Make this transformation slightly less agressive and more correct.
The 'CmpInst::isFalseWhenEqual' function returns 'false' for values other than
simply equality. For instance, it returns 'false' for <= or >=. This isn't the
correct behavior for this transformation, which is checking for strict equality
and non-equality. It was causing the gcc.c-torture/execute/frame-address.c test
to fail because it would completely (and incorrectly) optimize a whole function
into a 'ret i32 0'.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152497 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index c024e92..95fd48e 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1609,23 +1609,33 @@
if (llvm::isKnownNonNull(LHSPtr) || llvm::isKnownNonNull(RHSPtr)) {
// If both sides are different identified objects, they aren't equal
// unless they're null.
- if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr))
- return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
+ if (LHSPtr != RHSPtr && llvm::isIdentifiedObject(RHSPtr) &&
+ (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::FCMP_UEQ))
+ return ConstantInt::get(ITy, false);
// A local identified object (alloca or noalias call) can't equal any
// incoming argument, unless they're both null.
- if (isa<Instruction>(LHSPtr) && isa<Argument>(RHSPtr))
- return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
+ if (isa<Instruction>(LHSPtr) && isa<Argument>(RHSPtr) &&
+ (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::FCMP_UEQ))
+ return ConstantInt::get(ITy, false);
}
// Assume that the constant null is on the right.
- if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr))
- return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
+ if (llvm::isKnownNonNull(LHSPtr) && isa<ConstantPointerNull>(RHSPtr)) {
+ if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::FCMP_UEQ)
+ return ConstantInt::get(ITy, false);
+ else if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::FCMP_ONE)
+ return ConstantInt::get(ITy, true);
+ }
} else if (isa<Argument>(LHSPtr)) {
RHSPtr = RHSPtr->stripInBoundsOffsets();
// An alloca can't be equal to an argument.
- if (isa<AllocaInst>(RHSPtr))
- return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
+ if (isa<AllocaInst>(RHSPtr)) {
+ if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::FCMP_UEQ)
+ return ConstantInt::get(ITy, false);
+ else if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::FCMP_ONE)
+ return ConstantInt::get(ITy, true);
+ }
}
// If we are comparing with zero then try hard since this is a common case.