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| author | Richard Biener <rguenther@suse.de> | 2014-02-04 09:34:58 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2014-02-04 09:34:58 +0000 |
| commit | 5961d779d0f20b61363091ac7849d457cc80275d (patch) | |
| tree | 0de58989cf334be8504e47b257a2df2a1aab7bc8 /gcc/tree-vect-data-refs.c | |
| parent | 91da04811259e454dadc9c828024b1548030bd91 (diff) | |
| download | gcc-5961d779d0f20b61363091ac7849d457cc80275d.zip gcc-5961d779d0f20b61363091ac7849d457cc80275d.tar.gz gcc-5961d779d0f20b61363091ac7849d457cc80275d.tar.bz2 | |
re PR tree-optimization/60012 (Vectorizer generates unnecessary loop versioning for alias)
2014-02-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/60012
* tree-vect-data-refs.c (vect_analyze_data_ref_dependence): Apply
TBAA disambiguation to all DDRs.
* gcc.dg/vect/pr60012.c: New testcase.
From-SVN: r207455
Diffstat (limited to 'gcc/tree-vect-data-refs.c')
| -rw-r--r-- | gcc/tree-vect-data-refs.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c index c3e8f37..d018add 100644 --- a/gcc/tree-vect-data-refs.c +++ b/gcc/tree-vect-data-refs.c @@ -235,6 +235,18 @@ vect_analyze_data_ref_dependence (struct data_dependence_relation *ddr, || (DR_IS_READ (dra) && DR_IS_READ (drb))) return false; + /* Even if we have an anti-dependence then, as the vectorized loop covers at + least two scalar iterations, there is always also a true dependence. + As the vectorizer does not re-order loads and stores we can ignore + the anti-dependence if TBAA can disambiguate both DRs similar to the + case with known negative distance anti-dependences (positive + distance anti-dependences would violate TBAA constraints). */ + if (((DR_IS_READ (dra) && DR_IS_WRITE (drb)) + || (DR_IS_WRITE (dra) && DR_IS_READ (drb))) + && !alias_sets_conflict_p (get_alias_set (DR_REF (dra)), + get_alias_set (DR_REF (drb)))) + return false; + /* Unknown data dependence. */ if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know) { |