InstCombine: Directly use computeKnownFPClass in is.fpclass combines

[arsenm]

Summary

The various isKnownNever* calls can be merged into one.

[foad]

The various isKnownNever* calls can be merged into one.

That makes it sounds like an NFC change, but it is clearly improving some tests.

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

934

"must be false"?

946

Given the other case we've handled already, I think this one can simplify to if (Mask == Known.KnownFPClasses).

[arsenm]

In D148065#4260951, @foad wrote:

The various isKnownNever* calls can be merged into one.

That makes it sounds like an NFC change, but it is clearly improving some tests.

From the passing of the assumption cache. Could split the parts

[foad]

In D148065#4269885, @arsenm wrote:

In D148065#4260951, @foad wrote:

The various isKnownNever* calls can be merged into one.

That makes it sounds like an NFC change, but it is clearly improving some tests.

From the passing of the assumption cache. Could split the parts

I think it's fine to commit as-is if you mention this in the commit message.

[arsenm]

9156559254d8aff50abfe856bd1bf847b1c622f8

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

if (!IsStrict && (IsOrdered || IsUnordered) &&
     // Equivalent of !(x == 0).
     Value *FCmp = IsUnordered ? Builder.CreateFCmpUNE(Src0, Zero)
                               : Builder.CreateFCmpONE(Src0, Zero);
 
     FCmp->takeName(&II);
     return replaceInstUsesWith(II, FCmp);
   }
 
-  // fp_class (nnan x), qnan|snan|other -> fp_class (nnan x), other
-  if ((Mask & fcNan) && isKnownNeverNaN(Src0, DL, &getTargetLibraryInfo())) {
-    II.setArgOperand(1, ConstantInt::get(Src1->getType(), Mask & ~fcNan));
-    return ⅈ
-  }
-
-  // fp_class (nnan x), ~(qnan|snan) -> true
-  if (Mask == (~fcNan & fcAllFlags) &&
-      isKnownNeverNaN(Src0, DL, &getTargetLibraryInfo())) {
-    return replaceInstUsesWith(II, ConstantInt::get(II.getType(), true));
-  }
+  KnownFPClass Known = computeKnownFPClass(
+      Src0, DL, Mask, 0, &getTargetLibraryInfo(), &AC, &II, &DT, &ORE);
 
+  // Clear test bits we know must be true from the source value.
+  // fp_class (nnan x), qnan|snan|other -> fp_class (nnan x), other
   // fp_class (ninf x), ninf|pinf|other -> fp_class (ninf x), other
-  if ((Mask & fcInf) &&
-      isKnownNeverInfinity(Src0, DL, &getTargetLibraryInfo())) {
-    II.setArgOperand(1, ConstantInt::get(Src1->getType(), Mask & ~fcInf));
+  if ((Mask & Known.KnownFPClasses) != Mask) {
+    II.setArgOperand(
+        1, ConstantInt::get(Src1->getType(), Mask & Known.KnownFPClasses));
     return ⅈ
   }
 
+  // If none of the tests which can return false are possible, fold to true.
+  // fp_class (nnan x), ~(qnan|snan) -> true
   // fp_class (ninf x), ~(ninf|pinf) -> true
-  if (Mask == (~fcInf & fcAllFlags) &&
-      isKnownNeverInfinity(Src0, DL, &getTargetLibraryInfo())) {
+  if ((~Mask & Known.KnownFPClasses) == fcNone)
     return replaceInstUsesWith(II, ConstantInt::get(II.getType(), true));
-  }
 
   return nullptr;
 }
 
 static std::optional<bool> getKnownSign(Value *Op, Instruction *CxtI,
                                    const DataLayout &DL, AssumptionCache *AC,
                                    DominatorTree *DT) {
   KnownBits Known = computeKnownBits(Op, DL, 0, AC, CxtI, DT);

llvm/test/Transforms/InstCombine/is_fpclass.ll

 ; CHECK-NEXT:    ret i1 [[CLASS]]
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 96)
   ret i1 %class
 }
 
 define i1 @test_class_is_pzero_nozero_src(float nofpclass(zero) %arg) {
 ; CHECK-LABEL: @test_class_is_pzero_nozero_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 64)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 64)
   ret i1 %class
 }
 
 define i1 @test_class_is_pzero_nopzero_src(float nofpclass(pzero) %arg) {
 ; CHECK-LABEL: @test_class_is_pzero_nopzero_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 64)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 64)
   ret i1 %class
 }
 
 define i1 @test_class_is_pzero_nonzero_src(float nofpclass(nzero) %arg) {
 ; CHECK-LABEL: @test_class_is_pzero_nonzero_src(
 ; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 64)
 ; CHECK-NEXT:    ret i1 [[CLASS]]
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 64)
   ret i1 %class
 }
 
 define i1 @test_class_is_nzero_nozero_src(float nofpclass(zero) %arg) {
 ; CHECK-LABEL: @test_class_is_nzero_nozero_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 32)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 32)
   ret i1 %class
 }
 
 define i1 @test_class_is_nzero_nopzero_src(float nofpclass(pzero) %arg) {
 ; CHECK-LABEL: @test_class_is_nzero_nopzero_src(
 ; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 32)
 ; CHECK-NEXT:    ret i1 [[CLASS]]
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 32)
   ret i1 %class
 }
 
 define i1 @test_class_is_nzero_nonzero_src(float nofpclass(nzero) %arg) {
 ; CHECK-LABEL: @test_class_is_nzero_nonzero_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 32)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 32)
   ret i1 %class
 }
 
 define i1 @test_class_is_normal_or_zero_nozero_src(float nofpclass(zero) %arg) {
 ; CHECK-LABEL: @test_class_is_normal_or_zero_nozero_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 360)
+; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 264)
 ; CHECK-NEXT:    ret i1 [[CLASS]]
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 360)
   ret i1 %class
 }
 
 define i1 @test_class_is_inf_or_nan_nozero_src(float nofpclass(zero) %arg) {
 ; CHECK-LABEL: @test_class_is_inf_or_nan_nozero_src(

 ; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 512)
   ret i1 %class
 }
 
 define i1 @test_class_is_subnormal_nosub_src(float nofpclass(sub) %arg) {
 ; CHECK-LABEL: @test_class_is_subnormal_nosub_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 144)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 144)
   ret i1 %class
 }
 
 define i1 @test_class_is_subnormal_nonsub_src(float nofpclass(nsub) %arg) {
 ; CHECK-LABEL: @test_class_is_subnormal_nonsub_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 144)
+; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 128)
 ; CHECK-NEXT:    ret i1 [[CLASS]]
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 144)
   ret i1 %class
 }
 
 define i1 @test_class_is_not_subnormal_nosub_src(float nofpclass(sub) %arg) {
 ; CHECK-LABEL: @test_class_is_not_subnormal_nosub_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 879)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 true
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 879)
   ret i1 %class
 }
 
 define i1 @test_class_is_not_negsubnormal_nosub_src(float nofpclass(sub) %arg) {
 ; CHECK-LABEL: @test_class_is_not_negsubnormal_nosub_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 1007)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 true
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 1007)
   ret i1 %class
 }
 
 define i1 @test_class_is_not_negsubnormal_nonegsub_src(float nofpclass(nsub) %arg) {
 ; CHECK-LABEL: @test_class_is_not_negsubnormal_nonegsub_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 1007)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 true
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 1007)
   ret i1 %class
 }
 
 define i1 @test_class_is_nnormal_nonorm_src(float nofpclass(norm) %arg) {
 ; CHECK-LABEL: @test_class_is_nnormal_nonorm_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 264)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 264)
   ret i1 %class
 }
 
 define i1 @test_class_is_not_nnormal_nonorm_src(float nofpclass(norm) %arg) {
 ; CHECK-LABEL: @test_class_is_not_nnormal_nonorm_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 759)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 true
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 759)
   ret i1 %class
 }
 
 define i1 @test_class_is_not_nnormal_onlynorm_src(float nofpclass(nan inf zero sub) %arg) {
 ; CHECK-LABEL: @test_class_is_not_nnormal_onlynorm_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 240)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 759)
   ret i1 %class
 }
 
 define i1 @test_class_is_nnormal_onlynorm_src(float nofpclass(nan inf zero sub) %arg) {
 ; CHECK-LABEL: @test_class_is_nnormal_onlynorm_src(
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[ARG:%.*]], i32 264)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 true
 ;
   %class = call i1 @llvm.is.fpclass.f32(float %arg, i32 264)
   ret i1 %class
 }
 
 ; Make sure assume works
 define i1 @test_class_is_normal_assume_normal(float %x) {
 ; CHECK-LABEL: @test_class_is_normal_assume_normal(
 ; CHECK-NEXT:    [[ASSUMED_IS_NORMAL:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X:%.*]], i32 264)
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[ASSUMED_IS_NORMAL]])
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X]], i32 264)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 true
 ;
   %assumed.is.normal = call i1 @llvm.is.fpclass.f32(float %x, i32 264)
   call void @llvm.assume(i1 %assumed.is.normal)
   %class = call i1 @llvm.is.fpclass.f32(float %x, i32 264)
   ret i1 %class
 }
 
 define i1 @test_class_is_normal_assume_not_normal(float %x) {
 ; CHECK-LABEL: @test_class_is_normal_assume_not_normal(
 ; CHECK-NEXT:    [[ASSUMED_IS_NORMAL:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X:%.*]], i32 264)
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[ASSUMED_IS_NORMAL]])
-; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X]], i32 759)
-; CHECK-NEXT:    ret i1 [[CLASS]]
+; CHECK-NEXT:    ret i1 false
 ;
   %assumed.is.normal = call i1 @llvm.is.fpclass.f32(float %x, i32 264)
   call void @llvm.assume(i1 %assumed.is.normal)
   %class = call i1 @llvm.is.fpclass.f32(float %x, i32 759)
   ret i1 %class
 }
 
 define i1 @test_class_is_nan_assume_ord(float %x) {