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Diffstat (limited to 'gcc/tree-ssa.c')
| -rw-r--r-- | gcc/tree-ssa.c | 2255 |
1 files changed, 2255 insertions, 0 deletions
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c new file mode 100644 index 000000000..ad2d6c237 --- /dev/null +++ b/gcc/tree-ssa.c @@ -0,0 +1,2255 @@ +/* Miscellaneous SSA utility functions. + Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011 + 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 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 "tm.h" +#include "tree.h" +#include "flags.h" +#include "tm_p.h" +#include "target.h" +#include "ggc.h" +#include "langhooks.h" +#include "basic-block.h" +#include "output.h" +#include "function.h" +#include "tree-pretty-print.h" +#include "gimple-pretty-print.h" +#include "bitmap.h" +#include "pointer-set.h" +#include "tree-flow.h" +#include "gimple.h" +#include "tree-inline.h" +#include "timevar.h" +#include "hashtab.h" +#include "tree-dump.h" +#include "tree-pass.h" +#include "diagnostic-core.h" +#include "cfgloop.h" + +/* Pointer map of variable mappings, keyed by edge. */ +static struct pointer_map_t *edge_var_maps; + + +/* Add a mapping with PHI RESULT and PHI DEF associated with edge E. */ + +void +redirect_edge_var_map_add (edge e, tree result, tree def, source_location locus) +{ + void **slot; + edge_var_map_vector old_head, head; + edge_var_map new_node; + + if (edge_var_maps == NULL) + edge_var_maps = pointer_map_create (); + + slot = pointer_map_insert (edge_var_maps, e); + old_head = head = (edge_var_map_vector) *slot; + if (!head) + { + head = VEC_alloc (edge_var_map, heap, 5); + *slot = head; + } + new_node.def = def; + new_node.result = result; + new_node.locus = locus; + + VEC_safe_push (edge_var_map, heap, head, &new_node); + if (old_head != head) + { + /* The push did some reallocation. Update the pointer map. */ + *slot = head; + } +} + + +/* Clear the var mappings in edge E. */ + +void +redirect_edge_var_map_clear (edge e) +{ + void **slot; + edge_var_map_vector head; + + if (!edge_var_maps) + return; + + slot = pointer_map_contains (edge_var_maps, e); + + if (slot) + { + head = (edge_var_map_vector) *slot; + VEC_free (edge_var_map, heap, head); + *slot = NULL; + } +} + + +/* Duplicate the redirected var mappings in OLDE in NEWE. + + Since we can't remove a mapping, let's just duplicate it. This assumes a + pointer_map can have multiple edges mapping to the same var_map (many to + one mapping), since we don't remove the previous mappings. */ + +void +redirect_edge_var_map_dup (edge newe, edge olde) +{ + void **new_slot, **old_slot; + edge_var_map_vector head; + + if (!edge_var_maps) + return; + + new_slot = pointer_map_insert (edge_var_maps, newe); + old_slot = pointer_map_contains (edge_var_maps, olde); + if (!old_slot) + return; + head = (edge_var_map_vector) *old_slot; + + if (head) + *new_slot = VEC_copy (edge_var_map, heap, head); + else + *new_slot = VEC_alloc (edge_var_map, heap, 5); +} + + +/* Return the variable mappings for a given edge. If there is none, return + NULL. */ + +edge_var_map_vector +redirect_edge_var_map_vector (edge e) +{ + void **slot; + + /* Hey, what kind of idiot would... you'd be surprised. */ + if (!edge_var_maps) + return NULL; + + slot = pointer_map_contains (edge_var_maps, e); + if (!slot) + return NULL; + + return (edge_var_map_vector) *slot; +} + +/* Used by redirect_edge_var_map_destroy to free all memory. */ + +static bool +free_var_map_entry (const void *key ATTRIBUTE_UNUSED, + void **value, + void *data ATTRIBUTE_UNUSED) +{ + edge_var_map_vector head = (edge_var_map_vector) *value; + VEC_free (edge_var_map, heap, head); + return true; +} + +/* Clear the edge variable mappings. */ + +void +redirect_edge_var_map_destroy (void) +{ + if (edge_var_maps) + { + pointer_map_traverse (edge_var_maps, free_var_map_entry, NULL); + pointer_map_destroy (edge_var_maps); + edge_var_maps = NULL; + } +} + + +/* Remove the corresponding arguments from the PHI nodes in E's + destination block and redirect it to DEST. Return redirected edge. + The list of removed arguments is stored in a vector accessed + through edge_var_maps. */ + +edge +ssa_redirect_edge (edge e, basic_block dest) +{ + gimple_stmt_iterator gsi; + gimple phi; + + redirect_edge_var_map_clear (e); + + /* Remove the appropriate PHI arguments in E's destination block. */ + for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) + { + tree def; + source_location locus ; + + phi = gsi_stmt (gsi); + def = gimple_phi_arg_def (phi, e->dest_idx); + locus = gimple_phi_arg_location (phi, e->dest_idx); + + if (def == NULL_TREE) + continue; + + redirect_edge_var_map_add (e, gimple_phi_result (phi), def, locus); + } + + e = redirect_edge_succ_nodup (e, dest); + + return e; +} + + +/* Add PHI arguments queued in PENDING_STMT list on edge E to edge + E->dest. */ + +void +flush_pending_stmts (edge e) +{ + gimple phi; + edge_var_map_vector v; + edge_var_map *vm; + int i; + gimple_stmt_iterator gsi; + + v = redirect_edge_var_map_vector (e); + if (!v) + return; + + for (gsi = gsi_start_phis (e->dest), i = 0; + !gsi_end_p (gsi) && VEC_iterate (edge_var_map, v, i, vm); + gsi_next (&gsi), i++) + { + tree def; + + phi = gsi_stmt (gsi); + def = redirect_edge_var_map_def (vm); + add_phi_arg (phi, def, e, redirect_edge_var_map_location (vm)); + } + + redirect_edge_var_map_clear (e); +} + +/* Given a tree for an expression for which we might want to emit + locations or values in debug information (generally a variable, but + we might deal with other kinds of trees in the future), return the + tree that should be used as the variable of a DEBUG_BIND STMT or + VAR_LOCATION INSN or NOTE. Return NULL if VAR is not to be tracked. */ + +tree +target_for_debug_bind (tree var) +{ + if (!MAY_HAVE_DEBUG_STMTS) + return NULL_TREE; + + if (TREE_CODE (var) != VAR_DECL + && TREE_CODE (var) != PARM_DECL) + return NULL_TREE; + + if (DECL_HAS_VALUE_EXPR_P (var)) + return target_for_debug_bind (DECL_VALUE_EXPR (var)); + + if (DECL_IGNORED_P (var)) + return NULL_TREE; + + if (!is_gimple_reg (var)) + return NULL_TREE; + + return var; +} + +/* Called via walk_tree, look for SSA_NAMEs that have already been + released. */ + +static tree +find_released_ssa_name (tree *tp, int *walk_subtrees, void *data_) +{ + struct walk_stmt_info *wi = (struct walk_stmt_info *) data_; + + if (wi && wi->is_lhs) + return NULL_TREE; + + if (TREE_CODE (*tp) == SSA_NAME) + { + if (SSA_NAME_IN_FREE_LIST (*tp)) + return *tp; + + *walk_subtrees = 0; + } + else if (IS_TYPE_OR_DECL_P (*tp)) + *walk_subtrees = 0; + + return NULL_TREE; +} + +/* Insert a DEBUG BIND stmt before the DEF of VAR if VAR is referenced + by other DEBUG stmts, and replace uses of the DEF with the + newly-created debug temp. */ + +void +insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var) +{ + imm_use_iterator imm_iter; + use_operand_p use_p; + gimple stmt; + gimple def_stmt = NULL; + int usecount = 0; + tree value = NULL; + + if (!MAY_HAVE_DEBUG_STMTS) + return; + + /* If this name has already been registered for replacement, do nothing + as anything that uses this name isn't in SSA form. */ + if (name_registered_for_update_p (var)) + return; + + /* Check whether there are debug stmts that reference this variable and, + if there are, decide whether we should use a debug temp. */ + FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var) + { + stmt = USE_STMT (use_p); + + if (!gimple_debug_bind_p (stmt)) + continue; + + if (usecount++) + break; + + if (gimple_debug_bind_get_value (stmt) != var) + { + /* Count this as an additional use, so as to make sure we + use a temp unless VAR's definition has a SINGLE_RHS that + can be shared. */ + usecount++; + break; + } + } + + if (!usecount) + return; + + if (gsi) + def_stmt = gsi_stmt (*gsi); + else + def_stmt = SSA_NAME_DEF_STMT (var); + + /* If we didn't get an insertion point, and the stmt has already + been removed, we won't be able to insert the debug bind stmt, so + we'll have to drop debug information. */ + if (gimple_code (def_stmt) == GIMPLE_PHI) + { + value = degenerate_phi_result (def_stmt); + if (value && walk_tree (&value, find_released_ssa_name, NULL, NULL)) + value = NULL; + /* error_mark_node is what fixup_noreturn_call changes PHI arguments + to. */ + else if (value == error_mark_node) + value = NULL; + } + else if (is_gimple_assign (def_stmt)) + { + bool no_value = false; + + if (!dom_info_available_p (CDI_DOMINATORS)) + { + struct walk_stmt_info wi; + + memset (&wi, 0, sizeof (wi)); + + /* When removing blocks without following reverse dominance + order, we may sometimes encounter SSA_NAMEs that have + already been released, referenced in other SSA_DEFs that + we're about to release. Consider: + + <bb X>: + v_1 = foo; + + <bb Y>: + w_2 = v_1 + bar; + # DEBUG w => w_2 + + If we deleted BB X first, propagating the value of w_2 + won't do us any good. It's too late to recover their + original definition of v_1: when it was deleted, it was + only referenced in other DEFs, it couldn't possibly know + it should have been retained, and propagating every + single DEF just in case it might have to be propagated + into a DEBUG STMT would probably be too wasteful. + + When dominator information is not readily available, we + check for and accept some loss of debug information. But + if it is available, there's no excuse for us to remove + blocks in the wrong order, so we don't even check for + dead SSA NAMEs. SSA verification shall catch any + errors. */ + if ((!gsi && !gimple_bb (def_stmt)) + || walk_gimple_op (def_stmt, find_released_ssa_name, &wi)) + no_value = true; + } + + if (!no_value) + value = gimple_assign_rhs_to_tree (def_stmt); + } + + if (value) + { + /* If there's a single use of VAR, and VAR is the entire debug + expression (usecount would have been incremented again + otherwise), and the definition involves only constants and + SSA names, then we can propagate VALUE into this single use, + avoiding the temp. + + We can also avoid using a temp if VALUE can be shared and + propagated into all uses, without generating expressions that + wouldn't be valid gimple RHSs. + + Other cases that would require unsharing or non-gimple RHSs + are deferred to a debug temp, although we could avoid temps + at the expense of duplication of expressions. */ + + if (CONSTANT_CLASS_P (value) + || gimple_code (def_stmt) == GIMPLE_PHI + || (usecount == 1 + && (!gimple_assign_single_p (def_stmt) + || is_gimple_min_invariant (value))) + || is_gimple_reg (value)) + value = unshare_expr (value); + else + { + gimple def_temp; + tree vexpr = make_node (DEBUG_EXPR_DECL); + + def_temp = gimple_build_debug_bind (vexpr, + unshare_expr (value), + def_stmt); + + DECL_ARTIFICIAL (vexpr) = 1; + TREE_TYPE (vexpr) = TREE_TYPE (value); + if (DECL_P (value)) + DECL_MODE (vexpr) = DECL_MODE (value); + else + DECL_MODE (vexpr) = TYPE_MODE (TREE_TYPE (value)); + + if (gsi) + gsi_insert_before (gsi, def_temp, GSI_SAME_STMT); + else + { + gimple_stmt_iterator ngsi = gsi_for_stmt (def_stmt); + gsi_insert_before (&ngsi, def_temp, GSI_SAME_STMT); + } + + value = vexpr; + } + } + + FOR_EACH_IMM_USE_STMT (stmt, imm_iter, var) + { + if (!gimple_debug_bind_p (stmt)) + continue; + + if (value) + { + FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter) + /* unshare_expr is not needed here. vexpr is either a + SINGLE_RHS, that can be safely shared, some other RHS + that was unshared when we found it had a single debug + use, or a DEBUG_EXPR_DECL, that can be safely + shared. */ + SET_USE (use_p, value); + /* If we didn't replace uses with a debug decl fold the + resulting expression. Otherwise we end up with invalid IL. */ + if (TREE_CODE (value) != DEBUG_EXPR_DECL) + fold_stmt_inplace (stmt); + } + else + gimple_debug_bind_reset_value (stmt); + + update_stmt (stmt); + } +} + + +/* Insert a DEBUG BIND stmt before STMT for each DEF referenced by + other DEBUG stmts, and replace uses of the DEF with the + newly-created debug temp. */ + +void +insert_debug_temps_for_defs (gimple_stmt_iterator *gsi) +{ + gimple stmt; + ssa_op_iter op_iter; + def_operand_p def_p; + + if (!MAY_HAVE_DEBUG_STMTS) + return; + + stmt = gsi_stmt (*gsi); + + FOR_EACH_PHI_OR_STMT_DEF (def_p, stmt, op_iter, SSA_OP_DEF) + { + tree var = DEF_FROM_PTR (def_p); + + if (TREE_CODE (var) != SSA_NAME) + continue; + + insert_debug_temp_for_var_def (gsi, var); + } +} + +/* Reset all debug stmts that use SSA_NAME(s) defined in STMT. */ + +void +reset_debug_uses (gimple stmt) +{ + ssa_op_iter op_iter; + def_operand_p def_p; + imm_use_iterator imm_iter; + gimple use_stmt; + + if (!MAY_HAVE_DEBUG_STMTS) + return; + + FOR_EACH_PHI_OR_STMT_DEF (def_p, stmt, op_iter, SSA_OP_DEF) + { + tree var = DEF_FROM_PTR (def_p); + + if (TREE_CODE (var) != SSA_NAME) + continue; + + FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, var) + { + if (!gimple_debug_bind_p (use_stmt)) + continue; + + gimple_debug_bind_reset_value (use_stmt); + update_stmt (use_stmt); + } + } +} + +/* Delete SSA DEFs for SSA versions in the TOREMOVE bitmap, removing + dominated stmts before their dominators, so that release_ssa_defs + stands a chance of propagating DEFs into debug bind stmts. */ + +void +release_defs_bitset (bitmap toremove) +{ + unsigned j; + bitmap_iterator bi; + + /* Performing a topological sort is probably overkill, this will + most likely run in slightly superlinear time, rather than the + pathological quadratic worst case. */ + while (!bitmap_empty_p (toremove)) + EXECUTE_IF_SET_IN_BITMAP (toremove, 0, j, bi) + { + bool remove_now = true; + tree var = ssa_name (j); + gimple stmt; + imm_use_iterator uit; + + FOR_EACH_IMM_USE_STMT (stmt, uit, var) + { + ssa_op_iter dit; + def_operand_p def_p; + + /* We can't propagate PHI nodes into debug stmts. */ + if (gimple_code (stmt) == GIMPLE_PHI + || is_gimple_debug (stmt)) + continue; + + /* If we find another definition to remove that uses + the one we're looking at, defer the removal of this + one, so that it can be propagated into debug stmts + after the other is. */ + FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, dit, SSA_OP_DEF) + { + tree odef = DEF_FROM_PTR (def_p); + + if (bitmap_bit_p (toremove, SSA_NAME_VERSION (odef))) + { + remove_now = false; + break; + } + } + + if (!remove_now) + BREAK_FROM_IMM_USE_STMT (uit); + } + + if (remove_now) + { + gimple def = SSA_NAME_DEF_STMT (var); + gimple_stmt_iterator gsi = gsi_for_stmt (def); + + if (gimple_code (def) == GIMPLE_PHI) + remove_phi_node (&gsi, true); + else + { + gsi_remove (&gsi, true); + release_defs (def); + } + + bitmap_clear_bit (toremove, j); + } + } +} + +/* Return true if SSA_NAME is malformed and mark it visited. + + IS_VIRTUAL is true if this SSA_NAME was found inside a virtual + operand. */ + +static bool +verify_ssa_name (tree ssa_name, bool is_virtual) +{ + if (TREE_CODE (ssa_name) != SSA_NAME) + { + error ("expected an SSA_NAME object"); + return true; + } + + if (TREE_TYPE (ssa_name) != TREE_TYPE (SSA_NAME_VAR (ssa_name))) + { + error ("type mismatch between an SSA_NAME and its symbol"); + return true; + } + + if (SSA_NAME_IN_FREE_LIST (ssa_name)) + { + error ("found an SSA_NAME that had been released into the free pool"); + return true; + } + + if (is_virtual && is_gimple_reg (ssa_name)) + { + error ("found a virtual definition for a GIMPLE register"); + return true; + } + + if (is_virtual && SSA_NAME_VAR (ssa_name) != gimple_vop (cfun)) + { + error ("virtual SSA name for non-VOP decl"); + return true; + } + + if (!is_virtual && !is_gimple_reg (ssa_name)) + { + error ("found a real definition for a non-register"); + return true; + } + + if (SSA_NAME_IS_DEFAULT_DEF (ssa_name) + && !gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name))) + { + error ("found a default name with a non-empty defining statement"); + return true; + } + + return false; +} + + +/* Return true if the definition of SSA_NAME at block BB is malformed. + + STMT is the statement where SSA_NAME is created. + + DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME + version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set, + it means that the block in that array slot contains the + definition of SSA_NAME. + + IS_VIRTUAL is true if SSA_NAME is created by a VDEF. */ + +static bool +verify_def (basic_block bb, basic_block *definition_block, tree ssa_name, + gimple stmt, bool is_virtual) +{ + if (verify_ssa_name (ssa_name, is_virtual)) + goto err; + + if (TREE_CODE (SSA_NAME_VAR (ssa_name)) == RESULT_DECL + && DECL_BY_REFERENCE (SSA_NAME_VAR (ssa_name))) + { + error ("RESULT_DECL should be read only when DECL_BY_REFERENCE is set"); + goto err; + } + + if (definition_block[SSA_NAME_VERSION (ssa_name)]) + { + error ("SSA_NAME created in two different blocks %i and %i", + definition_block[SSA_NAME_VERSION (ssa_name)]->index, bb->index); + goto err; + } + + definition_block[SSA_NAME_VERSION (ssa_name)] = bb; + + if (SSA_NAME_DEF_STMT (ssa_name) != stmt) + { + error ("SSA_NAME_DEF_STMT is wrong"); + fprintf (stderr, "Expected definition statement:\n"); + print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (ssa_name), 4, TDF_VOPS); + fprintf (stderr, "\nActual definition statement:\n"); + print_gimple_stmt (stderr, stmt, 4, TDF_VOPS); + goto err; + } + + return false; + +err: + fprintf (stderr, "while verifying SSA_NAME "); + print_generic_expr (stderr, ssa_name, 0); + fprintf (stderr, " in statement\n"); + print_gimple_stmt (stderr, stmt, 4, TDF_VOPS); + + return true; +} + + +/* Return true if the use of SSA_NAME at statement STMT in block BB is + malformed. + + DEF_BB is the block where SSA_NAME was found to be created. + + IDOM contains immediate dominator information for the flowgraph. + + CHECK_ABNORMAL is true if the caller wants to check whether this use + is flowing through an abnormal edge (only used when checking PHI + arguments). + + If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names + that are defined before STMT in basic block BB. */ + +static bool +verify_use (basic_block bb, basic_block def_bb, use_operand_p use_p, + gimple stmt, bool check_abnormal, bitmap names_defined_in_bb) +{ + bool err = false; + tree ssa_name = USE_FROM_PTR (use_p); + + if (!TREE_VISITED (ssa_name)) + if (verify_imm_links (stderr, ssa_name)) + err = true; + + TREE_VISITED (ssa_name) = 1; + + if (gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name)) + && SSA_NAME_IS_DEFAULT_DEF (ssa_name)) + ; /* Default definitions have empty statements. Nothing to do. */ + else if (!def_bb) + { + error ("missing definition"); + err = true; + } + else if (bb != def_bb + && !dominated_by_p (CDI_DOMINATORS, bb, def_bb)) + { + error ("definition in block %i does not dominate use in block %i", + def_bb->index, bb->index); + err = true; + } + else if (bb == def_bb + && names_defined_in_bb != NULL + && !bitmap_bit_p (names_defined_in_bb, SSA_NAME_VERSION (ssa_name))) + { + error ("definition in block %i follows the use", def_bb->index); + err = true; + } + + if (check_abnormal + && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ssa_name)) + { + error ("SSA_NAME_OCCURS_IN_ABNORMAL_PHI should be set"); + err = true; + } + + /* Make sure the use is in an appropriate list by checking the previous + element to make sure it's the same. */ + if (use_p->prev == NULL) + { + error ("no immediate_use list"); + err = true; + } + else + { + tree listvar; + if (use_p->prev->use == NULL) + listvar = use_p->prev->loc.ssa_name; + else + listvar = USE_FROM_PTR (use_p->prev); + if (listvar != ssa_name) + { + error ("wrong immediate use list"); + err = true; + } + } + + if (err) + { + fprintf (stderr, "for SSA_NAME: "); + print_generic_expr (stderr, ssa_name, TDF_VOPS); + fprintf (stderr, " in statement:\n"); + print_gimple_stmt (stderr, stmt, 0, TDF_VOPS); + } + + return err; +} + + +/* Return true if any of the arguments for PHI node PHI at block BB is + malformed. + + DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME + version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set, + it means that the block in that array slot contains the + definition of SSA_NAME. */ + +static bool +verify_phi_args (gimple phi, basic_block bb, basic_block *definition_block) +{ + edge e; + bool err = false; + size_t i, phi_num_args = gimple_phi_num_args (phi); + + if (EDGE_COUNT (bb->preds) != phi_num_args) + { + error ("incoming edge count does not match number of PHI arguments"); + err = true; + goto error; + } + + for (i = 0; i < phi_num_args; i++) + { + use_operand_p op_p = gimple_phi_arg_imm_use_ptr (phi, i); + tree op = USE_FROM_PTR (op_p); + + e = EDGE_PRED (bb, i); + + if (op == NULL_TREE) + { + error ("PHI argument is missing for edge %d->%d", + e->src->index, + e->dest->index); + err = true; + goto error; + } + + if (TREE_CODE (op) != SSA_NAME && !is_gimple_min_invariant (op)) + { + error ("PHI argument is not SSA_NAME, or invariant"); + err = true; + } + + if (TREE_CODE (op) == SSA_NAME) + { + err = verify_ssa_name (op, !is_gimple_reg (gimple_phi_result (phi))); + err |= verify_use (e->src, definition_block[SSA_NAME_VERSION (op)], + op_p, phi, e->flags & EDGE_ABNORMAL, NULL); + } + + if (TREE_CODE (op) == ADDR_EXPR) + { + tree base = TREE_OPERAND (op, 0); + while (handled_component_p (base)) + base = TREE_OPERAND (base, 0); + if ((TREE_CODE (base) == VAR_DECL + || TREE_CODE (base) == PARM_DECL + || TREE_CODE (base) == RESULT_DECL) + && !TREE_ADDRESSABLE (base)) + { + error ("address taken, but ADDRESSABLE bit not set"); + err = true; + } + } + + if (e->dest != bb) + { + error ("wrong edge %d->%d for PHI argument", + e->src->index, e->dest->index); + err = true; + } + + if (err) + { + fprintf (stderr, "PHI argument\n"); + print_generic_stmt (stderr, op, TDF_VOPS); + goto error; + } + } + +error: + if (err) + { + fprintf (stderr, "for PHI node\n"); + print_gimple_stmt (stderr, phi, 0, TDF_VOPS|TDF_MEMSYMS); + } + + + return err; +} + + +/* Verify common invariants in the SSA web. + TODO: verify the variable annotations. */ + +DEBUG_FUNCTION void +verify_ssa (bool check_modified_stmt) +{ + size_t i; + basic_block bb; + basic_block *definition_block = XCNEWVEC (basic_block, num_ssa_names); + ssa_op_iter iter; + tree op; + enum dom_state orig_dom_state = dom_info_state (CDI_DOMINATORS); + bitmap names_defined_in_bb = BITMAP_ALLOC (NULL); + + gcc_assert (!need_ssa_update_p (cfun)); + + verify_stmts (); + + timevar_push (TV_TREE_SSA_VERIFY); + + /* Keep track of SSA names present in the IL. */ + for (i = 1; i < num_ssa_names; i++) + { + tree name = ssa_name (i); + if (name) + { + gimple stmt; + TREE_VISITED (name) = 0; + + stmt = SSA_NAME_DEF_STMT (name); + if (!gimple_nop_p (stmt)) + { + basic_block bb = gimple_bb (stmt); + verify_def (bb, definition_block, + name, stmt, !is_gimple_reg (name)); + + } + } + } + + calculate_dominance_info (CDI_DOMINATORS); + + /* Now verify all the uses and make sure they agree with the definitions + found in the previous pass. */ + FOR_EACH_BB (bb) + { + edge e; + gimple phi; + edge_iterator ei; + gimple_stmt_iterator gsi; + + /* Make sure that all edges have a clear 'aux' field. */ + FOR_EACH_EDGE (e, ei, bb->preds) + { + if (e->aux) + { + error ("AUX pointer initialized for edge %d->%d", e->src->index, + e->dest->index); + goto err; + } + } + + /* Verify the arguments for every PHI node in the block. */ + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + phi = gsi_stmt (gsi); + if (verify_phi_args (phi, bb, definition_block)) + goto err; + + bitmap_set_bit (names_defined_in_bb, + SSA_NAME_VERSION (gimple_phi_result (phi))); + } + + /* Now verify all the uses and vuses in every statement of the block. */ + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple stmt = gsi_stmt (gsi); + use_operand_p use_p; + bool has_err; + int count; + unsigned i; + + if (check_modified_stmt && gimple_modified_p (stmt)) + { + error ("stmt (%p) marked modified after optimization pass: ", + (void *)stmt); + print_gimple_stmt (stderr, stmt, 0, TDF_VOPS); + goto err; + } + + if (is_gimple_assign (stmt) + && TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME) + { + tree lhs, base_address; + + lhs = gimple_assign_lhs (stmt); + base_address = get_base_address (lhs); + + if (base_address + && SSA_VAR_P (base_address) + && !gimple_vdef (stmt) + && optimize > 0) + { + error ("statement makes a memory store, but has no VDEFS"); + print_gimple_stmt (stderr, stmt, 0, TDF_VOPS); + goto err; + } + } + else if (gimple_debug_bind_p (stmt) + && !gimple_debug_bind_has_value_p (stmt)) + continue; + + /* Verify the single virtual operand and its constraints. */ + has_err = false; + if (gimple_vdef (stmt)) + { + if (gimple_vdef_op (stmt) == NULL_DEF_OPERAND_P) + { + error ("statement has VDEF operand not in defs list"); + has_err = true; + } + if (!gimple_vuse (stmt)) + { + error ("statement has VDEF but no VUSE operand"); + has_err = true; + } + else if (SSA_NAME_VAR (gimple_vdef (stmt)) + != SSA_NAME_VAR (gimple_vuse (stmt))) + { + error ("VDEF and VUSE do not use the same symbol"); + has_err = true; + } + has_err |= verify_ssa_name (gimple_vdef (stmt), true); + } + if (gimple_vuse (stmt)) + { + if (gimple_vuse_op (stmt) == NULL_USE_OPERAND_P) + { + error ("statement has VUSE operand not in uses list"); + has_err = true; + } + has_err |= verify_ssa_name (gimple_vuse (stmt), true); + } + if (has_err) + { + error ("in statement"); + print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS); + goto err; + } + + count = 0; + FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE|SSA_OP_DEF) + { + if (verify_ssa_name (op, false)) + { + error ("in statement"); + print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS); + goto err; + } + count++; + } + + for (i = 0; i < gimple_num_ops (stmt); i++) + { + op = gimple_op (stmt, i); + if (op && TREE_CODE (op) == SSA_NAME && --count < 0) + { + error ("number of operands and imm-links don%'t agree" + " in statement"); + print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS); + goto err; + } + } + + FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE|SSA_OP_VUSE) + { + op = USE_FROM_PTR (use_p); + if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)], + use_p, stmt, false, names_defined_in_bb)) + goto err; + } + + FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS) + { + if (SSA_NAME_DEF_STMT (op) != stmt) + { + error ("SSA_NAME_DEF_STMT is wrong"); + fprintf (stderr, "Expected definition statement:\n"); + print_gimple_stmt (stderr, stmt, 4, TDF_VOPS); + fprintf (stderr, "\nActual definition statement:\n"); + print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (op), + 4, TDF_VOPS); + goto err; + } + bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op)); + } + } + + bitmap_clear (names_defined_in_bb); + } + + free (definition_block); + + /* Restore the dominance information to its prior known state, so + that we do not perturb the compiler's subsequent behavior. */ + if (orig_dom_state == DOM_NONE) + free_dominance_info (CDI_DOMINATORS); + else + set_dom_info_availability (CDI_DOMINATORS, orig_dom_state); + + BITMAP_FREE (names_defined_in_bb); + timevar_pop (TV_TREE_SSA_VERIFY); + return; + +err: + internal_error ("verify_ssa failed"); +} + +/* Return true if the uid in both int tree maps are equal. */ + +int +int_tree_map_eq (const void *va, const void *vb) +{ + const struct int_tree_map *a = (const struct int_tree_map *) va; + const struct int_tree_map *b = (const struct int_tree_map *) vb; + return (a->uid == b->uid); +} + +/* Hash a UID in a int_tree_map. */ + +unsigned int +int_tree_map_hash (const void *item) +{ + return ((const struct int_tree_map *)item)->uid; +} + +/* Return true if the DECL_UID in both trees are equal. */ + +int +uid_decl_map_eq (const void *va, const void *vb) +{ + const_tree a = (const_tree) va; + const_tree b = (const_tree) vb; + return (a->decl_minimal.uid == b->decl_minimal.uid); +} + +/* Hash a tree in a uid_decl_map. */ + +unsigned int +uid_decl_map_hash (const void *item) +{ + return ((const_tree)item)->decl_minimal.uid; +} + +/* Return true if the DECL_UID in both trees are equal. */ + +static int +uid_ssaname_map_eq (const void *va, const void *vb) +{ + const_tree a = (const_tree) va; + const_tree b = (const_tree) vb; + return (a->ssa_name.var->decl_minimal.uid == b->ssa_name.var->decl_minimal.uid); +} + +/* Hash a tree in a uid_decl_map. */ + +static unsigned int +uid_ssaname_map_hash (const void *item) +{ + return ((const_tree)item)->ssa_name.var->decl_minimal.uid; +} + + +/* Initialize global DFA and SSA structures. */ + +void +init_tree_ssa (struct function *fn) +{ + fn->gimple_df = ggc_alloc_cleared_gimple_df (); + fn->gimple_df->referenced_vars = htab_create_ggc (20, uid_decl_map_hash, + uid_decl_map_eq, NULL); + fn->gimple_df->default_defs = htab_create_ggc (20, uid_ssaname_map_hash, + uid_ssaname_map_eq, NULL); + pt_solution_reset (&fn->gimple_df->escaped); + init_ssanames (fn, 0); + init_phinodes (); +} + + +/* Deallocate memory associated with SSA data structures for FNDECL. */ + +void +delete_tree_ssa (void) +{ + referenced_var_iterator rvi; + tree var; + + /* Remove annotations from every referenced local variable. */ + FOR_EACH_REFERENCED_VAR (cfun, var, rvi) + { + if (is_global_var (var)) + continue; + if (var_ann (var)) + { + ggc_free (var_ann (var)); + *DECL_VAR_ANN_PTR (var) = NULL; + } + } + htab_delete (gimple_referenced_vars (cfun)); + cfun->gimple_df->referenced_vars = NULL; + + fini_ssanames (); + fini_phinodes (); + + /* We no longer maintain the SSA operand cache at this point. */ + if (ssa_operands_active ()) + fini_ssa_operands (); + + delete_alias_heapvars (); + + htab_delete (cfun->gimple_df->default_defs); + cfun->gimple_df->default_defs = NULL; + pt_solution_reset (&cfun->gimple_df->escaped); + if (cfun->gimple_df->decls_to_pointers != NULL) + pointer_map_destroy (cfun->gimple_df->decls_to_pointers); + cfun->gimple_df->decls_to_pointers = NULL; + cfun->gimple_df->modified_noreturn_calls = NULL; + cfun->gimple_df = NULL; + + /* We no longer need the edge variable maps. */ + redirect_edge_var_map_destroy (); +} + +/* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a + useless type conversion, otherwise return false. + + This function implicitly defines the middle-end type system. With + the notion of 'a < b' meaning that useless_type_conversion_p (a, b) + holds and 'a > b' meaning that useless_type_conversion_p (b, a) holds, + the following invariants shall be fulfilled: + + 1) useless_type_conversion_p is transitive. + If a < b and b < c then a < c. + + 2) useless_type_conversion_p is not symmetric. + From a < b does not follow a > b. + + 3) Types define the available set of operations applicable to values. + A type conversion is useless if the operations for the target type + is a subset of the operations for the source type. For example + casts to void* are useless, casts from void* are not (void* can't + be dereferenced or offsetted, but copied, hence its set of operations + is a strict subset of that of all other data pointer types). Casts + to const T* are useless (can't be written to), casts from const T* + to T* are not. */ + +bool +useless_type_conversion_p (tree outer_type, tree inner_type) +{ + /* Do the following before stripping toplevel qualifiers. */ + if (POINTER_TYPE_P (inner_type) + && POINTER_TYPE_P (outer_type)) + { + /* Do not lose casts between pointers to different address spaces. */ + if (TYPE_ADDR_SPACE (TREE_TYPE (outer_type)) + != TYPE_ADDR_SPACE (TREE_TYPE (inner_type))) + return false; + + /* Do not lose casts to restrict qualified pointers. */ + if ((TYPE_RESTRICT (outer_type) + != TYPE_RESTRICT (inner_type)) + && TYPE_RESTRICT (outer_type)) + return false; + + /* If the outer type is (void *) or a pointer to an incomplete + record type or a pointer to an unprototyped function, + then the conversion is not necessary. */ + if (VOID_TYPE_P (TREE_TYPE (outer_type)) + || ((TREE_CODE (TREE_TYPE (outer_type)) == FUNCTION_TYPE + || TREE_CODE (TREE_TYPE (outer_type)) == METHOD_TYPE) + && (TREE_CODE (TREE_TYPE (outer_type)) + == TREE_CODE (TREE_TYPE (inner_type))) + && !prototype_p (TREE_TYPE (outer_type)) + && useless_type_conversion_p (TREE_TYPE (TREE_TYPE (outer_type)), + TREE_TYPE (TREE_TYPE (inner_type))))) + return true; + } + + /* From now on qualifiers on value types do not matter. */ + inner_type = TYPE_MAIN_VARIANT (inner_type); + outer_type = TYPE_MAIN_VARIANT (outer_type); + + if (inner_type == outer_type) + return true; + + /* If we know the canonical types, compare them. */ + if (TYPE_CANONICAL (inner_type) + && TYPE_CANONICAL (inner_type) == TYPE_CANONICAL (outer_type)) + return true; + + /* Changes in machine mode are never useless conversions unless we + deal with aggregate types in which case we defer to later checks. */ + if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type) + && !AGGREGATE_TYPE_P (inner_type)) + return false; + + /* If both the inner and outer types are integral types, then the + conversion is not necessary if they have the same mode and + signedness and precision, and both or neither are boolean. */ + if (INTEGRAL_TYPE_P (inner_type) + && INTEGRAL_TYPE_P (outer_type)) + { + /* Preserve changes in signedness or precision. */ + if (TYPE_UNSIGNED (inner_type) != TYPE_UNSIGNED (outer_type) + || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type)) + return false; + + /* We don't need to preserve changes in the types minimum or + maximum value in general as these do not generate code + unless the types precisions are different. */ + return true; + } + + /* Scalar floating point types with the same mode are compatible. */ + else if (SCALAR_FLOAT_TYPE_P (inner_type) + && SCALAR_FLOAT_TYPE_P (outer_type)) + return true; + + /* Fixed point types with the same mode are compatible. */ + else if (FIXED_POINT_TYPE_P (inner_type) + && FIXED_POINT_TYPE_P (outer_type)) + return true; + + /* We need to take special care recursing to pointed-to types. */ + else if (POINTER_TYPE_P (inner_type) + && POINTER_TYPE_P (outer_type)) + { + /* Do not lose casts to function pointer types. */ + if ((TREE_CODE (TREE_TYPE (outer_type)) == FUNCTION_TYPE + || TREE_CODE (TREE_TYPE (outer_type)) == METHOD_TYPE) + && !useless_type_conversion_p (TREE_TYPE (outer_type), + TREE_TYPE (inner_type))) + return false; + + /* We do not care for const qualification of the pointed-to types + as const qualification has no semantic value to the middle-end. */ + + /* Otherwise pointers/references are equivalent. */ + return true; + } + + /* Recurse for complex types. */ + else if (TREE_CODE (inner_type) == COMPLEX_TYPE + && TREE_CODE (outer_type) == COMPLEX_TYPE) + return useless_type_conversion_p (TREE_TYPE (outer_type), + TREE_TYPE (inner_type)); + + /* Recurse for vector types with the same number of subparts. */ + else if (TREE_CODE (inner_type) == VECTOR_TYPE + && TREE_CODE (outer_type) == VECTOR_TYPE + && TYPE_PRECISION (inner_type) == TYPE_PRECISION (outer_type)) + return useless_type_conversion_p (TREE_TYPE (outer_type), + TREE_TYPE (inner_type)); + + else if (TREE_CODE (inner_type) == ARRAY_TYPE + && TREE_CODE (outer_type) == ARRAY_TYPE) + { + /* Preserve string attributes. */ + if (TYPE_STRING_FLAG (inner_type) != TYPE_STRING_FLAG (outer_type)) + return false; + + /* Conversions from array types with unknown extent to + array types with known extent are not useless. */ + if (!TYPE_DOMAIN (inner_type) + && TYPE_DOMAIN (outer_type)) + return false; + + /* Nor are conversions from array types with non-constant size to + array types with constant size or to different size. */ + if (TYPE_SIZE (outer_type) + && TREE_CODE (TYPE_SIZE (outer_type)) == INTEGER_CST + && (!TYPE_SIZE (inner_type) + || TREE_CODE (TYPE_SIZE (inner_type)) != INTEGER_CST + || !tree_int_cst_equal (TYPE_SIZE (outer_type), + TYPE_SIZE (inner_type)))) + return false; + + /* Check conversions between arrays with partially known extents. + If the array min/max values are constant they have to match. + Otherwise allow conversions to unknown and variable extents. + In particular this declares conversions that may change the + mode to BLKmode as useless. */ + if (TYPE_DOMAIN (inner_type) + && TYPE_DOMAIN (outer_type) + && TYPE_DOMAIN (inner_type) != TYPE_DOMAIN (outer_type)) + { + tree inner_min = TYPE_MIN_VALUE (TYPE_DOMAIN (inner_type)); + tree outer_min = TYPE_MIN_VALUE (TYPE_DOMAIN (outer_type)); + tree inner_max = TYPE_MAX_VALUE (TYPE_DOMAIN (inner_type)); + tree outer_max = TYPE_MAX_VALUE (TYPE_DOMAIN (outer_type)); + + /* After gimplification a variable min/max value carries no + additional information compared to a NULL value. All that + matters has been lowered to be part of the IL. */ + if (inner_min && TREE_CODE (inner_min) != INTEGER_CST) + inner_min = NULL_TREE; + if (outer_min && TREE_CODE (outer_min) != INTEGER_CST) + outer_min = NULL_TREE; + if (inner_max && TREE_CODE (inner_max) != INTEGER_CST) + inner_max = NULL_TREE; + if (outer_max && TREE_CODE (outer_max) != INTEGER_CST) + outer_max = NULL_TREE; + + /* Conversions NULL / variable <- cst are useless, but not + the other way around. */ + if (outer_min + && (!inner_min + || !tree_int_cst_equal (inner_min, outer_min))) + return false; + if (outer_max + && (!inner_max + || !tree_int_cst_equal (inner_max, outer_max))) + return false; + } + + /* Recurse on the element check. */ + return useless_type_conversion_p (TREE_TYPE (outer_type), + TREE_TYPE (inner_type)); + } + + else if ((TREE_CODE (inner_type) == FUNCTION_TYPE + || TREE_CODE (inner_type) == METHOD_TYPE) + && TREE_CODE (inner_type) == TREE_CODE (outer_type)) + { + tree outer_parm, inner_parm; + + /* If the return types are not compatible bail out. */ + if (!useless_type_conversion_p (TREE_TYPE (outer_type), + TREE_TYPE (inner_type))) + return false; + + /* Method types should belong to a compatible base class. */ + if (TREE_CODE (inner_type) == METHOD_TYPE + && !useless_type_conversion_p (TYPE_METHOD_BASETYPE (outer_type), + TYPE_METHOD_BASETYPE (inner_type))) + return false; + + /* A conversion to an unprototyped argument list is ok. */ + if (!prototype_p (outer_type)) + return true; + + /* If the unqualified argument types are compatible the conversion + is useless. */ + if (TYPE_ARG_TYPES (outer_type) == TYPE_ARG_TYPES (inner_type)) + return true; + + for (outer_parm = TYPE_ARG_TYPES (outer_type), + inner_parm = TYPE_ARG_TYPES (inner_type); + outer_parm && inner_parm; + outer_parm = TREE_CHAIN (outer_parm), + inner_parm = TREE_CHAIN (inner_parm)) + if (!useless_type_conversion_p + (TYPE_MAIN_VARIANT (TREE_VALUE (outer_parm)), + TYPE_MAIN_VARIANT (TREE_VALUE (inner_parm)))) + return false; + + /* If there is a mismatch in the number of arguments the functions + are not compatible. */ + if (outer_parm || inner_parm) + return false; + + /* Defer to the target if necessary. */ + if (TYPE_ATTRIBUTES (inner_type) || TYPE_ATTRIBUTES (outer_type)) + return targetm.comp_type_attributes (outer_type, inner_type) != 0; + + return true; + } + + /* For aggregates we rely on TYPE_CANONICAL exclusively and require + explicit conversions for types involving to be structurally + compared types. */ + else if (AGGREGATE_TYPE_P (inner_type) + && TREE_CODE (inner_type) == TREE_CODE (outer_type)) + return false; + + return false; +} + +/* Return true if a conversion from either type of TYPE1 and TYPE2 + to the other is not required. Otherwise return false. */ + +bool +types_compatible_p (tree type1, tree type2) +{ + return (type1 == type2 + || (useless_type_conversion_p (type1, type2) + && useless_type_conversion_p (type2, type1))); +} + +/* Return true if EXPR is a useless type conversion, otherwise return + false. */ + +bool +tree_ssa_useless_type_conversion (tree expr) +{ + /* If we have an assignment that merely uses a NOP_EXPR to change + the top of the RHS to the type of the LHS and the type conversion + is "safe", then strip away the type conversion so that we can + enter LHS = RHS into the const_and_copies table. */ + if (CONVERT_EXPR_P (expr) + || TREE_CODE (expr) == VIEW_CONVERT_EXPR + || TREE_CODE (expr) == NON_LVALUE_EXPR) + return useless_type_conversion_p + (TREE_TYPE (expr), + TREE_TYPE (TREE_OPERAND (expr, 0))); + + return false; +} + +/* Strip conversions from EXP according to + tree_ssa_useless_type_conversion and return the resulting + expression. */ + +tree +tree_ssa_strip_useless_type_conversions (tree exp) +{ + while (tree_ssa_useless_type_conversion (exp)) + exp = TREE_OPERAND (exp, 0); + return exp; +} + + +/* Internal helper for walk_use_def_chains. VAR, FN and DATA are as + described in walk_use_def_chains. + + VISITED is a pointer set used to mark visited SSA_NAMEs to avoid + infinite loops. We used to have a bitmap for this to just mark + SSA versions we had visited. But non-sparse bitmaps are way too + expensive, while sparse bitmaps may cause quadratic behavior. + + IS_DFS is true if the caller wants to perform a depth-first search + when visiting PHI nodes. A DFS will visit each PHI argument and + call FN after each one. Otherwise, all the arguments are + visited first and then FN is called with each of the visited + arguments in a separate pass. */ + +static bool +walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data, + struct pointer_set_t *visited, bool is_dfs) +{ + gimple def_stmt; + + if (pointer_set_insert (visited, var)) + return false; + + def_stmt = SSA_NAME_DEF_STMT (var); + + if (gimple_code (def_stmt) != GIMPLE_PHI) + { + /* If we reached the end of the use-def chain, call FN. */ + return fn (var, def_stmt, data); + } + else + { + size_t i; + + /* When doing a breadth-first search, call FN before following the + use-def links for each argument. */ + if (!is_dfs) + for (i = 0; i < gimple_phi_num_args (def_stmt); i++) + if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data)) + return true; + + /* Follow use-def links out of each PHI argument. */ + for (i = 0; i < gimple_phi_num_args (def_stmt); i++) + { + tree arg = gimple_phi_arg_def (def_stmt, i); + + /* ARG may be NULL for newly introduced PHI nodes. */ + if (arg + && TREE_CODE (arg) == SSA_NAME + && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs)) + return true; + } + + /* When doing a depth-first search, call FN after following the + use-def links for each argument. */ + if (is_dfs) + for (i = 0; i < gimple_phi_num_args (def_stmt); i++) + if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data)) + return true; + } + + return false; +} + + + +/* Walk use-def chains starting at the SSA variable VAR. Call + function FN at each reaching definition found. FN takes three + arguments: VAR, its defining statement (DEF_STMT) and a generic + pointer to whatever state information that FN may want to maintain + (DATA). FN is able to stop the walk by returning true, otherwise + in order to continue the walk, FN should return false. + + Note, that if DEF_STMT is a PHI node, the semantics are slightly + different. The first argument to FN is no longer the original + variable VAR, but the PHI argument currently being examined. If FN + wants to get at VAR, it should call PHI_RESULT (PHI). + + If IS_DFS is true, this function will: + + 1- walk the use-def chains for all the PHI arguments, and, + 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments. + + If IS_DFS is false, the two steps above are done in reverse order + (i.e., a breadth-first search). */ + +void +walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data, + bool is_dfs) +{ + gimple def_stmt; + + gcc_assert (TREE_CODE (var) == SSA_NAME); + + def_stmt = SSA_NAME_DEF_STMT (var); + + /* We only need to recurse if the reaching definition comes from a PHI + node. */ + if (gimple_code (def_stmt) != GIMPLE_PHI) + (*fn) (var, def_stmt, data); + else + { + struct pointer_set_t *visited = pointer_set_create (); + walk_use_def_chains_1 (var, fn, data, visited, is_dfs); + pointer_set_destroy (visited); + } +} + + +/* Emit warnings for uninitialized variables. This is done in two passes. + + The first pass notices real uses of SSA names with undefined values. + Such uses are unconditionally uninitialized, and we can be certain that + such a use is a mistake. This pass is run before most optimizations, + so that we catch as many as we can. + + The second pass follows PHI nodes to find uses that are potentially + uninitialized. In this case we can't necessarily prove that the use + is really uninitialized. This pass is run after most optimizations, + so that we thread as many jumps and possible, and delete as much dead + code as possible, in order to reduce false positives. We also look + again for plain uninitialized variables, since optimization may have + changed conditionally uninitialized to unconditionally uninitialized. */ + +/* Emit a warning for T, an SSA_NAME, being uninitialized. The exact + warning text is in MSGID and LOCUS may contain a location or be null. */ + +void +warn_uninit (tree t, const char *gmsgid, void *data) +{ + tree var = SSA_NAME_VAR (t); + gimple context = (gimple) data; + location_t location; + expanded_location xloc, floc; + + if (!ssa_undefined_value_p (t)) + return; + + /* TREE_NO_WARNING either means we already warned, or the front end + wishes to suppress the warning. */ + if (TREE_NO_WARNING (var)) + return; + + /* Do not warn if it can be initialized outside this module. */ + if (is_global_var (var)) + return; + + location = (context != NULL && gimple_has_location (context)) + ? gimple_location (context) + : DECL_SOURCE_LOCATION (var); + xloc = expand_location (location); + floc = expand_location (DECL_SOURCE_LOCATION (cfun->decl)); + if (warning_at (location, OPT_Wuninitialized, gmsgid, var)) + { + TREE_NO_WARNING (var) = 1; + + if (location == DECL_SOURCE_LOCATION (var)) + return; + if (xloc.file != floc.file + || xloc.line < floc.line + || xloc.line > LOCATION_LINE (cfun->function_end_locus)) + inform (DECL_SOURCE_LOCATION (var), "%qD was declared here", var); + } +} + +struct walk_data { + gimple stmt; + bool always_executed; + bool warn_possibly_uninitialized; +}; + +/* Called via walk_tree, look for SSA_NAMEs that have empty definitions + and warn about them. */ + +static tree +warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data_) +{ + struct walk_stmt_info *wi = (struct walk_stmt_info *) data_; + struct walk_data *data = (struct walk_data *) wi->info; + tree t = *tp; + + /* We do not care about LHS. */ + if (wi->is_lhs) + { + /* Except for operands of dereferences. */ + if (!INDIRECT_REF_P (t) + && TREE_CODE (t) != MEM_REF) + return NULL_TREE; + t = TREE_OPERAND (t, 0); + } + + switch (TREE_CODE (t)) + { + case ADDR_EXPR: + /* Taking the address of an uninitialized variable does not + count as using it. */ + *walk_subtrees = 0; + break; + + case VAR_DECL: + { + /* A VAR_DECL in the RHS of a gimple statement may mean that + this variable is loaded from memory. */ + use_operand_p vuse; + tree op; + + /* If there is not gimple stmt, + or alias information has not been computed, + then we cannot check VUSE ops. */ + if (data->stmt == NULL) + return NULL_TREE; + + /* If the load happens as part of a call do not warn about it. */ + if (is_gimple_call (data->stmt)) + return NULL_TREE; + + vuse = gimple_vuse_op (data->stmt); + if (vuse == NULL_USE_OPERAND_P) + return NULL_TREE; + + op = USE_FROM_PTR (vuse); + if (t != SSA_NAME_VAR (op) + || !SSA_NAME_IS_DEFAULT_DEF (op)) + return NULL_TREE; + /* If this is a VUSE of t and it is the default definition, + then warn about op. */ + t = op; + /* Fall through into SSA_NAME. */ + } + + case SSA_NAME: + /* We only do data flow with SSA_NAMEs, so that's all we + can warn about. */ + if (data->always_executed) + warn_uninit (t, "%qD is used uninitialized in this function", + data->stmt); + else if (data->warn_possibly_uninitialized) + warn_uninit (t, "%qD may be used uninitialized in this function", + data->stmt); + *walk_subtrees = 0; + break; + + case REALPART_EXPR: + case IMAGPART_EXPR: + /* The total store transformation performed during gimplification + creates uninitialized variable uses. If all is well, these will + be optimized away, so don't warn now. */ + if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME) + *walk_subtrees = 0; + break; + + default: + if (IS_TYPE_OR_DECL_P (t)) + *walk_subtrees = 0; + break; + } + + return NULL_TREE; +} + +unsigned int +warn_uninitialized_vars (bool warn_possibly_uninitialized) +{ + gimple_stmt_iterator gsi; + basic_block bb; + struct walk_data data; + + data.warn_possibly_uninitialized = warn_possibly_uninitialized; + + + FOR_EACH_BB (bb) + { + data.always_executed = dominated_by_p (CDI_POST_DOMINATORS, + single_succ (ENTRY_BLOCK_PTR), bb); + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + struct walk_stmt_info wi; + data.stmt = gsi_stmt (gsi); + if (is_gimple_debug (data.stmt)) + continue; + memset (&wi, 0, sizeof (wi)); + wi.info = &data; + walk_gimple_op (gsi_stmt (gsi), warn_uninitialized_var, &wi); + } + } + + return 0; +} + +static unsigned int +execute_early_warn_uninitialized (void) +{ + /* Currently, this pass runs always but + execute_late_warn_uninitialized only runs with optimization. With + optimization we want to warn about possible uninitialized as late + as possible, thus don't do it here. However, without + optimization we need to warn here about "may be uninitialized". + */ + calculate_dominance_info (CDI_POST_DOMINATORS); + + warn_uninitialized_vars (/*warn_possibly_uninitialized=*/!optimize); + + /* Post-dominator information can not be reliably updated. Free it + after the use. */ + + free_dominance_info (CDI_POST_DOMINATORS); + return 0; +} + +static bool +gate_warn_uninitialized (void) +{ + return warn_uninitialized != 0; +} + +struct gimple_opt_pass pass_early_warn_uninitialized = +{ + { + GIMPLE_PASS, + "*early_warn_uninitialized", /* name */ + gate_warn_uninitialized, /* gate */ + execute_early_warn_uninitialized, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_TREE_UNINIT, /* tv_id */ + PROP_ssa, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + 0 /* todo_flags_finish */ + } +}; + + +/* If necessary, rewrite the base of the reference tree *TP from + a MEM_REF to a plain or converted symbol. */ + +static void +maybe_rewrite_mem_ref_base (tree *tp) +{ + tree sym; + + while (handled_component_p (*tp)) + tp = &TREE_OPERAND (*tp, 0); + if (TREE_CODE (*tp) == MEM_REF + && TREE_CODE (TREE_OPERAND (*tp, 0)) == ADDR_EXPR + && integer_zerop (TREE_OPERAND (*tp, 1)) + && (sym = TREE_OPERAND (TREE_OPERAND (*tp, 0), 0)) + && DECL_P (sym) + && !TREE_ADDRESSABLE (sym) + && symbol_marked_for_renaming (sym)) + { + if (!useless_type_conversion_p (TREE_TYPE (*tp), + TREE_TYPE (sym))) + *tp = build1 (VIEW_CONVERT_EXPR, + TREE_TYPE (*tp), sym); + else + *tp = sym; + } +} + +/* For a tree REF return its base if it is the base of a MEM_REF + that cannot be rewritten into SSA form. Otherwise return NULL_TREE. */ + +static tree +non_rewritable_mem_ref_base (tree ref) +{ + tree base = ref; + + /* A plain decl does not need it set. */ + if (DECL_P (ref)) + return NULL_TREE; + + while (handled_component_p (base)) + base = TREE_OPERAND (base, 0); + + /* But watch out for MEM_REFs we cannot lower to a + VIEW_CONVERT_EXPR. */ + if (TREE_CODE (base) == MEM_REF + && TREE_CODE (TREE_OPERAND (base, 0)) == ADDR_EXPR) + { + tree decl = TREE_OPERAND (TREE_OPERAND (base, 0), 0); + if (DECL_P (decl) + && (!integer_zerop (TREE_OPERAND (base, 1)) + || (DECL_SIZE (decl) + != TYPE_SIZE (TREE_TYPE (base))) + || TREE_THIS_VOLATILE (decl) != TREE_THIS_VOLATILE (base))) + return decl; + } + + return NULL_TREE; +} + +/* For an lvalue tree LHS return true if it cannot be rewritten into SSA form. + Otherwise return true. */ + +static bool +non_rewritable_lvalue_p (tree lhs) +{ + /* A plain decl is always rewritable. */ + if (DECL_P (lhs)) + return false; + + /* A decl that is wrapped inside a MEM-REF that covers + it full is also rewritable. + ??? The following could be relaxed allowing component + references that do not change the access size. */ + if (TREE_CODE (lhs) == MEM_REF + && TREE_CODE (TREE_OPERAND (lhs, 0)) == ADDR_EXPR + && integer_zerop (TREE_OPERAND (lhs, 1))) + { + tree decl = TREE_OPERAND (TREE_OPERAND (lhs, 0), 0); + if (DECL_P (decl) + && DECL_SIZE (decl) == TYPE_SIZE (TREE_TYPE (lhs)) + && (TREE_THIS_VOLATILE (decl) == TREE_THIS_VOLATILE (lhs))) + return false; + } + + return true; +} + +/* When possible, clear TREE_ADDRESSABLE bit or set DECL_GIMPLE_REG_P bit and + mark the variable VAR for conversion into SSA. Return true when updating + stmts is required. */ + +static bool +maybe_optimize_var (tree var, bitmap addresses_taken, bitmap not_reg_needs) +{ + bool update_vops = false; + + /* Global Variables, result decls cannot be changed. */ + if (is_global_var (var) + || TREE_CODE (var) == RESULT_DECL + || bitmap_bit_p (addresses_taken, DECL_UID (var))) + return false; + + /* If the variable is not in the list of referenced vars then we + do not need to touch it nor can we rename it. */ + if (!referenced_var_lookup (cfun, DECL_UID (var))) + return false; + + if (TREE_ADDRESSABLE (var) + /* Do not change TREE_ADDRESSABLE if we need to preserve var as + a non-register. Otherwise we are confused and forget to + add virtual operands for it. */ + && (!is_gimple_reg_type (TREE_TYPE (var)) + || !bitmap_bit_p (not_reg_needs, DECL_UID (var)))) + { + TREE_ADDRESSABLE (var) = 0; + if (is_gimple_reg (var)) + mark_sym_for_renaming (var); + update_vops = true; + if (dump_file) + { + fprintf (dump_file, "No longer having address taken: "); + print_generic_expr (dump_file, var, 0); + fprintf (dump_file, "\n"); + } + } + + if (!DECL_GIMPLE_REG_P (var) + && !bitmap_bit_p (not_reg_needs, DECL_UID (var)) + && (TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE + || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE) + && !TREE_THIS_VOLATILE (var) + && (TREE_CODE (var) != VAR_DECL || !DECL_HARD_REGISTER (var))) + { + DECL_GIMPLE_REG_P (var) = 1; + mark_sym_for_renaming (var); + update_vops = true; + if (dump_file) + { + fprintf (dump_file, "Now a gimple register: "); + print_generic_expr (dump_file, var, 0); + fprintf (dump_file, "\n"); + } + } + + return update_vops; +} + +/* Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables. */ + +void +execute_update_addresses_taken (void) +{ + gimple_stmt_iterator gsi; + basic_block bb; + bitmap addresses_taken = BITMAP_ALLOC (NULL); + bitmap not_reg_needs = BITMAP_ALLOC (NULL); + bool update_vops = false; + tree var; + unsigned i; + + timevar_push (TV_ADDRESS_TAKEN); + + /* Collect into ADDRESSES_TAKEN all variables whose address is taken within + the function body. */ + FOR_EACH_BB (bb) + { + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple stmt = gsi_stmt (gsi); + enum gimple_code code = gimple_code (stmt); + tree decl; + + /* Note all addresses taken by the stmt. */ + gimple_ior_addresses_taken (addresses_taken, stmt); + + /* If we have a call or an assignment, see if the lhs contains + a local decl that requires not to be a gimple register. */ + if (code == GIMPLE_ASSIGN || code == GIMPLE_CALL) + { + tree lhs = gimple_get_lhs (stmt); + if (lhs + && TREE_CODE (lhs) != SSA_NAME + && non_rewritable_lvalue_p (lhs)) + { + decl = get_base_address (lhs); + if (DECL_P (decl)) + bitmap_set_bit (not_reg_needs, DECL_UID (decl)); + } + } + + if (gimple_assign_single_p (stmt)) + { + tree rhs = gimple_assign_rhs1 (stmt); + if ((decl = non_rewritable_mem_ref_base (rhs))) + bitmap_set_bit (not_reg_needs, DECL_UID (decl)); + } + + else if (code == GIMPLE_CALL) + { + for (i = 0; i < gimple_call_num_args (stmt); ++i) + { + tree arg = gimple_call_arg (stmt, i); + if ((decl = non_rewritable_mem_ref_base (arg))) + bitmap_set_bit (not_reg_needs, DECL_UID (decl)); + } + } + + else if (code == GIMPLE_ASM) + { + for (i = 0; i < gimple_asm_noutputs (stmt); ++i) + { + tree link = gimple_asm_output_op (stmt, i); + tree lhs = TREE_VALUE (link); + if (TREE_CODE (lhs) != SSA_NAME) + { + decl = get_base_address (lhs); + if (DECL_P (decl) + && (non_rewritable_lvalue_p (lhs) + /* We cannot move required conversions from + the lhs to the rhs in asm statements, so + require we do not need any. */ + || !useless_type_conversion_p + (TREE_TYPE (lhs), TREE_TYPE (decl)))) + bitmap_set_bit (not_reg_needs, DECL_UID (decl)); + } + } + for (i = 0; i < gimple_asm_ninputs (stmt); ++i) + { + tree link = gimple_asm_input_op (stmt, i); + if ((decl = non_rewritable_mem_ref_base (TREE_VALUE (link)))) + bitmap_set_bit (not_reg_needs, DECL_UID (decl)); + } + } + } + + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + size_t i; + gimple phi = gsi_stmt (gsi); + + for (i = 0; i < gimple_phi_num_args (phi); i++) + { + tree op = PHI_ARG_DEF (phi, i), var; + if (TREE_CODE (op) == ADDR_EXPR + && (var = get_base_address (TREE_OPERAND (op, 0))) != NULL + && DECL_P (var)) + bitmap_set_bit (addresses_taken, DECL_UID (var)); + } + } + } + + /* We cannot iterate over all referenced vars because that can contain + unused vars from BLOCK trees, which causes code generation differences + for -g vs. -g0. */ + for (var = DECL_ARGUMENTS (cfun->decl); var; var = DECL_CHAIN (var)) + update_vops |= maybe_optimize_var (var, addresses_taken, not_reg_needs); + + FOR_EACH_VEC_ELT (tree, cfun->local_decls, i, var) + update_vops |= maybe_optimize_var (var, addresses_taken, not_reg_needs); + + /* Operand caches need to be recomputed for operands referencing the updated + variables. */ + if (update_vops) + { + FOR_EACH_BB (bb) + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple stmt = gsi_stmt (gsi); + + /* Re-write TARGET_MEM_REFs of symbols we want to + rewrite into SSA form. */ + if (gimple_assign_single_p (stmt)) + { + tree lhs = gimple_assign_lhs (stmt); + tree rhs, *rhsp = gimple_assign_rhs1_ptr (stmt); + tree sym; + + /* We shouldn't have any fancy wrapping of + component-refs on the LHS, but look through + VIEW_CONVERT_EXPRs as that is easy. */ + while (TREE_CODE (lhs) == VIEW_CONVERT_EXPR) + lhs = TREE_OPERAND (lhs, 0); + if (TREE_CODE (lhs) == MEM_REF + && TREE_CODE (TREE_OPERAND (lhs, 0)) == ADDR_EXPR + && integer_zerop (TREE_OPERAND (lhs, 1)) + && (sym = TREE_OPERAND (TREE_OPERAND (lhs, 0), 0)) + && DECL_P (sym) + && !TREE_ADDRESSABLE (sym) + && symbol_marked_for_renaming (sym)) + lhs = sym; + else + lhs = gimple_assign_lhs (stmt); + + /* Rewrite the RHS and make sure the resulting assignment + is validly typed. */ + maybe_rewrite_mem_ref_base (rhsp); + rhs = gimple_assign_rhs1 (stmt); + if (gimple_assign_lhs (stmt) != lhs + && !useless_type_conversion_p (TREE_TYPE (lhs), + TREE_TYPE (rhs))) + rhs = fold_build1 (VIEW_CONVERT_EXPR, + TREE_TYPE (lhs), rhs); + + if (gimple_assign_lhs (stmt) != lhs) + gimple_assign_set_lhs (stmt, lhs); + + if (gimple_assign_rhs1 (stmt) != rhs) + { + gimple_stmt_iterator gsi = gsi_for_stmt (stmt); + gimple_assign_set_rhs_from_tree (&gsi, rhs); + } + } + + else if (gimple_code (stmt) == GIMPLE_CALL) + { + unsigned i; + for (i = 0; i < gimple_call_num_args (stmt); ++i) + { + tree *argp = gimple_call_arg_ptr (stmt, i); + maybe_rewrite_mem_ref_base (argp); + } + } + + else if (gimple_code (stmt) == GIMPLE_ASM) + { + unsigned i; + for (i = 0; i < gimple_asm_noutputs (stmt); ++i) + { + tree link = gimple_asm_output_op (stmt, i); + maybe_rewrite_mem_ref_base (&TREE_VALUE (link)); + } + for (i = 0; i < gimple_asm_ninputs (stmt); ++i) + { + tree link = gimple_asm_input_op (stmt, i); + maybe_rewrite_mem_ref_base (&TREE_VALUE (link)); + } + } + + else if (gimple_debug_bind_p (stmt) + && gimple_debug_bind_has_value_p (stmt)) + { + tree *valuep = gimple_debug_bind_get_value_ptr (stmt); + tree decl; + maybe_rewrite_mem_ref_base (valuep); + decl = non_rewritable_mem_ref_base (*valuep); + if (decl && symbol_marked_for_renaming (decl)) + gimple_debug_bind_reset_value (stmt); + } + + if (gimple_references_memory_p (stmt) + || is_gimple_debug (stmt)) + update_stmt (stmt); + } + + /* Update SSA form here, we are called as non-pass as well. */ + if (number_of_loops () > 1 && loops_state_satisfies_p (LOOP_CLOSED_SSA)) + rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa); + else + update_ssa (TODO_update_ssa); + } + + BITMAP_FREE (not_reg_needs); + BITMAP_FREE (addresses_taken); + timevar_pop (TV_ADDRESS_TAKEN); +} + +struct gimple_opt_pass pass_update_address_taken = +{ + { + GIMPLE_PASS, + "addressables", /* name */ + NULL, /* gate */ + NULL, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_ADDRESS_TAKEN, /* tv_id */ + PROP_ssa, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_update_address_taken + | TODO_dump_func /* todo_flags_finish */ + } +}; 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