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| author | Sanjoy Das <sanjoy@playingwithpointers.com> | 2015-02-23 23:22:58 +0000 |
|---|---|---|
| committer | Sanjoy Das <sanjoy@playingwithpointers.com> | 2015-02-23 23:22:58 +0000 |
| commit | 18c243b933740506b3262e56ef6f9a3a6e4afc08 (patch) | |
| tree | c7bf17f52b360208c3f47dda7953cc30201128e0 /llvm/test/Transforms/IndVarSimplify/overflowcheck.ll | |
| parent | c9cf0151cf73ed44dd3af74568a9c01d0bded8b9 (diff) | |
| download | bcm5719-llvm-18c243b933740506b3262e56ef6f9a3a6e4afc08.tar.gz bcm5719-llvm-18c243b933740506b3262e56ef6f9a3a6e4afc08.zip | |
Bugfix: SCEVExpander incorrectly marks increment operations as no-wrap
When emitting the increment operation, SCEVExpander marks the
operation as nuw or nsw based on the flags on the preincrement SCEV.
This is incorrect because, for instance, it is possible that {-6,+,1}
is <nuw> while {-6,+,1}+1 = {-5,+,1} is not.
This change teaches SCEV to mark the increment as nuw/nsw only if it
can explicitly prove that the increment operation won't overflow.
Apart from the attached test case, another (more realistic) manifestation
of the bug can be seen in Transforms/IndVarSimplify/pr20680.ll.
NOTE: this change was landed with an incorrect commit message in
rL230275 and was reverted for that reason in rL230279. This commit
message is the correct one.
Differential Revision: http://reviews.llvm.org/D7778
llvm-svn: 230280
Diffstat (limited to 'llvm/test/Transforms/IndVarSimplify/overflowcheck.ll')
| -rw-r--r-- | llvm/test/Transforms/IndVarSimplify/overflowcheck.ll | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/llvm/test/Transforms/IndVarSimplify/overflowcheck.ll b/llvm/test/Transforms/IndVarSimplify/overflowcheck.ll index 2603f363ab6..3864c6c0cfb 100644 --- a/llvm/test/Transforms/IndVarSimplify/overflowcheck.ll +++ b/llvm/test/Transforms/IndVarSimplify/overflowcheck.ll @@ -9,7 +9,7 @@ target triple = "x86_64-apple-macosx" ; CHECK: @llvm.sadd.with.overflow ; CHECK-LABEL: loop2: ; CHECK-NOT: extractvalue -; CHECK: add nuw nsw +; CHECK: add nuw ; CHECK: @llvm.sadd.with.overflow ; CHECK-LABEL: loop3: ; CHECK-NOT: extractvalue |
