diff options
Diffstat (limited to 'gcc/cfgexpand.c')
| -rw-r--r-- | gcc/cfgexpand.c | 471 |
1 files changed, 354 insertions, 117 deletions
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c index 7df9d06..0bc20f6 100644 --- a/gcc/cfgexpand.c +++ b/gcc/cfgexpand.c @@ -97,6 +97,8 @@ gimple currently_expanding_gimple_stmt; static rtx expand_debug_expr (tree); +static bool defer_stack_allocation (tree, bool); + /* Return an expression tree corresponding to the RHS of GIMPLE statement STMT. */ @@ -150,21 +152,149 @@ gimple_assign_rhs_to_tree (gimple stmt) #define SSAVAR(x) (TREE_CODE (x) == SSA_NAME ? SSA_NAME_VAR (x) : x) +/* Choose either CUR or NEXT as the leader DECL for a partition. + Prefer ignored decls, to simplify debug dumps and reduce ambiguity + out of the same user variable being in multiple partitions (this is + less likely for compiler-introduced temps). */ + +static tree +leader_merge (tree cur, tree next) +{ + if (cur == NULL || cur == next) + return next; + + if (DECL_P (cur) && DECL_IGNORED_P (cur)) + return cur; + + if (DECL_P (next) && DECL_IGNORED_P (next)) + return next; + + return cur; +} + +/* Return true if VAR is a PARM_DECL or a RESULT_DECL of type BLKmode. + Such parameters are likely passed as a pointer to the value, rather + than as a value, and so we must not coalesce them, nor allocate + stack space for them before determining the calling conventions for + them. For their SSA_NAMEs, expand_one_ssa_partition emits RTL as + MEMs with pc_rtx as the address, and then it replaces the pc_rtx + with NULL so as to make sure the MEM is not used before it is + adjusted in assign_parm_setup_reg. */ + +bool +parm_maybe_byref_p (tree var) +{ + if (!var || VAR_P (var)) + return false; + + gcc_assert (TREE_CODE (var) == PARM_DECL + || TREE_CODE (var) == RESULT_DECL); + + return TYPE_MODE (TREE_TYPE (var)) == BLKmode; +} + +/* Return the partition of the default SSA_DEF for decl VAR. */ + +static int +ssa_default_def_partition (tree var) +{ + tree name = ssa_default_def (cfun, var); + + if (!name) + return NO_PARTITION; + + return var_to_partition (SA.map, name); +} + +/* Return the RTL for the default SSA def of a PARM or RESULT, if + there is one. */ + +rtx +get_rtl_for_parm_ssa_default_def (tree var) +{ + gcc_assert (TREE_CODE (var) == PARM_DECL || TREE_CODE (var) == RESULT_DECL); + + if (!is_gimple_reg (var)) + return NULL_RTX; + + /* If we've already determined RTL for the decl, use it. This is + not just an optimization: if VAR is a PARM whose incoming value + is unused, we won't find a default def to use its partition, but + we still want to use the location of the parm, if it was used at + all. During assign_parms, until a location is assigned for the + VAR, RTL can only for a parm or result if we're not coalescing + across variables, when we know we're coalescing all SSA_NAMEs of + each parm or result, and we're not coalescing them with names + pertaining to other variables, such as other parms' default + defs. */ + if (DECL_RTL_SET_P (var)) + { + gcc_assert (DECL_RTL (var) != pc_rtx); + return DECL_RTL (var); + } + + int part = ssa_default_def_partition (var); + if (part == NO_PARTITION) + return NULL_RTX; + + return SA.partition_to_pseudo[part]; +} + /* Associate declaration T with storage space X. If T is no SSA name this is exactly SET_DECL_RTL, otherwise make the partition of T associated with X. */ static inline void set_rtl (tree t, rtx x) { + if (x && SSAVAR (t)) + { + bool skip = false; + tree cur = NULL_TREE; + + if (MEM_P (x)) + cur = MEM_EXPR (x); + else if (REG_P (x)) + cur = REG_EXPR (x); + else if (GET_CODE (x) == CONCAT + && REG_P (XEXP (x, 0))) + cur = REG_EXPR (XEXP (x, 0)); + else if (GET_CODE (x) == PARALLEL) + cur = REG_EXPR (XVECEXP (x, 0, 0)); + else if (x == pc_rtx) + skip = true; + else + gcc_unreachable (); + + tree next = skip ? cur : leader_merge (cur, SSAVAR (t)); + + if (cur != next) + { + if (MEM_P (x)) + set_mem_attributes (x, next, true); + else + set_reg_attrs_for_decl_rtl (next, x); + } + } + if (TREE_CODE (t) == SSA_NAME) { - SA.partition_to_pseudo[var_to_partition (SA.map, t)] = x; - if (x && !MEM_P (x)) - set_reg_attrs_for_decl_rtl (SSA_NAME_VAR (t), x); - /* For the benefit of debug information at -O0 (where vartracking - doesn't run) record the place also in the base DECL if it's - a normal variable (not a parameter). */ - if (x && x != pc_rtx && TREE_CODE (SSA_NAME_VAR (t)) == VAR_DECL) + int part = var_to_partition (SA.map, t); + if (part != NO_PARTITION) + { + if (SA.partition_to_pseudo[part]) + gcc_assert (SA.partition_to_pseudo[part] == x); + else if (x != pc_rtx) + SA.partition_to_pseudo[part] = x; + } + /* For the benefit of debug information at -O0 (where + vartracking doesn't run) record the place also in the base + DECL. For PARMs and RESULTs, we may end up resetting these + in function.c:maybe_reset_rtl_for_parm, but in some rare + cases we may need them (unused and overwritten incoming + value, that at -O0 must share the location with the other + uses in spite of the missing default def), and this may be + the only chance to preserve them. */ + if (x && x != pc_rtx && SSA_NAME_VAR (t)) { tree var = SSA_NAME_VAR (t); /* If we don't yet have something recorded, just record it now. */ @@ -248,8 +378,15 @@ static bool has_short_buffer; static unsigned int align_local_variable (tree decl) { - unsigned int align = LOCAL_DECL_ALIGNMENT (decl); - DECL_ALIGN (decl) = align; + unsigned int align; + + if (TREE_CODE (decl) == SSA_NAME) + align = TYPE_ALIGN (TREE_TYPE (decl)); + else + { + align = LOCAL_DECL_ALIGNMENT (decl); + DECL_ALIGN (decl) = align; + } return align / BITS_PER_UNIT; } @@ -315,12 +452,15 @@ add_stack_var (tree decl) decl_to_stack_part->put (decl, stack_vars_num); v->decl = decl; - v->size = tree_to_uhwi (DECL_SIZE_UNIT (SSAVAR (decl))); + tree size = TREE_CODE (decl) == SSA_NAME + ? TYPE_SIZE_UNIT (TREE_TYPE (decl)) + : DECL_SIZE_UNIT (decl); + v->size = tree_to_uhwi (size); /* Ensure that all variables have size, so that &a != &b for any two variables that are simultaneously live. */ if (v->size == 0) v->size = 1; - v->alignb = align_local_variable (SSAVAR (decl)); + v->alignb = align_local_variable (decl); /* An alignment of zero can mightily confuse us later. */ gcc_assert (v->alignb != 0); @@ -862,7 +1002,9 @@ expand_one_stack_var_at (tree decl, rtx base, unsigned base_align, gcc_assert (offset == trunc_int_for_mode (offset, Pmode)); x = plus_constant (Pmode, base, offset); - x = gen_rtx_MEM (DECL_MODE (SSAVAR (decl)), x); + x = gen_rtx_MEM (TREE_CODE (decl) == SSA_NAME + ? TYPE_MODE (TREE_TYPE (decl)) + : DECL_MODE (SSAVAR (decl)), x); if (TREE_CODE (decl) != SSA_NAME) { @@ -884,7 +1026,6 @@ expand_one_stack_var_at (tree decl, rtx base, unsigned base_align, DECL_USER_ALIGN (decl) = 0; } - set_mem_attributes (x, SSAVAR (decl), true); set_rtl (decl, x); } @@ -950,9 +1091,9 @@ expand_stack_vars (bool (*pred) (size_t), struct stack_vars_data *data) /* Skip variables that have already had rtl assigned. See also add_stack_var where we perpetrate this pc_rtx hack. */ decl = stack_vars[i].decl; - if ((TREE_CODE (decl) == SSA_NAME - ? SA.partition_to_pseudo[var_to_partition (SA.map, decl)] - : DECL_RTL (decl)) != pc_rtx) + if (TREE_CODE (decl) == SSA_NAME + ? SA.partition_to_pseudo[var_to_partition (SA.map, decl)] != NULL_RTX + : DECL_RTL (decl) != pc_rtx) continue; large_size += alignb - 1; @@ -981,9 +1122,9 @@ expand_stack_vars (bool (*pred) (size_t), struct stack_vars_data *data) /* Skip variables that have already had rtl assigned. See also add_stack_var where we perpetrate this pc_rtx hack. */ decl = stack_vars[i].decl; - if ((TREE_CODE (decl) == SSA_NAME - ? SA.partition_to_pseudo[var_to_partition (SA.map, decl)] - : DECL_RTL (decl)) != pc_rtx) + if (TREE_CODE (decl) == SSA_NAME + ? SA.partition_to_pseudo[var_to_partition (SA.map, decl)] != NULL_RTX + : DECL_RTL (decl) != pc_rtx) continue; /* Check the predicate to see whether this variable should be @@ -1099,13 +1240,22 @@ account_stack_vars (void) to a variable to be allocated in the stack frame. */ static void -expand_one_stack_var (tree var) +expand_one_stack_var_1 (tree var) { HOST_WIDE_INT size, offset; unsigned byte_align; - size = tree_to_uhwi (DECL_SIZE_UNIT (SSAVAR (var))); - byte_align = align_local_variable (SSAVAR (var)); + if (TREE_CODE (var) == SSA_NAME) + { + tree type = TREE_TYPE (var); + size = tree_to_uhwi (TYPE_SIZE_UNIT (type)); + byte_align = TYPE_ALIGN_UNIT (type); + } + else + { + size = tree_to_uhwi (DECL_SIZE_UNIT (var)); + byte_align = align_local_variable (var); + } /* We handle highly aligned variables in expand_stack_vars. */ gcc_assert (byte_align * BITS_PER_UNIT <= MAX_SUPPORTED_STACK_ALIGNMENT); @@ -1116,6 +1266,27 @@ expand_one_stack_var (tree var) crtl->max_used_stack_slot_alignment, offset); } +/* Wrapper for expand_one_stack_var_1 that checks SSA_NAMEs are + already assigned some MEM. */ + +static void +expand_one_stack_var (tree var) +{ + if (TREE_CODE (var) == SSA_NAME) + { + int part = var_to_partition (SA.map, var); + if (part != NO_PARTITION) + { + rtx x = SA.partition_to_pseudo[part]; + gcc_assert (x); + gcc_assert (MEM_P (x)); + return; + } + } + + return expand_one_stack_var_1 (var); +} + /* A subroutine of expand_one_var. Called to assign rtl to a VAR_DECL that will reside in a hard register. */ @@ -1125,13 +1296,136 @@ expand_one_hard_reg_var (tree var) rest_of_decl_compilation (var, 0, 0); } +/* Record the alignment requirements of some variable assigned to a + pseudo. */ + +static void +record_alignment_for_reg_var (unsigned int align) +{ + if (SUPPORTS_STACK_ALIGNMENT + && crtl->stack_alignment_estimated < align) + { + /* stack_alignment_estimated shouldn't change after stack + realign decision made */ + gcc_assert (!crtl->stack_realign_processed); + crtl->stack_alignment_estimated = align; + } + + /* stack_alignment_needed > PREFERRED_STACK_BOUNDARY is permitted. + So here we only make sure stack_alignment_needed >= align. */ + if (crtl->stack_alignment_needed < align) + crtl->stack_alignment_needed = align; + if (crtl->max_used_stack_slot_alignment < align) + crtl->max_used_stack_slot_alignment = align; +} + +/* Create RTL for an SSA partition. */ + +static void +expand_one_ssa_partition (tree var) +{ + int part = var_to_partition (SA.map, var); + gcc_assert (part != NO_PARTITION); + + if (SA.partition_to_pseudo[part]) + return; + + unsigned int align = MINIMUM_ALIGNMENT (TREE_TYPE (var), + TYPE_MODE (TREE_TYPE (var)), + TYPE_ALIGN (TREE_TYPE (var))); + + /* If the variable alignment is very large we'll dynamicaly allocate + it, which means that in-frame portion is just a pointer. */ + if (align > MAX_SUPPORTED_STACK_ALIGNMENT) + align = POINTER_SIZE; + + record_alignment_for_reg_var (align); + + if (!use_register_for_decl (var)) + { + if (parm_maybe_byref_p (SSA_NAME_VAR (var)) + && ssa_default_def_partition (SSA_NAME_VAR (var)) == part) + { + expand_one_stack_var_at (var, pc_rtx, 0, 0); + rtx x = SA.partition_to_pseudo[part]; + gcc_assert (GET_CODE (x) == MEM); + gcc_assert (GET_MODE (x) == BLKmode); + gcc_assert (XEXP (x, 0) == pc_rtx); + /* Reset the address, so that any attempt to use it will + ICE. It will be adjusted in assign_parm_setup_reg. */ + XEXP (x, 0) = NULL_RTX; + } + else if (defer_stack_allocation (var, true)) + add_stack_var (var); + else + expand_one_stack_var_1 (var); + return; + } + + machine_mode reg_mode = promote_ssa_mode (var, NULL); + + rtx x = gen_reg_rtx (reg_mode); + + set_rtl (var, x); +} + +/* Record the association between the RTL generated for a partition + and the underlying variable of the SSA_NAME. */ + +static void +adjust_one_expanded_partition_var (tree var) +{ + if (!var) + return; + + tree decl = SSA_NAME_VAR (var); + + int part = var_to_partition (SA.map, var); + if (part == NO_PARTITION) + return; + + rtx x = SA.partition_to_pseudo[part]; + + if (!x) + { + /* This var will get a stack slot later. */ + gcc_assert (defer_stack_allocation (var, true)); + return; + } + + set_rtl (var, x); + + if (!REG_P (x)) + return; + + /* Note if the object is a user variable. */ + if (decl && !DECL_ARTIFICIAL (decl)) + mark_user_reg (x); + + if (POINTER_TYPE_P (decl ? TREE_TYPE (decl) : TREE_TYPE (var))) + mark_reg_pointer (x, get_pointer_alignment (var)); +} + /* A subroutine of expand_one_var. Called to assign rtl to a VAR_DECL that will reside in a pseudo register. */ static void expand_one_register_var (tree var) { - tree decl = SSAVAR (var); + if (TREE_CODE (var) == SSA_NAME) + { + int part = var_to_partition (SA.map, var); + if (part != NO_PARTITION) + { + rtx x = SA.partition_to_pseudo[part]; + gcc_assert (x); + gcc_assert (REG_P (x)); + return; + } + gcc_unreachable (); + } + + tree decl = var; tree type = TREE_TYPE (decl); machine_mode reg_mode = promote_decl_mode (decl, NULL); rtx x = gen_reg_rtx (reg_mode); @@ -1177,10 +1471,14 @@ expand_one_error_var (tree var) static bool defer_stack_allocation (tree var, bool toplevel) { + tree size_unit = TREE_CODE (var) == SSA_NAME + ? TYPE_SIZE_UNIT (TREE_TYPE (var)) + : DECL_SIZE_UNIT (var); + /* Whether the variable is small enough for immediate allocation not to be a problem with regard to the frame size. */ bool smallish - = ((HOST_WIDE_INT) tree_to_uhwi (DECL_SIZE_UNIT (var)) + = ((HOST_WIDE_INT) tree_to_uhwi (size_unit) < PARAM_VALUE (PARAM_MIN_SIZE_FOR_STACK_SHARING)); /* If stack protection is enabled, *all* stack variables must be deferred, @@ -1189,16 +1487,24 @@ defer_stack_allocation (tree var, bool toplevel) if (flag_stack_protect || ((flag_sanitize & SANITIZE_ADDRESS) && ASAN_STACK)) return true; + unsigned int align = TREE_CODE (var) == SSA_NAME + ? TYPE_ALIGN (TREE_TYPE (var)) + : DECL_ALIGN (var); + /* We handle "large" alignment via dynamic allocation. We want to handle this extra complication in only one place, so defer them. */ - if (DECL_ALIGN (var) > MAX_SUPPORTED_STACK_ALIGNMENT) + if (align > MAX_SUPPORTED_STACK_ALIGNMENT) return true; + bool ignored = TREE_CODE (var) == SSA_NAME + ? !SSAVAR (var) || DECL_IGNORED_P (SSA_NAME_VAR (var)) + : DECL_IGNORED_P (var); + /* When optimization is enabled, DECL_IGNORED_P variables originally scoped might be detached from their block and appear at toplevel when we reach here. We want to coalesce them with variables from other blocks when the immediate contribution to the frame size would be noticeable. */ - if (toplevel && optimize > 0 && DECL_IGNORED_P (var) && !smallish) + if (toplevel && optimize > 0 && ignored && !smallish) return true; /* Variables declared in the outermost scope automatically conflict @@ -1265,21 +1571,7 @@ expand_one_var (tree var, bool toplevel, bool really_expand) align = POINTER_SIZE; } - if (SUPPORTS_STACK_ALIGNMENT - && crtl->stack_alignment_estimated < align) - { - /* stack_alignment_estimated shouldn't change after stack - realign decision made */ - gcc_assert (!crtl->stack_realign_processed); - crtl->stack_alignment_estimated = align; - } - - /* stack_alignment_needed > PREFERRED_STACK_BOUNDARY is permitted. - So here we only make sure stack_alignment_needed >= align. */ - if (crtl->stack_alignment_needed < align) - crtl->stack_alignment_needed = align; - if (crtl->max_used_stack_slot_alignment < align) - crtl->max_used_stack_slot_alignment = align; + record_alignment_for_reg_var (align); if (TREE_CODE (origvar) == SSA_NAME) { @@ -1722,48 +2014,18 @@ expand_used_vars (void) if (targetm.use_pseudo_pic_reg ()) pic_offset_table_rtx = gen_reg_rtx (Pmode); - hash_map<tree, tree> ssa_name_decls; for (i = 0; i < SA.map->num_partitions; i++) { tree var = partition_to_var (SA.map, i); gcc_assert (!virtual_operand_p (var)); - /* Assign decls to each SSA name partition, share decls for partitions - we could have coalesced (those with the same type). */ - if (SSA_NAME_VAR (var) == NULL_TREE) - { - tree *slot = &ssa_name_decls.get_or_insert (TREE_TYPE (var)); - if (!*slot) - *slot = create_tmp_reg (TREE_TYPE (var)); - replace_ssa_name_symbol (var, *slot); - } - - /* Always allocate space for partitions based on VAR_DECLs. But for - those based on PARM_DECLs or RESULT_DECLs and which matter for the - debug info, there is no need to do so if optimization is disabled - because all the SSA_NAMEs based on these DECLs have been coalesced - into a single partition, which is thus assigned the canonical RTL - location of the DECLs. If in_lto_p, we can't rely on optimize, - a function could be compiled with -O1 -flto first and only the - link performed at -O0. */ - if (TREE_CODE (SSA_NAME_VAR (var)) == VAR_DECL) - expand_one_var (var, true, true); - else if (DECL_IGNORED_P (SSA_NAME_VAR (var)) || optimize || in_lto_p) - { - /* This is a PARM_DECL or RESULT_DECL. For those partitions that - contain the default def (representing the parm or result itself) - we don't do anything here. But those which don't contain the - default def (representing a temporary based on the parm/result) - we need to allocate space just like for normal VAR_DECLs. */ - if (!bitmap_bit_p (SA.partition_has_default_def, i)) - { - expand_one_var (var, true, true); - gcc_assert (SA.partition_to_pseudo[i]); - } - } + expand_one_ssa_partition (var); } + for (i = 1; i < num_ssa_names; i++) + adjust_one_expanded_partition_var (ssa_name (i)); + if (flag_stack_protect == SPCT_FLAG_STRONG) gen_stack_protect_signal = stack_protect_decl_p () || stack_protect_return_slot_p (); @@ -5928,35 +6190,6 @@ pass_expand::execute (function *fun) parm_birth_insn = var_seq; } - /* Now that we also have the parameter RTXs, copy them over to our - partitions. */ - for (i = 0; i < SA.map->num_partitions; i++) - { - tree var = SSA_NAME_VAR (partition_to_var (SA.map, i)); - - if (TREE_CODE (var) != VAR_DECL - && !SA.partition_to_pseudo[i]) - SA.partition_to_pseudo[i] = DECL_RTL_IF_SET (var); - gcc_assert (SA.partition_to_pseudo[i]); - - /* If this decl was marked as living in multiple places, reset - this now to NULL. */ - if (DECL_RTL_IF_SET (var) == pc_rtx) - SET_DECL_RTL (var, NULL); - - /* Some RTL parts really want to look at DECL_RTL(x) when x - was a decl marked in REG_ATTR or MEM_ATTR. We could use - SET_DECL_RTL here making this available, but that would mean - to select one of the potentially many RTLs for one DECL. Instead - of doing that we simply reset the MEM_EXPR of the RTL in question, - then nobody can get at it and hence nobody can call DECL_RTL on it. */ - if (!DECL_RTL_SET_P (var)) - { - if (MEM_P (SA.partition_to_pseudo[i])) - set_mem_expr (SA.partition_to_pseudo[i], NULL); - } - } - /* If we have a class containing differently aligned pointers we need to merge those into the corresponding RTL pointer alignment. */ @@ -5964,7 +6197,6 @@ pass_expand::execute (function *fun) { tree name = ssa_name (i); int part; - rtx r; if (!name /* We might have generated new SSA names in @@ -5977,20 +6209,25 @@ pass_expand::execute (function *fun) if (part == NO_PARTITION) continue; - /* Adjust all partition members to get the underlying decl of - the representative which we might have created in expand_one_var. */ - if (SSA_NAME_VAR (name) == NULL_TREE) + gcc_assert (SA.partition_to_pseudo[part] + || defer_stack_allocation (name, true)); + + /* If this decl was marked as living in multiple places, reset + this now to NULL. */ + tree var = SSA_NAME_VAR (name); + if (var && DECL_RTL_IF_SET (var) == pc_rtx) + SET_DECL_RTL (var, NULL); + /* Check that the pseudos chosen by assign_parms are those of + the corresponding default defs. */ + else if (SSA_NAME_IS_DEFAULT_DEF (name) + && (TREE_CODE (var) == PARM_DECL + || TREE_CODE (var) == RESULT_DECL)) { - tree leader = partition_to_var (SA.map, part); - gcc_assert (SSA_NAME_VAR (leader) != NULL_TREE); - replace_ssa_name_symbol (name, SSA_NAME_VAR (leader)); + rtx in = DECL_RTL_IF_SET (var); + gcc_assert (in); + rtx out = SA.partition_to_pseudo[part]; + gcc_assert (in == out || rtx_equal_p (in, out)); } - if (!POINTER_TYPE_P (TREE_TYPE (name))) - continue; - - r = SA.partition_to_pseudo[part]; - if (REG_P (r)) - mark_reg_pointer (r, get_pointer_alignment (name)); } /* If this function is `main', emit a call to `__main' |