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| author | Richard Guenther <rguenther@suse.de> | 2012-07-04 12:10:40 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2012-07-04 12:10:40 +0000 |
| commit | 6c9df5a0014040115ebe576c4c0b7914a0414422 (patch) | |
| tree | 5351f6868c854e291586eee626ce32773354d355 /gcc/tree-ssa-dse.c | |
| parent | e1b6bbea37bb9e0dfaba80f5d7483fcd7ac9baa6 (diff) | |
| download | gcc-6c9df5a0014040115ebe576c4c0b7914a0414422.zip gcc-6c9df5a0014040115ebe576c4c0b7914a0414422.tar.gz gcc-6c9df5a0014040115ebe576c4c0b7914a0414422.tar.bz2 | |
re PR middle-end/53844 (GCC generates suboptimal code for unused members of classes in some cases on multiple targets.)
2012-07-04 Richard Guenther <rguenther@suse.de>
PR tree-optimization/53844
* tree-ssa-dse.c (dse_possible_dead_store_p): Properly handle
the loop virtual PHI.
* g++.dg/tree-ssa/pr53844.C: New testcase.
From-SVN: r189256
Diffstat (limited to 'gcc/tree-ssa-dse.c')
| -rw-r--r-- | gcc/tree-ssa-dse.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index 5fdba8c..04cc6ad 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -94,7 +94,7 @@ dse_possible_dead_store_p (gimple stmt, gimple *use_stmt) temp = stmt; do { - gimple use_stmt; + gimple use_stmt, defvar_def; imm_use_iterator ui; bool fail = false; tree defvar; @@ -108,6 +108,7 @@ dse_possible_dead_store_p (gimple stmt, gimple *use_stmt) defvar = PHI_RESULT (temp); else defvar = gimple_vdef (temp); + defvar_def = temp; temp = NULL; FOR_EACH_IMM_USE_STMT (use_stmt, ui, defvar) { @@ -139,7 +140,14 @@ dse_possible_dead_store_p (gimple stmt, gimple *use_stmt) fail = true; BREAK_FROM_IMM_USE_STMT (ui); } - temp = use_stmt; + /* Do not consider the PHI as use if it dominates the + stmt defining the virtual operand we are processing, + we have processed it already in this case. */ + if (gimple_bb (defvar_def) != gimple_bb (use_stmt) + && !dominated_by_p (CDI_DOMINATORS, + gimple_bb (defvar_def), + gimple_bb (use_stmt))) + temp = use_stmt; } /* If the statement is a use the store is not dead. */ else if (ref_maybe_used_by_stmt_p (use_stmt, |