The powers that be have decided that LLVM IR should now support 16-bit

"half precision" floating-point with a first-class type.

This patch adds basic IR support (but not codegen support).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146786 91177308-0d34-0410-b5e6-96231b3b80d8

13 files changed, 92 insertions, 37 deletions

diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index 1b6b11a..d93108f 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -574,6 +574,7 @@ lltok::Kind LLLexer::LexIdentifier() {
   if (Len == strlen(STR) && !memcmp(StartChar, STR, strlen(STR))) { \
     TyVal = LLVMTY; return lltok::Type; }
   TYPEKEYWORD("void",      Type::getVoidTy(Context));
+  TYPEKEYWORD("half",      Type::getHalfTy(Context));
   TYPEKEYWORD("float",     Type::getFloatTy(Context));
   TYPEKEYWORD("double",    Type::getDoubleTy(Context));
   TYPEKEYWORD("x86_fp80",  Type::getX86_FP80Ty(Context));
@@ -693,7 +694,7 @@ lltok::Kind LLLexer::Lex0x() {
   if (Kind == 'J') {
     // HexFPConstant - Floating point constant represented in IEEE format as a
     // hexadecimal number for when exponential notation is not precise enough.
-    // Float and double only.
+    // Half, Float, and double only.
     APFloatVal = APFloat(BitsToDouble(HexIntToVal(TokStart+2, CurPtr)));
     return lltok::APFloat;
   }
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 4678269..bccca4f 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -2483,13 +2483,16 @@ bool LLParser::ConvertValIDToValue(Type *Ty, ValID &ID, Value *&V,
         !ConstantFP::isValueValidForType(Ty, ID.APFloatVal))
       return Error(ID.Loc, "floating point constant invalid for type");
 
-    // The lexer has no type info, so builds all float and double FP constants
-    // as double.  Fix this here.  Long double does not need this.
-    if (&ID.APFloatVal.getSemantics() == &APFloat::IEEEdouble &&
-        Ty->isFloatTy()) {
+    // The lexer has no type info, so builds all half, float, and double FP
+    // constants as double.  Fix this here.  Long double does not need this.
+    if (&ID.APFloatVal.getSemantics() == &APFloat::IEEEdouble) {
       bool Ignored;
-      ID.APFloatVal.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven,
-                            &Ignored);
+      if (Ty->isHalfTy())
+        ID.APFloatVal.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven,
+                              &Ignored);
+      else if (Ty->isFloatTy())
+        ID.APFloatVal.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven,
+                              &Ignored);
     }
     V = ConstantFP::get(Context, ID.APFloatVal);
 
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index d584015..b86d6e0 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -565,6 +565,9 @@ bool BitcodeReader::ParseTypeTableBody() {
     case bitc::TYPE_CODE_VOID:      // VOID
       ResultTy = Type::getVoidTy(Context);
       break;
+    case bitc::TYPE_CODE_HALF:     // HALF
+      ResultTy = Type::getHalfTy(Context);
+      break;
     case bitc::TYPE_CODE_FLOAT:     // FLOAT
       ResultTy = Type::getFloatTy(Context);
       break;
@@ -1032,7 +1035,9 @@ bool BitcodeReader::ParseConstants() {
     case bitc::CST_CODE_FLOAT: {    // FLOAT: [fpval]
       if (Record.empty())
         return Error("Invalid FLOAT record");
-      if (CurTy->isFloatTy())
+      if (CurTy->isHalfTy())
+        V = ConstantFP::get(Context, APFloat(APInt(16, (uint16_t)Record[0])));
+      else if (CurTy->isFloatTy())
         V = ConstantFP::get(Context, APFloat(APInt(32, (uint32_t)Record[0])));
       else if (CurTy->isDoubleTy())
         V = ConstantFP::get(Context, APFloat(APInt(64, Record[0])));
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index d980163..f890786 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -266,6 +266,7 @@ static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
     switch (T->getTypeID()) {
     default: llvm_unreachable("Unknown type!");
     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;   break;
+    case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;   break;
     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;  break;
     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE; break;
     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80; break;
@@ -826,7 +827,7 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
       Code = bitc::CST_CODE_FLOAT;
       Type *Ty = CFP->getType();
-      if (Ty->isFloatTy() || Ty->isDoubleTy()) {
+      if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
       } else if (Ty->isX86_FP80Ty()) {
         // api needed to prevent premature destruction
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 46e4acd..49a498f 100644
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1160,6 +1160,9 @@ static Value *LookThroughFPExtensions(Value *V) {
   if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
     if (CFP->getType() == Type::getPPC_FP128Ty(V->getContext()))
       return V;  // No constant folding of this.
+    // See if the value can be truncated to half and then reextended.
+    if (Value *V = FitsInFPType(CFP, APFloat::IEEEhalf))
+      return V;
     // See if the value can be truncated to float and then reextended.
     if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle))
       return V;
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 144b92b..4427f4b 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2848,7 +2848,9 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
 
         const fltSemantics *Sem;
         // FIXME: This shouldn't be here.
-        if (LHSExt->getSrcTy()->isFloatTy())
+        if (LHSExt->getSrcTy()->isHalfTy())
+          Sem = &APFloat::IEEEhalf;
+        else if (LHSExt->getSrcTy()->isFloatTy())
           Sem = &APFloat::IEEEsingle;
         else if (LHSExt->getSrcTy()->isDoubleTy())
           Sem = &APFloat::IEEEdouble;
diff --git a/lib/VMCore/AsmWriter.cpp b/lib/VMCore/AsmWriter.cpp
index 4fb5fd3..3da4774 100644
--- a/lib/VMCore/AsmWriter.cpp
+++ b/lib/VMCore/AsmWriter.cpp
@@ -189,6 +189,7 @@ void TypePrinting::incorporateTypes(const Module &M) {
 void TypePrinting::print(Type *Ty, raw_ostream &OS) {
   switch (Ty->getTypeID()) {
   case Type::VoidTyID:      OS << "void"; break;
+  case Type::HalfTyID:      OS << "half"; break;
   case Type::FloatTyID:     OS << "float"; break;
   case Type::DoubleTyID:    OS << "double"; break;
   case Type::X86_FP80TyID:  OS << "x86_fp80"; break;
@@ -708,31 +709,35 @@ static void WriteConstantInternal(raw_ostream &Out, const Constant *CV,
   }
 
   if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
-    if (&CFP->getValueAPF().getSemantics() == &APFloat::IEEEdouble ||
-        &CFP->getValueAPF().getSemantics() == &APFloat::IEEEsingle) {
+    if (&CFP->getValueAPF().getSemantics() == &APFloat::IEEEhalf ||
+        &CFP->getValueAPF().getSemantics() == &APFloat::IEEEsingle ||
+        &CFP->getValueAPF().getSemantics() == &APFloat::IEEEdouble) {
       // We would like to output the FP constant value in exponential notation,
       // but we cannot do this if doing so will lose precision.  Check here to
       // make sure that we only output it in exponential format if we can parse
       // the value back and get the same value.
       //
       bool ignored;
+      bool isHalf = &CFP->getValueAPF().getSemantics()==&APFloat::IEEEhalf;
       bool isDouble = &CFP->getValueAPF().getSemantics()==&APFloat::IEEEdouble;
-      double Val = isDouble ? CFP->getValueAPF().convertToDouble() :
-                              CFP->getValueAPF().convertToFloat();
-      SmallString<128> StrVal;
-      raw_svector_ostream(StrVal) << Val;
-
-      // Check to make sure that the stringized number is not some string like
-      // "Inf" or NaN, that atof will accept, but the lexer will not.  Check
-      // that the string matches the "[-+]?[0-9]" regex.
-      //
-      if ((StrVal[0] >= '0' && StrVal[0] <= '9') ||
-          ((StrVal[0] == '-' || StrVal[0] == '+') &&
-           (StrVal[1] >= '0' && StrVal[1] <= '9'))) {
-        // Reparse stringized version!
-        if (atof(StrVal.c_str()) == Val) {
-          Out << StrVal.str();
-          return;
+      if (!isHalf) {
+        double Val = isDouble ? CFP->getValueAPF().convertToDouble() :
+                                CFP->getValueAPF().convertToFloat();
+        SmallString<128> StrVal;
+        raw_svector_ostream(StrVal) << Val;
+
+        // Check to make sure that the stringized number is not some string like
+        // "Inf" or NaN, that atof will accept, but the lexer will not.  Check
+        // that the string matches the "[-+]?[0-9]" regex.
+        //
+        if ((StrVal[0] >= '0' && StrVal[0] <= '9') ||
+            ((StrVal[0] == '-' || StrVal[0] == '+') &&
+             (StrVal[1] >= '0' && StrVal[1] <= '9'))) {
+          // Reparse stringized version!
+          if (atof(StrVal.c_str()) == Val) {
+            Out << StrVal.str();
+            return;
+          }
         }
       }
       // Otherwise we could not reparse it to exactly the same value, so we must
@@ -743,7 +748,7 @@ static void WriteConstantInternal(raw_ostream &Out, const Constant *CV,
              "assuming that double is 64 bits!");
       char Buffer[40];
       APFloat apf = CFP->getValueAPF();
-      // Floats are represented in ASCII IR as double, convert.
+      // Halves and floats are represented in ASCII IR as double, convert.
       if (!isDouble)
         apf.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven,
                           &ignored);
diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index d1a9e7a..4d7a857 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -571,7 +571,8 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
     if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
       bool ignored;
       APFloat Val = FPC->getValueAPF();
-      Val.convert(DestTy->isFloatTy() ? APFloat::IEEEsingle :
+      Val.convert(DestTy->isHalfTy() ? APFloat::IEEEhalf :
+                  DestTy->isFloatTy() ? APFloat::IEEEsingle :
                   DestTy->isDoubleTy() ? APFloat::IEEEdouble :
                   DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended :
                   DestTy->isFP128Ty() ? APFloat::IEEEquad :
diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp
index a148912..f17f9a2 100644
--- a/lib/VMCore/Constants.cpp
+++ b/lib/VMCore/Constants.cpp
@@ -84,6 +84,9 @@ Constant *Constant::getNullValue(Type *Ty) {
   switch (Ty->getTypeID()) {
   case Type::IntegerTyID:
     return ConstantInt::get(Ty, 0);
+  case Type::HalfTyID:
+    return ConstantFP::get(Ty->getContext(),
+                           APFloat::getZero(APFloat::IEEEhalf));
   case Type::FloatTyID:
     return ConstantFP::get(Ty->getContext(),
                            APFloat::getZero(APFloat::IEEEsingle));
@@ -468,6 +471,8 @@ ConstantInt* ConstantInt::get(IntegerType* Ty, StringRef Str,
 //===----------------------------------------------------------------------===//
 
 static const fltSemantics *TypeToFloatSemantics(Type *Ty) {
+  if (Ty->isHalfTy())
+    return &APFloat::IEEEhalf;
   if (Ty->isFloatTy())
     return &APFloat::IEEEsingle;
   if (Ty->isDoubleTy())
@@ -550,7 +555,9 @@ ConstantFP* ConstantFP::get(LLVMContext &Context, const APFloat& V) {
     
   if (!Slot) {
     Type *Ty;
-    if (&V.getSemantics() == &APFloat::IEEEsingle)
+    if (&V.getSemantics() == &APFloat::IEEEhalf)
+      Ty = Type::getHalfTy(Context);
+    else if (&V.getSemantics() == &APFloat::IEEEsingle)
       Ty = Type::getFloatTy(Context);
     else if (&V.getSemantics() == &APFloat::IEEEdouble)
       Ty = Type::getDoubleTy(Context);
@@ -939,6 +946,12 @@ bool ConstantFP::isValueValidForType(Type *Ty, const APFloat& Val) {
     return false;         // These can't be represented as floating point!
 
   // FIXME rounding mode needs to be more flexible
+  case Type::HalfTyID: {
+    if (&Val2.getSemantics() == &APFloat::IEEEhalf)
+      return true;
+    Val2.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &losesInfo);
+    return !losesInfo;
+  }
   case Type::FloatTyID: {
     if (&Val2.getSemantics() == &APFloat::IEEEsingle)
       return true;
@@ -946,22 +959,26 @@ bool ConstantFP::isValueValidForType(Type *Ty, const APFloat& Val) {
     return !losesInfo;
   }
   case Type::DoubleTyID: {
-    if (&Val2.getSemantics() == &APFloat::IEEEsingle ||
+    if (&Val2.getSemantics() == &APFloat::IEEEhalf ||
+        &Val2.getSemantics() == &APFloat::IEEEsingle ||
         &Val2.getSemantics() == &APFloat::IEEEdouble)
       return true;
     Val2.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven, &losesInfo);
     return !losesInfo;
   }
   case Type::X86_FP80TyID:
-    return &Val2.getSemantics() == &APFloat::IEEEsingle || 
+    return &Val2.getSemantics() == &APFloat::IEEEhalf ||
+           &Val2.getSemantics() == &APFloat::IEEEsingle || 
            &Val2.getSemantics() == &APFloat::IEEEdouble ||
            &Val2.getSemantics() == &APFloat::x87DoubleExtended;
   case Type::FP128TyID:
-    return &Val2.getSemantics() == &APFloat::IEEEsingle || 
+    return &Val2.getSemantics() == &APFloat::IEEEhalf ||
+           &Val2.getSemantics() == &APFloat::IEEEsingle || 
            &Val2.getSemantics() == &APFloat::IEEEdouble ||
            &Val2.getSemantics() == &APFloat::IEEEquad;
   case Type::PPC_FP128TyID:
-    return &Val2.getSemantics() == &APFloat::IEEEsingle || 
+    return &Val2.getSemantics() == &APFloat::IEEEhalf ||
+           &Val2.getSemantics() == &APFloat::IEEEsingle || 
            &Val2.getSemantics() == &APFloat::IEEEdouble ||
            &Val2.getSemantics() == &APFloat::PPCDoubleDouble;
   }
diff --git a/lib/VMCore/Core.cpp b/lib/VMCore/Core.cpp
index a505e4b..612d5fa 100644
--- a/lib/VMCore/Core.cpp
+++ b/lib/VMCore/Core.cpp
@@ -136,6 +136,8 @@ LLVMTypeKind LLVMGetTypeKind(LLVMTypeRef Ty) {
     assert(false && "Unhandled TypeID.");
   case Type::VoidTyID:
     return LLVMVoidTypeKind;
+  case Type::HalfTyID:
+    return LLVMHalfTypeKind;
   case Type::FloatTyID:
     return LLVMFloatTypeKind;
   case Type::DoubleTyID:
@@ -222,6 +224,9 @@ unsigned LLVMGetIntTypeWidth(LLVMTypeRef IntegerTy) {
 
 /*--.. Operations on real types ............................................--*/
 
+LLVMTypeRef LLVMHalfTypeInContext(LLVMContextRef C) {
+  return (LLVMTypeRef) Type::getHalfTy(*unwrap(C));
+}
 LLVMTypeRef LLVMFloatTypeInContext(LLVMContextRef C) {
   return (LLVMTypeRef) Type::getFloatTy(*unwrap(C));
 }
@@ -241,6 +246,9 @@ LLVMTypeRef LLVMX86MMXTypeInContext(LLVMContextRef C) {
   return (LLVMTypeRef) Type::getX86_MMXTy(*unwrap(C));
 }
 
+LLVMTypeRef LLVMHalfType(void) {
+  return LLVMHalfTypeInContext(LLVMGetGlobalContext());
+}
 LLVMTypeRef LLVMFloatType(void) {
   return LLVMFloatTypeInContext(LLVMGetGlobalContext());
 }
diff --git a/lib/VMCore/LLVMContextImpl.cpp b/lib/VMCore/LLVMContextImpl.cpp
index 504b372..252b340 100644
--- a/lib/VMCore/LLVMContextImpl.cpp
+++ b/lib/VMCore/LLVMContextImpl.cpp
@@ -21,6 +21,7 @@ LLVMContextImpl::LLVMContextImpl(LLVMContext &C)
   : TheTrueVal(0), TheFalseVal(0),
     VoidTy(C, Type::VoidTyID),
     LabelTy(C, Type::LabelTyID),
+    HalfTy(C, Type::HalfTyID),
     FloatTy(C, Type::FloatTyID),
     DoubleTy(C, Type::DoubleTyID),
     MetadataTy(C, Type::MetadataTyID),
diff --git a/lib/VMCore/LLVMContextImpl.h b/lib/VMCore/LLVMContextImpl.h
index a3f68fe..30f9d46 100644
--- a/lib/VMCore/LLVMContextImpl.h
+++ b/lib/VMCore/LLVMContextImpl.h
@@ -169,7 +169,7 @@ public:
   LeakDetectorImpl<Value> LLVMObjects;
   
   // Basic type instances.
-  Type VoidTy, LabelTy, FloatTy, DoubleTy, MetadataTy;
+  Type VoidTy, LabelTy, HalfTy, FloatTy, DoubleTy, MetadataTy;
   Type X86_FP80Ty, FP128Ty, PPC_FP128Ty, X86_MMXTy;
   IntegerType Int1Ty, Int8Ty, Int16Ty, Int32Ty, Int64Ty;
 
diff --git a/lib/VMCore/Type.cpp b/lib/VMCore/Type.cpp
index 469defd..f4fad66 100644
--- a/lib/VMCore/Type.cpp
+++ b/lib/VMCore/Type.cpp
@@ -25,6 +25,7 @@ using namespace llvm;
 Type *Type::getPrimitiveType(LLVMContext &C, TypeID IDNumber) {
   switch (IDNumber) {
   case VoidTyID      : return getVoidTy(C);
+  case HalfTyID      : return getHalfTy(C);
   case FloatTyID     : return getFloatTy(C);
   case DoubleTyID    : return getDoubleTy(C);
   case X86_FP80TyID  : return getX86_FP80Ty(C);
@@ -73,7 +74,7 @@ bool Type::isIntOrIntVectorTy() const {
 /// isFPOrFPVectorTy - Return true if this is a FP type or a vector of FP types.
 ///
 bool Type::isFPOrFPVectorTy() const {
-  if (ID == Type::FloatTyID || ID == Type::DoubleTyID || 
+  if (ID == Type::HalfTyID || ID == Type::FloatTyID || ID == Type::DoubleTyID ||
       ID == Type::FP128TyID || ID == Type::X86_FP80TyID || 
       ID == Type::PPC_FP128TyID)
     return true;
@@ -139,6 +140,7 @@ bool Type::isEmptyTy() const {
 
 unsigned Type::getPrimitiveSizeInBits() const {
   switch (getTypeID()) {
+  case Type::HalfTyID: return 16;
   case Type::FloatTyID: return 32;
   case Type::DoubleTyID: return 64;
   case Type::X86_FP80TyID: return 80;
@@ -165,6 +167,7 @@ int Type::getFPMantissaWidth() const {
   if (const VectorType *VTy = dyn_cast<VectorType>(this))
     return VTy->getElementType()->getFPMantissaWidth();
   assert(isFloatingPointTy() && "Not a floating point type!");
+  if (ID == HalfTyID) return 11;
   if (ID == FloatTyID) return 24;
   if (ID == DoubleTyID) return 53;
   if (ID == X86_FP80TyID) return 64;
@@ -207,6 +210,7 @@ bool Type::isSizedDerivedType() const {
 
 Type *Type::getVoidTy(LLVMContext &C) { return &C.pImpl->VoidTy; }
 Type *Type::getLabelTy(LLVMContext &C) { return &C.pImpl->LabelTy; }
+Type *Type::getHalfTy(LLVMContext &C) { return &C.pImpl->HalfTy; }
 Type *Type::getFloatTy(LLVMContext &C) { return &C.pImpl->FloatTy; }
 Type *Type::getDoubleTy(LLVMContext &C) { return &C.pImpl->DoubleTy; }
 Type *Type::getMetadataTy(LLVMContext &C) { return &C.pImpl->MetadataTy; }
@@ -225,6 +229,10 @@ IntegerType *Type::getIntNTy(LLVMContext &C, unsigned N) {
   return IntegerType::get(C, N);
 }
 
+PointerType *Type::getHalfPtrTy(LLVMContext &C, unsigned AS) {
+  return getHalfTy(C)->getPointerTo(AS);
+}
+
 PointerType *Type::getFloatPtrTy(LLVMContext &C, unsigned AS) {
   return getFloatTy(C)->getPointerTo(AS);
 }