/* Nested function decomposition for trees. Copyright (C) 2004 Free Software Foundation, Inc. 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 2, 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 COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "tree.h" #include "rtl.h" #include "tm_p.h" #include "function.h" #include "tree-dump.h" #include "tree-inline.h" #include "tree-gimple.h" #include "tree-iterator.h" #include "tree-flow.h" #include "cgraph.h" #include "expr.h" #include "langhooks.h" #include "ggc.h" /* The object of this pass is to lower the representation of a set of nested functions in order to expose all of the gory details of the various nonlocal references. We want to do this sooner rather than later, in order to give us more freedom in emitting all of the functions in question. Back in olden times, when gcc was young, we developed an insanely complicated scheme whereby variables which were referenced nonlocally were forced to live in the stack of the declaring function, and then the nested functions magically discovered where these variables were placed. In order for this scheme to function properly, it required that the outer function be partially expanded, then we switch to compiling the inner function, and once done with those we switch back to compiling the outer function. Such delicate ordering requirements makes it difficult to do whole translation unit optimizations involving such functions. The implementation here is much more direct. Everything that can be referenced by an inner function is a member of an explicitly created structure herein called the "nonlocal frame struct". The incomming static chain for a nested function is a pointer to this struct in the parent. In this way, we settle on known offsets from a known base, and so are decoupled from the logic that places objects in the function's stack frame. More importantly, we don't have to wait for that to happen -- since the compilation of the inner function is no longer tied to a real stack frame, the nonlocal frame struct can be allocated anywhere. Which means that the outer function is now inlinable. Theory of operation here is very simple. Iterate over all the statements in all the functions (depth first) several times, allocating structures and fields on demand. In general we want to examine inner functions first, so that we can avoid making changes to outer functions which are unnecessary. The order of the passes matters a bit, in that later passes will be skipped if it is discovered that the functions don't actually interact at all. That is, they're nested in the lexical sense but could have been written as independent functions without change. */ struct var_map_elt { tree old; tree new; }; struct nesting_info { struct nesting_info *outer; struct nesting_info *inner; struct nesting_info *next; htab_t var_map; tree context; tree new_local_var_chain; tree frame_type; tree frame_decl; tree chain_field; tree chain_decl; tree nl_goto_field; bool any_parm_remapped; bool any_tramp_created; }; /* Hashing and equality functions for nesting_info->var_map. */ static hashval_t var_map_hash (const void *x) { const struct var_map_elt *a = x; return htab_hash_pointer (a->old); } static int var_map_eq (const void *x, const void *y) { const struct var_map_elt *a = x; const struct var_map_elt *b = y; return a->old == b->old; } /* We're working in so many different function contexts simultaneously, that create_tmp_var is dangerous. Prevent mishap. */ #define create_tmp_var cant_use_create_tmp_var_here_dummy /* Like create_tmp_var, except record the variable for registration at the given nesting level. */ static tree create_tmp_var_for (struct nesting_info *info, tree type, const char *prefix) { tree tmp_var; #if defined ENABLE_CHECKING /* If the type is an array or a type which must be created by the frontend, something is wrong. Note that we explicitly allow incomplete types here, since we create them ourselves here. */ if (TREE_CODE (type) == ARRAY_TYPE || TREE_ADDRESSABLE (type)) abort (); if (TYPE_SIZE_UNIT (type) && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST) abort (); #endif tmp_var = create_tmp_var_raw (type, prefix); DECL_CONTEXT (tmp_var) = info->context; TREE_CHAIN (tmp_var) = info->new_local_var_chain; info->new_local_var_chain = tmp_var; return tmp_var; } /* Take the address of EXP. Mark it for addressability as necessary. */ static tree build_addr (tree exp) { tree base = exp; if (TREE_CODE (base) == REALPART_EXPR || TREE_CODE (base) == IMAGPART_EXPR) base = TREE_OPERAND (base, 0); else while (handled_component_p (base)) base = TREE_OPERAND (base, 0); if (DECL_P (base)) TREE_ADDRESSABLE (base) = 1; return build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (exp)), exp); } /* Insert FIELD into TYPE, sorted by alignment requirements. */ static void insert_field_into_struct (tree type, tree field) { tree *p; DECL_CONTEXT (field) = type; for (p = &TYPE_FIELDS (type); *p ; p = &TREE_CHAIN (*p)) if (DECL_ALIGN (field) >= DECL_ALIGN (*p)) break; TREE_CHAIN (field) = *p; *p = field; } /* Build or return the RECORD_TYPE that describes the frame state that is shared between INFO->CONTEXT and its nested functions. This record will not be complete until finalize_nesting_tree; up until that point we'll be adding fields as necessary. We also build the DECL that represents this frame in the function. */ static tree get_frame_type (struct nesting_info *info) { tree type = info->frame_type; if (!type) { char *name; type = make_node (RECORD_TYPE); name = concat ("FRAME.", IDENTIFIER_POINTER (DECL_NAME (info->context)), NULL); TYPE_NAME (type) = get_identifier (name); free (name); info->frame_type = type; info->frame_decl = create_tmp_var_for (info, type, "FRAME"); } return type; } /* Return true if DECL should be referenced by pointer in the non-local frame structure. */ static bool use_pointer_in_frame (tree decl) { if (TREE_CODE (decl) == PARM_DECL) { /* It's illegal to copy TREE_ADDRESSABLE, impossible to copy variable sized decls, and inefficient to copy large aggregates. Don't bother moving anything but scalar variables. */ return AGGREGATE_TYPE_P (TREE_TYPE (decl)); } else { /* Variable sized types make things "interesting" in the frame. */ return DECL_SIZE (decl) == NULL || !TREE_CONSTANT (DECL_SIZE (decl)); } } /* Given DECL, a non-locally accessed variable, find or create a field in the non-local frame structure for the given nesting context. */ static tree lookup_field_for_decl (struct nesting_info *info, tree decl, enum insert_option insert) { struct var_map_elt *elt, dummy; void **slot; tree field; dummy.old = decl; slot = htab_find_slot (info->var_map, &dummy, insert); if (!slot) { if (insert == INSERT) abort (); return NULL; } elt = *slot; if (!elt && insert == INSERT) { field = make_node (FIELD_DECL); DECL_NAME (field) = DECL_NAME (decl); if (use_pointer_in_frame (decl)) { TREE_TYPE (field) = build_pointer_type (TREE_TYPE (decl)); DECL_ALIGN (field) = TYPE_ALIGN (TREE_TYPE (field)); DECL_NONADDRESSABLE_P (field) = 1; } else { TREE_TYPE (field) = TREE_TYPE (decl); DECL_SOURCE_LOCATION (field) = DECL_SOURCE_LOCATION (decl); DECL_ALIGN (field) = DECL_ALIGN (decl); DECL_USER_ALIGN (field) = DECL_USER_ALIGN (decl); TREE_ADDRESSABLE (field) = TREE_ADDRESSABLE (decl); DECL_NONADDRESSABLE_P (field) = !TREE_ADDRESSABLE (decl); TREE_THIS_VOLATILE (field) = TREE_THIS_VOLATILE (decl); } insert_field_into_struct (get_frame_type (info), field); elt = xmalloc (sizeof (*elt)); elt->old = decl; elt->new = field; *slot = elt; if (TREE_CODE (decl) == PARM_DECL) info->any_parm_remapped = true; } else field = elt ? elt->new : NULL; return field; } /* Build or return the variable that holds the static chain within INFO->CONTEXT. This variable may only be used within INFO->CONTEXT. */ static tree get_chain_decl (struct nesting_info *info) { tree decl = info->chain_decl; if (!decl) { tree type; type = get_frame_type (info->outer); type = build_pointer_type (type); /* Note that this variable is *not* entered into any BIND_EXPR; the construction of this variable is handled specially in expand_function_start and initialize_inlined_parameters. Note also that it's represented as a parameter. This is more close to the truth, since the initial value does come from the caller. */ decl = build_decl (PARM_DECL, create_tmp_var_name ("CHAIN"), type); DECL_ARTIFICIAL (decl) = 1; DECL_IGNORED_P (decl) = 1; TREE_USED (decl) = 1; DECL_CONTEXT (decl) = info->context; DECL_ARG_TYPE (decl) = type; /* Tell tree-inline.c that we never write to this variable, so it can copy-prop the replacement value immediately. */ TREE_READONLY (decl) = 1; info->chain_decl = decl; } return decl; } /* Build or return the field within the non-local frame state that holds the static chain for INFO->CONTEXT. This is the way to walk back up multiple nesting levels. */ static tree get_chain_field (struct nesting_info *info) { tree field = info->chain_field; if (!field) { tree type = build_pointer_type (get_frame_type (info->outer)); field = make_node (FIELD_DECL); DECL_NAME (field) = get_identifier ("__chain"); TREE_TYPE (field) = type; DECL_ALIGN (field) = TYPE_ALIGN (type); DECL_NONADDRESSABLE_P (field) = 1; insert_field_into_struct (get_frame_type (info), field); info->chain_field = field; } return field; } /* Copy EXP into a temporary. Allocate the temporary in the context of INFO and insert the initialization statement before TSI. */ static tree init_tmp_var (struct nesting_info *info, tree exp, tree_stmt_iterator *tsi) { tree t, stmt; t = create_tmp_var_for (info, TREE_TYPE (exp), NULL); stmt = build (MODIFY_EXPR, TREE_TYPE (t), t, exp); SET_EXPR_LOCUS (stmt, EXPR_LOCUS (tsi_stmt (*tsi))); tsi_link_before (tsi, stmt, TSI_SAME_STMT); return t; } /* Similarly, but only do so to force EXP to satisfy is_gimple_val. */ static tree gimplify_val (struct nesting_info *info, tree exp, tree_stmt_iterator *tsi) { if (is_gimple_val (exp)) return exp; else return init_tmp_var (info, exp, tsi); } /* Build or return the type used to represent a nested function trampoline. */ static GTY(()) tree trampoline_type; static tree get_trampoline_type (void) { tree record, t; unsigned align, size; if (trampoline_type) return trampoline_type; align = TRAMPOLINE_ALIGNMENT; size = TRAMPOLINE_SIZE; /* If we won't be able to guarantee alignment simply via TYPE_ALIGN, then allocate extra space so that we can do dynamic alignment. */ if (align > STACK_BOUNDARY) { size += ((align/BITS_PER_UNIT) - 1) & -(STACK_BOUNDARY/BITS_PER_UNIT); align = STACK_BOUNDARY; } t = build_index_type (build_int_2 (size - 1, 0)); t = build_array_type (char_type_node, t); t = build_decl (FIELD_DECL, get_identifier ("__data"), t); DECL_ALIGN (t) = align; DECL_USER_ALIGN (t) = 1; record = make_node (RECORD_TYPE); TYPE_NAME (record) = get_identifier ("__builtin_trampoline"); TYPE_FIELDS (record) = t; layout_type (record); return record; } /* Given DECL, a nested function, find or create a field in the non-local frame structure for a trampoline for this function. */ static tree lookup_tramp_for_decl (struct nesting_info *info, tree decl, enum insert_option insert) { struct var_map_elt *elt, dummy; void **slot; tree field; dummy.old = decl; slot = htab_find_slot (info->var_map, &dummy, insert); if (!slot) { if (insert == INSERT) abort (); return NULL; } elt = *slot; if (!elt && insert == INSERT) { field = make_node (FIELD_DECL); DECL_NAME (field) = DECL_NAME (decl); TREE_TYPE (field) = get_trampoline_type (); TREE_ADDRESSABLE (field) = 1; insert_field_into_struct (get_frame_type (info), field); elt = xmalloc (sizeof (*elt)); elt->old = decl; elt->new = field; *slot = elt; info->any_tramp_created = true; } else field = elt ? elt->new : NULL; return field; } /* Build or return the field within the non-local frame state that holds the non-local goto "jmp_buf". The buffer itself is maintained by the rtl middle-end as dynamic stack space is allocated. */ static tree get_nl_goto_field (struct nesting_info *info) { tree field = info->nl_goto_field; if (!field) { unsigned size; tree type; /* For __builtin_nonlocal_goto, we need N words. The first is the frame pointer, the rest is for the target's stack pointer save area. The number of words is controlled by STACK_SAVEAREA_MODE; not the best interface, but it'll do for now. */ if (Pmode == ptr_mode) type = ptr_type_node; else type = lang_hooks.types.type_for_mode (Pmode, 1); size = GET_MODE_SIZE (STACK_SAVEAREA_MODE (SAVE_NONLOCAL)); size = size / GET_MODE_SIZE (Pmode); size = size + 1; type = build_array_type (type, build_index_type (build_int_2 (size, 0))); field = make_node (FIELD_DECL); DECL_NAME (field) = get_identifier ("__nl_goto_buf"); TREE_TYPE (field) = type; DECL_ALIGN (field) = TYPE_ALIGN (type); TREE_ADDRESSABLE (field) = 1; insert_field_into_struct (get_frame_type (info), field); info->nl_goto_field = field; } return field; } /* Convenience routines to walk all statements of a gimple function. For each statement, we invoke CALLBACK via walk_tree. The passed data is a walk_stmt_info structure. Of note here is a TSI that points to the current statement being walked. The VAL_ONLY flag that indicates whether the *TP being examined may be replaced with something that matches is_gimple_val (if true) or something slightly more complicated (if false). "Something" technically means the common subset of is_gimple_lvalue and is_gimple_rhs, but we never try to form anything more complicated than that, so we don't bother checking. */ struct walk_stmt_info { walk_tree_fn callback; tree_stmt_iterator tsi; struct nesting_info *info; bool val_only; }; /* A subroutine of walk_function. Iterate over all sub-statements of *TP. */ static void walk_stmts (struct walk_stmt_info *wi, tree *tp) { tree t = *tp; if (!t) return; switch (TREE_CODE (t)) { case STATEMENT_LIST: { tree_stmt_iterator i; for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) { wi->tsi = i; walk_stmts (wi, tsi_stmt_ptr (i)); } } break; case COND_EXPR: walk_tree (&COND_EXPR_COND (t), wi->callback, wi, NULL); walk_stmts (wi, &COND_EXPR_THEN (t)); walk_stmts (wi, &COND_EXPR_ELSE (t)); break; case CATCH_EXPR: walk_stmts (wi, &CATCH_BODY (t)); break; case EH_FILTER_EXPR: walk_stmts (wi, &EH_FILTER_FAILURE (t)); break; case TRY_CATCH_EXPR: case TRY_FINALLY_EXPR: walk_stmts (wi, &TREE_OPERAND (t, 0)); walk_stmts (wi, &TREE_OPERAND (t, 1)); break; case BIND_EXPR: walk_stmts (wi, &BIND_EXPR_BODY (t)); break; case RETURN_EXPR: walk_stmts (wi, &TREE_OPERAND (t, 0)); break; case MODIFY_EXPR: /* The immediate arguments of a MODIFY_EXPR may use COMPONENT_REF. */ wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), wi->callback, wi, NULL); wi->val_only = false; walk_tree (&TREE_OPERAND (t, 1), wi->callback, wi, NULL); wi->val_only = true; break; default: wi->val_only = true; walk_tree (tp, wi->callback, wi, NULL); break; } } /* Invoke CALLBACK on all statements of INFO->CONTEXT. */ static void walk_function (walk_tree_fn callback, struct nesting_info *info) { struct walk_stmt_info wi; memset (&wi, 0, sizeof (wi)); wi.callback = callback; wi.info = info; wi.val_only = true; walk_stmts (&wi, &DECL_SAVED_TREE (info->context)); } /* Similarly for ROOT and all functions nested underneath, depth first. */ static void walk_all_functions (walk_tree_fn callback, struct nesting_info *root) { do { if (root->inner) walk_all_functions (callback, root->inner); walk_function (callback, root); root = root->next; } while (root); } /* Construct our local datastructure describing the function nesting tree rooted by CGN. */ static struct nesting_info * create_nesting_tree (struct cgraph_node *cgn) { struct nesting_info *info = xcalloc (1, sizeof (*info)); info->var_map = htab_create (7, var_map_hash, var_map_eq, free); info->context = cgn->decl; for (cgn = cgn->nested; cgn ; cgn = cgn->next_nested) { struct nesting_info *sub = create_nesting_tree (cgn); sub->outer = info; sub->next = info->inner; info->inner = sub; } return info; } /* Return an expression computing the static chain for TARGET_CONTEXT from INFO->CONTEXT. Insert any necessary computations before TSI. */ static tree get_static_chain (struct nesting_info *info, tree target_context, tree_stmt_iterator *tsi) { struct nesting_info *i; tree x; if (info->context == target_context) { x = build_addr (info->frame_decl); } else { x = get_chain_decl (info); for (i = info->outer; i->context != target_context; i = i->outer) { tree field = get_chain_field (i); x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); x = build (COMPONENT_REF, TREE_TYPE (field), x, field, NULL_TREE); x = init_tmp_var (info, x, tsi); } } return x; } /* Return an expression referencing FIELD from TARGET_CONTEXT's non-local frame as seen from INFO->CONTEXT. Insert any necessary computations before TSI. */ static tree get_frame_field (struct nesting_info *info, tree target_context, tree field, tree_stmt_iterator *tsi) { struct nesting_info *i; tree x; if (info->context == target_context) { /* Make sure frame_decl gets created. */ (void) get_frame_type (info); x = info->frame_decl; } else { x = get_chain_decl (info); for (i = info->outer; i->context != target_context; i = i->outer) { tree field = get_chain_field (i); x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); x = build (COMPONENT_REF, TREE_TYPE (field), x, field, NULL_TREE); x = init_tmp_var (info, x, tsi); } x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); } x = build (COMPONENT_REF, TREE_TYPE (field), x, field, NULL_TREE); return x; } /* Called via walk_function+walk_tree, rewrite all references to VAR and PARM_DECLs that belong to outer functions. The rewrite will involve some number of structure accesses back up the static chain. E.g. for a variable FOO up one nesting level it'll be CHAIN->FOO. For two levels it'll be CHAIN->__chain->FOO. Further indirections apply to decls for which use_pointer_in_frame is true. */ static tree convert_nonlocal_reference (tree *tp, int *walk_subtrees, void *data) { struct walk_stmt_info *wi = data; struct nesting_info *info = wi->info; tree t = *tp; *walk_subtrees = 0; switch (TREE_CODE (t)) { case VAR_DECL: /* Non-automatic variables are never processed. */ if (TREE_STATIC (t) || DECL_EXTERNAL (t)) break; /* FALLTHRU */ case PARM_DECL: if (decl_function_context (t) != info->context) { tree target_context = decl_function_context (t); struct nesting_info *i; tree x; for (i = info->outer; i->context != target_context; i = i->outer) continue; x = lookup_field_for_decl (i, t, INSERT); x = get_frame_field (info, target_context, x, &wi->tsi); if (use_pointer_in_frame (t)) { x = init_tmp_var (info, x, &wi->tsi); x = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (x)), x); } if (wi->val_only) x = init_tmp_var (info, x, &wi->tsi); *tp = x; } break; case GOTO_EXPR: /* Don't walk non-local gotos for now. */ if (TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL) { *walk_subtrees = 1; wi->val_only = true; } break; case LABEL_DECL: /* We're taking the address of a label from a parent function, but this is not itself a non-local goto. Mark the label such that it will not be deleted, much as we would with a label address in static storage. */ if (decl_function_context (t) != info->context) FORCED_LABEL (t) = 1; break; case ADDR_EXPR: { bool save_val_only = wi->val_only; tree save_sub = TREE_OPERAND (t, 0); wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); wi->val_only = true; if (save_sub != TREE_OPERAND (t, 0)) { /* If we changed anything, then TREE_INVARIANT is be wrong, since we're no longer directly referencing a decl. */ TREE_INVARIANT (t) = 0; /* If the callback converted the address argument in a context where we only accept variables (and min_invariant, presumably), then compute the address into a temporary. */ if (save_val_only) *tp = gimplify_val (wi->info, t, &wi->tsi); } } break; case COMPONENT_REF: case REALPART_EXPR: case IMAGPART_EXPR: wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); wi->val_only = true; break; case ARRAY_REF: case ARRAY_RANGE_REF: wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); wi->val_only = true; walk_tree (&TREE_OPERAND (t, 1), convert_nonlocal_reference, wi, NULL); walk_tree (&TREE_OPERAND (t, 2), convert_nonlocal_reference, wi, NULL); walk_tree (&TREE_OPERAND (t, 3), convert_nonlocal_reference, wi, NULL); break; case BIT_FIELD_REF: wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_nonlocal_reference, wi, NULL); wi->val_only = true; walk_tree (&TREE_OPERAND (t, 1), convert_nonlocal_reference, wi, NULL); walk_tree (&TREE_OPERAND (t, 2), convert_nonlocal_reference, wi, NULL); break; default: if (!DECL_P (t) && !TYPE_P (t)) { *walk_subtrees = 1; wi->val_only = true; } break; } return NULL_TREE; } /* Called via walk_function+walk_tree, rewrite all references to VAR and PARM_DECLs that were referenced by inner nested functions. The rewrite will be a structure reference to the local frame variable. */ static tree convert_local_reference (tree *tp, int *walk_subtrees, void *data) { struct walk_stmt_info *wi = data; struct nesting_info *info = wi->info; tree t = *tp, field, x, y; switch (TREE_CODE (t)) { case VAR_DECL: /* Non-automatic variables are never processed. */ if (TREE_STATIC (t) || DECL_EXTERNAL (t)) break; /* FALLTHRU */ case PARM_DECL: if (decl_function_context (t) == info->context) { /* If we copied a pointer to the frame, then the original decl is used unchanged in the parent function. */ if (use_pointer_in_frame (t)) break; /* No need to transform anything if no child references the variable. */ field = lookup_field_for_decl (info, t, NO_INSERT); if (!field) break; x = get_frame_field (info, info->context, field, &wi->tsi); if (wi->val_only) x = init_tmp_var (info, x, &wi->tsi); *tp = x; } break; case ADDR_EXPR: { bool save_val_only = wi->val_only; tree save_sub = TREE_OPERAND (t, 0); wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); wi->val_only = save_val_only; /* If we converted anything ... */ if (TREE_OPERAND (t, 0) != save_sub) { /* Then the frame decl is now addressable. */ TREE_ADDRESSABLE (info->frame_decl) = 1; /* If we are in a context where we only accept values, then compute the address into a temporary. */ if (save_val_only) *tp = gimplify_val (wi->info, t, &wi->tsi); } } break; case CALL_EXPR: *walk_subtrees = 1; /* Ready for some fun? We need to recognize __builtin_stack_alloc (&x, n) and insert FRAME.x = &x after that. X should have use_pointer_in_frame set. We can't do this any earlier, since we can't meaningfully evaluate &x. */ x = get_callee_fndecl (t); if (!x || DECL_BUILT_IN_CLASS (x) != BUILT_IN_NORMAL) break; if (DECL_FUNCTION_CODE (x) != BUILT_IN_STACK_ALLOC) break; t = TREE_VALUE (TREE_OPERAND (t, 1)); if (TREE_CODE (t) != ADDR_EXPR) abort (); t = TREE_OPERAND (t, 0); if (TREE_CODE (t) != VAR_DECL) abort (); field = lookup_field_for_decl (info, t, NO_INSERT); if (!field) break; if (!use_pointer_in_frame (t)) abort (); x = build_addr (t); y = get_frame_field (info, info->context, field, &wi->tsi); x = build (MODIFY_EXPR, void_type_node, y, x); SET_EXPR_LOCUS (x, EXPR_LOCUS (tsi_stmt (wi->tsi))); tsi_link_after (&wi->tsi, x, TSI_SAME_STMT); break; case COMPONENT_REF: case REALPART_EXPR: case IMAGPART_EXPR: wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); wi->val_only = true; break; case ARRAY_REF: case ARRAY_RANGE_REF: wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); wi->val_only = true; walk_tree (&TREE_OPERAND (t, 1), convert_local_reference, wi, NULL); walk_tree (&TREE_OPERAND (t, 2), convert_local_reference, wi, NULL); walk_tree (&TREE_OPERAND (t, 3), convert_local_reference, wi, NULL); break; case BIT_FIELD_REF: wi->val_only = false; walk_tree (&TREE_OPERAND (t, 0), convert_local_reference, wi, NULL); wi->val_only = true; walk_tree (&TREE_OPERAND (t, 1), convert_local_reference, wi, NULL); walk_tree (&TREE_OPERAND (t, 2), convert_local_reference, wi, NULL); break; default: if (!DECL_P (t) && !TYPE_P (t)) { *walk_subtrees = 1; wi->val_only = true; } break; } return NULL_TREE; } /* Called via walk_function+walk_tree, rewrite all GOTO_EXPRs that reference labels from outer functions. The rewrite will be a call to __builtin_nonlocal_goto. */ static tree convert_nl_goto_reference (tree *tp, int *walk_subtrees, void *data) { struct walk_stmt_info *wi = data; struct nesting_info *info = wi->info, *i; tree t = *tp, label, new_label, target_context, x, arg, field; struct var_map_elt *elt; void **slot; *walk_subtrees = 0; if (TREE_CODE (t) != GOTO_EXPR) return NULL_TREE; label = GOTO_DESTINATION (t); if (TREE_CODE (label) != LABEL_DECL) return NULL_TREE; target_context = decl_function_context (label); if (target_context == info->context) return NULL_TREE; for (i = info->outer; target_context != i->context; i = i->outer) continue; /* The original user label may also be use for a normal goto, therefore we must create a new label that will actually receive the abnormal control transfer. This new label will be marked LABEL_NONLOCAL; this mark will trigger proper behavior in the cfg, as well as cause the (hairy target-specific) non-local goto receiver code to be generated when we expand rtl. */ new_label = create_artificial_label (); DECL_NONLOCAL (new_label) = 1; /* Enter this association into var_map so that we can insert the new label into the IL during a second pass. */ elt = xmalloc (sizeof (*elt)); elt->old = label; elt->new = new_label; slot = htab_find_slot (i->var_map, elt, INSERT); *slot = elt; /* Build: __builtin_nl_goto(new_label, &chain->nl_goto_field). */ field = get_nl_goto_field (i); x = get_frame_field (info, target_context, field, &wi->tsi); x = build_addr (x); x = gimplify_val (info, x, &wi->tsi); arg = tree_cons (NULL, x, NULL); x = build_addr (new_label); arg = tree_cons (NULL, x, arg); x = implicit_built_in_decls[BUILT_IN_NONLOCAL_GOTO]; x = build_function_call_expr (x, arg); SET_EXPR_LOCUS (x, EXPR_LOCUS (tsi_stmt (wi->tsi))); *tsi_stmt_ptr (wi->tsi) = x; return NULL_TREE; } /* Called via walk_function+walk_tree, rewrite all LABEL_EXPRs that are referenced via nonlocal goto from a nested function. The rewrite will involve installing a newly generated DECL_NONLOCAL label, and (potentially) a branch around the rtl gunk that is assumed to be attached to such a label. */ static tree convert_nl_goto_receiver (tree *tp, int *walk_subtrees, void *data) { struct walk_stmt_info *wi = data; struct nesting_info *info = wi->info; tree t = *tp, label, new_label, x; struct var_map_elt *elt, dummy; tree_stmt_iterator tmp_tsi; *walk_subtrees = 0; if (TREE_CODE (t) != LABEL_EXPR) return NULL_TREE; label = LABEL_EXPR_LABEL (t); dummy.old = label; elt = htab_find (info->var_map, &dummy); if (!elt) return NULL_TREE; new_label = elt->new; /* If there's any possibility that the previous statement falls through, then we must branch around the new non-local label. */ tmp_tsi = wi->tsi; tsi_prev (&tmp_tsi); if (tsi_end_p (tmp_tsi) || block_may_fallthru (tsi_stmt (tmp_tsi))) { x = build1 (GOTO_EXPR, void_type_node, label); tsi_link_before (&wi->tsi, x, TSI_SAME_STMT); } x = build1 (LABEL_EXPR, void_type_node, new_label); tsi_link_before (&wi->tsi, x, TSI_SAME_STMT); return NULL_TREE; } /* Called via walk_function+walk_tree, rewrite all references to addresses of nested functions that require the use of trampolines. The rewrite will involve a reference a trampoline generated for the occasion. */ static tree convert_tramp_reference (tree *tp, int *walk_subtrees, void *data) { struct walk_stmt_info *wi = data; struct nesting_info *info = wi->info, *i; tree t = *tp, decl, target_context, x, arg; *walk_subtrees = 0; switch (TREE_CODE (t)) { case ADDR_EXPR: /* Build T.1 = &CHAIN->tramp; T.2 = __builtin_adjust_trampoline (T.1); T.3 = (func_type)T.2; */ decl = TREE_OPERAND (t, 0); if (TREE_CODE (decl) != FUNCTION_DECL) break; /* Only need to process nested functions. */ target_context = decl_function_context (decl); if (!target_context) break; /* If the nested function doesn't use a static chain, then it doesn't need a trampoline. */ if (DECL_NO_STATIC_CHAIN (decl)) break; /* Lookup the immediate parent of the callee, as that's where we need to insert the trampoline. */ for (i = info; i->context != target_context; i = i->outer) continue; x = lookup_tramp_for_decl (i, decl, INSERT); /* Compute the address of the field holding the trampoline. */ x = get_frame_field (info, target_context, x, &wi->tsi); x = build_addr (x); x = gimplify_val (info, x, &wi->tsi); arg = tree_cons (NULL, x, NULL); /* Do machine-specific ugliness. Normally this will involve computing extra alignment, but it can really be anything. */ x = implicit_built_in_decls[BUILT_IN_ADJUST_TRAMPOLINE]; x = build_function_call_expr (x, arg); x = init_tmp_var (info, x, &wi->tsi); /* Cast back to the proper function type. */ x = build1 (NOP_EXPR, TREE_TYPE (t), x); x = init_tmp_var (info, x, &wi->tsi); *tp = x; break; case CALL_EXPR: /* Only walk call arguments, lest we generate trampolines for direct calls. */ walk_tree (&TREE_OPERAND (t, 1), convert_tramp_reference, wi, NULL); break; default: if (!DECL_P (t) && !TYPE_P (t)) *walk_subtrees = 1; break; } return NULL_TREE; } /* Called via walk_function+walk_tree, rewrite all CALL_EXPRs that reference nested functions to make sure that the static chain is set up properly for the call. */ static tree convert_call_expr (tree *tp, int *walk_subtrees, void *data) { struct walk_stmt_info *wi = data; struct nesting_info *info = wi->info; tree t = *tp, decl, target_context; *walk_subtrees = 0; switch (TREE_CODE (t)) { case CALL_EXPR: decl = get_callee_fndecl (t); if (!decl) break; target_context = decl_function_context (decl); if (target_context && !DECL_NO_STATIC_CHAIN (decl)) TREE_OPERAND (t, 2) = get_static_chain (info, target_context, &wi->tsi); break; case RETURN_EXPR: case MODIFY_EXPR: /* Only return and modify may contain calls. */ *walk_subtrees = 1; break; default: break; } return NULL_TREE; } /* Walk the nesting tree starting with ROOT, depth first. Convert all trampolines and call expressions. On the way back up, determine if a nested function actually uses its static chain; if not, remember that. */ static void convert_all_function_calls (struct nesting_info *root) { do { if (root->inner) convert_all_function_calls (root->inner); walk_function (convert_tramp_reference, root); walk_function (convert_call_expr, root); /* If the function does not use a static chain, then remember that. */ if (root->outer && !root->chain_decl && !root->chain_field) DECL_NO_STATIC_CHAIN (root->context) = 1; else { #ifdef ENABLE_CHECKING if (DECL_NO_STATIC_CHAIN (root->context)) abort (); #endif } root = root->next; } while (root); } /* Do "everything else" to clean up or complete state collected by the various walking passes -- lay out the types and decls, generate code to initialize the frame decl, store critical expressions in the struct function for rtl to find. */ static void finalize_nesting_tree_1 (struct nesting_info *root) { tree stmt_list = NULL; tree context = root->context; struct function *sf; /* If we created a non-local frame type or decl, we need to lay them out at this time. */ if (root->frame_type) { layout_type (root->frame_type); layout_decl (root->frame_decl, 0); } /* If any parameters were referenced non-locally, then we need to insert a copy. Likewise, if any variables were referenced by pointer, we need to initialize the address. */ if (root->any_parm_remapped) { tree p; for (p = DECL_ARGUMENTS (context); p ; p = TREE_CHAIN (p)) { tree field, x, y; field = lookup_field_for_decl (root, p, NO_INSERT); if (!field) continue; if (use_pointer_in_frame (p)) x = build_addr (p); else x = p; y = build (COMPONENT_REF, TREE_TYPE (field), root->frame_decl, field, NULL_TREE); x = build (MODIFY_EXPR, TREE_TYPE (field), y, x); append_to_statement_list (x, &stmt_list); } } /* If a chain_field was created, then it needs to be initialized from chain_decl. */ if (root->chain_field) { tree x = build (COMPONENT_REF, TREE_TYPE (root->chain_field), root->frame_decl, root->chain_field, NULL_TREE); x = build (MODIFY_EXPR, TREE_TYPE (x), x, get_chain_decl (root)); append_to_statement_list (x, &stmt_list); } /* If trampolines were created, then we need to initialize them. */ if (root->any_tramp_created) { struct nesting_info *i; for (i = root->inner; i ; i = i->next) { tree arg, x, field; field = lookup_tramp_for_decl (root, i->context, NO_INSERT); if (!field) continue; if (DECL_NO_STATIC_CHAIN (i->context)) x = null_pointer_node; else x = build_addr (root->frame_decl); arg = tree_cons (NULL, x, NULL); x = build_addr (i->context); arg = tree_cons (NULL, x, arg); x = build (COMPONENT_REF, TREE_TYPE (field), root->frame_decl, field, NULL_TREE); x = build_addr (x); arg = tree_cons (NULL, x, arg); x = implicit_built_in_decls[BUILT_IN_INIT_TRAMPOLINE]; x = build_function_call_expr (x, arg); append_to_statement_list (x, &stmt_list); } } /* If we created initialization statements, insert them. */ if (stmt_list) { annotate_all_with_locus (&stmt_list, DECL_SOURCE_LOCATION (context)); append_to_statement_list (BIND_EXPR_BODY (DECL_SAVED_TREE (context)), &stmt_list); BIND_EXPR_BODY (DECL_SAVED_TREE (context)) = stmt_list; } /* If a chain_decl was created, then it needs to be registered with struct function so that it gets initialized from the static chain register at the beginning of the function. */ sf = DECL_STRUCT_FUNCTION (root->context); sf->static_chain_decl = root->chain_decl; /* Similarly for the non-local goto save area. */ if (root->nl_goto_field) { sf->nonlocal_goto_save_area = get_frame_field (root, context, root->nl_goto_field, NULL); sf->has_nonlocal_label = 1; } /* Make sure all new local variables get inserted into the proper BIND_EXPR. */ if (root->new_local_var_chain) declare_tmp_vars (root->new_local_var_chain, DECL_SAVED_TREE (root->context)); /* Dump the translated tree function. */ dump_function (TDI_nested, root->context); } static void finalize_nesting_tree (struct nesting_info *root) { do { if (root->inner) finalize_nesting_tree (root->inner); finalize_nesting_tree_1 (root); root = root->next; } while (root); } /* Free the data structures allocated during this pass. */ static void free_nesting_tree (struct nesting_info *root) { struct nesting_info *next; do { if (root->inner) free_nesting_tree (root->inner); htab_delete (root->var_map); next = root->next; free (root); root = next; } while (root); } /* Main entry point for this pass. Process FNDECL and all of its nested subroutines and turn them into something less tightly bound. */ void lower_nested_functions (tree fndecl) { struct nesting_info *root; struct cgraph_node *cgn; /* If there are no nested functions, there's nothing to do. */ cgn = cgraph_node (fndecl); if (!cgn->nested) return; root = create_nesting_tree (cgn); walk_all_functions (convert_nonlocal_reference, root); walk_all_functions (convert_local_reference, root); walk_all_functions (convert_nl_goto_reference, root); walk_all_functions (convert_nl_goto_receiver, root); convert_all_function_calls (root); finalize_nesting_tree (root); free_nesting_tree (root); } #include "gt-tree-nested.h"