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[ConstantFolding] Guard against unfolded FP binop 

Check that the operation actually folded before trying to flush
denormals. A minor variation of the pr33453 test exposed this
with the FP binops marked as undesirable.
This commit is contained in:
Nikita Popov 2022-07-08 17:43:55 +02:00
parent 74a8fce6e8
commit d686ea32b1
2 changed files with 6 additions and 2 deletions
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2
llvm/lib/Analysis/ConstantFolding.cpp
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@ -1397,6 +1397,8 @@ Constant *llvm::ConstantFoldFPInstOperands(unsigned Opcode, Constant *LHS,
// Calculate constant result.
Constant *C = ConstantFoldBinaryOpOperands(Opcode, Op0, Op1, DL);
if (!C)
return nullptr;
// Flush denormal output if needed.
return FlushFPConstant(C, I, /* IsOutput */ true);

6
llvm/test/Transforms/InstCombine/pr33453.ll
View File

@ -6,9 +6,11 @@
define float @patatino() {
; CHECK-LABEL: @patatino(
; CHECK-NEXT: ret float fmul (float uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float), float uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float))
; CHECK-NEXT: [[FMUL:%.*]] = fmul float uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float), uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float)
; CHECK-NEXT: ret float [[FMUL]]
;
%call = call float @fabsf(float fmul (float uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float), float uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float)))
%fmul = fmul float uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float), uitofp (i1 icmp eq (i16* getelementptr inbounds (i16, i16* @g2, i64 1), i16* @g1) to float)
%call = call float @fabsf(float %fmul)
ret float %call
}