Index: lib/Transforms/InstCombine/InstructionCombining.cpp =================================================================== --- lib/Transforms/InstCombine/InstructionCombining.cpp +++ lib/Transforms/InstCombine/InstructionCombining.cpp @@ -739,9 +739,9 @@ Value *V2 = SimplifyBinOp(Opcode, B, D, SQ.getWithInstruction(&I)); if (V1 && V2) SI = Builder.CreateSelect(A, V2, V1); - else if (V2) + else if (LHS->hasOneUse() && RHS->hasOneUse() && V2) SI = Builder.CreateSelect(A, V2, Builder.CreateBinOp(Opcode, C, E)); - else if (V1) + else if (LHS->hasOneUse() && RHS->hasOneUse() && V1) SI = Builder.CreateSelect(A, Builder.CreateBinOp(Opcode, B, D), V1); if (SI) Index: test/Transforms/InstCombine/select_arithmetic.ll =================================================================== --- test/Transforms/InstCombine/select_arithmetic.ll +++ test/Transforms/InstCombine/select_arithmetic.ll @@ -38,3 +38,31 @@ ; CHECK: ret float %tmp2 } +declare void @use_float(float) +; Tests folding constants if the selects have multiple uses but +; we can fold away the binary op with a select. +define float @test4(i1 zeroext %arg) #0 { + %tmp = select i1 %arg, float 5.000000e+00, float 6.000000e+00 + %tmp1 = select i1 %arg, float 1.000000e+00, float 9.000000e+00 + %tmp2 = fmul float %tmp, %tmp1 + call void @use_float(float %tmp) + ret float %tmp2 +; CHECK-LABEL: @test4( +; CHECK: select i1 %arg, float 5.000000e+00, float 6.000000e+00 +; CHECK-NEXT: select i1 %arg, float 5.000000e+00, float 5.400000e+01 +; CHECK-NEXT: call void @use_float(float %tmp) +; CHECK: ret float %tmp2 +} + +; Tests not folding constants if we cannot fold away any of the selects. +define float @test5(i1 zeroext %arg, float %div) { + %tmp = select i1 %arg, float %div, float 5.000000e+00 + %mul = fmul contract float %tmp, %tmp + call void @use_float(float %tmp) + ret float %mul +; CHECK-LABEL: @test5( +; CHECK: [[TMP:%.*]] = select i1 %arg, float %div, float 5.000000e+00 +; CHECK-NEXT: [[MUL:%.*]] = fmul contract float [[TMP]], [[TMP]] +; CHECK-NOT: fmul contract float %div, %div +; CHECK: ret float [[MUL]] +}