diff options
author | Richard Guenther <rguenther@suse.de> | 2008-03-05 16:13:04 +0000 |
---|---|---|
committer | Richard Biener <rguenth@gcc.gnu.org> | 2008-03-05 16:13:04 +0000 |
commit | 1bdcf037b30e17f8f9182952494c7d98b9a100d1 (patch) | |
tree | f34248a3bddd1b90c01b24609c94f0ff59cae43d /gcc/tree-ssa-dse.c | |
parent | fec5fe47e641ed2f95e60197a9a3977176427749 (diff) | |
download | gcc-1bdcf037b30e17f8f9182952494c7d98b9a100d1.zip gcc-1bdcf037b30e17f8f9182952494c7d98b9a100d1.tar.gz gcc-1bdcf037b30e17f8f9182952494c7d98b9a100d1.tar.bz2 |
re PR tree-optimization/35472 (tree DSE is broken)
2008-03-05 Richard Guenther <rguenther@suse.de>
PR tree-optimization/35472
* tree-ssa-dse.c (dse_optimize_stmt): Do not delete a store
whose single use_stmt has a overlapping set of loaded and
stored symbols as that use_stmt might be a noop assignment then.
* gcc.c-torture/execute/pr35472.c: New testcase.
From-SVN: r132899
Diffstat (limited to 'gcc/tree-ssa-dse.c')
-rw-r--r-- | gcc/tree-ssa-dse.c | 33 |
1 files changed, 16 insertions, 17 deletions
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index 3e0f04b..f2ec9a5 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -470,24 +470,23 @@ dse_optimize_stmt (struct dom_walk_data *walk_data, vuse_vec_p vv; tree stmt_lhs; - if (LOADED_SYMS (use_stmt)) + /* If use_stmt is or might be a nop assignment, e.g. for + struct { ... } S a, b, *p; ... + b = a; b = b; + or + b = a; b = *p; where p might be &b, + or + *p = a; *p = b; where p might be &b, + or + *p = *u; *p = *v; where p might be v, then USE_STMT + acts as a use as well as definition, so store in STMT + is not dead. */ + if (LOADED_SYMS (use_stmt) + && bitmap_intersect_p (LOADED_SYMS (use_stmt), + STORED_SYMS (use_stmt))) { - tree use_base - = get_base_address (GIMPLE_STMT_OPERAND (use_stmt, 0)); - /* If use_stmt is or might be a nop assignment, e.g. for - struct { ... } S a, b, *p; ... - b = a; b = b; - or - b = a; b = *p; where p might be &b, then USE_STMT - acts as a use as well as definition, so store in STMT - is not dead. */ - if (TREE_CODE (use_base) == VAR_DECL - && bitmap_bit_p (LOADED_SYMS (use_stmt), - DECL_UID (use_base))) - { - record_voperand_set (dse_gd->stores, &bd->stores, ann->uid); - return; - } + record_voperand_set (dse_gd->stores, &bd->stores, ann->uid); + return; } if (dump_file && (dump_flags & TDF_DETAILS)) |