ValueTracking: Implement computeKnownFPClass for llvm.trunc

[arsenm]

Test ppcf128

[jcranmer-intel]

You can also propagate the normal fpclasses as well here (and positive/negative zero if both that class and the corresponding subnormal and normal class are known not to be, I think).

[arsenm]

Apparently this was 3dabcdc78b718db8136e27c8bec7b99eeabac5bf

I've added the extra improvements in D148533

llvm/include/llvm/Analysis/ValueTracking.h

bool isKnownNeverInfinity() const {
     return (KnownFPClasses & fcInf) == fcNone;
   }
 
   /// Return true if it's known this can never be +infinity.
   bool isKnownNeverPosInfinity() const {
     return (KnownFPClasses & fcPosInf) == fcNone;
   }
 
+  /// Return true if it's known this can never be -infinity.
+  bool isKnownNeverNegInfinity() const {
+    return (KnownFPClasses & fcNegInf) == fcNone;
+  }
+
   /// Return true if it's known this can never be a zero.
   bool isKnownNeverZero() const {
     return (KnownFPClasses & fcZero) == fcNone;
   }
 
   KnownFPClass &operator|=(const KnownFPClass &RHS) {
     KnownFPClasses = KnownFPClasses | RHS.KnownFPClasses;
 

llvm/lib/Analysis/ValueTracking.cpp

if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op)) {
 
         if (DenormMode.Input == DenormalMode::PositiveZero ||
             (DenormMode.Output == DenormalMode::PositiveZero &&
              DenormMode.Input == DenormalMode::IEEE))
           Known.knownNot(fcNegZero);
 
         break;
       }
+      case Intrinsic::trunc: {
+        KnownFPClass KnownSrc;
+        computeKnownFPClass(II->getArgOperand(0), DemandedElts,
+                            InterestedClasses, KnownSrc, Depth + 1, Q, TLI);
+
+        // Integer results cannot be subnormal.
+        Known.knownNot(fcSubnormal);
+
+        // trunc passes through infinities.
+        if (KnownSrc.isKnownNeverPosInfinity())
+          Known.knownNot(fcPosInf);
+        if (KnownSrc.isKnownNeverNegInfinity())
+          Known.knownNot(fcNegInf);
+
+        // Non-constrained intrinsics do not guarantee signaling nan quieting.
+        if (KnownSrc.isKnownNeverNaN())
+          Known.knownNot(fcNan);
+        break;
+      }
       default:
         break;
       }
     }
 
     break;
   }
   case Instruction::FAdd:

llvm/test/Transforms/Attributor/nofpclass-trunc.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
 
 declare float @llvm.trunc.f32(float)
 declare ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128)
 
 define float @ret_trunc(float %arg0) {
-; CHECK-LABEL: define float @ret_trunc
+; CHECK-LABEL: define nofpclass(sub) float @ret_trunc
 ; CHECK-SAME: (float [[ARG0:%.*]]) #[[ATTR1:[0-9]+]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2:[0-9]+]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2:[0-9]+]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_noinf(float nofpclass(inf) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_noinf
+; CHECK-LABEL: define nofpclass(inf sub) float @ret_trunc_noinf
 ; CHECK-SAME: (float nofpclass(inf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(inf sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_nopinf(float nofpclass(pinf) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_nopinf
+; CHECK-LABEL: define nofpclass(pinf sub) float @ret_trunc_nopinf
 ; CHECK-SAME: (float nofpclass(pinf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(pinf sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_noninf(float nofpclass(ninf) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_noninf
+; CHECK-LABEL: define nofpclass(ninf sub) float @ret_trunc_noninf
 ; CHECK-SAME: (float nofpclass(ninf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(ninf sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_nonan(float nofpclass(nan) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_nonan
+; CHECK-LABEL: define nofpclass(nan sub) float @ret_trunc_nonan
 ; CHECK-SAME: (float nofpclass(nan) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(nan sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_noqnan(float nofpclass(qnan) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_noqnan
+; CHECK-LABEL: define nofpclass(sub) float @ret_trunc_noqnan
 ; CHECK-SAME: (float nofpclass(qnan) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_nosnan(float nofpclass(snan) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_nosnan
+; CHECK-LABEL: define nofpclass(sub) float @ret_trunc_nosnan
 ; CHECK-SAME: (float nofpclass(snan) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_nozero(float nofpclass(zero) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_nozero
+; CHECK-LABEL: define nofpclass(sub) float @ret_trunc_nozero
 ; CHECK-SAME: (float nofpclass(zero) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_nopzero(float nofpclass(pzero) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_nopzero
+; CHECK-LABEL: define nofpclass(sub) float @ret_trunc_nopzero
 ; CHECK-SAME: (float nofpclass(pzero) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_nonzero(float nofpclass(nzero) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_nonzero
+; CHECK-LABEL: define nofpclass(sub) float @ret_trunc_nonzero
 ; CHECK-SAME: (float nofpclass(nzero) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define float @ret_trunc_nonorm(float nofpclass(norm) %arg0) {
-; CHECK-LABEL: define float @ret_trunc_nonorm
+; CHECK-LABEL: define nofpclass(sub) float @ret_trunc_nonorm
 ; CHECK-SAME: (float nofpclass(norm) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) float @llvm.trunc.f32(float [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.trunc.f32(float %arg0)
   ret float %call
 }
 
 define ppc_fp128 @ret_trunc_ppcf128(ppc_fp128 %arg0) {
-; CHECK-LABEL: define ppc_fp128 @ret_trunc_ppcf128
+; CHECK-LABEL: define nofpclass(sub) ppc_fp128 @ret_trunc_ppcf128
 ; CHECK-SAME: (ppc_fp128 [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(sub) ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret ppc_fp128 [[CALL]]
 ;
   %call = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 %arg0)
   ret ppc_fp128 %call
 }
 
 define ppc_fp128 @ret_trunc_noinf_ppcf128(ppc_fp128 nofpclass(inf) %arg0) {
-; CHECK-LABEL: define ppc_fp128 @ret_trunc_noinf_ppcf128
+; CHECK-LABEL: define nofpclass(inf sub) ppc_fp128 @ret_trunc_noinf_ppcf128
 ; CHECK-SAME: (ppc_fp128 nofpclass(inf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(inf sub) ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret ppc_fp128 [[CALL]]
 ;
   %call = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 %arg0)
   ret ppc_fp128 %call
 }
 
 define ppc_fp128 @ret_trunc_nopinf_ppcf128(ppc_fp128 nofpclass(pinf) %arg0) {
-; CHECK-LABEL: define ppc_fp128 @ret_trunc_nopinf_ppcf128
+; CHECK-LABEL: define nofpclass(pinf sub) ppc_fp128 @ret_trunc_nopinf_ppcf128
 ; CHECK-SAME: (ppc_fp128 nofpclass(pinf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(pinf sub) ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret ppc_fp128 [[CALL]]
 ;
   %call = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 %arg0)
   ret ppc_fp128 %call
 }
 
 define ppc_fp128 @ret_trunc_noninf_ppcf128(ppc_fp128 nofpclass(ninf) %arg0) {
-; CHECK-LABEL: define ppc_fp128 @ret_trunc_noninf_ppcf128
+; CHECK-LABEL: define nofpclass(ninf sub) ppc_fp128 @ret_trunc_noninf_ppcf128
 ; CHECK-SAME: (ppc_fp128 nofpclass(ninf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(ninf sub) ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret ppc_fp128 [[CALL]]
 ;
   %call = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 %arg0)
   ret ppc_fp128 %call
 }
 
 define ppc_fp128 @ret_trunc_nonan_ppcf128(ppc_fp128 nofpclass(nan) %arg0) {
-; CHECK-LABEL: define ppc_fp128 @ret_trunc_nonan_ppcf128
+; CHECK-LABEL: define nofpclass(nan sub) ppc_fp128 @ret_trunc_nonan_ppcf128
 ; CHECK-SAME: (ppc_fp128 nofpclass(nan) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(nan sub) ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 [[ARG0]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret ppc_fp128 [[CALL]]
 ;
   %call = call ppc_fp128 @llvm.trunc.ppcf128(ppc_fp128 %arg0)
   ret ppc_fp128 %call
 }
 ;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
 ; TUNIT: {{.*}}