diff options
| author | rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4> | 2008-03-05 16:13:04 +0000 |
|---|---|---|
| committer | rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4> | 2008-03-05 16:13:04 +0000 |
| commit | 7cf3d2829371ab6a0a98f7c504942d290ab81c79 (patch) | |
| tree | f34248a3bddd1b90c01b24609c94f0ff59cae43d /gcc/tree-ssa-dse.c | |
| parent | 2349cd3e43379cd107ab0248ed10ff5c3352e0eb (diff) | |
| download | gcc-7cf3d2829371ab6a0a98f7c504942d290ab81c79.tar.gz | |
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.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@132899 138bc75d-0d04-0410-961f-82ee72b054a4
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 3e0f04be124..f2ec9a505c7 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)) |