if (Value *V = SimplifyFDivInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
+ if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
+ const APFloat &Op1F = Op1C->getValueAPF();
+
+ // If the divisor has an exact multiplicative inverse we can turn the fdiv
+ // into a cheaper fmul.
+ APFloat Reciprocal(Op1F.getSemantics());
+ if (Op1F.getExactInverse(&Reciprocal)) {
+ ConstantFP *RFP = ConstantFP::get(Builder->getContext(), Reciprocal);
+ return BinaryOperator::CreateFMul(Op0, RFP);
+ }
+ }
+
return 0;
}
--- /dev/null
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+define float @test1(float %x) nounwind readnone ssp {
+ %div = fdiv float %x, 0x3810000000000000
+ ret float %div
+
+; CHECK: @test1
+; CHECK-NEXT: fmul float %x, 0x47D0000000000000
+}
+
+define float @test2(float %x) nounwind readnone ssp {
+ %div = fdiv float %x, 0x47E0000000000000
+ ret float %div
+
+; CHECK: @test2
+; CHECK-NEXT: fmul float %x, 0x3800000000000000
+}
+
+define float @test3(float %x) nounwind readnone ssp {
+ %div = fdiv float %x, 0x36A0000000000000
+ ret float %div
+
+; CHECK: @test3
+; CHECK-NEXT: fdiv float %x, 0x36A0000000000000
+}