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| author | Stuart Hastings <stuart@apple.com> | 2011-05-14 05:55:10 +0000 |
|---|---|---|
| committer | Stuart Hastings <stuart@apple.com> | 2011-05-14 05:55:10 +0000 |
| commit | 67f071e69795dca1151cdb8d57d222b6f041d748 (patch) | |
| tree | c0f6dec117078c1c224aba3b698d1993cb974235 | |
| parent | d0118a2371f35faa6af97e67be69e1debc615c42 (diff) | |
| download | llvm-67f071e69795dca1151cdb8d57d222b6f041d748.tar.gz llvm-67f071e69795dca1151cdb8d57d222b6f041d748.tar.bz2 llvm-67f071e69795dca1151cdb8d57d222b6f041d748.tar.xz | |
Avoid combining GEPs that might overflow at runtime.
rdar://problem/9267970
Patch by Julien Lerouge!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131339 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCompares.cpp | 4 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2011-05-13-InBoundsGEP.ll | 19 |
2 files changed, 22 insertions, 1 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index b6963c5499..ede659b011 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -634,6 +634,7 @@ Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, if (AllZeros) return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); + bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds(); if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { // If the GEPs only differ by one index, compare it. unsigned NumDifferences = 0; // Keep track of # differences. @@ -656,7 +657,7 @@ Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, ConstantInt::get(Type::getInt1Ty(I.getContext()), ICmpInst::isTrueWhenEqual(Cond))); - else if (NumDifferences == 1) { + else if (NumDifferences == 1 && GEPsInBounds) { Value *LHSV = GEPLHS->getOperand(DiffOperand); Value *RHSV = GEPRHS->getOperand(DiffOperand); // Make sure we do a signed comparison here. @@ -667,6 +668,7 @@ Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, // Only lower this if the icmp is the only user of the GEP or if we expect // the result to fold to a constant! if (TD && + GEPsInBounds && (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) && (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) { // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) diff --git a/test/Transforms/InstCombine/2011-05-13-InBoundsGEP.ll b/test/Transforms/InstCombine/2011-05-13-InBoundsGEP.ll new file mode 100644 index 0000000000..d65173db8c --- /dev/null +++ b/test/Transforms/InstCombine/2011-05-13-InBoundsGEP.ll @@ -0,0 +1,19 @@ +; RUN: opt < %s -instcombine | lli +; rdar://problem/9267970 +; ideally this test will run on a 32-bit host +; must not discard GEPs that might overflow at runtime (aren't inbounds) + +define i32 @main(i32 %argc) { +entry: + %tmp1 = add i32 %argc, -2 + %tmp2 = add i32 %argc, 1879048192 + %p = alloca i8 + %p1 = getelementptr i8* %p, i32 %tmp1 + %p2 = getelementptr i8* %p, i32 %tmp2 + %cmp = icmp ult i8* %p1, %p2 + br i1 %cmp, label %bbtrue, label %bbfalse +bbtrue: ; preds = %entry + ret i32 -1 +bbfalse: ; preds = %entry + ret i32 0 +} |