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DAGCombine: prevent formation of illegal ConstantFP nodes.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207850 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tim Northover 2014-05-02 17:25:02 +00:00
parent 3cddd1607c
commit b20252764d
2 changed files with 24 additions and 5 deletions
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15
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -7181,11 +7181,16 @@ SDValue DAGCombiner::visitFNEG(SDNode *N) {
// (fneg (fmul c, x)) -> (fmul -c, x)
if (N0.getOpcode() == ISD::FMUL) {
ConstantFPSDNode *CFP1 = dyn_cast<ConstantFPSDNode>(N0.getOperand(1));
if (CFP1)
return DAG.getNode(ISD::FMUL, SDLoc(N), VT,
N0.getOperand(0),
DAG.getNode(ISD::FNEG, SDLoc(N), VT,
N0.getOperand(1)));
if (CFP1) {
APFloat CVal = CFP1->getValueAPF();
CVal.changeSign();
if (Level >= AfterLegalizeDAG &&
(TLI.isFPImmLegal(CVal, N->getValueType(0)) ||
TLI.isOperationLegal(ISD::ConstantFP, N->getValueType(0))))
return DAG.getNode(
ISD::FMUL, SDLoc(N), VT, N0.getOperand(0),
DAG.getNode(ISD::FNEG, SDLoc(N), VT, N0.getOperand(1)));
}
}
return SDValue();

14
test/CodeGen/ARM64/fp-contract-zero.ll Normal file
View File

@ -0,0 +1,14 @@
; RUN: llc -mtriple=arm64 -fp-contract=fast -o - %s | FileCheck %s
; Make sure we don't try to fold an fneg into +0.0, creating an illegal constant
; -0.0. It's also good, though not essential, that we don't resort to a litpool.
define double @test_fms_fold(double %a, double %b) {
; CHECK-LABEL: test_fms_fold:
; CHECK: fmov {{d[0-9]+}}, xzr
; CHECK: ret
%mul = fmul double %a, 0.000000e+00
%mul1 = fmul double %b, 0.000000e+00
%sub = fsub double %mul, %mul1
ret double %sub
}