[backport gcc-4.8/trunk r195883, the nt_init_block hunk has a context dependency on the PR56098 fix added to 4.7 branch 2013-02-01 ] gcc/ 2013-02-08 Michael Matz PR tree-optimization/52448 * tree-ssa-phiopt.c (struct name_to_bb): Add phase member. (nt_call_phase): New static. (add_or_mark_expr): Only mark accesses with newer phase than any call seen. (nonfreeing_call_p): New. (nt_init_block): Update nt_call_phase, mark blocks as visited. (nt_fini_block): Keep blocks marked as visited. (get_non_trapping): Initialize nt_call_phase, and reset aux pointer. gcc/testsuite/ 2013-02-08 Michael Matz PR tree-optimization/52448 * gcc.dg/pr52448.c: New test. --- gcc-4.7-20130202/gcc/testsuite/gcc.dg/pr52448.c.~1~ 1970-01-01 01:00:00.000000000 +0100 +++ gcc-4.7-20130202/gcc/testsuite/gcc.dg/pr52448.c 2013-02-10 12:59:42.180827545 +0100 @@ -0,0 +1,30 @@ +/* PR tree-optimization/52448 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -ftree-cselim -fdump-tree-cselim-details" } */ + +extern void perhaps_free_something (void); + +void f1 (int *p, int a, int b, int cond, int cond2) +{ + *p = a; + if (cond) + perhaps_free_something (); + if (cond2) + *p = b; +} + +void f2 (int *p, int a, int b, int *cond, int *cond2) +{ + int i; + *p = a; + for (i = 0; cond[i]; i++) + { + if (cond2[i]) + *p = b; + perhaps_free_something (); + } +} + +/* None of the above conditional stores might be made unconditional. */ +/* { dg-final { scan-tree-dump-not "cstore" "cselim" } } */ +/* { dg-final { cleanup-tree-dump "cselim" } } */ --- gcc-4.7-20130202/gcc/tree-ssa-phiopt.c.~1~ 2013-02-01 15:16:20.000000000 +0100 +++ gcc-4.7-20130202/gcc/tree-ssa-phiopt.c 2013-02-10 12:59:42.180827545 +0100 @@ -1123,6 +1123,7 @@ abs_replacement (basic_block cond_bb, ba struct name_to_bb { unsigned int ssa_name_ver; + unsigned int phase; bool store; HOST_WIDE_INT offset, size; basic_block bb; @@ -1131,6 +1132,10 @@ struct name_to_bb /* The hash table for remembering what we've seen. */ static htab_t seen_ssa_names; +/* Used for quick clearing of the hash-table when we see calls. + Hash entries with phase < nt_call_phase are invalid. */ +static unsigned int nt_call_phase; + /* The set of MEM_REFs which can't trap. */ static struct pointer_set_t *nontrap_set; @@ -1181,6 +1186,7 @@ add_or_mark_expr (basic_block bb, tree e /* Try to find the last seen MEM_REF through the same SSA_NAME, which can trap. */ map.ssa_name_ver = SSA_NAME_VERSION (name); + map.phase = 0; map.bb = 0; map.store = store; map.offset = tree_low_cst (TREE_OPERAND (exp, 1), 0); @@ -1188,13 +1194,13 @@ add_or_mark_expr (basic_block bb, tree e slot = htab_find_slot (seen_ssa_names, &map, INSERT); n2bb = (struct name_to_bb *) *slot; - if (n2bb) + if (n2bb && n2bb->phase >= nt_call_phase) found_bb = n2bb->bb; /* If we've found a trapping MEM_REF, _and_ it dominates EXP (it's in a basic block on the path from us to the dominator root) then we can't trap. */ - if (found_bb && found_bb->aux == (void *)1) + if (found_bb && (((size_t)found_bb->aux) & 1) == 1) { pointer_set_insert (nontrap, exp); } @@ -1203,12 +1209,14 @@ add_or_mark_expr (basic_block bb, tree e /* EXP might trap, so insert it into the hash table. */ if (n2bb) { + n2bb->phase = nt_call_phase; n2bb->bb = bb; } else { n2bb = XNEW (struct name_to_bb); n2bb->ssa_name_ver = SSA_NAME_VERSION (name); + n2bb->phase = nt_call_phase; n2bb->bb = bb; n2bb->store = store; n2bb->offset = map.offset; @@ -1219,20 +1227,55 @@ add_or_mark_expr (basic_block bb, tree e } } +/* Return true when CALL is a call stmt that definitely doesn't + free any memory or makes it unavailable otherwise. */ +static bool +nonfreeing_call_p (gimple call) +{ + if (gimple_call_builtin_p (call, BUILT_IN_NORMAL) + && gimple_call_flags (call) & ECF_LEAF) + switch (DECL_FUNCTION_CODE (gimple_call_fndecl (call))) + { + /* Just in case these become ECF_LEAF in the future. */ + case BUILT_IN_FREE: + case BUILT_IN_TM_FREE: + case BUILT_IN_REALLOC: + case BUILT_IN_STACK_RESTORE: + return false; + default: + return true; + } + + return false; +} + /* Called by walk_dominator_tree, when entering the block BB. */ static void nt_init_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb) { + edge e; + edge_iterator ei; gimple_stmt_iterator gsi; - /* Mark this BB as being on the path to dominator root. */ - bb->aux = (void*)1; + + /* If we haven't seen all our predecessors, clear the hash-table. */ + FOR_EACH_EDGE (e, ei, bb->preds) + if ((((size_t)e->src->aux) & 2) == 0) + { + nt_call_phase++; + break; + } + + /* Mark this BB as being on the path to dominator root and as visited. */ + bb->aux = (void*)(1 | 2); /* And walk the statements in order. */ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple stmt = gsi_stmt (gsi); - if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt)) + if (is_gimple_call (stmt) && !nonfreeing_call_p (stmt)) + nt_call_phase++; + else if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt)) { add_or_mark_expr (bb, gimple_assign_lhs (stmt), nontrap_set, true); add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), nontrap_set, false); @@ -1245,7 +1288,7 @@ static void nt_fini_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb) { /* This BB isn't on the path to dominator root anymore. */ - bb->aux = NULL; + bb->aux = (void*)2; } /* This is the entry point of gathering non trapping memory accesses. @@ -1258,6 +1301,7 @@ get_non_trapping (void) struct pointer_set_t *nontrap; struct dom_walk_data walk_data; + nt_call_phase = 0; nontrap = pointer_set_create (); seen_ssa_names = htab_create (128, name_to_bb_hash, name_to_bb_eq, free); @@ -1279,6 +1323,7 @@ get_non_trapping (void) fini_walk_dominator_tree (&walk_data); htab_delete (seen_ssa_names); + clear_aux_for_blocks (); return nontrap; }