[InstCombine] Add more tests. NFC.

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -2835,12 +2835,15 @@ static bool ignoreSignBitOfNaN(Instruction &I) {
         return true;
       case Intrinsic::copysign:
         return II->getArgOperand(0) == &I;
+      // fmin/fmax returns one of its operands, so the sign bit cannot be
+      // ignored.
       case Intrinsic::maxnum:
       case Intrinsic::minnum:
       case Intrinsic::maximum:
       case Intrinsic::minimum:
       case Intrinsic::maximumnum:
       case Intrinsic::minimumnum:
+      // llvm.canonicalize preserves the sign bit of NaN.
       case Intrinsic::canonicalize:
         return false;
       default:

llvm/test/Transforms/InstCombine/fabs.ll

@@ -1342,6 +1342,19 @@ define float @test_fabs_used_by_fpop_nsz(float %x, float %y) {
   ret float %add
 }
 
+define float @test_fabs_used_by_fcopysign_mag(float %x, float %y) {
+; CHECK-LABEL: @test_fabs_used_by_fcopysign_mag(
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[X:%.*]], float [[Y:%.*]])
+; CHECK-NEXT:    ret float [[COPYSIGN]]
+;
+  %cmp = fcmp oge float %x, 0.000000e+00
+  %neg = fneg float %x
+  %sel = select i1 %cmp, float %x, float %neg
+  %copysign = call float @llvm.copysign.f32(float %sel, float %y)
+  ret float %copysign
+}
+
+
 ; Negative tests
 
 define float @test_fabs_used_by_fpop_nnan(float %x, float %y) {
@@ -1375,3 +1388,63 @@ define i1 @test_fabs_used_by_fcmp_multiuse(float %x, float %y) {
   call void @use(float %sel)
   ret i1 %cmp2
 }
+
+define float @test_fabs_used_by_fcopysign_sign(float %x, float %y) {
+; CHECK-LABEL: @test_fabs_used_by_fcopysign_sign(
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oge float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[NEG:%.*]] = fneg float [[X]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], float [[X]], float [[NEG]]
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[Y:%.*]], float [[SEL]])
+; CHECK-NEXT:    ret float [[COPYSIGN]]
+;
+  %cmp = fcmp oge float %x, 0.000000e+00
+  %neg = fneg float %x
+  %sel = select i1 %cmp, float %x, float %neg
+  %copysign = call float @llvm.copysign.f32(float %y, float %sel)
+  ret float %copysign
+}
+
+define float @test_fabs_used_by_maxnum(float %x, float %y) {
+; CHECK-LABEL: @test_fabs_used_by_maxnum(
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oge float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[NEG:%.*]] = fneg float [[X]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], float [[X]], float [[NEG]]
+; CHECK-NEXT:    [[MAX:%.*]] = call float @llvm.maxnum.f32(float [[Y:%.*]], float [[SEL]])
+; CHECK-NEXT:    ret float [[MAX]]
+;
+  %cmp = fcmp oge float %x, 0.000000e+00
+  %neg = fneg float %x
+  %sel = select i1 %cmp, float %x, float %neg
+  %max = call float @llvm.maxnum.f32(float %y, float %sel)
+  ret float %max
+}
+
+define float @test_fabs_used_by_canonicalize(float %x) {
+; CHECK-LABEL: @test_fabs_used_by_canonicalize(
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oge float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[NEG:%.*]] = fneg float [[X]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], float [[X]], float [[NEG]]
+; CHECK-NEXT:    [[CANON:%.*]] = call float @llvm.canonicalize.f32(float [[SEL]])
+; CHECK-NEXT:    ret float [[CANON]]
+;
+  %cmp = fcmp oge float %x, 0.000000e+00
+  %neg = fneg float %x
+  %sel = select i1 %cmp, float %x, float %neg
+  %canon = call float @llvm.canonicalize.f32(float %sel)
+  ret float %canon
+}
+
+define float @test_fabs_used_by_select(float %x, i1 %cond) {
+; CHECK-LABEL: @test_fabs_used_by_select(
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oge float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[NEG:%.*]] = fneg float [[X]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], float [[X]], float [[NEG]]
+; CHECK-NEXT:    [[SEL2:%.*]] = select i1 [[COND:%.*]], float [[SEL]], float 0.000000e+00
+; CHECK-NEXT:    ret float [[SEL2]]
+;
+  %cmp = fcmp oge float %x, 0.000000e+00
+  %neg = fneg float %x
+  %sel = select i1 %cmp, float %x, float %neg
+  %sel2 = select i1 %cond, float %sel, float 0.000000e+00
+  ret float %sel2
+}