ValueTracking: Implement computeKnownFPClass for fpext

[arsenm]

Summary

Not sure the denormal handling logic applies for some of the exotic FP types

[krzysz00]

Nine of the really exotic formats I know (the FP8 series) have type-level representations in LLVM unless I missed something ... and for them it's fptrunc I'd be worried about, not fpext

But also, I don't think the "abnormals extend to normals" property is true for bfloat -> float, since a bfloat is an IEEE float with the bottom 16 bits of the mantissa cut off.

[arsenm]

Check exponent range for subnormal handling

[arsenm]

Fix vectors

[jcranmer-intel]

llvm/lib/Analysis/ValueTracking.cpp

4627–4631

If the mantissa is sufficiently long, then a subnormal could still be a subnormal in a number with longer range. While this holds true for all the >=16-bit fp types, I'm not sure this holds true for the different FP8 types.

[arsenm]

llvm/lib/Analysis/ValueTracking.cpp

4627–4631

I missed fltSemantics::isRepresentableBy (don't understand why fltSemantics is treated so opaquely)

[arsenm]

llvm/lib/Analysis/ValueTracking.cpp

4627–4631

Which also seems to not behave as expected for the bf16->f32 case

[arsenm]

llvm/lib/Analysis/ValueTracking.cpp

4627–4631

Which would be because it doesn't have the same purpose

[arsenm]

Move condition into APFloat. Take a stab at guarding against exotic formats with large mantissas, although I don't think this is a practical problem (if the precision isn't larger, should fpext even be a valid operation to perform)?

[arsenm]

ping, this is the most annoying of the set since the APFloat touch triggers large rebuilds

[krzysz00]

Seems reasonable to me.

[arsenm]

69668590592fcca2c2b22ba2257be57f0319fc9c

llvm/include/llvm/ADT/APFloat.h

struct APFloatBase {
   };
 
   static unsigned int semanticsPrecision(const fltSemantics &);
   static ExponentType semanticsMinExponent(const fltSemantics &);
   static ExponentType semanticsMaxExponent(const fltSemantics &);
   static unsigned int semanticsSizeInBits(const fltSemantics &);
   static unsigned int semanticsIntSizeInBits(const fltSemantics&, bool);
 
+  // Returns true if any number described by \p Src can be precisely represented
+  // by a normal (not subnormal) value in \p Dst.
+  static bool isRepresentableAsNormalIn(const fltSemantics &Src,
+                                        const fltSemantics &Dst);
+
   /// Returns the size of the floating point number (in bits) in the given
   /// semantics.
   static unsigned getSizeInBits(const fltSemantics &Sem);
 };
 
 namespace detail {
 
 class IEEEFloat final : public APFloatBase {

llvm/lib/Analysis/ValueTracking.cpp

if (KnownRHS.isKnownNeverNaN() &&
            KnownLHS.isKnownNeverLogicalZero(*F, Op->getType())) &&
           (KnownRHS.isKnownNeverInfinity() ||
            KnownRHS.isKnownNeverLogicalZero(*F, Op->getType())))
         Known.knownNot(fcNan);
     }
 
     break;
   }
+  case Instruction::FPExt: {
+    // Infinity, nan and zero propagate from source.
+    computeKnownFPClass(Op->getOperand(0), DemandedElts, InterestedClasses,
+                        Known, Depth + 1, Q, TLI);
+
+    const fltSemantics &DstTy =
+        Op->getType()->getScalarType()->getFltSemantics();
+    const fltSemantics &SrcTy =
+        Op->getOperand(0)->getType()->getScalarType()->getFltSemantics();
+
+    // All subnormal inputs should be in the normal range in the result type.
+    if (APFloat::isRepresentableAsNormalIn(SrcTy, DstTy))
+      Known.knownNot(fcSubnormal);
+
+    // Sign bit of a nan isn't guaranteed.
+    if (!Known.isKnownNeverNaN())
+      Known.SignBit = std::nullopt;
+    break;
+  }
   case Instruction::FPTrunc: {
     if ((InterestedClasses & fcNan) == fcNone)
       break;
 
     KnownFPClass KnownSrc;
     computeKnownFPClass(Op->getOperand(0), DemandedElts,
                         InterestedClasses, KnownSrc, Depth + 1, Q, TLI);
     if (KnownSrc.isKnownNeverNaN())

llvm/lib/Support/APFloat.cpp

unsigned int APFloatBase::semanticsIntSizeInBits(const fltSemantics &semantics,
   // at least one more bit than the MaxExponent to hold the max FP value.
   unsigned int MinBitWidth = semanticsMaxExponent(semantics) + 1;
   // Extra sign bit needed.
   if (isSigned)
     ++MinBitWidth;
   return MinBitWidth;
 }
 
+bool APFloatBase::isRepresentableAsNormalIn(const fltSemantics &Src,
+                                            const fltSemantics &Dst) {
+  // Exponent range must be larger.
+  if (Src.maxExponent >= Dst.maxExponent || Src.minExponent <= Dst.minExponent)
+    return false;
+
+  // If the mantissa is long enough, the result value could still be denormal
+  // with a larger exponent range.
+  //
+  // FIXME: This condition is probably not accurate but also shouldn't be a
+  // practical concern with existing types.
+  return Dst.precision >= Src.precision;
+}
+
 unsigned APFloatBase::getSizeInBits(const fltSemantics &Sem) {
   return Sem.sizeInBits;
 }
 
 static constexpr APFloatBase::ExponentType
 exponentZero(const fltSemantics &semantics) {
   return semantics.minExponent - 1;
 }

llvm/test/Transforms/Attributor/nofpclass-fpext.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
 ; RUN: opt -aa-pipeline=basic-aa -passes=attributor -attributor-manifest-internal -S < %s | FileCheck %s --check-prefixes=CHECK,TUNIT
 
 define double @ret_fpext_f32_to_f64(float %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64
+; CHECK-LABEL: define nofpclass(sub) double @ret_fpext_f32_to_f64
 ; CHECK-SAME: (float [[ARG0:%.*]]) #[[ATTR0:[0-9]+]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define <2 x double> @ret_fpext_v2f32_to_v2f64(<2 x float> %arg0) {
-; CHECK-LABEL: define <2 x double> @ret_fpext_v2f32_to_v2f64
+; CHECK-LABEL: define nofpclass(sub) <2 x double> @ret_fpext_v2f32_to_v2f64
 ; CHECK-SAME: (<2 x float> [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext <2 x float> [[ARG0]] to <2 x double>
 ; CHECK-NEXT:    ret <2 x double> [[EXT]]
 ;
   %ext = fpext <2 x float> %arg0 to <2 x double>
   ret <2 x double> %ext
 }
 
 define double @ret_fpext_f32_to_f64_nonan(float nofpclass(nan) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nonan
+; CHECK-LABEL: define nofpclass(nan sub) double @ret_fpext_f32_to_f64_nonan
 ; CHECK-SAME: (float nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define <2 x double> @ret_fpext_v2f32_to_v2f64_nonan(<2 x float> nofpclass(nan) %arg0) {
-; CHECK-LABEL: define <2 x double> @ret_fpext_v2f32_to_v2f64_nonan
+; CHECK-LABEL: define nofpclass(nan sub) <2 x double> @ret_fpext_v2f32_to_v2f64_nonan
 ; CHECK-SAME: (<2 x float> nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext <2 x float> [[ARG0]] to <2 x double>
 ; CHECK-NEXT:    ret <2 x double> [[EXT]]
 ;
   %ext = fpext <2 x float> %arg0 to <2 x double>
   ret <2 x double> %ext
 }
 
 define double @ret_fpext_f32_to_f64_noqnan(float nofpclass(qnan) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_noqnan
+; CHECK-LABEL: define nofpclass(qnan sub) double @ret_fpext_f32_to_f64_noqnan
 ; CHECK-SAME: (float nofpclass(qnan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nosnan(float nofpclass(snan) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nosnan
+; CHECK-LABEL: define nofpclass(snan sub) double @ret_fpext_f32_to_f64_nosnan
 ; CHECK-SAME: (float nofpclass(snan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_noinf(float nofpclass(inf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_noinf
+; CHECK-LABEL: define nofpclass(inf sub) double @ret_fpext_f32_to_f64_noinf
 ; CHECK-SAME: (float nofpclass(inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nopinf(float nofpclass(pinf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nopinf
+; CHECK-LABEL: define nofpclass(pinf sub) double @ret_fpext_f32_to_f64_nopinf
 ; CHECK-SAME: (float nofpclass(pinf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_noninf(float nofpclass(ninf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_noninf
+; CHECK-LABEL: define nofpclass(ninf sub) double @ret_fpext_f32_to_f64_noninf
 ; CHECK-SAME: (float nofpclass(ninf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nozero(float nofpclass(zero) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nozero
+; CHECK-LABEL: define nofpclass(zero sub) double @ret_fpext_f32_to_f64_nozero
 ; CHECK-SAME: (float nofpclass(zero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nopzero(float nofpclass(pzero) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nopzero
+; CHECK-LABEL: define nofpclass(pzero sub) double @ret_fpext_f32_to_f64_nopzero
 ; CHECK-SAME: (float nofpclass(pzero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nonzero(float nofpclass(nzero) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nonzero
+; CHECK-LABEL: define nofpclass(nzero sub) double @ret_fpext_f32_to_f64_nonzero
 ; CHECK-SAME: (float nofpclass(nzero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nonan_noinf(float nofpclass(nan inf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nonan_noinf
+; CHECK-LABEL: define nofpclass(nan inf sub) double @ret_fpext_f32_to_f64_nonan_noinf
 ; CHECK-SAME: (float nofpclass(nan inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nosub(float nofpclass(sub) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nosub
+; CHECK-LABEL: define nofpclass(sub) double @ret_fpext_f32_to_f64_nosub
 ; CHECK-SAME: (float nofpclass(sub) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_f32_to_f64_nonorm(float nofpclass(norm) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_f32_to_f64_nonorm
+; CHECK-LABEL: define nofpclass(sub norm) double @ret_fpext_f32_to_f64_nonorm
 ; CHECK-SAME: (float nofpclass(norm) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext float [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext float %arg0 to double
   ret double %ext
 }
 

 ; CHECK-NEXT:    [[EXT:%.*]] = fpext <2 x bfloat> [[ARG0]] to <2 x float>
 ; CHECK-NEXT:    ret <2 x float> [[EXT]]
 ;
   %ext = fpext <2 x bfloat> %arg0 to <2 x float>
   ret <2 x float> %ext
 }
 
 define float @ret_fpext_bf16_f32_nonan(bfloat nofpclass(nan) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nonan
+; CHECK-LABEL: define nofpclass(nan) float @ret_fpext_bf16_f32_nonan
 ; CHECK-SAME: (bfloat nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define <2 x float> @ret_fpext_v2bf16_v2f32_nonan(<2 x bfloat> nofpclass(nan) %arg0) {
-; CHECK-LABEL: define <2 x float> @ret_fpext_v2bf16_v2f32_nonan
+; CHECK-LABEL: define nofpclass(nan) <2 x float> @ret_fpext_v2bf16_v2f32_nonan
 ; CHECK-SAME: (<2 x bfloat> nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext <2 x bfloat> [[ARG0]] to <2 x float>
 ; CHECK-NEXT:    ret <2 x float> [[EXT]]
 ;
   %ext = fpext <2 x bfloat> %arg0 to <2 x float>
   ret <2 x float> %ext
 }
 
 define float @ret_fpext_bf16_f32_noqnan(bfloat nofpclass(qnan) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_noqnan
+; CHECK-LABEL: define nofpclass(qnan) float @ret_fpext_bf16_f32_noqnan
 ; CHECK-SAME: (bfloat nofpclass(qnan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nosnan(bfloat nofpclass(snan) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nosnan
+; CHECK-LABEL: define nofpclass(snan) float @ret_fpext_bf16_f32_nosnan
 ; CHECK-SAME: (bfloat nofpclass(snan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_noinf(bfloat nofpclass(inf) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_noinf
+; CHECK-LABEL: define nofpclass(inf) float @ret_fpext_bf16_f32_noinf
 ; CHECK-SAME: (bfloat nofpclass(inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nopinf(bfloat nofpclass(pinf) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nopinf
+; CHECK-LABEL: define nofpclass(pinf) float @ret_fpext_bf16_f32_nopinf
 ; CHECK-SAME: (bfloat nofpclass(pinf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_noninf(bfloat nofpclass(ninf) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_noninf
+; CHECK-LABEL: define nofpclass(ninf) float @ret_fpext_bf16_f32_noninf
 ; CHECK-SAME: (bfloat nofpclass(ninf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nozero(bfloat nofpclass(zero) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nozero
+; CHECK-LABEL: define nofpclass(zero) float @ret_fpext_bf16_f32_nozero
 ; CHECK-SAME: (bfloat nofpclass(zero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nopzero(bfloat nofpclass(pzero) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nopzero
+; CHECK-LABEL: define nofpclass(pzero) float @ret_fpext_bf16_f32_nopzero
 ; CHECK-SAME: (bfloat nofpclass(pzero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nonzero(bfloat nofpclass(nzero) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nonzero
+; CHECK-LABEL: define nofpclass(nzero) float @ret_fpext_bf16_f32_nonzero
 ; CHECK-SAME: (bfloat nofpclass(nzero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nonan_noinf(bfloat nofpclass(nan inf) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nonan_noinf
+; CHECK-LABEL: define nofpclass(nan inf) float @ret_fpext_bf16_f32_nonan_noinf
 ; CHECK-SAME: (bfloat nofpclass(nan inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nosub(bfloat nofpclass(sub) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nosub
+; CHECK-LABEL: define nofpclass(sub) float @ret_fpext_bf16_f32_nosub
 ; CHECK-SAME: (bfloat nofpclass(sub) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define float @ret_fpext_bf16_f32_nonorm(bfloat nofpclass(norm) %arg0) {
-; CHECK-LABEL: define float @ret_fpext_bf16_f32_nonorm
+; CHECK-LABEL: define nofpclass(norm) float @ret_fpext_bf16_f32_nonorm
 ; CHECK-SAME: (bfloat nofpclass(norm) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to float
   ret float %ext
 }
 
 define double @ret_fpext_bf16_f64(bfloat %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64
+; CHECK-LABEL: define nofpclass(sub) double @ret_fpext_bf16_f64
 ; CHECK-SAME: (bfloat [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nonan(bfloat nofpclass(nan) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nonan
+; CHECK-LABEL: define nofpclass(nan sub) double @ret_fpext_bf16_f64_nonan
 ; CHECK-SAME: (bfloat nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_noqnan(bfloat nofpclass(qnan) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_noqnan
+; CHECK-LABEL: define nofpclass(qnan sub) double @ret_fpext_bf16_f64_noqnan
 ; CHECK-SAME: (bfloat nofpclass(qnan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nosnan(bfloat nofpclass(snan) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nosnan
+; CHECK-LABEL: define nofpclass(snan sub) double @ret_fpext_bf16_f64_nosnan
 ; CHECK-SAME: (bfloat nofpclass(snan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_noinf(bfloat nofpclass(inf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_noinf
+; CHECK-LABEL: define nofpclass(inf sub) double @ret_fpext_bf16_f64_noinf
 ; CHECK-SAME: (bfloat nofpclass(inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nopinf(bfloat nofpclass(pinf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nopinf
+; CHECK-LABEL: define nofpclass(pinf sub) double @ret_fpext_bf16_f64_nopinf
 ; CHECK-SAME: (bfloat nofpclass(pinf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_noninf(bfloat nofpclass(ninf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_noninf
+; CHECK-LABEL: define nofpclass(ninf sub) double @ret_fpext_bf16_f64_noninf
 ; CHECK-SAME: (bfloat nofpclass(ninf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nozero(bfloat nofpclass(zero) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nozero
+; CHECK-LABEL: define nofpclass(zero sub) double @ret_fpext_bf16_f64_nozero
 ; CHECK-SAME: (bfloat nofpclass(zero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nopzero(bfloat nofpclass(pzero) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nopzero
+; CHECK-LABEL: define nofpclass(pzero sub) double @ret_fpext_bf16_f64_nopzero
 ; CHECK-SAME: (bfloat nofpclass(pzero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nonzero(bfloat nofpclass(nzero) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nonzero
+; CHECK-LABEL: define nofpclass(nzero sub) double @ret_fpext_bf16_f64_nonzero
 ; CHECK-SAME: (bfloat nofpclass(nzero) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nonan_noinf(bfloat nofpclass(nan inf) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nonan_noinf
+; CHECK-LABEL: define nofpclass(nan inf sub) double @ret_fpext_bf16_f64_nonan_noinf
 ; CHECK-SAME: (bfloat nofpclass(nan inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nosub(bfloat nofpclass(sub) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nosub
+; CHECK-LABEL: define nofpclass(sub) double @ret_fpext_bf16_f64_nosub
 ; CHECK-SAME: (bfloat nofpclass(sub) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 
 define double @ret_fpext_bf16_f64_nonorm(bfloat nofpclass(norm) %arg0) {
-; CHECK-LABEL: define double @ret_fpext_bf16_f64_nonorm
+; CHECK-LABEL: define nofpclass(sub norm) double @ret_fpext_bf16_f64_nonorm
 ; CHECK-SAME: (bfloat nofpclass(norm) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fpext bfloat [[ARG0]] to double
 ; CHECK-NEXT:    ret double [[EXT]]
 ;
   %ext = fpext bfloat %arg0 to double
   ret double %ext
 }
 ;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
 ; TUNIT: {{.*}}