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When InstCombine tries to fold away (fsub x, (fneg y)) into (fadd x, y), it is
also worthwhile for it to look through FP extensions and truncations, whose application commutes with fneg. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187249 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1528,9 +1528,21 @@ Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
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if (Instruction *NV = FoldOpIntoSelect(I, SI))
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return NV;
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// If this is a 'B = x-(-A)', change to B = x+A...
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// If this is a 'B = x-(-A)', change to B = x+A, potentially looking
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// through FP extensions/truncations along the way.
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if (Value *V = dyn_castFNegVal(Op1))
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return BinaryOperator::CreateFAdd(Op0, V);
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if (FPTruncInst *FPTI = dyn_cast<FPTruncInst>(Op1)) {
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if (Value *V = dyn_castFNegVal(FPTI->getOperand(0))) {
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Value *NewTrunc = Builder->CreateFPTrunc(V, I.getType());
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return BinaryOperator::CreateFAdd(Op0, NewTrunc);
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}
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} else if (FPExtInst *FPEI = dyn_cast<FPExtInst>(Op1)) {
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if (Value *V = dyn_castFNegVal(FPEI->getOperand(0))) {
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Value *NewTrunc = Builder->CreateFPExt(V, I.getType());
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return BinaryOperator::CreateFAdd(Op0, NewTrunc);
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}
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}
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if (I.hasUnsafeAlgebra()) {
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if (Value *V = FAddCombine(Builder).simplify(&I))
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12
test/Transforms/InstCombine/fneg-ext.ll
Normal file
12
test/Transforms/InstCombine/fneg-ext.ll
Normal file
@ -0,0 +1,12 @@
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; RUN: opt -instcombine -S < %s | FileCheck %s
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; CHECK: test1
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define double @test1(float %a, double %b) nounwind readnone ssp uwtable {
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; CHECK-NOT: fsub
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; CHECK: fpext
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; CHECK: fadd
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%1 = fsub float -0.000000e+00, %a
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%2 = fpext float %1 to double
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%3 = fsub double %b, %2
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ret double %3
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}
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