Remove the x86_mmx IR type. (#98505)

Summary:
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.

Test Plan: 

Reviewers: 

Subscribers: 

Tasks: 

Tags: 


Differential Revision: https://phabricator.intern.facebook.com/D60250667

llvm/bindings/ocaml/llvm/llvm.mli

@@ -760,10 +760,6 @@ val void_type : llcontext -> lltype
     [llvm::Type::LabelTy]. *)
 val label_type : llcontext -> lltype
 
-(** [x86_mmx_type c] returns the x86 64-bit MMX register type in the
-    context [c]. See [llvm::Type::X86_MMXTy]. *)
-val x86_mmx_type : llcontext -> lltype
-
 (** [type_by_name m name] returns the specified type from the current module
     if it exists.
     See the method [llvm::Module::getTypeByName] *)

llvm/bindings/ocaml/llvm/llvm_ocaml.c

@@ -686,11 +686,6 @@ value llvm_label_type(value Context) {
   return to_val(LLVMLabelTypeInContext(Context_val(Context)));
 }
 
-/* llcontext -> lltype */
-value llvm_x86_mmx_type(value Context) {
-  return to_val(LLVMX86MMXTypeInContext(Context_val(Context)));
-}
-
 /* llmodule -> string -> lltype option */
 value llvm_type_by_name(value M, value Name) {
   return ptr_to_option(LLVMGetTypeByName(Module_val(M), String_val(Name)));

llvm/docs/BitCodeFormat.rst

@@ -1291,7 +1291,7 @@ TYPE_CODE_X86_MMX Record
 
 ``[X86_MMX]``
 
-The ``X86_MMX`` record (code 17) adds an ``x86_mmx`` type to the type table.
+The ``X86_MMX`` record (code 17) is deprecated, and imported as a <1 x i64> vector.
 
 TYPE_CODE_STRUCT_ANON Record
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

llvm/docs/LangRef.rst

@@ -3945,24 +3945,6 @@ or constants of this type.
       x86_amx
 
 
-X86_mmx Type
-""""""""""""
-
-:Overview:
-
-The x86_mmx type represents a value held in an MMX register on an x86
-machine. The operations allowed on it are quite limited: parameters and
-return values, load and store, and bitcast. User-specified MMX
-instructions are represented as intrinsic or asm calls with arguments
-and/or results of this type. There are no arrays, vectors or constants
-of this type.
-
-:Syntax:
-
-::
-
-      x86_mmx
-
 
 .. _t_pointer:
 
@@ -4396,7 +4378,7 @@ represented by ``0xH`` followed by 4 hexadecimal digits. The bfloat 16-bit
 format is represented by ``0xR`` followed by 4 hexadecimal digits. All
 hexadecimal formats are big-endian (sign bit at the left).
 
-There are no constants of type x86_mmx and x86_amx.
+There are no constants of type x86_amx.
 
 .. _complexconstants:
 

llvm/docs/ReleaseNotes.rst

@@ -50,6 +50,9 @@ Update on required toolchains to build LLVM
 Changes to the LLVM IR
 ----------------------
 
+* The ``x86_mmx`` IR type has been removed. It will be translated to
+  the standard vector type ``<1 x i64>`` in bitcode upgrade.
+
 Changes to LLVM infrastructure
 ------------------------------
 
@@ -120,6 +123,12 @@ Changes to the X86 Backend
   encoding. To use optimised NOP filling in a code section, leave off the
   "fillval" argument, i.e. `.balign N`, `.p2align N` or `.align N` respectively.
 
+* Due to the removal of the ``x86_mmx`` IR type, functions with
+  ``x86_mmx`` arguments or return values will use a different,
+  incompatible, calling convention ABI. Such functions are not
+  generally seen in the wild (Clang never generates them!), so this is
+  not expected to result in real-world compatibility problems.
+
 Changes to the OCaml bindings
 -----------------------------
 
@@ -129,6 +138,12 @@ Changes to the Python bindings
 Changes to the C API
 --------------------
 
+* The following symbols are deleted due to the removal of the ``x86_mmx`` IR type:
+
+  * ``LLVMX86_MMXTypeKind``
+  * ``LLVMX86MMXTypeInContext``
+  * ``LLVMX86MMXType``
+
 Changes to the CodeGen infrastructure
 -------------------------------------
 

llvm/include/llvm-c/Core.h

@@ -146,27 +146,27 @@ typedef enum {
 } LLVMOpcode;
 
 typedef enum {
-  LLVMVoidTypeKind,      /**< type with no size */
-  LLVMHalfTypeKind,      /**< 16 bit floating point type */
-  LLVMFloatTypeKind,     /**< 32 bit floating point type */
-  LLVMDoubleTypeKind,    /**< 64 bit floating point type */
-  LLVMX86_FP80TypeKind,  /**< 80 bit floating point type (X87) */
-  LLVMFP128TypeKind,     /**< 128 bit floating point type (112-bit mantissa)*/
-  LLVMPPC_FP128TypeKind, /**< 128 bit floating point type (two 64-bits) */
-  LLVMLabelTypeKind,     /**< Labels */
-  LLVMIntegerTypeKind,   /**< Arbitrary bit width integers */
-  LLVMFunctionTypeKind,  /**< Functions */
-  LLVMStructTypeKind,    /**< Structures */
-  LLVMArrayTypeKind,     /**< Arrays */
-  LLVMPointerTypeKind,   /**< Pointers */
-  LLVMVectorTypeKind,    /**< Fixed width SIMD vector type */
-  LLVMMetadataTypeKind,  /**< Metadata */
-  LLVMX86_MMXTypeKind,   /**< X86 MMX */
-  LLVMTokenTypeKind,     /**< Tokens */
-  LLVMScalableVectorTypeKind, /**< Scalable SIMD vector type */
-  LLVMBFloatTypeKind,    /**< 16 bit brain floating point type */
-  LLVMX86_AMXTypeKind,   /**< X86 AMX */
-  LLVMTargetExtTypeKind, /**< Target extension type */
+  LLVMVoidTypeKind = 0,     /**< type with no size */
+  LLVMHalfTypeKind = 1,     /**< 16 bit floating point type */
+  LLVMFloatTypeKind = 2,    /**< 32 bit floating point type */
+  LLVMDoubleTypeKind = 3,   /**< 64 bit floating point type */
+  LLVMX86_FP80TypeKind = 4, /**< 80 bit floating point type (X87) */
+  LLVMFP128TypeKind = 5, /**< 128 bit floating point type (112-bit mantissa)*/
+  LLVMPPC_FP128TypeKind = 6, /**< 128 bit floating point type (two 64-bits) */
+  LLVMLabelTypeKind = 7,     /**< Labels */
+  LLVMIntegerTypeKind = 8,   /**< Arbitrary bit width integers */
+  LLVMFunctionTypeKind = 9,  /**< Functions */
+  LLVMStructTypeKind = 10,   /**< Structures */
+  LLVMArrayTypeKind = 11,    /**< Arrays */
+  LLVMPointerTypeKind = 12,  /**< Pointers */
+  LLVMVectorTypeKind = 13,   /**< Fixed width SIMD vector type */
+  LLVMMetadataTypeKind = 14, /**< Metadata */
+                             /* 15 previously used by LLVMX86_MMXTypeKind */
+  LLVMTokenTypeKind = 16,    /**< Tokens */
+  LLVMScalableVectorTypeKind = 17, /**< Scalable SIMD vector type */
+  LLVMBFloatTypeKind = 18,         /**< 16 bit brain floating point type */
+  LLVMX86_AMXTypeKind = 19,        /**< X86 AMX */
+  LLVMTargetExtTypeKind = 20,      /**< Target extension type */
 } LLVMTypeKind;
 
 typedef enum {
@@ -1716,11 +1716,6 @@ LLVMTypeRef LLVMVoidTypeInContext(LLVMContextRef C);
  */
 LLVMTypeRef LLVMLabelTypeInContext(LLVMContextRef C);
 
-/**
- * Create a X86 MMX type in a context.
- */
-LLVMTypeRef LLVMX86MMXTypeInContext(LLVMContextRef C);
-
 /**
  * Create a X86 AMX type in a context.
  */
@@ -1742,7 +1737,6 @@ LLVMTypeRef LLVMMetadataTypeInContext(LLVMContextRef C);
  */
 LLVMTypeRef LLVMVoidType(void);
 LLVMTypeRef LLVMLabelType(void);
-LLVMTypeRef LLVMX86MMXType(void);
 LLVMTypeRef LLVMX86AMXType(void);
 
 /**

llvm/include/llvm/IR/DataLayout.h

@@ -693,7 +693,6 @@ inline TypeSize DataLayout::getTypeSizeInBits(Type *Ty) const {
   case Type::FloatTyID:
     return TypeSize::getFixed(32);
   case Type::DoubleTyID:
-  case Type::X86_MMXTyID:
     return TypeSize::getFixed(64);
   case Type::PPC_FP128TyID:
   case Type::FP128TyID:

llvm/include/llvm/IR/Type.h

@@ -63,7 +63,6 @@ class Type {
     VoidTyID,      ///< type with no size
     LabelTyID,     ///< Labels
     MetadataTyID,  ///< Metadata
-    X86_MMXTyID,   ///< MMX vectors (64 bits, X86 specific)
     X86_AMXTyID,   ///< AMX vectors (8192 bits, X86 specific)
     TokenTyID,     ///< Tokens
 
@@ -197,9 +196,6 @@ class Type {
 
   const fltSemantics &getFltSemantics() const;
 
-  /// Return true if this is X86 MMX.
-  bool isX86_MMXTy() const { return getTypeID() == X86_MMXTyID; }
-
   /// Return true if this is X86 AMX.
   bool isX86_AMXTy() const { return getTypeID() == X86_AMXTyID; }
 
@@ -285,8 +281,8 @@ class Type {
   /// Return true if the type is a valid type for a register in codegen. This
   /// includes all first-class types except struct and array types.
   bool isSingleValueType() const {
-    return isFloatingPointTy() || isX86_MMXTy() || isIntegerTy() ||
-           isPointerTy() || isVectorTy() || isX86_AMXTy() || isTargetExtTy();
+    return isFloatingPointTy() || isIntegerTy() || isPointerTy() ||
+           isVectorTy() || isX86_AMXTy() || isTargetExtTy();
   }
 
   /// Return true if the type is an aggregate type. This means it is valid as
@@ -302,8 +298,7 @@ class Type {
   bool isSized(SmallPtrSetImpl<Type*> *Visited = nullptr) const {
     // If it's a primitive, it is always sized.
     if (getTypeID() == IntegerTyID || isFloatingPointTy() ||
-        getTypeID() == PointerTyID || getTypeID() == X86_MMXTyID ||
-        getTypeID() == X86_AMXTyID)
+        getTypeID() == PointerTyID || getTypeID() == X86_AMXTyID)
       return true;
     // If it is not something that can have a size (e.g. a function or label),
     // it doesn't have a size.
@@ -453,7 +448,6 @@ class Type {
   static Type *getX86_FP80Ty(LLVMContext &C);
   static Type *getFP128Ty(LLVMContext &C);
   static Type *getPPC_FP128Ty(LLVMContext &C);
-  static Type *getX86_MMXTy(LLVMContext &C);
   static Type *getX86_AMXTy(LLVMContext &C);
   static Type *getTokenTy(LLVMContext &C);
   static IntegerType *getIntNTy(LLVMContext &C, unsigned N);

llvm/lib/Analysis/ConstantFolding.cpp

@@ -564,16 +564,14 @@ Constant *FoldReinterpretLoadFromConst(Constant *C, Type *LoadTy,
     Type *MapTy = Type::getIntNTy(C->getContext(),
                                   DL.getTypeSizeInBits(LoadTy).getFixedValue());
     if (Constant *Res = FoldReinterpretLoadFromConst(C, MapTy, Offset, DL)) {
-      if (Res->isNullValue() && !LoadTy->isX86_MMXTy() &&
-          !LoadTy->isX86_AMXTy())
+      if (Res->isNullValue() && !LoadTy->isX86_AMXTy())
         // Materializing a zero can be done trivially without a bitcast
         return Constant::getNullValue(LoadTy);
       Type *CastTy = LoadTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(LoadTy) : LoadTy;
       Res = FoldBitCast(Res, CastTy, DL);
       if (LoadTy->isPtrOrPtrVectorTy()) {
         // For vector of pointer, we needed to first convert to a vector of integer, then do vector inttoptr
-        if (Res->isNullValue() && !LoadTy->isX86_MMXTy() &&
-            !LoadTy->isX86_AMXTy())
+        if (Res->isNullValue() && !LoadTy->isX86_AMXTy())
           return Constant::getNullValue(LoadTy);
         if (DL.isNonIntegralPointerType(LoadTy->getScalarType()))
           // Be careful not to replace a load of an addrspace value with an inttoptr here
@@ -764,7 +762,7 @@ Constant *llvm::ConstantFoldLoadFromUniformValue(Constant *C, Type *Ty,
   // uniform.
   if (!DL.typeSizeEqualsStoreSize(C->getType()))
     return nullptr;
-  if (C->isNullValue() && !Ty->isX86_MMXTy() && !Ty->isX86_AMXTy())
+  if (C->isNullValue() && !Ty->isX86_AMXTy())
     return Constant::getNullValue(Ty);
   if (C->isAllOnesValue() &&
       (Ty->isIntOrIntVectorTy() || Ty->isFPOrFPVectorTy()))

llvm/lib/AsmParser/LLLexer.cpp

@@ -838,7 +838,8 @@ lltok::Kind LLLexer::LexIdentifier() {
   TYPEKEYWORD("ppc_fp128", Type::getPPC_FP128Ty(Context));
   TYPEKEYWORD("label",     Type::getLabelTy(Context));
   TYPEKEYWORD("metadata",  Type::getMetadataTy(Context));
-  TYPEKEYWORD("x86_mmx",   Type::getX86_MMXTy(Context));
+  TYPEKEYWORD("x86_mmx", llvm::FixedVectorType::get(
+                             llvm::IntegerType::get(Context, 64), 1));
   TYPEKEYWORD("x86_amx",   Type::getX86_AMXTy(Context));
   TYPEKEYWORD("token",     Type::getTokenTy(Context));
   TYPEKEYWORD("ptr",       PointerType::getUnqual(Context));

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -2496,7 +2496,9 @@ Error BitcodeReader::parseTypeTableBody() {
       ResultTy = Type::getMetadataTy(Context);
       break;
     case bitc::TYPE_CODE_X86_MMX:   // X86_MMX
-      ResultTy = Type::getX86_MMXTy(Context);
+      // Deprecated: decodes as <1 x i64>
+      ResultTy =
+          llvm::FixedVectorType::get(llvm::IntegerType::get(Context, 64), 1);
       break;
     case bitc::TYPE_CODE_X86_AMX:   // X86_AMX
       ResultTy = Type::getX86_AMXTy(Context);

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -1088,8 +1088,9 @@ void ModuleBitcodeWriter::writeTypeTable() {
     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
-    case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
-    case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
+    case Type::MetadataTyID:
+      Code = bitc::TYPE_CODE_METADATA;
+      break;
     case Type::X86_AMXTyID:   Code = bitc::TYPE_CODE_X86_AMX;   break;
     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
     case Type::IntegerTyID:

llvm/lib/CodeGen/ValueTypes.cpp

@@ -207,7 +207,7 @@ Type *EVT::getTypeForEVT(LLVMContext &Context) const {
     assert(isExtended() && "Type is not extended!");
     return LLVMTy;
   case MVT::isVoid:  return Type::getVoidTy(Context);
-  case MVT::x86mmx:  return Type::getX86_MMXTy(Context);
+  case MVT::x86mmx:  return llvm::FixedVectorType::get(llvm::IntegerType::get(Context, 64), 1);
   case MVT::aarch64svcount:
     return TargetExtType::get(Context, "aarch64.svcount");
   case MVT::x86amx:  return Type::getX86_AMXTy(Context);
@@ -241,8 +241,8 @@ MVT MVT::getVT(Type *Ty, bool HandleUnknown){
   case Type::BFloatTyID:    return MVT(MVT::bf16);
   case Type::FloatTyID:     return MVT(MVT::f32);
   case Type::DoubleTyID:    return MVT(MVT::f64);
-  case Type::X86_FP80TyID:  return MVT(MVT::f80);
-  case Type::X86_MMXTyID:   return MVT(MVT::x86mmx);
+  case Type::X86_FP80TyID:
+    return MVT(MVT::f80);
   case Type::TargetExtTyID: {
     TargetExtType *TargetExtTy = cast<TargetExtType>(Ty);
     if (TargetExtTy->getName() == "aarch64.svcount")
@@ -302,4 +302,3 @@ void MVT::print(raw_ostream &OS) const {
   else
     OS << EVT(*this).getEVTString();
 }
-

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:

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);
 

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());
 }

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();