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| author | David Majnemer <david.majnemer@gmail.com> | 2013-06-29 10:28:04 +0000 |
|---|---|---|
| committer | David Majnemer <david.majnemer@gmail.com> | 2013-06-29 10:28:04 +0000 |
| commit | c22a4eeec6967454c73d1430398298259e468b92 (patch) | |
| tree | 14b9792948e7e52a4812d49e5016835663f4f861 /test/Transforms | |
| parent | df703257c1dafed4cdb803996a5c277d95780799 (diff) | |
| download | external_llvm-c22a4eeec6967454c73d1430398298259e468b92.zip external_llvm-c22a4eeec6967454c73d1430398298259e468b92.tar.gz external_llvm-c22a4eeec6967454c73d1430398298259e468b92.tar.bz2 | |
InstCombine: FoldGEPICmp shouldn't change sign of base pointer comparison
Changing the sign when comparing the base pointer would introduce all
sorts of unexpected things like:
%gep.i = getelementptr inbounds [1 x i8]* %a, i32 0, i32 0
%gep2.i = getelementptr inbounds [1 x i8]* %b, i32 0, i32 0
%cmp.i = icmp ult i8* %gep.i, %gep2.i
%cmp.i1 = icmp ult [1 x i8]* %a, %b
%cmp = icmp ne i1 %cmp.i, %cmp.i1
ret i1 %cmp
into:
%cmp.i = icmp slt [1 x i8]* %a, %b
%cmp.i1 = icmp ult [1 x i8]* %a, %b
%cmp = xor i1 %cmp.i, %cmp.i1
ret i1 %cmp
By preserving the original sign, we now get:
ret i1 false
This fixes PR16483.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185259 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/Transforms')
| -rw-r--r-- | test/Transforms/InstCombine/getelementptr.ll | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/test/Transforms/InstCombine/getelementptr.ll b/test/Transforms/InstCombine/getelementptr.ll index bb07736..844678a 100644 --- a/test/Transforms/InstCombine/getelementptr.ll +++ b/test/Transforms/InstCombine/getelementptr.ll @@ -509,4 +509,14 @@ define void @test39(%struct.ham* %arg, i8 %arg1) nounwind { ; CHECK: getelementptr inbounds i8* %tmp3, i64 -8 } +define i1 @pr16483([1 x i8]* %a, [1 x i8]* %b) { + %c = getelementptr [1 x i8]* %a, i32 0, i32 0 + %d = getelementptr [1 x i8]* %b, i32 0, i32 0 + %cmp = icmp ult i8* %c, %d + ret i1 %cmp + +; CHECK: @pr16483 +; CHECK-NEXT: icmp ult [1 x i8]* %a, %b +} + ; CHECK: attributes [[NUW]] = { nounwind } |