Signficantly generalize our ability to constant fold floating point intrinsics, including ones on half types.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174555 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/ConstantFolding.cpp

@@ -289,6 +289,10 @@ static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset,
       C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), TD);
       return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
     }
+    if (CFP->getType()->isHalfTy()){
+      C = FoldBitCast(C, Type::getInt16Ty(C->getContext()), TD);
+      return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
+    }
     return false;
   }
 
@@ -381,7 +385,9 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
     // that address spaces don't matter here since we're not going to result in
     // an actual new load.
     Type *MapTy;
-    if (LoadTy->isFloatTy())
+    if (LoadTy->isHalfTy())
+      MapTy = Type::getInt16PtrTy(C->getContext());
+    else if (LoadTy->isFloatTy())
       MapTy = Type::getInt32PtrTy(C->getContext());
     else if (LoadTy->isDoubleTy())
       MapTy = Type::getInt64PtrTy(C->getContext());
@@ -1089,6 +1095,13 @@ Constant *llvm::ConstantFoldLoadThroughGEPIndices(Constant *C,
 bool
 llvm::canConstantFoldCallTo(const Function *F) {
   switch (F->getIntrinsicID()) {
+  case Intrinsic::fabs:
+  case Intrinsic::log:
+  case Intrinsic::log2:
+  case Intrinsic::log10:
+  case Intrinsic::exp:
+  case Intrinsic::exp2:
+  case Intrinsic::floor:
   case Intrinsic::sqrt:
   case Intrinsic::pow:
   case Intrinsic::powi:
@@ -1156,11 +1169,17 @@ static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
     return 0;
   }
 
+  if (Ty->isHalfTy()) {
+    APFloat APF(V);
+    bool unused;
+    APF.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &unused);
+    return ConstantFP::get(Ty->getContext(), APF);
+  }
   if (Ty->isFloatTy())
     return ConstantFP::get(Ty->getContext(), APFloat((float)V));
   if (Ty->isDoubleTy())
     return ConstantFP::get(Ty->getContext(), APFloat(V));
-  llvm_unreachable("Can only constant fold float/double");
+  llvm_unreachable("Can only constant fold half/float/double");
 }
 
 static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
@@ -1172,11 +1191,17 @@ static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
     return 0;
   }
 
+  if (Ty->isHalfTy()) {
+    APFloat APF(V);
+    bool unused;
+    APF.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &unused);
+    return ConstantFP::get(Ty->getContext(), APF);
+  }
   if (Ty->isFloatTy())
     return ConstantFP::get(Ty->getContext(), APFloat((float)V));
   if (Ty->isDoubleTy())
     return ConstantFP::get(Ty->getContext(), APFloat(V));
-  llvm_unreachable("Can only constant fold float/double");
+  llvm_unreachable("Can only constant fold half/float/double");
 }
 
 /// ConstantFoldConvertToInt - Attempt to an SSE floating point to integer
@@ -1228,7 +1253,7 @@ llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
       if (!TLI)
         return 0;
 
-      if (!Ty->isFloatTy() && !Ty->isDoubleTy())
+      if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
         return 0;
 
       /// We only fold functions with finite arguments. Folding NaN and inf is
@@ -1241,8 +1266,36 @@ llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
       /// the host native double versions.  Float versions are not called
       /// directly but for all these it is true (float)(f((double)arg)) ==
       /// f(arg).  Long double not supported yet.
-      double V = Ty->isFloatTy() ? (double)Op->getValueAPF().convertToFloat() :
+      double V;
-                                     Op->getValueAPF().convertToDouble();
+      if (Ty->isFloatTy())
+        V = Op->getValueAPF().convertToFloat();
+      else if (Ty->isDoubleTy())
+        V = Op->getValueAPF().convertToDouble();
+      else {
+        bool unused;
+        APFloat APF = Op->getValueAPF();
+        APF.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven, &unused);
+        V = APF.convertToDouble();
+      }
+
+      switch (F->getIntrinsicID()) {
+        default: break;
+        case Intrinsic::fabs:
+          return ConstantFoldFP(fabs, V, Ty);
+        case Intrinsic::log2:
+          return ConstantFoldFP(log2, V, Ty);
+        case Intrinsic::log:
+          return ConstantFoldFP(log, V, Ty);
+        case Intrinsic::log10:
+          return ConstantFoldFP(log10, V, Ty);
+        case Intrinsic::exp:
+          return ConstantFoldFP(exp, V, Ty);
+        case Intrinsic::exp2:
+          return ConstantFoldFP(exp2, V, Ty);
+        case Intrinsic::floor:
+          return ConstantFoldFP(floor, V, Ty);
+      }
+
       switch (Name[0]) {
       case 'a':
         if (Name == "acos" && TLI->has(LibFunc::acos))
@@ -1284,7 +1337,7 @@ llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
         else if (Name == "log10" && V > 0 && TLI->has(LibFunc::log10))
           return ConstantFoldFP(log10, V, Ty);
         else if (F->getIntrinsicID() == Intrinsic::sqrt &&
-                 (Ty->isFloatTy() || Ty->isDoubleTy())) {
+                 (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy())) {
           if (V >= -0.0)
             return ConstantFoldFP(sqrt, V, Ty);
           else // Undefined
@@ -1376,18 +1429,35 @@ llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
 
   if (Operands.size() == 2) {
     if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
-      if (!Ty->isFloatTy() && !Ty->isDoubleTy())
+      if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
         return 0;
-      double Op1V = Ty->isFloatTy() ?
+      double Op1V;
-                      (double)Op1->getValueAPF().convertToFloat() :
+      if (Ty->isFloatTy())
-                      Op1->getValueAPF().convertToDouble();
+        Op1V = Op1->getValueAPF().convertToFloat();
+      else if (Ty->isDoubleTy())
+        Op1V = Op1->getValueAPF().convertToDouble();
+      else {
+        bool unused;
+        APFloat APF = Op1->getValueAPF();
+        APF.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven, &unused);
+        Op1V = APF.convertToDouble();
+      }
+
       if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
         if (Op2->getType() != Op1->getType())
           return 0;
 
-        double Op2V = Ty->isFloatTy() ?
+        double Op2V;
-                      (double)Op2->getValueAPF().convertToFloat():
+        if (Ty->isFloatTy())
-                      Op2->getValueAPF().convertToDouble();
+          Op2V = Op2->getValueAPF().convertToFloat();
+        else if (Ty->isDoubleTy())
+          Op2V = Op2->getValueAPF().convertToDouble();
+        else {
+          bool unused;
+          APFloat APF = Op2->getValueAPF();
+          APF.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven, &unused);
+          Op2V = APF.convertToDouble();
+        }
 
         if (F->getIntrinsicID() == Intrinsic::pow) {
           return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
@@ -1401,6 +1471,10 @@ llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
         if (Name == "atan2" && TLI->has(LibFunc::atan2))
           return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
       } else if (ConstantInt *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
+        if (F->getIntrinsicID() == Intrinsic::powi && Ty->isHalfTy())
+          return ConstantFP::get(F->getContext(),
+                                 APFloat((float)std::pow((float)Op1V,
+                                                 (int)Op2C->getZExtValue())));
         if (F->getIntrinsicID() == Intrinsic::powi && Ty->isFloatTy())
           return ConstantFP::get(F->getContext(),
                                  APFloat((float)std::pow((float)Op1V,

test/Transforms/ConstProp/half.ll

@@ -0,0 +1,42 @@
+; RUN: opt -constprop -S < %s | FileCheck %s
+
+; CHECK: fabs_call
+define half @fabs_call() {
+; CHECK: ret half 0xH5140
+  %x = call half @llvm.fabs.f16(half -42.0)
+  ret half %x
+}
+declare half @llvm.fabs.f16(half %x)
+
+; CHECK: exp_call
+define half @exp_call() {
+; CHECK: ret half 0xH4170
+  %x = call half @llvm.exp.f16(half 1.0)
+  ret half %x
+}
+declare half @llvm.exp.f16(half %x)
+
+; CHECK: sqrt_call
+define half @sqrt_call() {
+; CHECK: ret half 0xH4000
+  %x = call half @llvm.sqrt.f16(half 4.0)
+  ret half %x
+}
+declare half @llvm.sqrt.f16(half %x)
+
+; CHECK: floor_call
+define half @floor_call() {
+; CHECK: ret half 0xH4000
+  %x = call half @llvm.floor.f16(half 2.5)
+  ret half %x
+}
+declare half @llvm.floor.f16(half %x)
+
+; CHECK: pow_call
+define half @pow_call() {
+; CHECK: ret half 0xH4400
+  %x = call half @llvm.pow.f16(half 2.0, half 2.0)
+  ret half %x
+}
+declare half @llvm.pow.f16(half %x, half %y)
+