diff options
| author | Richard Biener <rguenther@suse.de> | 2013-03-20 13:26:19 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2013-03-20 13:26:19 +0000 |
| commit | 92a8d7a7332ca2d53a70d856052b148331da518a (patch) | |
| tree | 4cf6946974a9a59ae3ef87513ac71079e3170b97 /gcc/tree-ssa-sccvn.c | |
| parent | 54714c680a46d4290c10b7369c1c1b2afd1e8d97 (diff) | |
| download | gcc-92a8d7a7332ca2d53a70d856052b148331da518a.zip gcc-92a8d7a7332ca2d53a70d856052b148331da518a.tar.gz gcc-92a8d7a7332ca2d53a70d856052b148331da518a.tar.bz2 | |
re PR tree-optimization/56661 (Incorrect code with -O1 -ftree-pre)
2013-03-20 Richard Biener <rguenther@suse.de>
PR tree-optimization/56661
* tree-ssa-sccvn.c (visit_use): Only value-number calls if
the result does not have to be distinct.
* gcc.dg/torture/pr56661.c: New testcase.
From-SVN: r196825
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 8360cc7..e7aefbf 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -3506,8 +3506,13 @@ visit_use (tree use) We can value number 2 calls to the same function with the same vuse and the same operands which are not subsequent the same, because there is no code in the program that can - compare the 2 values. */ - || gimple_vdef (stmt))) + compare the 2 values... */ + || (gimple_vdef (stmt) + /* ... unless the call returns a pointer which does + not alias with anything else. In which case the + information that the values are distinct are encoded + in the IL. */ + && !(gimple_call_return_flags (stmt) & ERF_NOALIAS)))) changed = visit_reference_op_call (lhs, stmt); else changed = defs_to_varying (stmt); |