Remove the `x86_mmx` IR type. (#98505)

It is now translated to `<1 x i64>`, which allows the removal of a bunch
of special casing.

This _incompatibly_ changes the ABI of any LLVM IR function with
`x86_mmx` arguments or returns: instead of passing in mmx registers,
they will now be passed via integer registers. However, the real-world
incompatibility caused by this is expected to be minimal, because Clang
never uses the x86_mmx type -- it lowers `__m64` to either `<1 x i64>`
or `double`, depending on ABI.

This change does _not_ eliminate the SelectionDAG `MVT::x86mmx` type.
That type simply no longer corresponds to an IR type, and is used only
by MMX intrinsics and inline-asm operands.

Because SelectionDAGBuilder only knows how to generate the
operands/results of intrinsics based on the IR type, it thus now
generates the intrinsics with the type MVT::v1i64, instead of
MVT::x86mmx. We need to fix this before the DAG LegalizeTypes, and thus
have the X86 backend fix them up in DAGCombine. (This may be a
short-lived hack, if all the MMX intrinsics can be removed in upcoming
changes.)

Works towards issue #98272.

9 files changed, 18 insertions, 41 deletions

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 6599730..01a16cc 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -573,8 +573,9 @@ void TypePrinting::print(Type *Ty, raw_ostream &OS) {
   case Type::FP128TyID:     OS << "fp128"; return;
   case Type::PPC_FP128TyID: OS << "ppc_fp128"; return;
   case Type::LabelTyID:     OS << "label"; return;
-  case Type::MetadataTyID:  OS << "metadata"; return;
-  case Type::X86_MMXTyID:   OS << "x86_mmx"; return;
+  case Type::MetadataTyID:
+    OS << "metadata";
+    return;
   case Type::X86_AMXTyID:   OS << "x86_amx"; return;
   case Type::TokenTyID:     OS << "token"; return;
   case Type::IntegerTyID:
diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index 693674a..05ab096 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -142,7 +142,7 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
     return UndefValue::get(DestTy);
   }
 
-  if (V->isNullValue() && !DestTy->isX86_MMXTy() && !DestTy->isX86_AMXTy() &&
+  if (V->isNullValue() && !DestTy->isX86_AMXTy() &&
       opc != Instruction::AddrSpaceCast)
     return Constant::getNullValue(DestTy);
 
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index cf7bbf6..17c0bf7 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -609,8 +609,6 @@ LLVMTypeKind LLVMGetTypeKind(LLVMTypeRef Ty) {
     return LLVMPointerTypeKind;
   case Type::FixedVectorTyID:
     return LLVMVectorTypeKind;
-  case Type::X86_MMXTyID:
-    return LLVMX86_MMXTypeKind;
   case Type::X86_AMXTyID:
     return LLVMX86_AMXTypeKind;
   case Type::TokenTyID:
@@ -725,9 +723,6 @@ LLVMTypeRef LLVMFP128TypeInContext(LLVMContextRef C) {
 LLVMTypeRef LLVMPPCFP128TypeInContext(LLVMContextRef C) {
   return (LLVMTypeRef) Type::getPPC_FP128Ty(*unwrap(C));
 }
-LLVMTypeRef LLVMX86MMXTypeInContext(LLVMContextRef C) {
-  return (LLVMTypeRef) Type::getX86_MMXTy(*unwrap(C));
-}
 LLVMTypeRef LLVMX86AMXTypeInContext(LLVMContextRef C) {
   return (LLVMTypeRef) Type::getX86_AMXTy(*unwrap(C));
 }
@@ -753,9 +748,6 @@ LLVMTypeRef LLVMFP128Type(void) {
 LLVMTypeRef LLVMPPCFP128Type(void) {
   return LLVMPPCFP128TypeInContext(LLVMGetGlobalContext());
 }
-LLVMTypeRef LLVMX86MMXType(void) {
-  return LLVMX86MMXTypeInContext(LLVMGetGlobalContext());
-}
 LLVMTypeRef LLVMX86AMXType(void) {
   return LLVMX86AMXTypeInContext(LLVMGetGlobalContext());
 }
diff --git a/llvm/lib/IR/DataLayout.cpp b/llvm/lib/IR/DataLayout.cpp
index 27411653..17897f7 100644
--- a/llvm/lib/IR/DataLayout.cpp
+++ b/llvm/lib/IR/DataLayout.cpp
@@ -835,7 +835,6 @@ Align DataLayout::getAlignment(Type *Ty, bool abi_or_pref) const {
     // layout.
     return Align(PowerOf2Ceil(BitWidth / 8));
   }
-  case Type::X86_MMXTyID:
   case Type::FixedVectorTyID:
   case Type::ScalableVectorTyID: {
     unsigned BitWidth = getTypeSizeInBits(Ty).getKnownMinValue();
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 2087198..9b0dd5f 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -1052,8 +1052,9 @@ static std::string getMangledTypeStr(Type *Ty, bool &HasUnnamedType) {
     case Type::DoubleTyID:    Result += "f64";      break;
     case Type::X86_FP80TyID:  Result += "f80";      break;
     case Type::FP128TyID:     Result += "f128";     break;
-    case Type::PPC_FP128TyID: Result += "ppcf128";  break;
-    case Type::X86_MMXTyID:   Result += "x86mmx";   break;
+    case Type::PPC_FP128TyID:
+      Result += "ppcf128";
+      break;
     case Type::X86_AMXTyID:   Result += "x86amx";   break;
     case Type::IntegerTyID:
       Result += "i" + utostr(cast<IntegerType>(Ty)->getBitWidth());
@@ -1397,7 +1398,8 @@ static Type *DecodeFixedType(ArrayRef<Intrinsic::IITDescriptor> &Infos,
   switch (D.Kind) {
   case IITDescriptor::Void: return Type::getVoidTy(Context);
   case IITDescriptor::VarArg: return Type::getVoidTy(Context);
-  case IITDescriptor::MMX: return Type::getX86_MMXTy(Context);
+  case IITDescriptor::MMX:
+    return llvm::FixedVectorType::get(llvm::IntegerType::get(Context, 64), 1);
   case IITDescriptor::AMX: return Type::getX86_AMXTy(Context);
   case IITDescriptor::Token: return Type::getTokenTy(Context);
   case IITDescriptor::Metadata: return Type::getMetadataTy(Context);
@@ -1580,7 +1582,11 @@ static bool matchIntrinsicType(
   switch (D.Kind) {
     case IITDescriptor::Void: return !Ty->isVoidTy();
     case IITDescriptor::VarArg: return true;
-    case IITDescriptor::MMX:  return !Ty->isX86_MMXTy();
+    case IITDescriptor::MMX: {
+      FixedVectorType *VT = dyn_cast<FixedVectorType>(Ty);
+      return !VT || VT->getNumElements() != 1 ||
+             !VT->getElementType()->isIntegerTy(64);
+    }
     case IITDescriptor::AMX:  return !Ty->isX86_AMXTy();
     case IITDescriptor::Token: return !Ty->isTokenTy();
     case IITDescriptor::Metadata: return !Ty->isMetadataTy();
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 7a8cf8c..58ebe7e 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -3116,9 +3116,6 @@ bool CastInst::isBitCastable(Type *SrcTy, Type *DestTy) {
   if (SrcBits != DestBits)
     return false;
 
-  if (DestTy->isX86_MMXTy() || SrcTy->isX86_MMXTy())
-    return false;
-
   return true;
 }
 
@@ -3228,12 +3225,6 @@ CastInst::getCastOpcode(
       return IntToPtr;                              // int -> ptr
     }
     llvm_unreachable("Casting pointer to other than pointer or int");
-  } else if (DestTy->isX86_MMXTy()) {
-    if (SrcTy->isVectorTy()) {
-      assert(DestBits == SrcBits && "Casting vector of wrong width to X86_MMX");
-      return BitCast;                               // 64-bit vector to MMX
-    }
-    llvm_unreachable("Illegal cast to X86_MMX");
   }
   llvm_unreachable("Casting to type that is not first-class");
 }
diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 0a37617..4f1ef8c 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -40,9 +40,9 @@ LLVMContextImpl::LLVMContextImpl(LLVMContext &C)
       FloatTy(C, Type::FloatTyID), DoubleTy(C, Type::DoubleTyID),
       MetadataTy(C, Type::MetadataTyID), TokenTy(C, Type::TokenTyID),
       X86_FP80Ty(C, Type::X86_FP80TyID), FP128Ty(C, Type::FP128TyID),
-      PPC_FP128Ty(C, Type::PPC_FP128TyID), X86_MMXTy(C, Type::X86_MMXTyID),
-      X86_AMXTy(C, Type::X86_AMXTyID), Int1Ty(C, 1), Int8Ty(C, 8),
-      Int16Ty(C, 16), Int32Ty(C, 32), Int64Ty(C, 64), Int128Ty(C, 128) {}
+      PPC_FP128Ty(C, Type::PPC_FP128TyID), X86_AMXTy(C, Type::X86_AMXTyID),
+      Int1Ty(C, 1), Int8Ty(C, 8), Int16Ty(C, 16), Int32Ty(C, 32),
+      Int64Ty(C, 64), Int128Ty(C, 128) {}
 
 LLVMContextImpl::~LLVMContextImpl() {
 #ifndef NDEBUG
diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index 937a87d..8e9ca21 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -1582,7 +1582,7 @@ public:
   // Basic type instances.
   Type VoidTy, LabelTy, HalfTy, BFloatTy, FloatTy, DoubleTy, MetadataTy,
       TokenTy;
-  Type X86_FP80Ty, FP128Ty, PPC_FP128Ty, X86_MMXTy, X86_AMXTy;
+  Type X86_FP80Ty, FP128Ty, PPC_FP128Ty, X86_AMXTy;
   IntegerType Int1Ty, Int8Ty, Int16Ty, Int32Ty, Int64Ty, Int128Ty;
 
   std::unique_ptr<ConstantTokenNone> TheNoneToken;
diff --git a/llvm/lib/IR/Type.cpp b/llvm/lib/IR/Type.cpp
index 5c61ad9..9ddccce 100644
--- a/llvm/lib/IR/Type.cpp
+++ b/llvm/lib/IR/Type.cpp
@@ -45,7 +45,6 @@ Type *Type::getPrimitiveType(LLVMContext &C, TypeID IDNumber) {
   case PPC_FP128TyID : return getPPC_FP128Ty(C);
   case LabelTyID     : return getLabelTy(C);
   case MetadataTyID  : return getMetadataTy(C);
-  case X86_MMXTyID   : return getX86_MMXTy(C);
   case X86_AMXTyID   : return getX86_AMXTy(C);
   case TokenTyID     : return getTokenTy(C);
   default:
@@ -125,14 +124,6 @@ bool Type::canLosslesslyBitCastTo(Type *Ty) const {
   if (isa<VectorType>(this) && isa<VectorType>(Ty))
     return getPrimitiveSizeInBits() == Ty->getPrimitiveSizeInBits();
 
-  //  64-bit fixed width vector types can be losslessly converted to x86mmx.
-  if (((isa<FixedVectorType>(this)) && Ty->isX86_MMXTy()) &&
-      getPrimitiveSizeInBits().getFixedValue() == 64)
-    return true;
-  if ((isX86_MMXTy() && isa<FixedVectorType>(Ty)) &&
-      Ty->getPrimitiveSizeInBits().getFixedValue() == 64)
-    return true;
-
   //  8192-bit fixed width vector types can be losslessly converted to x86amx.
   if (((isa<FixedVectorType>(this)) && Ty->isX86_AMXTy()) &&
       getPrimitiveSizeInBits().getFixedValue() == 8192)
@@ -179,8 +170,6 @@ TypeSize Type::getPrimitiveSizeInBits() const {
     return TypeSize::getFixed(128);
   case Type::PPC_FP128TyID:
     return TypeSize::getFixed(128);
-  case Type::X86_MMXTyID:
-    return TypeSize::getFixed(64);
   case Type::X86_AMXTyID:
     return TypeSize::getFixed(8192);
   case Type::IntegerTyID:
@@ -245,7 +234,6 @@ Type *Type::getTokenTy(LLVMContext &C) { return &C.pImpl->TokenTy; }
 Type *Type::getX86_FP80Ty(LLVMContext &C) { return &C.pImpl->X86_FP80Ty; }
 Type *Type::getFP128Ty(LLVMContext &C) { return &C.pImpl->FP128Ty; }
 Type *Type::getPPC_FP128Ty(LLVMContext &C) { return &C.pImpl->PPC_FP128Ty; }
-Type *Type::getX86_MMXTy(LLVMContext &C) { return &C.pImpl->X86_MMXTy; }
 Type *Type::getX86_AMXTy(LLVMContext &C) { return &C.pImpl->X86_AMXTy; }
 
 IntegerType *Type::getInt1Ty(LLVMContext &C) { return &C.pImpl->Int1Ty; }