[InstCombine] Fix crashing from (icmp (bitcast ([su]itofp X)), Y)
This fixes a class of bugs introduced by D44367,
which transforms various cases of icmp (bitcast ([su]itofp X)), Y to icmp X, Y.
If the bitcast is between vector types with a different number of elements,
the current code will produce bad IR along the lines of: icmp <N x i32> ..., <M x i32> <...>.
This patch suppresses the transform if the bitcast changes the number of vector elements.
Patch by: @AndrewScheidecker (Andrew Scheidecker)
Differential Revision: https://reviews.llvm.org/D57871
llvm-svn: 353467
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 5a63d55..dc26725 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2510,39 +2510,43 @@
if (!Bitcast)
return nullptr;
- // Zero-equality and sign-bit checks are preserved through sitofp + bitcast.
- // FIXME: This needs to check that the bitcast does not change the number of
- // elements in a vector.
ICmpInst::Predicate Pred = Cmp.getPredicate();
Value *Op1 = Cmp.getOperand(1);
Value *BCSrcOp = Bitcast->getOperand(0);
- Value *X;
- if (match(BCSrcOp, m_SIToFP(m_Value(X)))) {
- // icmp eq (bitcast (sitofp X)), 0 --> icmp eq X, 0
- // icmp ne (bitcast (sitofp X)), 0 --> icmp ne X, 0
- // icmp slt (bitcast (sitofp X)), 0 --> icmp slt X, 0
- // icmp sgt (bitcast (sitofp X)), 0 --> icmp sgt X, 0
- if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_SLT ||
- Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT) &&
- match(Op1, m_Zero()))
- return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
- // icmp slt (bitcast (sitofp X)), 1 --> icmp slt X, 1
- if (Pred == ICmpInst::ICMP_SLT && match(Op1, m_One()))
- return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), 1));
+ // Make sure the bitcast doesn't change the number of vector elements.
+ if (Bitcast->getSrcTy()->getScalarSizeInBits() ==
+ Bitcast->getDestTy()->getScalarSizeInBits()) {
+ // Zero-equality and sign-bit checks are preserved through sitofp + bitcast.
+ Value *X;
+ if (match(BCSrcOp, m_SIToFP(m_Value(X)))) {
+ // icmp eq (bitcast (sitofp X)), 0 --> icmp eq X, 0
+ // icmp ne (bitcast (sitofp X)), 0 --> icmp ne X, 0
+ // icmp slt (bitcast (sitofp X)), 0 --> icmp slt X, 0
+ // icmp sgt (bitcast (sitofp X)), 0 --> icmp sgt X, 0
+ if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_SLT ||
+ Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT) &&
+ match(Op1, m_Zero()))
+ return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
- // icmp sgt (bitcast (sitofp X)), -1 --> icmp sgt X, -1
- if (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))
- return new ICmpInst(Pred, X, ConstantInt::getAllOnesValue(X->getType()));
+ // icmp slt (bitcast (sitofp X)), 1 --> icmp slt X, 1
+ if (Pred == ICmpInst::ICMP_SLT && match(Op1, m_One()))
+ return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), 1));
+
+ // icmp sgt (bitcast (sitofp X)), -1 --> icmp sgt X, -1
+ if (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))
+ return new ICmpInst(Pred, X,
+ ConstantInt::getAllOnesValue(X->getType()));
+ }
+
+ // Zero-equality checks are preserved through unsigned floating-point casts:
+ // icmp eq (bitcast (uitofp X)), 0 --> icmp eq X, 0
+ // icmp ne (bitcast (uitofp X)), 0 --> icmp ne X, 0
+ if (match(BCSrcOp, m_UIToFP(m_Value(X))))
+ if (Cmp.isEquality() && match(Op1, m_Zero()))
+ return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
}
- // Zero-equality checks are preserved through unsigned floating-point casts:
- // icmp eq (bitcast (uitofp X)), 0 --> icmp eq X, 0
- // icmp ne (bitcast (uitofp X)), 0 --> icmp ne X, 0
- if (match(BCSrcOp, m_UIToFP(m_Value(X))))
- if (Cmp.isEquality() && match(Op1, m_Zero()))
- return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
-
// Test to see if the operands of the icmp are casted versions of other
// values. If the ptr->ptr cast can be stripped off both arguments, do so.
if (Bitcast->getType()->isPointerTy() &&