[InstCombine] Update fptrunc (fneg x)) -> (fneg (fptrunc x) for unary FNeg
Differential Revision: https://reviews.llvm.org/D62629
llvm-svn: 363080
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 36be8bd..2c9ba20 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1615,12 +1615,20 @@
return CastInst::CreateFPCast(ExactResult, Ty);
}
}
+ }
- // (fptrunc (fneg x)) -> (fneg (fptrunc x))
- Value *X;
- if (match(OpI, m_FNeg(m_Value(X)))) {
+ // (fptrunc (fneg x)) -> (fneg (fptrunc x))
+ Value *X;
+ Instruction *Op = dyn_cast<Instruction>(FPT.getOperand(0));
+ if (Op && Op->hasOneUse()) {
+ if (match(Op, m_FNeg(m_Value(X)))) {
Value *InnerTrunc = Builder.CreateFPTrunc(X, Ty);
- return BinaryOperator::CreateFNegFMF(InnerTrunc, OpI);
+
+ // FIXME: Once we're sure that unary FNeg optimizations are on par with
+ // binary FNeg, this should always return a unary operator.
+ if (isa<BinaryOperator>(Op))
+ return BinaryOperator::CreateFNegFMF(InnerTrunc, Op);
+ return UnaryOperator::CreateFNegFMF(InnerTrunc, Op);
}
}