diff options
| author | Chris Lattner <sabre@nondot.org> | 2008-01-05 01:18:20 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2008-01-05 01:18:20 +0000 |
| commit | b656601943b2f1a76ee93fc3767de2ea75694672 (patch) | |
| tree | 41583c62138e241d3fc3dead44ad3514182d6ec8 | |
| parent | a393cd3306b865e8e5d82dc4e6cfabcdf5d8dc44 (diff) | |
remove the (x-y) < 0 comparison xform, it miscompiles
things that are not equality comparisons, for example:
(2147479553+4096)-2147479553 < 0 != (2147479553+4096) < 2147479553
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45612 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 489f0de5ef..83cacbab71 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -4835,17 +4835,11 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { Value *A, *B; - // (icmp cond (sub A B) 0) -> ... - if (CI->isNullValue() && match(Op0, m_Sub(m_Value(A), m_Value(B)))) { - // (icmp cond A B) if cond is signed or equality - if (CmpInst::isSigned(I.getPredicate()) || I.isEquality()) - return new ICmpInst(I.getPredicate(), A, B); - // (icmp ne A B) if cond is ugt - else if (I.getPredicate() == ICmpInst::ICMP_UGT) - return new ICmpInst(ICmpInst::ICMP_NE, A, B); - // (icmp eq A B) if cond is ule - else if (I.getPredicate() == ICmpInst::ICMP_ULE) - return new ICmpInst(ICmpInst::ICMP_EQ, A, B); + // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B) + if (I.isEquality() && CI->isNullValue() && + match(Op0, m_Sub(m_Value(A), m_Value(B)))) { + // (icmp cond A B) if cond is equality + return new ICmpInst(I.getPredicate(), A, B); } switch (I.getPredicate()) { |