Author: lattner
Date: Fri Jan 4 19:18:20 2008
New Revision: 45612
URL: http://llvm.org/viewvc/llvm-project?rev=45612&view=rev
Log:
remove the (x-y) < 0 comparison xform, it miscompiles
things that are not equality comparisons, for example:
(2147479553+4096)-2147479553 < 0 != (2147479553+4096) < 2147479553
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=45612&r1=45611&r2=45612&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Fri Jan 4
19:18:20 2008
@@ -4835,17 +4835,11 @@
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()) {
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
