strub attribute of MODE. + We know we use a single parameter, so we bypass the creation of a + tree list. */ + +static tree +get_strub_mode_attr_value (enum strub_mode mode) +{ + return get_strub_mode_attr_parm (mode); +} + +/* Determine whether ID is a well-formed strub mode-specifying attribute + parameter for a function (type). Only user-visible modes are accepted, and + ID must be non-NULL. + + For unacceptable parms, return 0, otherwise a nonzero value as below. + + If the parm enables strub, return positive, otherwise negative. + + If the affected type must be a distinct, incompatible type,return an integer + of absolute value 2, otherwise 1. */ + +int +strub_validate_fn_attr_parm (tree id) +{ + int ret; + const char *s = NULL; + size_t len = 0; + + /* do NOT test for NULL. This is only to be called with non-NULL arguments. + We assume that the strub parameter applies to a function, because only + functions accept an explicit argument. If we accepted NULL, and we + happened to be called to verify the argument for a variable, our return + values would be wrong. */ + if (TREE_CODE (id) == STRING_CST) + { + s = TREE_STRING_POINTER (id); + len = TREE_STRING_LENGTH (id) - 1; + } + else if (TREE_CODE (id) == IDENTIFIER_NODE) + { + s = IDENTIFIER_POINTER (id); + len = IDENTIFIER_LENGTH (id); + } + else + return 0; + + enum strub_mode mode; + + if (len != 8) + return 0; + + switch (s[0]) + { + case 'd': + mode = STRUB_DISABLED; + ret = -1; + break; + + case 'a': + mode = STRUB_AT_CALLS; + ret = 2; + break; + + case 'i': + mode = STRUB_INTERNAL; + ret = 1; + break; + + case 'c': + mode = STRUB_CALLABLE; + ret = -2; + break; + + default: + /* Other parms are for internal use only. */ + return 0; + } + + tree mode_id = get_strub_mode_attr_parm (mode); + + if (TREE_CODE (id) == IDENTIFIER_NODE + ? id != mode_id + : strncmp (s, IDENTIFIER_POINTER (mode_id), len) != 0) + return 0; + + return ret; +} + +/* Return the strub mode from STRUB_ATTR. VAR_P should be TRUE if the attribute + is taken from a variable, rather than from a function, or a type thereof. */ + +static enum strub_mode +get_strub_mode_from_attr (tree strub_attr, bool var_p = false) +{ + enum strub_mode mode = STRUB_DISABLED; + + if (strub_attr) + { + if (!TREE_VALUE (strub_attr)) + mode = !var_p ? STRUB_AT_CALLS : STRUB_INTERNAL; + else + { + gcc_checking_assert (!var_p); + tree id = TREE_VALUE (strub_attr); + if (TREE_CODE (id) == TREE_LIST) + id = TREE_VALUE (id); + const char *s = (TREE_CODE (id) == STRING_CST + ? TREE_STRING_POINTER (id) + : IDENTIFIER_POINTER (id)); + size_t len = (TREE_CODE (id) == STRING_CST + ? TREE_STRING_LENGTH (id) - 1 + : IDENTIFIER_LENGTH (id)); + + switch (len) + { + case 7: + switch (s[6]) + { + case 'r': + mode = STRUB_WRAPPER; + break; + + case 'd': + mode = STRUB_WRAPPED; + break; + + default: + gcc_unreachable (); + } + break; + + case 8: + switch (s[0]) + { + case 'd': + mode = STRUB_DISABLED; + break; + + case 'a': + mode = STRUB_AT_CALLS; + break; + + case 'i': + mode = STRUB_INTERNAL; + break; + + case 'c': + mode = STRUB_CALLABLE; + break; + + default: + gcc_unreachable (); + } + break; + + case 9: + mode = STRUB_INLINABLE; + break; + + case 12: + mode = STRUB_AT_CALLS_OPT; + break; + + default: + gcc_unreachable (); + } + + gcc_checking_assert (TREE_CODE (id) == IDENTIFIER_NODE + ? id == get_strub_mode_attr_parm (mode) + : strncmp (IDENTIFIER_POINTER + (get_strub_mode_attr_parm (mode)), + s, len) == 0); + } + } + + return mode; +} + +/* Look up, decode and return the strub mode associated with FNDECL. */ + +static enum strub_mode +get_strub_mode_from_fndecl (tree fndecl) +{ + return get_strub_mode_from_attr (get_strub_attr_from_decl (fndecl)); +} + +/* Look up, decode and return the strub mode associated with NODE. */ + +static enum strub_mode +get_strub_mode (cgraph_node *node) +{ + return get_strub_mode_from_fndecl (node->decl); +} + +/* Look up, decode and return the strub mode associated with TYPE. */ + +static enum strub_mode +get_strub_mode_from_type (tree type) +{ + bool var_p = !FUNC_OR_METHOD_TYPE_P (type); + tree attr = get_strub_attr_from_type (type); + + if (attr) + return get_strub_mode_from_attr (attr, var_p); + + if (flag_strub >= -1 && !var_p) + return STRUB_CALLABLE; + + return STRUB_DISABLED; +} + + +/* Return TRUE iff NODE calls builtin va_start. */ + +static bool +calls_builtin_va_start_p (cgraph_node *node) +{ + bool result = false; + + for (cgraph_edge *e = node->callees; e; e = e->next_callee) + { + tree cdecl = e->callee->decl; + if (fndecl_built_in_p (cdecl, BUILT_IN_VA_START)) + return true; + } + + return result; +} + +/* Return TRUE iff NODE calls builtin apply_args, and optionally REPORT it. */ + +static bool +calls_builtin_apply_args_p (cgraph_node *node, bool report = false) +{ + bool result = false; + + for (cgraph_edge *e = node->callees; e; e = e->next_callee) + { + tree cdecl = e->callee->decl; + if (!fndecl_built_in_p (cdecl, BUILT_IN_APPLY_ARGS)) + continue; + + result = true; + + if (!report) + break; + + sorry_at (e->call_stmt + ? gimple_location (e->call_stmt) + : DECL_SOURCE_LOCATION (node->decl), + "at-calls %<strub%> does not support call to %qD", + cdecl); + } + + return result; +} + +/* Return TRUE iff NODE carries the always_inline attribute. */ + +static inline bool +strub_always_inline_p (cgraph_node *node) +{ + return lookup_attribute ("always_inline", DECL_ATTRIBUTES (node->decl)); +} + +/* Return TRUE iff NODE is potentially eligible for any strub-enabled mode, and + optionally REPORT the reasons for ineligibility. */ + +static inline bool +can_strub_p (cgraph_node *node, bool report = false) +{ + bool result = true; + + if (!report && strub_always_inline_p (node)) + return result; + + if (lookup_attribute ("noipa", DECL_ATTRIBUTES (node->decl))) + { + result = false; + + if (!report) + return result; + + sorry_at (DECL_SOURCE_LOCATION (node->decl), + "%qD is not eligible for %<strub%>" + " because of attribute %<noipa%>", + node->decl); + } + + /* We can't, and don't want to vectorize the watermark and other + strub-introduced parms. */ + if (lookup_attribute ("simd", DECL_ATTRIBUTES (node->decl))) + { + result = false; + + if (!report) + return result; + + sorry_at (DECL_SOURCE_LOCATION (node->decl), + "%qD is not eligible for %<strub%>" + " because of attribute %<simd%>", + node->decl); + } + + return result; +} + +/* Return TRUE iff NODE is eligible for at-calls strub, and optionally REPORT + the reasons for ineligibility. Besides general non-eligibility for + strub-enabled modes, at-calls rules out calling builtin apply_args. */ + +static bool +can_strub_at_calls_p (cgraph_node *node, bool report = false) +{ + bool result = !report || can_strub_p (node, report); + + if (!result && !report) + return result; + + return !calls_builtin_apply_args_p (node, report); +} + +/* Return TRUE iff the called function (pointer or, if available, + decl) undergoes a significant type conversion for the call. Strub + mode changes between function types, and other non-useless type + conversions, are regarded as significant. When the function type + is overridden, the effective strub mode for the call is that of the + call fntype, rather than that of the pointer or of the decl. + Functions called with type overrides cannot undergo type changes; + it's as if their address was taken, so they're considered + non-viable for implicit at-calls strub mode. */ + +static inline bool +strub_call_fntype_override_p (const gcall *gs) +{ + if (gimple_call_internal_p (gs)) + return false; + tree fn_type = TREE_TYPE (TREE_TYPE (gimple_call_fn (gs))); + if (tree decl = gimple_call_fndecl (gs)) + fn_type = TREE_TYPE (decl); + + /* We do NOT want to take the mode from the decl here. This + function is used to tell whether we can change the strub mode of + a function, and whether the effective mode for the call is to be + taken from the decl or from an overrider type. When the strub + mode is explicitly declared, or overridden with a type cast, the + difference will be noticed in function types. However, if the + strub mode is implicit due to e.g. strub variables or -fstrub=* + command-line flags, we will adjust call types along with function + types. In either case, the presence of type or strub mode + overriders in calls will prevent a function from having its strub + modes changed in ways that would imply type changes, but taking + strub modes from decls would defeat this, since we set strub + modes and then call this function to tell whether the original + type was overridden to decide whether to adjust the call. We + need the answer to be about the type, not the decl. */ + enum strub_mode mode = get_strub_mode_from_type (fn_type); + return (get_strub_mode_from_type (gs->u.fntype) != mode + || !useless_type_conversion_p (gs->u.fntype, fn_type)); +} + +/* Return TRUE iff NODE is called directly with a type override. */ + +static bool +called_directly_with_type_override_p (cgraph_node *node, void *) +{ + for (cgraph_edge *e = node->callers; e; e = e->next_caller) + if (e->call_stmt && strub_call_fntype_override_p (e->call_stmt)) + return true; + + return false; +} + +/* Return TRUE iff NODE or any other nodes aliased to it are called + with type overrides. We can't safely change the type of such + functions. */ + +static bool +called_with_type_override_p (cgraph_node *node) +{ + return (node->call_for_symbol_thunks_and_aliases + (called_directly_with_type_override_p, NULL, true, true)); +} + +/* Symbolic macro for the max number of arguments that internal strub may add to + a function. */ + +#define STRUB_INTERNAL_MAX_EXTRA_ARGS 3 + +/* We can't perform internal strubbing if the function body involves certain + features: + + - a non-default __builtin_va_start (e.g. x86's __builtin_ms_va_start) is + currently unsupported because we can't discover the corresponding va_copy and + va_end decls in the wrapper, and we don't convey the alternate variable + arguments ABI to the modified wrapped function. The default + __builtin_va_start is supported by calling va_start/va_end at the wrapper, + that takes variable arguments, passing a pointer to the va_list object to the + wrapped function, that runs va_copy from it where the original function ran + va_start. + + __builtin_next_arg is currently unsupported because the wrapped function + won't be a variable argument function. We could process it in the wrapper, + that remains a variable argument function, and replace calls in the wrapped + body, but we currently don't. + + __builtin_return_address is rejected because it's generally used when the + actual caller matters, and introducing a wrapper breaks such uses as those in + the unwinder. */ + +static bool +can_strub_internally_p (cgraph_node *node, bool report = false) +{ + bool result = !report || can_strub_p (node, report); + + if (!result && !report) + return result; + + if (!report && strub_always_inline_p (node)) + return result; + + /* Since we're not changing the function identity proper, just + moving its full implementation, we *could* disable + fun->cannot_be_copied_reason and/or temporarily drop a noclone + attribute, but we'd have to prevent remapping of the labels. */ + if (lookup_attribute ("noclone", DECL_ATTRIBUTES (node->decl))) + { + result = false; + + if (!report) + return result; + + sorry_at (DECL_SOURCE_LOCATION (node->decl), + "%qD is not eligible for internal %<strub%>" + " because of attribute %<noclone%>", + node->decl); + } + + if (node->has_gimple_body_p ()) + { + for (cgraph_edge *e = node->callees; e; e = e->next_callee) + { + tree cdecl = e->callee->decl; + if (!((fndecl_built_in_p (cdecl, BUILT_IN_VA_START) + && cdecl != builtin_decl_explicit (BUILT_IN_VA_START)) + || fndecl_built_in_p (cdecl, BUILT_IN_NEXT_ARG) + || fndecl_built_in_p (cdecl, BUILT_IN_RETURN_ADDRESS))) + continue; + + result = false; + + if (!report) + return result; + + sorry_at (e->call_stmt + ? gimple_location (e->call_stmt) + : DECL_SOURCE_LOCATION (node->decl), + "%qD is not eligible for internal %<strub%> " + "because it calls %qD", + node->decl, cdecl); + } + + struct function *fun = DECL_STRUCT_FUNCTION (node->decl); + if (fun->has_nonlocal_label) + { + result = false; + + if (!report) + return result; + + sorry_at (DECL_SOURCE_LOCATION (node->decl), + "%qD is not eligible for internal %<strub%> " + "because it contains a non-local goto target", + node->decl); + } + + if (fun->has_forced_label_in_static) + { + result = false; + + if (!report) + return result; + + sorry_at (DECL_SOURCE_LOCATION (node->decl), + "%qD is not eligible for internal %<strub%> " + "because the address of a local label escapes", + node->decl); + } + + /* Catch any other case that would prevent versioning/cloning + so as to also have it covered above. */ + gcc_checking_assert (!result /* || !node->has_gimple_body_p () */ + || tree_versionable_function_p (node->decl)); + + + /* Label values references are not preserved when copying. If referenced + in nested functions, as in 920415-1.c and 920721-4.c their decls get + remapped independently. The exclusion below might be too broad, in + that we might be able to support correctly cases in which the labels + are only used internally in a function, but disconnecting forced labels + from their original declarations is undesirable in general. */ + basic_block bb; + FOR_EACH_BB_FN (bb, DECL_STRUCT_FUNCTION (node->decl)) + for (gimple_stmt_iterator gsi = gsi_start_bb (bb); + !gsi_end_p (gsi); gsi_next (&gsi)) + { + glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gsi)); + tree target; + + if (!label_stmt) + break; + + target = gimple_label_label (label_stmt); + + if (!FORCED_LABEL (target)) + continue; + + result = false; + + if (!report) + return result; + + sorry_at (gimple_location (label_stmt), + "internal %<strub%> does not support forced labels"); + } + } + + if (list_length (TYPE_ARG_TYPES (TREE_TYPE (node->decl))) + >= (((HOST_WIDE_INT) 1 << IPA_PARAM_MAX_INDEX_BITS) + - STRUB_INTERNAL_MAX_EXTRA_ARGS)) + { + result = false; + + if (!report) + return result; + + sorry_at (DECL_SOURCE_LOCATION (node->decl), + "%qD has too many arguments for internal %<strub%>", + node->decl); + } + + return result; +} + +/* Return TRUE iff NODE has any strub-requiring local variable, or accesses (as + in reading) any variable through a strub-requiring type. */ + +static bool +strub_from_body_p (cgraph_node *node) +{ + if (!node->has_gimple_body_p ()) + return false; + + /* If any local variable is marked for strub... */ + unsigned i; + tree var; + FOR_EACH_LOCAL_DECL (DECL_STRUCT_FUNCTION (node->decl), + i, var) + if (get_strub_mode_from_type (TREE_TYPE (var)) + != STRUB_DISABLED) + return true; + + /* Now scan the body for loads with strub-requiring types. + ??? Compound types don't propagate the strub requirement to + component types. */ + basic_block bb; + FOR_EACH_BB_FN (bb, DECL_STRUCT_FUNCTION (node->decl)) + for (gimple_stmt_iterator gsi = gsi_start_bb (bb); + !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple *stmt = gsi_stmt (gsi); + + if (!gimple_assign_load_p (stmt)) + continue; + + tree rhs = gimple_assign_rhs1 (stmt); + if (get_strub_mode_from_type (TREE_TYPE (rhs)) + != STRUB_DISABLED) + return true; + } + + return false; +} + +/* Return TRUE iff node is associated with a builtin that should be callable + from strub contexts. */ + +static inline bool +strub_callable_builtin_p (cgraph_node *node) +{ + if (DECL_BUILT_IN_CLASS (node->decl) != BUILT_IN_NORMAL) + return false; + + enum built_in_function fcode = DECL_FUNCTION_CODE (node->decl); + + switch (fcode) + { + case BUILT_IN_NONE: + gcc_unreachable (); + + /* This temporarily allocates stack for the call, and we can't reasonably + update the watermark for that. Besides, we don't check the actual call + target, nor its signature, and it seems to be overkill to as much as + try to do so. */ + case BUILT_IN_APPLY: + return false; + + /* Conversely, this shouldn't be called from within strub contexts, since + the caller may have had its signature modified. STRUB_INTERNAL is ok, + the call will remain in the STRUB_WRAPPER, and removed from the + STRUB_WRAPPED clone. */ + case BUILT_IN_APPLY_ARGS: + return false; + + /* ??? Make all other builtins callable. We wish to make any builtin call + the compiler might introduce on its own callable. Anything that is + predictable enough as to be known not to allow stack data that should + be strubbed to unintentionally escape to non-strub contexts can be + allowed, and pretty much every builtin appears to fit this description. + The exceptions to this rule seem to be rare, and only available as + explicit __builtin calls, so let's keep it simple and allow all of + them... */ + default: + return true; + } +} + +/* Compute the strub mode to be used for NODE. STRUB_ATTR should be the strub + attribute,found for NODE, if any. */ + +static enum strub_mode +compute_strub_mode (cgraph_node *node, tree strub_attr) +{ + enum strub_mode req_mode = get_strub_mode_from_attr (strub_attr); + + gcc_checking_assert (flag_strub >= -2 && flag_strub <= 3); + + /* Symbolic encodings of the -fstrub-* flags. */ + /* Enable strub when explicitly requested through attributes to functions or + variables, reporting errors if the requests cannot be satisfied. */ + const bool strub_flag_auto = flag_strub < 0; + /* strub_flag_auto with strub call verification; without this, functions are + implicitly callable. */ + const bool strub_flag_strict = flag_strub < -1; + /* Disable strub altogether, ignore attributes entirely. */ + const bool strub_flag_disabled = flag_strub == 0; + /* On top of _auto, also enable strub implicitly for functions that can + safely undergo at-calls strubbing. Internal mode will still be used in + functions that request it explicitly with attribute strub(2), or when the + function body requires strubbing and at-calls strubbing is not viable. */ + const bool strub_flag_at_calls = flag_strub == 1; + /* On top of default, also enable strub implicitly for functions that can + safely undergo internal strubbing. At-calls mode will still be used in + functions that requiest it explicitly with attribute strub() or strub(1), + or when the function body requires strubbing and internal strubbing is not + viable. */ + const bool strub_flag_internal = flag_strub == 2; + /* On top of default, also enable strub implicitly for functions that can + safely undergo strubbing in either mode. When both modes are viable, + at-calls is preferred. */ + const bool strub_flag_either = flag_strub == 3; + /* Besides the default behavior, enable strub implicitly for all viable + functions. */ + const bool strub_flag_viable = flag_strub > 0; + + /* The consider_* variables should be TRUE if selecting the corresponding + strub modes would be consistent with requests from attributes and command + line flags. Attributes associated with functions pretty much mandate a + selection, and should report an error if not satisfied; strub_flag_auto + implicitly enables some viable strub mode if that's required by references + to variables marked for strub; strub_flag_viable enables strub if viable + (even when favoring one mode, body-requested strub can still be satisfied + by either mode), and falls back to callable, silently unless variables + require strubbing. */ + + const bool consider_at_calls + = (!strub_flag_disabled + && (strub_attr + ? req_mode == STRUB_AT_CALLS + : true)); + const bool consider_internal + = (!strub_flag_disabled + && (strub_attr + ? req_mode == STRUB_INTERNAL + : true)); + + const bool consider_callable + = (!strub_flag_disabled + && (strub_attr + ? req_mode == STRUB_CALLABLE + : (!strub_flag_strict + || strub_callable_builtin_p (node)))); + + /* This is a shorthand for either strub-enabled mode. */ + const bool consider_strub + = (consider_at_calls || consider_internal); + + /* We can cope with always_inline functions even with noipa and noclone, + because we just leave them alone. */ + const bool is_always_inline + = strub_always_inline_p (node); + + /* Strubbing in general, and each specific strub mode, may have its own set of + requirements. We require noipa for strubbing, either because of cloning + required for internal strub, or because of caller enumeration required for + at-calls strub. We don't consider the at-calls mode eligible if it's not + even considered, it has no further requirements. Internal mode requires + cloning and the absence of certain features in the body and, like at-calls, + it's not eligible if it's not even under consideration. + + ??? Do we need target hooks for further constraints? E.g., x86's + "interrupt" attribute breaks internal strubbing because the wrapped clone + carries the attribute and thus isn't callable; in this case, we could use a + target hook to adjust the clone instead. */ + const bool strub_eligible + = (consider_strub + && (is_always_inline || can_strub_p (node))); + const bool at_calls_eligible + = (consider_at_calls && strub_eligible + && can_strub_at_calls_p (node)); + const bool internal_eligible + = (consider_internal && strub_eligible + && (is_always_inline + || can_strub_internally_p (node))); + + /* In addition to the strict eligibility requirements, some additional + constraints are placed on implicit selection of certain modes. These do + not prevent the selection of a mode if explicitly specified as part of a + function interface (the strub attribute), but they may prevent modes from + being selected by the command line or by function bodies. The only actual + constraint is on at-calls mode: since we change the function's exposed + signature, we won't do it implicitly if the function can possibly be used + in ways that do not expect the signature change, e.g., if the function is + available to or interposable by other units, if its address is taken, + etc. */ + const bool at_calls_viable + = (at_calls_eligible + && (strub_attr + || (node->has_gimple_body_p () + && (!node->externally_visible + || (node->binds_to_current_def_p () + && node->can_be_local_p ())) + && node->only_called_directly_p () + && !called_with_type_override_p (node)))); + const bool internal_viable + = (internal_eligible); + + /* Shorthand. */ + const bool strub_viable + = (at_calls_viable || internal_viable); + + /* We wish to analyze the body, to look for implicit requests for strub, both + to implicitly enable it when the body calls for it, and to report errors if + the body calls for it but neither mode is viable (even if that follows from + non-eligibility because of the explicit specification of some non-strubbing + mode). We can refrain from scanning the body only in rare circumstances: + when strub is enabled by a function attribute (scanning might be redundant + in telling us to also enable it), and when we are enabling strub implicitly + but there are non-viable modes: we want to know whether strubbing is + required, to fallback to another mode, even if we're only enabling a + certain mode, or, when either mode would do, to report an error if neither + happens to be viable. */ + const bool analyze_body + = (strub_attr + ? !consider_strub + : (strub_flag_auto + || (strub_flag_viable && (!at_calls_viable && !internal_viable)) + || (strub_flag_either && !strub_viable))); + + /* Cases in which strubbing is enabled or disabled by strub_flag_auto. + Unsatisfiable requests ought to be reported. */ + const bool strub_required + = ((strub_attr && consider_strub) + || (analyze_body && strub_from_body_p (node))); + + /* Besides the required cases, we want to abide by the requests to enabling on + an if-viable basis. */ + const bool strub_enable + = (strub_required + || (strub_flag_at_calls && at_calls_viable) + || (strub_flag_internal && internal_viable) + || (strub_flag_either && strub_viable)); + + /* And now we're finally ready to select a mode that abides by the viability + and eligibility constraints, and that satisfies the strubbing requirements + and requests, subject to the constraints. If both modes are viable and + strub is to be enabled, pick STRUB_AT_CALLS unless STRUB_INTERNAL was named + as preferred. */ + const enum strub_mode mode + = ((strub_enable && is_always_inline) + ? (strub_required ? STRUB_INLINABLE : STRUB_CALLABLE) + : (strub_enable && internal_viable + && (strub_flag_internal || !at_calls_viable)) + ? STRUB_INTERNAL + : (strub_enable && at_calls_viable) + ? (strub_required && !strub_attr + ? STRUB_AT_CALLS_OPT + : STRUB_AT_CALLS) + : consider_callable + ? STRUB_CALLABLE + : STRUB_DISABLED); + + switch (mode) + { + case STRUB_CALLABLE: + if (is_always_inline) + break; + /* Fall through. */ + + case STRUB_DISABLED: + if (strub_enable && !strub_attr) + { + gcc_checking_assert (analyze_body); + error_at (DECL_SOURCE_LOCATION (node->decl), + "%qD requires %<strub%>," + " but no viable %<strub%> mode was found", + node->decl); + break; + } + /* Fall through. */ + + case STRUB_AT_CALLS: + case STRUB_INTERNAL: + case STRUB_INLINABLE: + /* Differences from an mode requested through a function attribute are + reported in set_strub_mode_to. */ + break; + + case STRUB_AT_CALLS_OPT: + /* Functions that select this mode do so because of references to strub + variables. Even if we choose at-calls as an optimization, the + requirements for internal strub must still be satisfied. Optimization + options may render implicit at-calls strub not viable (-O0 sets + force_output for static non-inline functions), and it would not be good + if changing optimization options turned a well-formed into an + ill-formed one. */ + if (!internal_viable) + can_strub_internally_p (node, true); + break; + + case STRUB_WRAPPED: + case STRUB_WRAPPER: + default: + gcc_unreachable (); + } + + return mode; +} + +/* Set FNDT's strub mode to MODE; FNDT may be a function decl or + function type. If OVERRIDE, do not check whether a mode is already + set. */ + +static void +strub_set_fndt_mode_to (tree fndt, enum strub_mode mode, bool override) +{ + gcc_checking_assert (override + || !(DECL_P (fndt) + ? get_strub_attr_from_decl (fndt) + : get_strub_attr_from_type (fndt))); + + tree attr = tree_cons (get_identifier ("strub"), + get_strub_mode_attr_value (mode), + NULL_TREE); + tree *attrp = NULL; + if (DECL_P (fndt)) + { + gcc_checking_assert (FUNC_OR_METHOD_TYPE_P (TREE_TYPE (fndt))); + attrp = &DECL_ATTRIBUTES (fndt); + } + else if (FUNC_OR_METHOD_TYPE_P (fndt)) + attrp = &TYPE_ATTRIBUTES (fndt); + else + gcc_unreachable (); + + TREE_CHAIN (attr) = *attrp; + *attrp = attr; +} + +/* Set FNDT's strub mode to callable. + FNDT may be a function decl or a function type. */ + +void +strub_make_callable (tree fndt) +{ + strub_set_fndt_mode_to (fndt, STRUB_CALLABLE, false); +} + +/* Set NODE to strub MODE. Report incompatibilities between MODE and the mode + requested through explicit attributes, and cases of non-eligibility. */ + +static void +set_strub_mode_to (cgraph_node *node, enum strub_mode mode) +{ + tree attr = get_strub_attr_from_decl (node->decl); + enum strub_mode req_mode = get_strub_mode_from_attr (attr); + + if (attr) + { + /* Check for and report incompatible mode changes. */ + if (mode != req_mode + && !(req_mode == STRUB_INTERNAL + && (mode == STRUB_WRAPPED + || mode == STRUB_WRAPPER)) + && !((req_mode == STRUB_INTERNAL + || req_mode == STRUB_AT_CALLS + || req_mode == STRUB_CALLABLE) + && mode == STRUB_INLINABLE)) + { + error_at (DECL_SOURCE_LOCATION (node->decl), + "%<strub%> mode %qE selected for %qD, when %qE was requested", + get_strub_mode_attr_parm (mode), + node->decl, + get_strub_mode_attr_parm (req_mode)); + if (node->alias) + { + cgraph_node *target = node->ultimate_alias_target (); + if (target != node) + error_at (DECL_SOURCE_LOCATION (target->decl), + "the incompatible selection was determined" + " by ultimate alias target %qD", + target->decl); + } + + /* Report any incompatibilities with explicitly-requested strub. */ + switch (req_mode) + { + case STRUB_AT_CALLS: + can_strub_at_calls_p (node, true); + break; + + case STRUB_INTERNAL: + can_strub_internally_p (node, true); + break; + + default: + break; + } + } + + /* Drop any incompatible strub attributes leading the decl attribute + chain. Return if we find one with the mode we need. */ + for (;;) + { + if (mode == req_mode) + return; + + if (DECL_ATTRIBUTES (node->decl) != attr) + break; + + DECL_ATTRIBUTES (node->decl) = TREE_CHAIN (attr); + attr = get_strub_attr_from_decl (node->decl); + if (!attr) + break; + + req_mode = get_strub_mode_from_attr (attr); + } + } + else if (mode == req_mode) + return; + + strub_set_fndt_mode_to (node->decl, mode, attr); +} + +/* Compute and set NODE's strub mode. */ + +static void +set_strub_mode (cgraph_node *node) +{ + tree attr = get_strub_attr_from_decl (node->decl); + + if (attr) + switch (get_strub_mode_from_attr (attr)) + { + /* These can't have been requested through user attributes, so we must + have already gone through them. */ + case STRUB_WRAPPER: + case STRUB_WRAPPED: + case STRUB_INLINABLE: + case STRUB_AT_CALLS_OPT: + return; + + case STRUB_DISABLED: + case STRUB_AT_CALLS: + case STRUB_INTERNAL: + case STRUB_CALLABLE: + break; + + default: + gcc_unreachable (); + } + + cgraph_node *xnode = node; + if (node->alias) + xnode = node->ultimate_alias_target (); + /* Weakrefs may remain unresolved (the above will return node) if + their targets are not defined, so make sure we compute a strub + mode for them, instead of defaulting to STRUB_DISABLED and + rendering them uncallable. */ + enum strub_mode mode = (xnode != node && !xnode->alias + ? get_strub_mode (xnode) + : compute_strub_mode (node, attr)); + + set_strub_mode_to (node, mode); +} + + +/* Non-strub functions shouldn't be called from within strub contexts, + except through callable ones. Always inline strub functions can + only be called from strub functions. */ + +static bool +strub_callable_from_p (strub_mode caller_mode, strub_mode callee_mode) +{ + switch (caller_mode) + { + case STRUB_WRAPPED: + case STRUB_AT_CALLS_OPT: + case STRUB_AT_CALLS: + case STRUB_INTERNAL: + case STRUB_INLINABLE: + break; + + case STRUB_WRAPPER: + case STRUB_DISABLED: + case STRUB_CALLABLE: + return callee_mode != STRUB_INLINABLE; + + default: + gcc_unreachable (); + } + + switch (callee_mode) + { + case STRUB_WRAPPED: + case STRUB_AT_CALLS: + case STRUB_INLINABLE: + break; + + case STRUB_AT_CALLS_OPT: + case STRUB_INTERNAL: + case STRUB_WRAPPER: + return (flag_strub >= -1); + + case STRUB_DISABLED: + return false; + + case STRUB_CALLABLE: + break; + + default: + gcc_unreachable (); + } + + return true; +} + +/* Return TRUE iff CALLEE can be inlined into CALLER. We wish to avoid inlining + WRAPPED functions back into their WRAPPERs. More generally, we wish to avoid + inlining strubbed functions into non-strubbed ones. CALLER doesn't have to + be an immediate caller of CALLEE: the immediate caller may have already been + cloned for inlining, and then CALLER may be further up the original call + chain. ??? It would be nice if our own caller would retry inlining callee + if caller gets inlined. */ + +bool +strub_inlinable_to_p (cgraph_node *callee, cgraph_node *caller) +{ + strub_mode callee_mode = get_strub_mode (callee); + + switch (callee_mode) + { + case STRUB_WRAPPED: + case STRUB_AT_CALLS: + case STRUB_INTERNAL: + case STRUB_INLINABLE: + case STRUB_AT_CALLS_OPT: + break; + + case STRUB_WRAPPER: + case STRUB_DISABLED: + case STRUB_CALLABLE: + /* When we consider inlining, we've already verified callability, so we + can even inline callable and then disabled into a strub context. That + will get strubbed along with the context, so it's hopefully not a + problem. */ + return true; + + default: + gcc_unreachable (); + } + + strub_mode caller_mode = get_strub_mode (caller); + + switch (caller_mode) + { + case STRUB_WRAPPED: + case STRUB_AT_CALLS: + case STRUB_INTERNAL: + case STRUB_INLINABLE: + case STRUB_AT_CALLS_OPT: + return true; + + case STRUB_WRAPPER: + case STRUB_DISABLED: + case STRUB_CALLABLE: + break; + + default: + gcc_unreachable (); + } + + return false; +} + +/* Check that types T1 and T2 are strub-compatible. Return 1 if the strub modes + are the same, 2 if they are interchangeable, and 0 otherwise. */ + +int +strub_comptypes (tree t1, tree t2) +{ + if (TREE_CODE (t1) != TREE_CODE (t2)) + return 0; + + enum strub_mode m1 = get_strub_mode_from_type (t1); + enum strub_mode m2 = get_strub_mode_from_type (t2); + + if (m1 == m2) + return 1; + + /* We're dealing with types, so only strub modes that can be selected by + attributes in the front end matter. If either mode is at-calls (for + functions) or internal (for variables), the conversion is not + compatible. */ + bool var_p = !FUNC_OR_METHOD_TYPE_P (t1); + enum strub_mode mr = var_p ? STRUB_INTERNAL : STRUB_AT_CALLS; + if (m1 == mr || m2 == mr) + return 0; + + return 2; +} + +/* Return the effective strub mode used for CALL, and set *TYPEP to + the effective type used for the call. The effective type and mode + are those of the callee, unless the call involves a typecast. */ + +static enum strub_mode +effective_strub_mode_for_call (gcall *call, tree *typep) +{ + tree type; + enum strub_mode mode; + + if (strub_call_fntype_override_p (call)) + { + type = gimple_call_fntype (call); + mode = get_strub_mode_from_type (type); + } + else + { + type = TREE_TYPE (TREE_TYPE (gimple_call_fn (call))); + tree decl = gimple_call_fndecl (call); + if (decl) + mode = get_strub_mode_from_fndecl (decl); + else + mode = get_strub_mode_from_type (type); + } + + if (typep) + *typep = type; + + return mode; +} + +/* Create a distinct copy of the type of NODE's function, and change + the fntype of all calls to it with the same main type to the new + type. */ + +static void +distinctify_node_type (cgraph_node *node) +{ + tree old_type = TREE_TYPE (node->decl); + tree new_type = build_distinct_type_copy (old_type); + tree new_ptr_type = NULL_TREE; + + /* Remap any calls to node->decl that use old_type, or a variant + thereof, to new_type as well. We don't look for aliases, their + declarations will have their types changed independently, and + we'll adjust their fntypes then. */ + for (cgraph_edge *e = node->callers; e; e = e->next_caller) + { + if (!e->call_stmt) + continue; + tree fnaddr = gimple_call_fn (e->call_stmt); + gcc_checking_assert (TREE_CODE (fnaddr) == ADDR_EXPR + && TREE_OPERAND (fnaddr, 0) == node->decl); + if (strub_call_fntype_override_p (e->call_stmt)) + continue; + if (!new_ptr_type) + new_ptr_type = build_pointer_type (new_type); + TREE_TYPE (fnaddr) = new_ptr_type; + gimple_call_set_fntype (e->call_stmt, new_type); + } + + TREE_TYPE (node->decl) = new_type; +} + +/* Return TRUE iff TYPE and any variants have the same strub mode. */ + +static bool +same_strub_mode_in_variants_p (tree type) +{ + enum strub_mode mode = get_strub_mode_from_type (type); + + for (tree other = TYPE_MAIN_VARIANT (type); + other != NULL_TREE; other = TYPE_NEXT_VARIANT (other)) + if (type != other && mode != get_strub_mode_from_type (other)) + return false; + + /* Check that the canonical type, if set, either is in the same + variant chain, or has the same strub mode as type. Also check + the variants of the canonical type. */ + if (TYPE_CANONICAL (type) + && (TYPE_MAIN_VARIANT (TYPE_CANONICAL (type)) + != TYPE_MAIN_VARIANT (type))) + { + if (mode != get_strub_mode_from_type (TYPE_CANONICAL (type))) + return false; + else + return same_strub_mode_in_variants_p (TYPE_CANONICAL (type)); + } + + return true; +} + +/* Check that strub functions don't call non-strub functions, and that + always_inline strub functions are only called by strub + functions. */ + +static void +verify_strub () +{ + cgraph_node *node; + + /* It's expected that check strub-wise pointer type compatibility of variables + and of functions is already taken care of by front-ends, on account of the + attribute's being marked as affecting type identity and of the creation of + distinct types. */ + + /* Check that call targets in strub contexts have strub-callable types. */ + + FOR_EACH_FUNCTION_WITH_GIMPLE_BODY (node) + { + enum strub_mode caller_mode = get_strub_mode (node); + + for (cgraph_edge *e = node->indirect_calls; e; e = e->next_callee) + { + gcc_checking_assert (e->indirect_unknown_callee); + + if (!e->call_stmt) + continue; + + enum strub_mode callee_mode + = effective_strub_mode_for_call (e->call_stmt, NULL); + + if (!strub_callable_from_p (caller_mode, callee_mode)) + error_at (gimple_location (e->call_stmt), + "indirect non-%<strub%> call in %<strub%> context %qD", + node->decl); + } + + for (cgraph_edge *e = node->callees; e; e = e->next_callee) + { + gcc_checking_assert (!e->indirect_unknown_callee); + + if (!e->call_stmt) + continue; + + tree callee_fntype; + enum strub_mode callee_mode + = effective_strub_mode_for_call (e->call_stmt, &callee_fntype); + + if (!strub_callable_from_p (caller_mode, callee_mode)) + { + if (callee_mode == STRUB_INLINABLE) + error_at (gimple_location (e->call_stmt), + "calling %<always_inline%> %<strub%> %qD" + " in non-%<strub%> context %qD", + e->callee->decl, node->decl); + else if (fndecl_built_in_p (e->callee->decl, BUILT_IN_APPLY_ARGS) + && caller_mode == STRUB_INTERNAL) + /* This is ok, it will be kept in the STRUB_WRAPPER, and removed + from the STRUB_WRAPPED's strub context. */ + continue; + else if (!strub_call_fntype_override_p (e->call_stmt)) + error_at (gimple_location (e->call_stmt), + "calling non-%<strub%> %qD in %<strub%> context %qD", + e->callee->decl, node->decl); + else + error_at (gimple_location (e->call_stmt), + "calling %qD using non-%<strub%> type %qT" + " in %<strub%> context %qD", + e->callee->decl, callee_fntype, node->decl); + } + } + } +} + +namespace { + +/* Define a pass to compute strub modes. */ +const pass_data pass_data_ipa_strub_mode = { + SIMPLE_IPA_PASS, + "strubm", + OPTGROUP_NONE, + TV_NONE, + PROP_cfg, // properties_required + 0, // properties_provided + 0, // properties_destroyed + 0, // properties_start + 0, // properties_finish +}; + +class pass_ipa_strub_mode : public simple_ipa_opt_pass +{ +public: + pass_ipa_strub_mode (gcc::context *ctxt) + : simple_ipa_opt_pass (pass_data_ipa_strub_mode, ctxt) + {} + opt_pass *clone () { return new pass_ipa_strub_mode (m_ctxt); } + virtual bool gate (function *) { + /* In relaxed (-3) and strict (-4) settings, that only enable strub at a + function or variable attribute's request, the attribute handler changes + flag_strub to -1 or -2, respectively, if any strub-enabling occurence of + the attribute is found. Therefore, if it remains at -3 or -4, nothing + that would enable strub was found, so we can disable it and avoid the + overhead. */ + if (flag_strub < -2) + flag_strub = 0; + return flag_strub; + } + virtual unsigned int execute (function *); +}; + +/* Define a pass to introduce strub transformations. */ +const pass_data pass_data_ipa_strub = { + SIMPLE_IPA_PASS, + "strub", + OPTGROUP_NONE, + TV_NONE, + PROP_cfg | PROP_ssa, // properties_required + 0, // properties_provided + 0, // properties_destroyed + 0, // properties_start + TODO_update_ssa + | TODO_cleanup_cfg + | TODO_rebuild_cgraph_edges + | TODO_verify_il, // properties_finish +}; + +class pass_ipa_strub : public simple_ipa_opt_pass +{ +public: + pass_ipa_strub (gcc::context *ctxt) + : simple_ipa_opt_pass (pass_data_ipa_strub, ctxt) + {} + opt_pass *clone () { return new pass_ipa_strub (m_ctxt); } + virtual bool gate (function *) { return flag_strub && !seen_error (); } + virtual unsigned int execute (function *); + + /* Define on demand and cache some types we use often. */ +#define DEF_TYPE(IDX, NAME, INIT) \ + static inline tree get_ ## NAME () { \ + int idx = STRUB_TYPE_BASE + IDX; \ + static tree type = strub_cache[idx]; \ + if (!type) \ + strub_cache[idx] = type = (INIT); \ + return type; \ + } + + /* Use a distinct ptr_type_node to denote the watermark, so that we can + recognize it in arg lists and avoid modifying types twice. */ + DEF_TYPE (0, wmt, build_variant_type_copy (ptr_type_node)) + + DEF_TYPE (1, pwmt, build_reference_type (get_wmt ())) + + DEF_TYPE (2, qpwmt, + build_qualified_type (get_pwmt (), + TYPE_QUAL_RESTRICT + /* | TYPE_QUAL_CONST */)) + + DEF_TYPE (3, qptr, + build_qualified_type (ptr_type_node, + TYPE_QUAL_RESTRICT + | TYPE_QUAL_CONST)) + + DEF_TYPE (4, qpvalst, + build_qualified_type (build_reference_type + (va_list_type_node), + TYPE_QUAL_RESTRICT + /* | TYPE_QUAL_CONST */)) + +#undef DEF_TYPE + + /* Define non-strub builtins on demand. */ +#define DEF_NM_BUILTIN(NAME, CODE, FNTYPELIST) \ + static tree get_ ## NAME () { \ + tree decl = builtin_decl_explicit (CODE); \ + if (!decl) \ + { \ + tree type = build_function_type_list FNTYPELIST; \ + decl = add_builtin_function \ + ("__builtin_" #NAME, \ + type, CODE, BUILT_IN_NORMAL, \ + NULL, NULL); \ + TREE_NOTHROW (decl) = true; \ + set_builtin_decl ((CODE), decl, true); \ + } \ + return decl; \ + } + + DEF_NM_BUILTIN (stack_address, + BUILT_IN_STACK_ADDRESS, + (ptr_type_node, NULL)) + +#undef DEF_NM_BUILTIN + + /* Define strub builtins on demand. */ +#define DEF_SS_BUILTIN(NAME, FNSPEC, CODE, FNTYPELIST) \ + static tree get_ ## NAME () { \ + tree decl = builtin_decl_explicit (CODE); \ + if (!decl) \ + { \ + tree type = build_function_type_list FNTYPELIST; \ + tree attrs = NULL; \ + if (FNSPEC) \ + attrs = tree_cons (get_identifier ("fn spec"), \ + build_tree_list \ + (NULL_TREE, \ + build_string (strlen (FNSPEC), \ + (FNSPEC))), \ + attrs); \ + decl = add_builtin_function_ext_scope \ + ("__builtin___strub_" #NAME, \ + type, CODE, BUILT_IN_NORMAL, \ + "__strub_" #NAME, attrs); \ + TREE_NOTHROW (decl) = true; \ + set_builtin_decl ((CODE), decl, true); \ + } \ + return decl; \ + } + + DEF_SS_BUILTIN (enter, ". Ot", + BUILT_IN___STRUB_ENTER, + (void_type_node, get_qpwmt (), NULL)) + DEF_SS_BUILTIN (update, ". Wt", + BUILT_IN___STRUB_UPDATE, + (void_type_node, get_qpwmt (), NULL)) + DEF_SS_BUILTIN (leave, ". w ", + BUILT_IN___STRUB_LEAVE, + (void_type_node, get_qpwmt (), NULL)) + +#undef DEF_SS_BUILTIN + + /* Define strub identifiers on demand. */ +#define DEF_IDENT(IDX, NAME) \ + static inline tree get_ ## NAME () { \ + int idx = STRUB_IDENT_BASE + IDX; \ + tree identifier = strub_cache[idx]; \ + if (!identifier) \ + strub_cache[idx] = identifier = get_identifier (".strub." #NAME); \ + return identifier; \ + } + + DEF_IDENT (0, watermark_ptr) + DEF_IDENT (1, va_list_ptr) + DEF_IDENT (2, apply_args) + +#undef DEF_IDENT + + static inline int adjust_at_calls_type (tree); + static inline void adjust_at_calls_call (cgraph_edge *, int, tree); + static inline void adjust_at_calls_calls (cgraph_node *); + + /* Add to SEQ a call to the strub watermark update builtin, taking NODE's + location if given. Optionally add the corresponding edge from NODE, with + execution frequency COUNT. Return the modified SEQ. */ + + static inline gimple_seq + call_update_watermark (tree wmptr, cgraph_node *node, profile_count count, + gimple_seq seq = NULL) + { + tree uwm = get_update (); + gcall *update = gimple_build_call (uwm, 1, wmptr); + if (node) + gimple_set_location (update, DECL_SOURCE_LOCATION (node->decl)); + gimple_seq_add_stmt (&seq, update); + if (node) + node->create_edge (cgraph_node::get_create (uwm), update, count, false); + return seq; + } + +}; + +} // anon namespace + +/* Gather with this type a collection of parameters that we're turning into + explicit references. */ + +typedef hash_set<tree> indirect_parms_t; + +/* Dereference OP's incoming turned-into-reference parm if it's an + INDIRECT_PARMS or an ADDR_EXPR thereof. Set *REC and return according to + gimple-walking expectations. */ + +static tree +maybe_make_indirect (indirect_parms_t &indirect_parms, tree op, int *rec) +{ + if (DECL_P (op)) + { + *rec = 0; + if (indirect_parms.contains (op)) + { + tree ret = gimple_fold_indirect_ref (op); + if (!ret) + ret = build2 (MEM_REF, + TREE_TYPE (TREE_TYPE (op)), + op, + build_int_cst (TREE_TYPE (op), 0)); + return ret; + } + } + else if (TREE_CODE (op) == ADDR_EXPR + && DECL_P (TREE_OPERAND (op, 0))) + { + *rec = 0; + if (indirect_parms.contains (TREE_OPERAND (op, 0))) + { + op = TREE_OPERAND (op, 0); + return op; + } + } + + return NULL_TREE; +} + +/* A gimple-walking function that adds dereferencing to indirect parms. */ + +static tree +walk_make_indirect (tree *op, int *rec, void *arg) +{ + walk_stmt_info *wi = (walk_stmt_info *)arg; + indirect_parms_t &indirect_parms = *(indirect_parms_t *)wi->info; + + if (!*op || TYPE_P (*op)) + { + *rec = 0; + return NULL_TREE; + } + + if (tree repl = maybe_make_indirect (indirect_parms, *op, rec)) + { + *op = repl; + wi->changed = true; + } + + return NULL_TREE; +} + +/* A gimple-walking function that turns any non-gimple-val ADDR_EXPRs into a + separate SSA. Though addresses of e.g. parameters, and of members thereof, + are gimple vals, turning parameters into references, with an extra layer of + indirection and thus explicit dereferencing, need to be regimplified. */ + +static tree +walk_regimplify_addr_expr (tree *op, int *rec, void *arg) +{ + walk_stmt_info *wi = (walk_stmt_info *)arg; + gimple_stmt_iterator &gsi = *(gimple_stmt_iterator *)wi->info; + + *rec = 0; + + if (!*op || TREE_CODE (*op) != ADDR_EXPR) + return NULL_TREE; + + if (!is_gimple_val (*op)) + { + tree ret = force_gimple_operand_gsi (&gsi, *op, true, + NULL_TREE, true, GSI_SAME_STMT); + gcc_assert (ret != *op); + *op = ret; + wi->changed = true; + } + + return NULL_TREE; +} + +/* Turn STMT's PHI arg defs into separate SSA defs if they've become + non-gimple_val. Return TRUE if any edge insertions need to be committed. */ + +static bool +walk_regimplify_phi (gphi *stmt) +{ + bool needs_commit = false; + + for (unsigned i = 0, n = gimple_phi_num_args (stmt); i < n; i++) + { + tree op = gimple_phi_arg_def (stmt, i); + if ((TREE_CODE (op) == ADDR_EXPR + && !is_gimple_val (op)) + /* ??? A PARM_DECL that was addressable in the original function and + had its address in PHI nodes, but that became a reference in the + wrapped clone would NOT be updated by update_ssa in PHI nodes. + Alas, if we were to create a default def for it now, update_ssa + would complain that the symbol that needed rewriting already has + SSA names associated with it. OTOH, leaving the PARM_DECL alone, + it eventually causes errors because it remains unchanged in PHI + nodes, but it gets rewritten as expected if it appears in other + stmts. So we cheat a little here, and force the PARM_DECL out of + the PHI node and into an assignment. It's a little expensive, + because we insert it at the edge, which introduces a basic block + that's entirely unnecessary, but it works, and the block will be + removed as the default def gets propagated back into the PHI node, + so the final optimized code looks just as expected. */ + || (TREE_CODE (op) == PARM_DECL + && !TREE_ADDRESSABLE (op))) + { + tree temp = make_ssa_name (TREE_TYPE (op), stmt); + if (TREE_CODE (op) == PARM_DECL) + SET_SSA_NAME_VAR_OR_IDENTIFIER (temp, DECL_NAME (op)); + SET_PHI_ARG_DEF (stmt, i, temp); + + gimple *assign = gimple_build_assign (temp, op); + if (gimple_phi_arg_has_location (stmt, i)) + gimple_set_location (assign, gimple_phi_arg_location (stmt, i)); + gsi_insert_on_edge (gimple_phi_arg_edge (stmt, i), assign); + needs_commit = true; + } + } + + return needs_commit; +} + +/* Create a reference type to use for PARM when turning it into a reference. + NONALIASED causes the reference type to gain its own separate alias set, so + that accessing the indirectly-passed parm won'will not add aliasing + noise. */ + +static tree +build_ref_type_for (tree parm, bool nonaliased = true) +{ + gcc_checking_assert (TREE_CODE (parm) == PARM_DECL); + + tree ref_type = build_reference_type (TREE_TYPE (parm)); + + if (!nonaliased) + return ref_type; + + /* Each PARM turned indirect still points to the distinct memory area at the + wrapper, and the reference in unchanging, so we might qualify it, but... + const is not really important, since we're only using default defs for the + reference parm anyway, and not introducing any defs, and restrict seems to + cause trouble. E.g., libgnat/s-concat3.adb:str_concat_3 has memmoves that, + if it's wrapped, the memmoves are deleted in dse1. Using a distinct alias + set seems to not run afoul of this problem, and it hopefully enables the + compiler to tell the pointers do point to objects that are not otherwise + aliased. */ + tree qref_type = build_variant_type_copy (ref_type); + + TYPE_ALIAS_SET (qref_type) = new_alias_set (); + record_alias_subset (TYPE_ALIAS_SET (qref_type), get_alias_set (ref_type)); + + return qref_type; +} + +/* Add cgraph edges from current_function_decl to callees in SEQ with frequency + COUNT, assuming all calls in SEQ are direct. */ + +static void +add_call_edges_for_seq (gimple_seq seq, profile_count count) +{ + cgraph_node *node = cgraph_node::get_create (current_function_decl); + + for (gimple_stmt_iterator gsi = gsi_start (seq); + !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple *stmt = gsi_stmt (gsi); + + gcall *call = dyn_cast <gcall *> (stmt); + if (!call) + continue; + + tree callee = gimple_call_fndecl (call); + gcc_checking_assert (callee); + node->create_edge (cgraph_node::get_create (callee), call, count, false); + } +} + +/* Insert SEQ after the call at GSI, as if the call was in a try block with SEQ + as finally, i.e., SEQ will run after the call whether it returns or + propagates an exception. This handles block splitting, EH edge and block + creation, noreturn and nothrow optimizations, and even throwing calls without + preexisting local handlers. */ + +static void +gsi_insert_finally_seq_after_call (gimple_stmt_iterator gsi, gimple_seq seq) +{ + if (!seq) + return; + + gimple *stmt = gsi_stmt (gsi); + + if (gimple_has_location (stmt)) + annotate_all_with_location (seq, gimple_location (stmt)); + + gcall *call = dyn_cast <gcall *> (stmt); + bool noreturn_p = call && gimple_call_noreturn_p (call); + int eh_lp = lookup_stmt_eh_lp (stmt); + bool must_not_throw_p = eh_lp < 0; + bool nothrow_p = (must_not_throw_p + || (call && gimple_call_nothrow_p (call)) + || (eh_lp <= 0 + && (TREE_NOTHROW (cfun->decl) + || !flag_exceptions))); + + if (noreturn_p && nothrow_p) + return; + + /* Don't expect an EH edge if we're not to throw, or if we're not in an EH + region yet. */ + bool no_eh_edge_p = (nothrow_p || !eh_lp); + bool must_end_bb = stmt_ends_bb_p (stmt); + + edge eft = NULL, eeh = NULL; + if (must_end_bb && !(noreturn_p && no_eh_edge_p)) + { + gcc_checking_assert (gsi_one_before_end_p (gsi)); + + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, gsi_bb (gsi)->succs) + { + if ((e->flags & EDGE_EH)) + { + gcc_checking_assert (!eeh); + eeh = e; +#if !CHECKING_P + if (eft || noreturn_p) + break; +#endif + } + if ((e->flags & EDGE_FALLTHRU)) + { + gcc_checking_assert (!eft); + eft = e; +#if !CHECKING_P + if (eeh || no_eh_edge_p) + break; +#endif + } + } + + gcc_checking_assert (!(eft && (eft->flags & EDGE_FALLTHRU)) + == noreturn_p); + gcc_checking_assert (!(eeh && (eeh->flags & EDGE_EH)) + == no_eh_edge_p); + gcc_checking_assert (eft != eeh); + } + + if (!noreturn_p) + { + gimple_seq nseq = nothrow_p ? seq : gimple_seq_copy (seq); + + if (must_end_bb) + { + gcc_checking_assert (gsi_one_before_end_p (gsi)); + add_call_edges_for_seq (nseq, eft->count ()); + gsi_insert_seq_on_edge_immediate (eft, nseq); + } + else + { + add_call_edges_for_seq (nseq, gsi_bb (gsi)->count); + gsi_insert_seq_after (&gsi, nseq, GSI_SAME_STMT); + } + } + + if (nothrow_p) + return; + + if (eh_lp) + { + add_call_edges_for_seq (seq, eeh->count ()); + gsi_insert_seq_on_edge_immediate (eeh, seq); + return; + } + + /* A throwing call may appear within a basic block in a function that doesn't + have any EH regions. We're going to add a cleanup if so, therefore the + block will have to be split. */ + basic_block bb = gsi_bb (gsi); + if (!gsi_one_before_end_p (gsi)) + split_block (bb, stmt); + + /* Create a new block for the EH cleanup. */ + basic_block bb_eh_cleanup = create_empty_bb (bb); + if (dom_info_available_p (CDI_DOMINATORS)) + set_immediate_dominator (CDI_DOMINATORS, bb_eh_cleanup, bb); + if (current_loops) + add_bb_to_loop (bb_eh_cleanup, current_loops->tree_root); + + /* Make the new block an EH cleanup for the call. */ + eh_region new_r = gen_eh_region_cleanup (NULL); + eh_landing_pad lp = gen_eh_landing_pad (new_r); + tree label = gimple_block_label (bb_eh_cleanup); + lp->post_landing_pad = label; + EH_LANDING_PAD_NR (label) = lp->index; + add_stmt_to_eh_lp (stmt, lp->index); + + /* Add the cleanup code to the EH cleanup block. */ + gsi = gsi_after_labels (bb_eh_cleanup); + gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT); + + /* And then propagate the exception further. */ + gresx *resx = gimple_build_resx (new_r->index); + if (gimple_has_location (stmt)) + gimple_set_location (resx, gimple_location (stmt)); + gsi_insert_before (&gsi, resx, GSI_SAME_STMT); + + /* Finally, wire the EH cleanup block into the CFG. */ + edge neeh = make_eh_edge (stmt); + neeh->probability = profile_probability::never (); + gcc_checking_assert (neeh->dest == bb_eh_cleanup); + gcc_checking_assert (!neeh->dest->count.initialized_p ()); + neeh->dest->count = neeh->count (); + add_call_edges_for_seq (seq, neeh->dest->count); +} + +/* Copy the attribute list at *ATTRS, minus any NAME attributes, leaving + shareable trailing nodes alone. */ + +static inline void +remove_named_attribute_unsharing (const char *name, tree *attrs) +{ + while (tree found = lookup_attribute (name, *attrs)) + { + /* Copy nodes up to the next NAME attribute. */ + while (*attrs != found) + { + *attrs = tree_cons (TREE_PURPOSE (*attrs), + TREE_VALUE (*attrs), + TREE_CHAIN (*attrs)); + attrs = &TREE_CHAIN (*attrs); + } + /* Then drop it. */ + gcc_checking_assert (*attrs == found); + *attrs = TREE_CHAIN (*attrs); + } +} + +/* Record the order of the last cgraph entry whose mode we've already set, so + that we can perform mode setting incrementally without duplication. */ +static int last_cgraph_order; + +/* Set strub modes for functions introduced since the last call. */ + +static void +ipa_strub_set_mode_for_new_functions () +{ + if (symtab->order == last_cgraph_order) + return; + + cgraph_node *node; + + /* Go through the functions twice, once over non-aliases, and then over + aliases, so that aliases can reuse the mode computation of their ultimate + targets. */ + for (int aliases = 0; aliases <= 1; aliases++) + FOR_EACH_FUNCTION (node) + { + if (!node->alias != !aliases) + continue; + + /* Already done. */ + if (node->order < last_cgraph_order) + continue; + + set_strub_mode (node); + } + + last_cgraph_order = symtab->order; +} + +/* Return FALSE if NODE is a strub context, and TRUE otherwise. */ + +bool +strub_splittable_p (cgraph_node *node) +{ + switch (get_strub_mode (node)) + { + case STRUB_WRAPPED: + case STRUB_AT_CALLS: + case STRUB_AT_CALLS_OPT: + case STRUB_INLINABLE: + case STRUB_INTERNAL: + case STRUB_WRAPPER: + return false; + + case STRUB_CALLABLE: + case STRUB_DISABLED: + break; + + default: + gcc_unreachable (); + } + + return true; +} + +/* Return the PARM_DECL of the incoming watermark pointer, if there is one. */ + +tree +strub_watermark_parm (tree fndecl) +{ + switch (get_strub_mode_from_fndecl (fndecl)) + { + case STRUB_WRAPPED: + case STRUB_AT_CALLS: + case STRUB_AT_CALLS_OPT: + break; + + case STRUB_INTERNAL: + case STRUB_WRAPPER: + case STRUB_CALLABLE: + case STRUB_DISABLED: + case STRUB_INLINABLE: + return NULL_TREE; + + default: + gcc_unreachable (); + } + + for (tree parm = DECL_ARGUMENTS (fndecl); parm; parm = DECL_CHAIN (parm)) + /* The type (variant) compare finds the parameter even in a just-created + clone, before we set its name, but the type-based compare doesn't work + during builtin expansion within the lto compiler, because we'll have + created a separate variant in that run. */ + if (TREE_TYPE (parm) == pass_ipa_strub::get_qpwmt () + || DECL_NAME (parm) == pass_ipa_strub::get_watermark_ptr ()) + return parm; + + gcc_unreachable (); +} + +/* Adjust a STRUB_AT_CALLS function TYPE, adding a watermark pointer if it + hasn't been added yet. Return the named argument count. */ + +int +pass_ipa_strub::adjust_at_calls_type (tree type) +{ + int named_args = 0; + + gcc_checking_assert (same_strub_mode_in_variants_p (type)); + + if (!TYPE_ARG_TYPES (type)) + return named_args; + + tree *tlist = &TYPE_ARG_TYPES (type); + tree qpwmptrt = get_qpwmt (); + while (*tlist && TREE_VALUE (*tlist) != void_type_node) + { + /* The type has already been adjusted. */ + if (TREE_VALUE (*tlist) == qpwmptrt) + return named_args; + named_args++; + *tlist = tree_cons (TREE_PURPOSE (*tlist), + TREE_VALUE (*tlist), + TREE_CHAIN (*tlist)); + tlist = &TREE_CHAIN (*tlist); + } + + /* Add the new argument after all named arguments, so as to not mess with + attributes that reference parameters. */ + *tlist = tree_cons (NULL_TREE, get_qpwmt (), *tlist); + +#if ATTR_FNSPEC_DECONST_WATERMARK + if (!type_already_adjusted) + { + int flags = flags_from_decl_or_type (type); + tree fnspec = lookup_attribute ("fn spec", type); + + if ((flags & (ECF_CONST | ECF_PURE | ECF_NOVOPS)) || fnspec) + { + size_t xargs = 1; + size_t curlen = 0, tgtlen = 2 + 2 * (named_args + xargs); + auto_vec<char> nspecv (tgtlen); + char *nspec = &nspecv[0]; /* It will *not* be NUL-terminated! */ + if (fnspec) + { + tree fnspecstr = TREE_VALUE (TREE_VALUE (fnspec)); + curlen = TREE_STRING_LENGTH (fnspecstr); + memcpy (nspec, TREE_STRING_POINTER (fnspecstr), curlen); + } + if (!curlen) + { + nspec[curlen++] = '.'; + nspec[curlen++] = ((flags & ECF_CONST) + ? 'c' + : (flags & ECF_PURE) + ? 'p' + : ' '); + } + while (curlen < tgtlen - 2 * xargs) + { + nspec[curlen++] = '.'; + nspec[curlen++] = ' '; + } + nspec[curlen++] = 'W'; + nspec[curlen++] = 't'; + + /* The type has already been copied, if needed, before adding + parameters. */ + TYPE_ATTRIBUTES (type) + = tree_cons (get_identifier ("fn spec"), + build_tree_list (NULL_TREE, + build_string (tgtlen, nspec)), + TYPE_ATTRIBUTES (type)); + } + } +#endif + + return named_args; +} + +/* Adjust a call to an at-calls call target. Create a watermark local variable + if needed, initialize it before, pass it to the callee according to the + modified at-calls interface, and release the callee's stack space after the + call, if not deferred. If the call is const or pure, arrange for the + watermark to not be assumed unused or unchanged. */ + +void +pass_ipa_strub::adjust_at_calls_call (cgraph_edge *e, int named_args, + tree callee_fntype) +{ + gcc_checking_assert (e->call_stmt); + gcall *ocall = e->call_stmt; + gimple_stmt_iterator gsi = gsi_for_stmt (ocall); + + /* Make sure we haven't modified this call yet. */ + gcc_checking_assert (!(int (gimple_call_num_args (ocall)) > named_args + && (TREE_TYPE (gimple_call_arg (ocall, named_args)) + == get_pwmt ()))); + + /* If we're already within a strub context, pass on the incoming watermark + pointer, and omit the enter and leave calls around the modified call, as an + optimization, or as a means to satisfy a tail-call requirement. */ + tree swmp = ((optimize_size || optimize > 2 + || gimple_call_must_tail_p (ocall) + || (optimize == 2 && gimple_call_tail_p (ocall))) + ? strub_watermark_parm (e->caller->decl) + : NULL_TREE); + bool omit_own_watermark = swmp; + tree swm = NULL_TREE; + if (!omit_own_watermark) + { + swm = create_tmp_var (get_wmt (), ".strub.watermark"); + TREE_ADDRESSABLE (swm) = true; + swmp = build1 (ADDR_EXPR, get_pwmt (), swm); + + /* Initialize the watermark before the call. */ + tree enter = get_enter (); + gcall *stptr = gimple_build_call (enter, 1, + unshare_expr (swmp)); + if (gimple_has_location (ocall)) + gimple_set_location (stptr, gimple_location (ocall)); + gsi_insert_before (&gsi, stptr, GSI_SAME_STMT); + e->caller->create_edge (cgraph_node::get_create (enter), + stptr, gsi_bb (gsi)->count, false); + } + + + /* Replace the call with one that passes the swmp argument first. */ + gcall *wrcall; + { gcall *stmt = ocall; + // Mostly copied from gimple_call_copy_skip_args. + int i = 0; + int nargs = gimple_call_num_args (stmt); + auto_vec<tree> vargs (MAX (nargs, named_args) + 1); + gcall *new_stmt; + + /* pr71109.c calls a prototypeless function, then defines it with + additional arguments. It's ill-formed, but after it's inlined, + it somehow works out. */ + for (; i < named_args && i < nargs; i++) + vargs.quick_push (gimple_call_arg (stmt, i)); + for (; i < named_args; i++) + vargs.quick_push (null_pointer_node); + + vargs.quick_push (unshare_expr (swmp)); + + for (; i < nargs; i++) + vargs.quick_push (gimple_call_arg (stmt, i)); + + if (gimple_call_internal_p (stmt)) + gcc_unreachable (); + else + new_stmt = gimple_build_call_vec (gimple_call_fn (stmt), vargs); + gimple_call_set_fntype (new_stmt, callee_fntype); + + if (gimple_call_lhs (stmt)) + gimple_call_set_lhs (new_stmt, gimple_call_lhs (stmt)); + + gimple_move_vops (new_stmt, stmt); + + if (gimple_has_location (stmt)) + gimple_set_location (new_stmt, gimple_location (stmt)); + gimple_call_copy_flags (new_stmt, stmt); + gimple_call_set_chain (new_stmt, gimple_call_chain (stmt)); + + gimple_set_modified (new_stmt, true); + + wrcall = new_stmt; + } + + update_stmt (wrcall); + gsi_replace (&gsi, wrcall, true); + cgraph_edge::set_call_stmt (e, wrcall, false); + + /* Insert the strub code after the call. */ + gimple_seq seq = NULL; + +#if !ATTR_FNSPEC_DECONST_WATERMARK + /* If the call will be assumed to not modify or even read the + watermark, make it read and modified ourselves. */ + if ((gimple_call_flags (wrcall) + & (ECF_CONST | ECF_PURE | ECF_NOVOPS))) + { + if (!swm) + swm = build2 (MEM_REF, + TREE_TYPE (TREE_TYPE (swmp)), + swmp, + build_int_cst (TREE_TYPE (swmp), 0)); + + vec<tree, va_gc> *inputs = NULL; + vec<tree, va_gc> *outputs = NULL; + vec_safe_push (outputs, + build_tree_list + (build_tree_list + (NULL_TREE, build_string (2, "=m")), + unshare_expr (swm))); + vec_safe_push (inputs, + build_tree_list + (build_tree_list + (NULL_TREE, build_string (1, "m")), + unshare_expr (swm))); + gasm *forcemod = gimple_build_asm_vec ("", inputs, outputs, + NULL, NULL); + gimple_seq_add_stmt (&seq, forcemod); + + /* If the call will be assumed to not even read the watermark, + make sure it is already in memory before the call. */ + if ((gimple_call_flags (wrcall) & ECF_CONST)) + { + vec<tree, va_gc> *inputs = NULL; + vec_safe_push (inputs, + build_tree_list + (build_tree_list + (NULL_TREE, build_string (1, "m")), + unshare_expr (swm))); + gasm *force_store = gimple_build_asm_vec ("", inputs, NULL, + NULL, NULL); + if (gimple_has_location (wrcall)) + gimple_set_location (force_store, gimple_location (wrcall)); + gsi_insert_before (&gsi, force_store, GSI_SAME_STMT); + } + } +#endif + + if (!omit_own_watermark) + { + gcall *sleave = gimple_build_call (get_leave (), 1, + unshare_expr (swmp)); + gimple_seq_add_stmt (&seq, sleave); + + gassign *clobber = gimple_build_assign (swm, + build_clobber + (TREE_TYPE (swm))); + gimple_seq_add_stmt (&seq, clobber); + } + + gsi_insert_finally_seq_after_call (gsi, seq); +} + +/* Adjust all at-calls calls in NODE. */ + +void +pass_ipa_strub::adjust_at_calls_calls (cgraph_node *node) +{ + /* Adjust unknown-callee indirect calls with STRUB_AT_CALLS types within + onode. */ + if (node->indirect_calls) + { + push_cfun (DECL_STRUCT_FUNCTION (node->decl)); + for (cgraph_edge *e = node->indirect_calls; e; e = e->next_callee) + { + gcc_checking_assert (e->indirect_unknown_callee); + + if (!e->call_stmt) + continue; + + tree callee_fntype; + enum strub_mode callee_mode + = effective_strub_mode_for_call (e->call_stmt, &callee_fntype); + + if (callee_mode != STRUB_AT_CALLS + && callee_mode != STRUB_AT_CALLS_OPT) + continue; + + int named_args = adjust_at_calls_type (callee_fntype); + + adjust_at_calls_call (e, named_args, callee_fntype); + } + pop_cfun (); + } + + if (node->callees) + { + push_cfun (DECL_STRUCT_FUNCTION (node->decl)); + for (cgraph_edge *e = node->callees; e; e = e->next_callee) + { + gcc_checking_assert (!e->indirect_unknown_callee); + + if (!e->call_stmt) + continue; + + tree callee_fntype; + enum strub_mode callee_mode + = effective_strub_mode_for_call (e->call_stmt, &callee_fntype); + + if (callee_mode != STRUB_AT_CALLS + && callee_mode != STRUB_AT_CALLS_OPT) + continue; + + int named_args = adjust_at_calls_type (callee_fntype); + + adjust_at_calls_call (e, named_args, callee_fntype); + } + pop_cfun (); + } +} + +/* The strubm (strub mode) pass computes a strub mode for each function in the + call graph, and checks, before any inlining, that strub callability + requirements in effect are satisfied. */ + +unsigned int +pass_ipa_strub_mode::execute (function *) +{ + last_cgraph_order = 0; + ipa_strub_set_mode_for_new_functions (); + + /* Verify before any inlining or other transformations. */ + verify_strub (); + + return 0; +} + +/* Create a strub mode pass. */ + +simple_ipa_opt_pass * +make_pass_ipa_strub_mode (gcc::context *ctxt) +{ + return new pass_ipa_strub_mode (ctxt); +} + +/* The strub pass proper adjusts types, signatures, and at-calls calls, and + splits internal-strub functions. */ + +unsigned int +pass_ipa_strub::execute (function *) +{ + cgraph_node *onode; + + ipa_strub_set_mode_for_new_functions (); + + /* First, adjust the signature of at-calls functions. We adjust types of + at-calls functions first, so that we don't modify types in place unless + strub is explicitly requested. */ + FOR_EACH_FUNCTION (onode) + { + enum strub_mode mode = get_strub_mode (onode); + + if (mode == STRUB_AT_CALLS + || mode == STRUB_AT_CALLS_OPT) + { + /* Create a type variant if strubbing was not explicitly requested in + the function type. */ + if (get_strub_mode_from_type (TREE_TYPE (onode->decl)) != mode) + distinctify_node_type (onode); + + int named_args = adjust_at_calls_type (TREE_TYPE (onode->decl)); + + /* An external function explicitly declared with strub won't have a + body. Even with implicit at-calls strub, a function may have had its + body removed after we selected the mode, and then we have nothing + further to do. */ + if (!onode->has_gimple_body_p ()) + continue; + + tree *pargs = &DECL_ARGUMENTS (onode->decl); + + /* A noninterposable_alias reuses the same parm decl chain, don't add + the parm twice. */ + bool aliased_parms = (onode->alias && *pargs + && DECL_CONTEXT (*pargs) != onode->decl); + + if (aliased_parms) + continue; + + for (int i = 0; i < named_args; i++) + pargs = &DECL_CHAIN (*pargs); + + tree wmptr = build_decl (DECL_SOURCE_LOCATION (onode->decl), + PARM_DECL, + get_watermark_ptr (), + get_qpwmt ()); + DECL_ARTIFICIAL (wmptr) = 1; + DECL_ARG_TYPE (wmptr) = get_qpwmt (); + DECL_CONTEXT (wmptr) = onode->decl; + TREE_USED (wmptr) = 1; + DECL_CHAIN (wmptr) = *pargs; + *pargs = wmptr; + + if (onode->alias) + continue; + + cgraph_node *nnode = onode; + push_cfun (DECL_STRUCT_FUNCTION (nnode->decl)); + + { + edge e = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun)); + gimple_seq seq = call_update_watermark (wmptr, nnode, e->src->count); + gsi_insert_seq_on_edge_immediate (e, seq); + } + + if (DECL_STRUCT_FUNCTION (nnode->decl)->calls_alloca) + { + basic_block bb; + FOR_EACH_BB_FN (bb, cfun) + for (gimple_stmt_iterator gsi = gsi_start_bb (bb); + !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple *stmt = gsi_stmt (gsi); + + gcall *call = dyn_cast <gcall *> (stmt); + + if (!call) + continue; + + if (gimple_alloca_call_p (call)) + { + /* Capture stack growth. */ + gimple_seq seq = call_update_watermark (wmptr, NULL, + gsi_bb (gsi) + ->count); + gsi_insert_finally_seq_after_call (gsi, seq); + } + } + } + + pop_cfun (); + } + } + + FOR_EACH_FUNCTION (onode) + { + if (!onode->has_gimple_body_p ()) + continue; + + enum strub_mode mode = get_strub_mode (onode); + + if (mode != STRUB_INTERNAL) + { + adjust_at_calls_calls (onode); + continue; + } + + bool is_stdarg = calls_builtin_va_start_p (onode);; + bool apply_args = calls_builtin_apply_args_p (onode); + + vec<ipa_adjusted_param, va_gc> *nparms = NULL; + unsigned j = 0; + { + // The following loop copied from ipa-split.c:split_function. + for (tree parm = DECL_ARGUMENTS (onode->decl); + parm; parm = DECL_CHAIN (parm), j++) + { + ipa_adjusted_param adj = {}; + adj.op = IPA_PARAM_OP_COPY; + adj.base_index = j; + adj.prev_clone_index = j; + vec_safe_push (nparms, adj); + } + + if (apply_args) + { + ipa_adjusted_param aaadj = {}; + aaadj.op = IPA_PARAM_OP_NEW; + aaadj.type = get_qptr (); + vec_safe_push (nparms, aaadj); + } + + if (is_stdarg) + { + ipa_adjusted_param vladj = {}; + vladj.op = IPA_PARAM_OP_NEW; + vladj.type = get_qpvalst (); + vec_safe_push (nparms, vladj); + } + + ipa_adjusted_param wmadj = {}; + wmadj.op = IPA_PARAM_OP_NEW; + wmadj.type = get_qpwmt (); + vec_safe_push (nparms, wmadj); + } + ipa_param_adjustments adj (nparms, -1, false); + + cgraph_node *nnode = onode->create_version_clone_with_body + (auto_vec<cgraph_edge *> (0), + NULL, &adj, NULL, NULL, "strub", NULL); + + if (!nnode) + { + error_at (DECL_SOURCE_LOCATION (onode->decl), + "failed to split %qD for %<strub%>", + onode->decl); + continue; + } + + onode->split_part = true; + if (onode->calls_comdat_local) + nnode->add_to_same_comdat_group (onode); + + set_strub_mode_to (onode, STRUB_WRAPPER); + set_strub_mode_to (nnode, STRUB_WRAPPED); + + adjust_at_calls_calls (nnode); + + /* Decide which of the wrapped function's parms we want to turn into + references to the argument passed to the wrapper. In general, we want to + copy small arguments, and avoid copying large ones. Variable-sized array + lengths given by other arguments, as in 20020210-1.c, would lead to + problems if passed by value, after resetting the original function and + dropping the length computation; passing them by reference works. + DECL_BY_REFERENCE is *not* a substitute for this: it involves copying + anyway, but performed at the caller. */ + indirect_parms_t indirect_nparms (3, false); + unsigned adjust_ftype = 0; + unsigned named_args = 0; + for (tree parm = DECL_ARGUMENTS (onode->decl), + nparm = DECL_ARGUMENTS (nnode->decl), + nparmt = TYPE_ARG_TYPES (TREE_TYPE (nnode->decl)); + parm; + named_args++, + parm = DECL_CHAIN (parm), + nparm = DECL_CHAIN (nparm), + nparmt = nparmt ? TREE_CHAIN (nparmt) : NULL_TREE) + if (!(0 /* DECL_BY_REFERENCE (narg) */ + || is_gimple_reg_type (TREE_TYPE (nparm)) + || VECTOR_TYPE_P (TREE_TYPE (nparm)) + || TREE_CODE (TREE_TYPE (nparm)) == COMPLEX_TYPE + || (tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (nparm))) + && (tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (nparm))) + <= 4 * UNITS_PER_WORD)))) + { + indirect_nparms.add (nparm); + + /* ??? Is there any case in which it is not safe to suggest the parms + turned indirect don't alias anything else? They are distinct, + unaliased memory in the wrapper, and the wrapped can't possibly + take pointers into them because none of the pointers passed to the + wrapper can alias other incoming parameters passed by value, even + if with transparent reference, and the wrapper doesn't take any + extra parms that could point into wrapper's parms. So we can + probably drop the TREE_ADDRESSABLE and keep the TRUE. */ + tree ref_type = build_ref_type_for (nparm, + true + || !TREE_ADDRESSABLE (parm)); + + DECL_ARG_TYPE (nparm) = TREE_TYPE (nparm) = ref_type; + relayout_decl (nparm); + TREE_ADDRESSABLE (nparm) = 0; + DECL_BY_REFERENCE (nparm) = 0; + DECL_NOT_GIMPLE_REG_P (nparm) = 0; + /* ??? This avoids mismatches in debug info bind stmts in + e.g. a-chahan . */ + DECL_ABSTRACT_ORIGIN (nparm) = NULL; + + if (nparmt) + adjust_ftype++; + } + + /* Also adjust the wrapped function type, if needed. */ + if (adjust_ftype) + { + tree nftype = TREE_TYPE (nnode->decl); + + /* We always add at least one argument at the end of the signature, when + cloning the function, so we don't expect to need to duplicate the + type here. */ + gcc_checking_assert (TYPE_ARG_TYPES (nftype) + != TYPE_ARG_TYPES (TREE_TYPE (onode->decl))); + + /* Check that fnspec still works for the modified function signature, + and drop it otherwise. */ + bool drop_fnspec = false; + tree fnspec = lookup_attribute ("fn spec", TYPE_ATTRIBUTES (nftype)); + attr_fnspec spec = fnspec ? attr_fnspec (fnspec) : attr_fnspec (""); + + unsigned retcopy; + if (!(fnspec && spec.returns_arg (&retcopy))) + retcopy = (unsigned) -1; + + unsigned i = 0; + for (tree nparm = DECL_ARGUMENTS (nnode->decl), + nparmt = TYPE_ARG_TYPES (nftype); + adjust_ftype > 0; + i++, nparm = DECL_CHAIN (nparm), nparmt = TREE_CHAIN (nparmt)) + if (indirect_nparms.contains (nparm)) + { + TREE_VALUE (nparmt) = TREE_TYPE (nparm); + adjust_ftype--; + + if (fnspec && !drop_fnspec) + { + if (i == retcopy) + drop_fnspec = true; + else if (spec.arg_specified_p (i)) + { + /* Properties that apply to pointers only must not be + present, because we don't make pointers further + indirect. */ + gcc_checking_assert + (!spec.arg_max_access_size_given_by_arg_p (i, NULL)); + gcc_checking_assert (!spec.arg_copied_to_arg_p (i, NULL)); + + /* Any claim of direct access only is invalidated by + adding an indirection level. */ + if (spec.arg_direct_p (i)) + drop_fnspec = true; + + /* If there's a claim the argument is not read from, the + added indirection invalidates it: if the argument is + used at all, then the pointer will necessarily be + read. */ + if (!spec.arg_maybe_read_p (i) + && spec.arg_used_p (i)) + drop_fnspec = true; + } + } + } + + /* ??? Maybe we could adjust it instead. */ + if (drop_fnspec) + remove_named_attribute_unsharing ("fn spec", + &TYPE_ATTRIBUTES (nftype)); + + TREE_TYPE (nnode->decl) = nftype; + } + +#if ATTR_FNSPEC_DECONST_WATERMARK + { + int flags = flags_from_decl_or_type (nnode->decl); + tree fnspec = lookup_attribute ("fn spec", TREE_TYPE (nnode->decl)); + + if ((flags & (ECF_CONST | ECF_PURE | ECF_NOVOPS)) || fnspec) + { + size_t xargs = 1 + int (is_stdarg) + int (apply_args); + size_t curlen = 0, tgtlen = 2 + 2 * (named_args + xargs); + auto_vec<char> nspecv (tgtlen); + char *nspec = &nspecv[0]; /* It will *not* be NUL-terminated! */ + bool no_writes_p = true; + if (fnspec) + { + tree fnspecstr = TREE_VALUE (TREE_VALUE (fnspec)); + curlen = TREE_STRING_LENGTH (fnspecstr); + memcpy (nspec, TREE_STRING_POINTER (fnspecstr), curlen); + if (!(flags & (ECF_CONST | ECF_PURE | ECF_NOVOPS)) + && curlen >= 2 + && nspec[1] != 'c' && nspec[1] != 'C' + && nspec[1] != 'p' && nspec[1] != 'P') + no_writes_p = false; + } + if (!curlen) + { + nspec[curlen++] = '.'; + nspec[curlen++] = ((flags & ECF_CONST) + ? 'c' + : (flags & ECF_PURE) + ? 'p' + : ' '); + } + while (curlen < tgtlen - 2 * xargs) + { + nspec[curlen++] = '.'; + nspec[curlen++] = ' '; + } + + /* These extra args are unlikely to be present in const or pure + functions. It's conceivable that a function that takes variable + arguments, or that passes its arguments on to another function, + could be const or pure, but it would not modify the arguments, and, + being pure or const, it couldn't possibly modify or even access + memory referenced by them. But it can read from these internal + data structures created by the wrapper, and from any + argument-passing memory referenced by them, so we denote the + possibility of reading from multiple levels of indirection, but + only of reading because const/pure. */ + if (apply_args) + { + nspec[curlen++] = 'r'; + nspec[curlen++] = ' '; + } + if (is_stdarg) + { + nspec[curlen++] = (no_writes_p ? 'r' : '.'); + nspec[curlen++] = (no_writes_p ? 't' : ' '); + } + + nspec[curlen++] = 'W'; + nspec[curlen++] = 't'; + + /* The type has already been copied before adding parameters. */ + gcc_checking_assert (TYPE_ARG_TYPES (TREE_TYPE (nnode->decl)) + != TYPE_ARG_TYPES (TREE_TYPE (onode->decl))); + TYPE_ATTRIBUTES (TREE_TYPE (nnode->decl)) + = tree_cons (get_identifier ("fn spec"), + build_tree_list (NULL_TREE, + build_string (tgtlen, nspec)), + TYPE_ATTRIBUTES (TREE_TYPE (nnode->decl))); + } + } +#endif + + { + tree decl = onode->decl; + cgraph_node *target = nnode; + + { // copied from create_wrapper + + /* Preserve DECL_RESULT so we get right by reference flag. */ + tree decl_result = DECL_RESULT (decl); + + /* Remove the function's body but keep arguments to be reused + for thunk. */ + onode->release_body (true); + onode->reset (/* unlike create_wrapper: preserve_comdat_group = */true); + + DECL_UNINLINABLE (decl) = false; + DECL_RESULT (decl) = decl_result; + DECL_INITIAL (decl) = NULL; + allocate_struct_function (decl, false); + set_cfun (NULL); + + /* Turn alias into thunk and expand it into GIMPLE representation. */ + onode->definition = true; + + thunk_info::get_create (onode); + onode->thunk = true; + onode->create_edge (target, NULL, onode->count); + onode->callees->can_throw_external = !TREE_NOTHROW (target->decl); + + tree arguments = DECL_ARGUMENTS (decl); + + while (arguments) + { + TREE_ADDRESSABLE (arguments) = false; + arguments = TREE_CHAIN (arguments); + } + + { + tree alias = onode->callees->callee->decl; + tree thunk_fndecl = decl; + tree a; + + int nxargs = 1 + is_stdarg + apply_args; + + { // Simplified from expand_thunk. + tree restype; + basic_block bb, then_bb, else_bb, return_bb; + gimple_stmt_iterator bsi; + int nargs = 0; + tree arg; + int i; + tree resdecl; + tree restmp = NULL; + + gcall *call; + greturn *ret; + bool alias_is_noreturn = TREE_THIS_VOLATILE (alias); + + a = DECL_ARGUMENTS (thunk_fndecl); + + current_function_decl = thunk_fndecl; + + /* Ensure thunks are emitted in their correct sections. */ + resolve_unique_section (thunk_fndecl, 0, + flag_function_sections); + + bitmap_obstack_initialize (NULL); + + /* Build the return declaration for the function. */ + restype = TREE_TYPE (TREE_TYPE (thunk_fndecl)); + if (DECL_RESULT (thunk_fndecl) == NULL_TREE) + { + resdecl = build_decl (input_location, RESULT_DECL, 0, restype); + DECL_ARTIFICIAL (resdecl) = 1; + DECL_IGNORED_P (resdecl) = 1; + DECL_CONTEXT (resdecl) = thunk_fndecl; + DECL_RESULT (thunk_fndecl) = resdecl; + } + else + resdecl = DECL_RESULT (thunk_fndecl); + + profile_count cfg_count = onode->count; + if (!cfg_count.initialized_p ()) + cfg_count = profile_count::from_gcov_type (BB_FREQ_MAX).guessed_local (); + + bb = then_bb = else_bb = return_bb + = init_lowered_empty_function (thunk_fndecl, true, cfg_count); + + bsi = gsi_start_bb (bb); + + /* Build call to the function being thunked. */ + if (!VOID_TYPE_P (restype) + && (!alias_is_noreturn + || TREE_ADDRESSABLE (restype) + || TREE_CODE (TYPE_SIZE_UNIT (restype)) != INTEGER_CST)) + { + if (DECL_BY_REFERENCE (resdecl)) + { + restmp = gimple_fold_indirect_ref (resdecl); + if (!restmp) + restmp = build2 (MEM_REF, + TREE_TYPE (TREE_TYPE (resdecl)), + resdecl, + build_int_cst (TREE_TYPE (resdecl), 0)); + } + else if (!is_gimple_reg_type (restype)) + { + if (aggregate_value_p (resdecl, TREE_TYPE (thunk_fndecl))) + { + restmp = resdecl; + + if (VAR_P (restmp)) + { + add_local_decl (cfun, restmp); + BLOCK_VARS (DECL_INITIAL (current_function_decl)) + = restmp; + } + } + else + restmp = create_tmp_var (restype, "retval"); + } + else + restmp = create_tmp_reg (restype, "retval"); + } + + for (arg = a; arg; arg = DECL_CHAIN (arg)) + nargs++; + auto_vec<tree> vargs (nargs + nxargs); + i = 0; + arg = a; + + if (nargs) + for (tree nparm = DECL_ARGUMENTS (nnode->decl); + i < nargs; + i++, arg = DECL_CHAIN (arg), nparm = DECL_CHAIN (nparm)) + { + tree save_arg = arg; + tree tmp = arg; + + /* Arrange to pass indirectly the parms, if we decided to do + so, and revert its type in the wrapper. */ + if (indirect_nparms.contains (nparm)) + { + tree ref_type = TREE_TYPE (nparm); + TREE_ADDRESSABLE (arg) = true; + tree addr = build1 (ADDR_EXPR, ref_type, arg); + tmp = arg = addr; + } + else + DECL_NOT_GIMPLE_REG_P (arg) = 0; + + /* Convert the argument back to the type used by the calling + conventions, e.g. a non-prototyped float type is passed as + double, as in 930603-1.c, and needs to be converted back to + double to be passed on unchanged to the wrapped + function. */ + if (TREE_TYPE (nparm) != DECL_ARG_TYPE (nparm)) + arg = fold_convert (DECL_ARG_TYPE (nparm), arg); + + if (!is_gimple_val (arg)) + { + tmp = create_tmp_reg (TYPE_MAIN_VARIANT + (TREE_TYPE (arg)), "arg"); + gimple *stmt = gimple_build_assign (tmp, arg); + gsi_insert_after (&bsi, stmt, GSI_NEW_STMT); + } + vargs.quick_push (tmp); + arg = save_arg; + } + /* These strub arguments are adjusted later. */ + if (apply_args) + vargs.quick_push (null_pointer_node); + if (is_stdarg) + vargs.quick_push (null_pointer_node); + vargs.quick_push (null_pointer_node); + call = gimple_build_call_vec (build_fold_addr_expr_loc (0, alias), + vargs); + onode->callees->call_stmt = call; + // gimple_call_set_from_thunk (call, true); + if (DECL_STATIC_CHAIN (alias)) + { + tree p = DECL_STRUCT_FUNCTION (alias)->static_chain_decl; + tree type = TREE_TYPE (p); + tree decl = build_decl (DECL_SOURCE_LOCATION (thunk_fndecl), + PARM_DECL, create_tmp_var_name ("CHAIN"), + type); + DECL_ARTIFICIAL (decl) = 1; + DECL_IGNORED_P (decl) = 1; + TREE_USED (decl) = 1; + DECL_CONTEXT (decl) = thunk_fndecl; + DECL_ARG_TYPE (decl) = type; + TREE_READONLY (decl) = 1; + + struct function *sf = DECL_STRUCT_FUNCTION (thunk_fndecl); + sf->static_chain_decl = decl; + + gimple_call_set_chain (call, decl); + } + + /* Return slot optimization is always possible and in fact required to + return values with DECL_BY_REFERENCE. */ + if (aggregate_value_p (resdecl, TREE_TYPE (thunk_fndecl)) + && (!is_gimple_reg_type (TREE_TYPE (resdecl)) + || DECL_BY_REFERENCE (resdecl))) + gimple_call_set_return_slot_opt (call, true); + + if (restmp) + { + gimple_call_set_lhs (call, restmp); + gcc_assert (useless_type_conversion_p (TREE_TYPE (restmp), + TREE_TYPE (TREE_TYPE (alias)))); + } + gsi_insert_after (&bsi, call, GSI_NEW_STMT); + if (!alias_is_noreturn) + { + /* Build return value. */ + if (!DECL_BY_REFERENCE (resdecl)) + ret = gimple_build_return (restmp); + else + ret = gimple_build_return (resdecl); + + gsi_insert_after (&bsi, ret, GSI_NEW_STMT); + } + else + { + remove_edge (single_succ_edge (bb)); + } + + cfun->gimple_df->in_ssa_p = true; + update_max_bb_count (); + profile_status_for_fn (cfun) + = cfg_count.initialized_p () && cfg_count.ipa_p () + ? PROFILE_READ : PROFILE_GUESSED; + /* FIXME: C++ FE should stop setting TREE_ASM_WRITTEN on thunks. */ + // TREE_ASM_WRITTEN (thunk_fndecl) = false; + delete_unreachable_blocks (); + update_ssa (TODO_update_ssa); + checking_verify_flow_info (); + free_dominance_info (CDI_DOMINATORS); + + /* Since we want to emit the thunk, we explicitly mark its name as + referenced. */ + onode->thunk = false; + onode->lowered = true; + bitmap_obstack_release (NULL); + } + current_function_decl = NULL; + set_cfun (NULL); + } + + thunk_info::remove (onode); + + // some more of create_wrapper at the end of the next block. + } + } + + { + tree aaval = NULL_TREE; + tree vaptr = NULL_TREE; + tree wmptr = NULL_TREE; + for (tree arg = DECL_ARGUMENTS (nnode->decl); arg; arg = DECL_CHAIN (arg)) + { + aaval = vaptr; + vaptr = wmptr; + wmptr = arg; + } + + if (!apply_args) + aaval = NULL_TREE; + /* The trailing args are [apply_args], [va_list_ptr], and + watermark. If we don't have a va_list_ptr, the penultimate + argument is apply_args. + */ + else if (!is_stdarg) + aaval = vaptr; + + if (!is_stdarg) + vaptr = NULL_TREE; + + DECL_NAME (wmptr) = get_watermark_ptr (); + DECL_ARTIFICIAL (wmptr) = 1; + DECL_IGNORED_P (wmptr) = 1; + TREE_USED (wmptr) = 1; + + if (is_stdarg) + { + DECL_NAME (vaptr) = get_va_list_ptr (); + DECL_ARTIFICIAL (vaptr) = 1; + DECL_IGNORED_P (vaptr) = 1; + TREE_USED (vaptr) = 1; + } + + if (apply_args) + { + DECL_NAME (aaval) = get_apply_args (); + DECL_ARTIFICIAL (aaval) = 1; + DECL_IGNORED_P (aaval) = 1; + TREE_USED (aaval) = 1; + } + + push_cfun (DECL_STRUCT_FUNCTION (nnode->decl)); + + { + edge e = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun)); + gimple_seq seq = call_update_watermark (wmptr, nnode, e->src->count); + gsi_insert_seq_on_edge_immediate (e, seq); + } + + bool any_indirect = !indirect_nparms.is_empty (); + + if (any_indirect) + { + basic_block bb; + bool needs_commit = false; + FOR_EACH_BB_FN (bb, cfun) + { + for (gphi_iterator gsi = gsi_start_nonvirtual_phis (bb); + !gsi_end_p (gsi); + gsi_next_nonvirtual_phi (&gsi)) + { + gphi *stmt = gsi.phi (); + + walk_stmt_info wi = {}; + wi.info = &indirect_nparms; + walk_gimple_op (stmt, walk_make_indirect, &wi); + if (wi.changed && !is_gimple_debug (gsi_stmt (gsi))) + if (walk_regimplify_phi (stmt)) + needs_commit = true; + } + + for (gimple_stmt_iterator gsi = gsi_start_bb (bb); + !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple *stmt = gsi_stmt (gsi); + + walk_stmt_info wi = {}; + wi.info = &indirect_nparms; + walk_gimple_op (stmt, walk_make_indirect, &wi); + if (wi.changed) + { + if (!is_gimple_debug (stmt)) + { + wi.info = &gsi; + walk_gimple_op (stmt, walk_regimplify_addr_expr, + &wi); + } + update_stmt (stmt); + } + } + } + if (needs_commit) + gsi_commit_edge_inserts (); + } + + if (DECL_STRUCT_FUNCTION (nnode->decl)->calls_alloca + || is_stdarg || apply_args) + for (cgraph_edge *e = nnode->callees, *enext; e; e = enext) + { + if (!e->call_stmt) + continue; + + gcall *call = e->call_stmt; + gimple_stmt_iterator gsi = gsi_for_stmt (call); + tree fndecl = e->callee->decl; + + enext = e->next_callee; + + if (gimple_alloca_call_p (call)) + { + gimple_seq seq = call_update_watermark (wmptr, NULL, + gsi_bb (gsi)->count); + gsi_insert_finally_seq_after_call (gsi, seq); + } + else if (fndecl && is_stdarg + && fndecl_built_in_p (fndecl, BUILT_IN_VA_START)) + { + /* Using a non-default stdarg ABI makes the function ineligible + for internal strub. */ + gcc_checking_assert (builtin_decl_explicit (BUILT_IN_VA_START) + == fndecl); + tree bvacopy = builtin_decl_explicit (BUILT_IN_VA_COPY); + gimple_call_set_fndecl (call, bvacopy); + tree arg = vaptr; + /* The va_copy source must be dereferenced, unless it's an array + type, that would have decayed to a pointer. */ + if (TREE_CODE (TREE_TYPE (TREE_TYPE (vaptr))) != ARRAY_TYPE) + { + arg = gimple_fold_indirect_ref (vaptr); + if (!arg) + arg = build2 (MEM_REF, + TREE_TYPE (TREE_TYPE (vaptr)), + vaptr, + build_int_cst (TREE_TYPE (vaptr), 0)); + if (!is_gimple_val (arg)) + arg = force_gimple_operand_gsi (&gsi, arg, true, + NULL_TREE, true, GSI_SAME_STMT); + } + gimple_call_set_arg (call, 1, arg); + update_stmt (call); + e->redirect_callee (cgraph_node::get_create (bvacopy)); + } + else if (fndecl && apply_args + && fndecl_built_in_p (fndecl, BUILT_IN_APPLY_ARGS)) + { + tree lhs = gimple_call_lhs (call); + gimple *assign = (lhs + ? gimple_build_assign (lhs, aaval) + : gimple_build_nop ()); + gsi_replace (&gsi, assign, true); + cgraph_edge::remove (e); + } + } + + { // a little more copied from create_wrapper + + /* Inline summary set-up. */ + nnode->analyze (); + // inline_analyze_function (nnode); + } + + pop_cfun (); + } + + { + push_cfun (DECL_STRUCT_FUNCTION (onode->decl)); + gimple_stmt_iterator gsi + = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun))); + + gcall *wrcall; + while (!(wrcall = dyn_cast <gcall *> (gsi_stmt (gsi)))) + gsi_next (&gsi); + + tree swm = create_tmp_var (get_wmt (), ".strub.watermark"); + TREE_ADDRESSABLE (swm) = true; + tree swmp = build1 (ADDR_EXPR, get_pwmt (), swm); + + tree enter = get_enter (); + gcall *stptr = gimple_build_call (enter, 1, unshare_expr (swmp)); + gimple_set_location (stptr, gimple_location (wrcall)); + gsi_insert_before (&gsi, stptr, GSI_SAME_STMT); + onode->create_edge (cgraph_node::get_create (enter), + stptr, gsi_bb (gsi)->count, false); + + int nargs = gimple_call_num_args (wrcall); + + gimple_seq seq = NULL; + + if (apply_args) + { + tree aalst = create_tmp_var (ptr_type_node, ".strub.apply_args"); + tree bappargs = builtin_decl_explicit (BUILT_IN_APPLY_ARGS); + gcall *appargs = gimple_build_call (bappargs, 0); + gimple_call_set_lhs (appargs, aalst); + gimple_set_location (appargs, gimple_location (wrcall)); + gsi_insert_before (&gsi, appargs, GSI_SAME_STMT); + gimple_call_set_arg (wrcall, nargs - 2 - is_stdarg, aalst); + onode->create_edge (cgraph_node::get_create (bappargs), + appargs, gsi_bb (gsi)->count, false); + } + + if (is_stdarg) + { + tree valst = create_tmp_var (va_list_type_node, ".strub.va_list"); + TREE_ADDRESSABLE (valst) = true; + tree vaptr = build1 (ADDR_EXPR, + build_pointer_type (va_list_type_node), + valst); + gimple_call_set_arg (wrcall, nargs - 2, unshare_expr (vaptr)); + + tree bvastart = builtin_decl_explicit (BUILT_IN_VA_START); + gcall *vastart = gimple_build_call (bvastart, 2, + unshare_expr (vaptr), + integer_zero_node); + gimple_set_location (vastart, gimple_location (wrcall)); + gsi_insert_before (&gsi, vastart, GSI_SAME_STMT); + onode->create_edge (cgraph_node::get_create (bvastart), + vastart, gsi_bb (gsi)->count, false); + + tree bvaend = builtin_decl_explicit (BUILT_IN_VA_END); + gcall *vaend = gimple_build_call (bvaend, 1, unshare_expr (vaptr)); + gimple_set_location (vaend, gimple_location (wrcall)); + gimple_seq_add_stmt (&seq, vaend); + } + + gimple_call_set_arg (wrcall, nargs - 1, unshare_expr (swmp)); + // gimple_call_set_tail (wrcall, false); + update_stmt (wrcall); + + { +#if !ATTR_FNSPEC_DECONST_WATERMARK + /* If the call will be assumed to not modify or even read the + watermark, make it read and modified ourselves. */ + if ((gimple_call_flags (wrcall) + & (ECF_CONST | ECF_PURE | ECF_NOVOPS))) + { + vec<tree, va_gc> *inputs = NULL; + vec<tree, va_gc> *outputs = NULL; + vec_safe_push (outputs, + build_tree_list + (build_tree_list + (NULL_TREE, build_string (2, "=m")), + swm)); + vec_safe_push (inputs, + build_tree_list + (build_tree_list + (NULL_TREE, build_string (1, "m")), + swm)); + gasm *forcemod = gimple_build_asm_vec ("", inputs, outputs, + NULL, NULL); + gimple_seq_add_stmt (&seq, forcemod); + + /* If the call will be assumed to not even read the watermark, + make sure it is already in memory before the call. */ + if ((gimple_call_flags (wrcall) & ECF_CONST)) + { + vec<tree, va_gc> *inputs = NULL; + vec_safe_push (inputs, + build_tree_list + (build_tree_list + (NULL_TREE, build_string (1, "m")), + swm)); + gasm *force_store = gimple_build_asm_vec ("", inputs, NULL, + NULL, NULL); + gimple_set_location (force_store, gimple_location (wrcall)); + gsi_insert_before (&gsi, force_store, GSI_SAME_STMT); + } + } +#endif + + gcall *sleave = gimple_build_call (get_leave (), 1, + unshare_expr (swmp)); + gimple_seq_add_stmt (&seq, sleave); + + gassign *clobber = gimple_build_assign (swm, + build_clobber + (TREE_TYPE (swm))); + gimple_seq_add_stmt (&seq, clobber); + } + + gsi_insert_finally_seq_after_call (gsi, seq); + + /* For nnode, we don't rebuild edges because we wish to retain + any redirections copied to it from earlier passes, so we add + call graph edges explicitly there, but for onode, we create a + fresh function, so we may as well just issue the calls and + then rebuild all cgraph edges. */ + // cgraph_edge::rebuild_edges (); + onode->analyze (); + // inline_analyze_function (onode); + + pop_cfun (); + } + } + + return 0; +} + +simple_ipa_opt_pass * +make_pass_ipa_strub (gcc::context *ctxt) +{ + return new pass_ipa_strub (ctxt); +} + +#include "gt-ipa-strub.h" |