[MLIR] Add f8E8M0FNU type (#111028)

This PR adds `f8E8M0FNU` type to MLIR.

`f8E8M0FNU` type is proposed in [OpenCompute MX
Specification](https://www.opencompute.org/documents/ocp-microscaling-formats-mx-v1-0-spec-final-pdf).
It defines a 8-bit floating point number with bit layout S0E8M0. Unlike
IEEE-754 types, there are no infinity, denormals, zeros or negative
values.

```c
f8E8M0FNU
- Exponent bias: 127
- Maximum stored exponent value: 254 (binary 1111'1110)
- Maximum unbiased exponent value: 254 - 127 = 127
- Minimum stored exponent value: 0 (binary 0000'0000)
- Minimum unbiased exponent value: 0 − 127 = -127
- Doesn't have zero
- Doesn't have infinity
- NaN is encoded as binary 1111'1111

Additional details:
- Zeros cannot be represented
- Negative values cannot be represented
- Mantissa is always 1
```

Related PRs:
- [PR-107127](https://github.com/llvm/llvm-project/pull/107127)
[APFloat] Add APFloat support for E8M0 type
- [PR-105573](https://github.com/llvm/llvm-project/pull/105573) [MLIR]
Add f6E3M2FN type - was used as a template for this PR
- [PR-107999](https://github.com/llvm/llvm-project/pull/107999) [MLIR]
Add f6E2M3FN type
- [PR-108877](https://github.com/llvm/llvm-project/pull/108877) [MLIR]
Add f4E2M1FN type

mlir/include/mlir-c/BuiltinTypes.h

@@ -179,6 +179,16 @@ MLIR_CAPI_EXPORTED bool mlirTypeIsAFloat8E3M4(MlirType type);
 /// context.
 MLIR_CAPI_EXPORTED MlirType mlirFloat8E3M4TypeGet(MlirContext ctx);
 
+/// Returns the typeID of an Float8E8M0FNU type.
+MLIR_CAPI_EXPORTED MlirTypeID mlirFloat8E8M0FNUTypeGetTypeID(void);
+
+/// Checks whether the given type is an f8E8M0FNU type.
+MLIR_CAPI_EXPORTED bool mlirTypeIsAFloat8E8M0FNU(MlirType type);
+
+/// Creates an f8E8M0FNU type in the given context. The type is owned by the
+/// context.
+MLIR_CAPI_EXPORTED MlirType mlirFloat8E8M0FNUTypeGet(MlirContext ctx);
+
 /// Returns the typeID of an BFloat16 type.
 MLIR_CAPI_EXPORTED MlirTypeID mlirBFloat16TypeGetTypeID(void);
 

mlir/include/mlir/IR/Builders.h

@@ -70,6 +70,7 @@ public:
   FloatType getFloat8E4M3FNUZType();
   FloatType getFloat8E4M3B11FNUZType();
   FloatType getFloat8E3M4Type();
+  FloatType getFloat8E8M0FNUType();
   FloatType getBF16Type();
   FloatType getF16Type();
   FloatType getTF32Type();

mlir/include/mlir/IR/BuiltinTypes.h

@@ -70,6 +70,7 @@ public:
   static FloatType getFloat4E2M1FN(MLIRContext *ctx);
   static FloatType getFloat6E2M3FN(MLIRContext *ctx);
   static FloatType getFloat6E3M2FN(MLIRContext *ctx);
+  static FloatType getFloat8E8M0FNU(MLIRContext *ctx);
 
   /// Methods for support type inquiry through isa, cast, and dyn_cast.
   static bool classof(Type type);
@@ -416,11 +417,12 @@ inline bool BaseMemRefType::isValidElementType(Type type) {
 }
 
 inline bool FloatType::classof(Type type) {
-  return llvm::isa<
-      Float4E2M1FNType, Float6E2M3FNType, Float6E3M2FNType, Float8E5M2Type,
-      Float8E4M3Type, Float8E4M3FNType, Float8E5M2FNUZType, Float8E4M3FNUZType,
-      Float8E4M3B11FNUZType, Float8E3M4Type, BFloat16Type, Float16Type,
-      FloatTF32Type, Float32Type, Float64Type, Float80Type, Float128Type>(type);
+  return llvm::isa<Float4E2M1FNType, Float6E2M3FNType, Float6E3M2FNType,
+                   Float8E5M2Type, Float8E4M3Type, Float8E4M3FNType,
+                   Float8E5M2FNUZType, Float8E4M3FNUZType,
+                   Float8E4M3B11FNUZType, Float8E3M4Type, Float8E8M0FNUType,
+                   BFloat16Type, Float16Type, FloatTF32Type, Float32Type,
+                   Float64Type, Float80Type, Float128Type>(type);
 }
 
 inline FloatType FloatType::getFloat4E2M1FN(MLIRContext *ctx) {
@@ -463,6 +465,10 @@ inline FloatType FloatType::getFloat8E3M4(MLIRContext *ctx) {
   return Float8E3M4Type::get(ctx);
 }
 
+inline FloatType FloatType::getFloat8E8M0FNU(MLIRContext *ctx) {
+  return Float8E8M0FNUType::get(ctx);
+}
+
 inline FloatType FloatType::getBF16(MLIRContext *ctx) {
   return BFloat16Type::get(ctx);
 }

mlir/include/mlir/IR/BuiltinTypes.td

@@ -296,6 +296,29 @@ def Builtin_Float6E3M2FN : Builtin_FloatType<"Float6E3M2FN", "f6E3M2FN"> {
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// Float8E8M0FNUType
+
+def Builtin_Float8E8M0FNU : Builtin_FloatType<"Float8E8M0FNU", "f8E8M0FNU"> {
+  let summary = "8-bit floating point with 8-bit exponent, no mantissa or sign";
+  let description = [{
+    An 8-bit floating point type with no sign bit, 8 bits exponent and no
+    mantissa. This is not a standard type as defined by IEEE-754; it is intended
+    to be used for representing scaling factors, so it cannot represent zeros
+    and negative numbers. The values it can represent are powers of two in the
+    range [-127,127] and NaN.
+
+      * bit encoding: S0E8M0
+      * exponent bias: 127
+      * infinities: Not supported
+      * NaNs: Supported with all bits set to 1
+      * denormals: Not supported
+
+    Open Compute Project (OCP) microscaling formats (MX) specification:
+    https://www.opencompute.org/documents/ocp-microscaling-formats-mx-v1-0-spec-final-pdf
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // BFloat16Type
 

mlir/include/mlir/IR/CommonTypeConstraints.td

@@ -353,6 +353,8 @@ def F6E2M3FN : Type<CPred<"$_self.isFloat6E2M3FN()">, "f6E2M3FN type">,
                BuildableType<"$_builder.getFloat6E2M3FNType()">;
 def F6E3M2FN : Type<CPred<"$_self.isFloat6E3M2FN()">, "f6E3M2FN type">,
                BuildableType<"$_builder.getFloat6E3M2FNType()">;
+def F8E8M0FNU : Type<CPred<"$_self.isFloat8E8M0FNU()">, "f8E8M0FNU type">,
+                BuildableType<"$_builder.getFloat8E8M0FNUType()">;
 
 def AnyComplex : Type<CPred<"::llvm::isa<::mlir::ComplexType>($_self)">,
                       "complex-type", "::mlir::ComplexType">;

mlir/include/mlir/IR/Types.h

@@ -135,6 +135,7 @@ public:
   bool isFloat8E4M3FNUZ() const;
   bool isFloat8E4M3B11FNUZ() const;
   bool isFloat8E3M4() const;
+  bool isFloat8E8M0FNU() const;
   bool isBF16() const;
   bool isF16() const;
   bool isTF32() const;

mlir/lib/AsmParser/TokenKinds.def

@@ -104,6 +104,7 @@ TOK_KEYWORD(f8E3M4)
 TOK_KEYWORD(f4E2M1FN)
 TOK_KEYWORD(f6E2M3FN)
 TOK_KEYWORD(f6E3M2FN)
+TOK_KEYWORD(f8E8M0FNU)
 TOK_KEYWORD(f128)
 TOK_KEYWORD(false)
 TOK_KEYWORD(floordiv)

mlir/lib/AsmParser/TypeParser.cpp

@@ -49,6 +49,7 @@ OptionalParseResult Parser::parseOptionalType(Type &type) {
   case Token::kw_f8E4M3FNUZ:
   case Token::kw_f8E4M3B11FNUZ:
   case Token::kw_f8E3M4:
+  case Token::kw_f8E8M0FNU:
   case Token::kw_bf16:
   case Token::kw_f16:
   case Token::kw_tf32:
@@ -336,6 +337,9 @@ Type Parser::parseNonFunctionType() {
   case Token::kw_f8E3M4:
     consumeToken(Token::kw_f8E3M4);
     return builder.getFloat8E3M4Type();
+  case Token::kw_f8E8M0FNU:
+    consumeToken(Token::kw_f8E8M0FNU);
+    return builder.getFloat8E8M0FNUType();
   case Token::kw_bf16:
     consumeToken(Token::kw_bf16);
     return builder.getBF16Type();

mlir/lib/Bindings/Python/IRTypes.cpp

@@ -331,6 +331,27 @@ public:
   }
 };
 
+/// Floating Point Type subclass - Float8E8M0FNUType.
+class PyFloat8E8M0FNUType
+    : public PyConcreteType<PyFloat8E8M0FNUType, PyFloatType> {
+public:
+  static constexpr IsAFunctionTy isaFunction = mlirTypeIsAFloat8E8M0FNU;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirFloat8E8M0FNUTypeGetTypeID;
+  static constexpr const char *pyClassName = "Float8E8M0FNUType";
+  using PyConcreteType::PyConcreteType;
+
+  static void bindDerived(ClassTy &c) {
+    c.def_static(
+        "get",
+        [](DefaultingPyMlirContext context) {
+          MlirType t = mlirFloat8E8M0FNUTypeGet(context->get());
+          return PyFloat8E8M0FNUType(context->getRef(), t);
+        },
+        py::arg("context") = py::none(), "Create a float8_e8m0fnu type.");
+  }
+};
+
 /// Floating Point Type subclass - BF16Type.
 class PyBF16Type : public PyConcreteType<PyBF16Type, PyFloatType> {
 public:
@@ -953,6 +974,7 @@ void mlir::python::populateIRTypes(py::module &m) {
   PyFloat8E4M3B11FNUZType::bind(m);
   PyFloat8E5M2FNUZType::bind(m);
   PyFloat8E3M4Type::bind(m);
+  PyFloat8E8M0FNUType::bind(m);
   PyBF16Type::bind(m);
   PyF16Type::bind(m);
   PyTF32Type::bind(m);

mlir/lib/CAPI/IR/BuiltinTypes.cpp

@@ -205,6 +205,18 @@ MlirType mlirFloat8E3M4TypeGet(MlirContext ctx) {
   return wrap(FloatType::getFloat8E3M4(unwrap(ctx)));
 }
 
+MlirTypeID mlirFloat8E8M0FNUTypeGetTypeID() {
+  return wrap(Float8E8M0FNUType::getTypeID());
+}
+
+bool mlirTypeIsAFloat8E8M0FNU(MlirType type) {
+  return unwrap(type).isFloat8E8M0FNU();
+}
+
+MlirType mlirFloat8E8M0FNUTypeGet(MlirContext ctx) {
+  return wrap(FloatType::getFloat8E8M0FNU(unwrap(ctx)));
+}
+
 MlirTypeID mlirBFloat16TypeGetTypeID() {
   return wrap(BFloat16Type::getTypeID());
 }

mlir/lib/Conversion/LLVMCommon/TypeConverter.cpp

@@ -250,7 +250,8 @@ Type LLVMTypeConverter::convertFloatType(FloatType type) const {
   if (type.isFloat8E5M2() || type.isFloat8E4M3() || type.isFloat8E4M3FN() ||
       type.isFloat8E5M2FNUZ() || type.isFloat8E4M3FNUZ() ||
       type.isFloat8E4M3B11FNUZ() || type.isFloat8E3M4() ||
-      type.isFloat4E2M1FN() || type.isFloat6E2M3FN() || type.isFloat6E3M2FN())
+      type.isFloat4E2M1FN() || type.isFloat6E2M3FN() || type.isFloat6E3M2FN() ||
+      type.isFloat8E8M0FNU())
     return IntegerType::get(&getContext(), type.getWidth());
   return type;
 }

mlir/lib/Dialect/Arith/Utils/Utils.cpp

@@ -370,6 +370,7 @@ std::optional<FloatType> parseFloatType(MLIRContext *ctx, StringRef name) {
       .Case("f8E5M2FNUZ", b.getFloat8E5M2FNUZType())
       .Case("f8E4M3FNUZ", b.getFloat8E4M3FNUZType())
       .Case("f8E3M4", b.getFloat8E3M4Type())
+      .Case("f8E8M0FNU", b.getFloat8E8M0FNUType())
       .Case("bf16", b.getBF16Type())
       .Case("f16", b.getF16Type())
       .Case("f32", b.getF32Type())

mlir/lib/IR/AsmPrinter.cpp

@@ -2593,6 +2593,7 @@ void AsmPrinter::Impl::printTypeImpl(Type type) {
       .Case<Float8E4M3FNUZType>([&](Type) { os << "f8E4M3FNUZ"; })
       .Case<Float8E4M3B11FNUZType>([&](Type) { os << "f8E4M3B11FNUZ"; })
       .Case<Float8E3M4Type>([&](Type) { os << "f8E3M4"; })
+      .Case<Float8E8M0FNUType>([&](Type) { os << "f8E8M0FNU"; })
       .Case<BFloat16Type>([&](Type) { os << "bf16"; })
       .Case<Float16Type>([&](Type) { os << "f16"; })
       .Case<FloatTF32Type>([&](Type) { os << "tf32"; })

mlir/lib/IR/Builders.cpp

@@ -74,6 +74,10 @@ FloatType Builder::getFloat8E3M4Type() {
   return FloatType::getFloat8E3M4(context);
 }
 
+FloatType Builder::getFloat8E8M0FNUType() {
+  return FloatType::getFloat8E8M0FNU(context);
+}
+
 FloatType Builder::getBF16Type() { return FloatType::getBF16(context); }
 
 FloatType Builder::getF16Type() { return FloatType::getF16(context); }

mlir/lib/IR/BuiltinTypes.cpp

@@ -121,6 +121,8 @@ const llvm::fltSemantics &FloatType::getFloatSemantics() {
     return APFloat::Float8E4M3B11FNUZ();
   if (llvm::isa<Float8E3M4Type>(*this))
     return APFloat::Float8E3M4();
+  if (llvm::isa<Float8E8M0FNUType>(*this))
+    return APFloat::Float8E8M0FNU();
   if (llvm::isa<BFloat16Type>(*this))
     return APFloat::BFloat();
   if (llvm::isa<Float16Type>(*this))

mlir/lib/IR/MLIRContext.cpp

@@ -231,6 +231,7 @@ public:
   Float8E4M3FNUZType f8E4M3FNUZTy;
   Float8E4M3B11FNUZType f8E4M3B11FNUZTy;
   Float8E3M4Type f8E3M4Ty;
+  Float8E8M0FNUType f8E8M0FNUTy;
   BFloat16Type bf16Ty;
   Float16Type f16Ty;
   FloatTF32Type tf32Ty;
@@ -326,6 +327,7 @@ MLIRContext::MLIRContext(const DialectRegistry &registry, Threading setting)
   impl->f8E4M3FNUZTy = TypeUniquer::get<Float8E4M3FNUZType>(this);
   impl->f8E4M3B11FNUZTy = TypeUniquer::get<Float8E4M3B11FNUZType>(this);
   impl->f8E3M4Ty = TypeUniquer::get<Float8E3M4Type>(this);
+  impl->f8E8M0FNUTy = TypeUniquer::get<Float8E8M0FNUType>(this);
   impl->bf16Ty = TypeUniquer::get<BFloat16Type>(this);
   impl->f16Ty = TypeUniquer::get<Float16Type>(this);
   impl->tf32Ty = TypeUniquer::get<FloatTF32Type>(this);
@@ -1049,6 +1051,9 @@ Float8E4M3B11FNUZType Float8E4M3B11FNUZType::get(MLIRContext *context) {
 Float8E3M4Type Float8E3M4Type::get(MLIRContext *context) {
   return context->getImpl().f8E3M4Ty;
 }
+Float8E8M0FNUType Float8E8M0FNUType::get(MLIRContext *context) {
+  return context->getImpl().f8E8M0FNUTy;
+}
 BFloat16Type BFloat16Type::get(MLIRContext *context) {
   return context->getImpl().bf16Ty;
 }

mlir/lib/IR/Types.cpp

@@ -49,6 +49,9 @@ bool Type::isFloat8E4M3FNUZ() const {
 bool Type::isFloat8E4M3B11FNUZ() const {
   return llvm::isa<Float8E4M3B11FNUZType>(*this);
 }
+bool Type::isFloat8E8M0FNU() const {
+  return llvm::isa<Float8E8M0FNUType>(*this);
+}
 bool Type::isFloat8E3M4() const { return llvm::isa<Float8E3M4Type>(*this); }
 bool Type::isBF16() const { return llvm::isa<BFloat16Type>(*this); }
 bool Type::isF16() const { return llvm::isa<Float16Type>(*this); }

mlir/python/mlir/_mlir_libs/_mlir/ir.pyi

@@ -117,6 +117,7 @@ __all__ = [
     "Float8E4M3Type",
     "Float8E5M2FNUZType",
     "Float8E5M2Type",
+    "Float8E8M0FNUType",
     "FloatAttr",
     "FloatTF32Type",
     "FloatType",
@@ -1660,6 +1661,19 @@ class Float8E5M2Type(FloatType):
     @property
     def typeid(self) -> TypeID: ...
 
+class Float8E8M0FNUType(FloatType):
+    static_typeid: ClassVar[TypeID]
+    @staticmethod
+    def get(context: Context | None = None) -> Float8E8M0FNUType:
+        """
+        Create a float8_e8m0fnu type.
+        """
+    @staticmethod
+    def isinstance(other: Type) -> bool: ...
+    def __init__(self, cast_from_type: Type) -> None: ...
+    @property
+    def typeid(self) -> TypeID: ...
+
 class FloatAttr(Attribute):
     static_typeid: ClassVar[TypeID]
     @staticmethod

mlir/python/mlir/extras/types.py

@@ -20,6 +20,7 @@ from ..ir import (
     Float8E4M3FNType,
     Float8E4M3Type,
     Float8E5M2Type,
+    Float8E8M0FNUType,
     FunctionType,
     IndexType,
     IntegerType,
@@ -80,6 +81,7 @@ f8E3M4 = lambda: Float8E3M4Type.get()
 f4E2M1FN = lambda: Float4E2M1FNType.get()
 f6E2M3FN = lambda: Float6E2M3FNType.get()
 f6E3M2FN = lambda: Float6E3M2FNType.get()
+f8E8M0FNU = lambda: Float8E8M0FNUType.get()
 
 none = lambda: NoneType.get()
 

mlir/test/IR/attribute.mlir

@@ -76,6 +76,10 @@ func.func @float_attrs_pass() {
     // CHECK: float_attr = 2.000000e+00 : f8E3M4
     float_attr = 2. : f8E3M4
   } : () -> ()
+  "test.float_attrs"() {
+    // CHECK: float_attr = 2.000000e+00 : f8E8M0FNU
+    float_attr = 2. : f8E8M0FNU
+  } : () -> ()
   "test.float_attrs"() {
     // CHECK: float_attr = 2.000000e+00 : f16
     float_attr = 2. : f16

mlir/test/Target/LLVMIR/llvmir.mlir

@@ -72,6 +72,9 @@ llvm.mlir.global internal @f8E5M2FNUZ_global_as_i8(1.5 : f8E5M2FNUZ) : i8
 // CHECK: @f8E4M3B11FNUZ_global_as_i8 = internal global i8 92
 llvm.mlir.global internal @f8E4M3B11FNUZ_global_as_i8(1.5 : f8E4M3B11FNUZ) : i8
 
+// CHECK: @f8E8M0FNU_global_as_i8 = internal global i8 127
+llvm.mlir.global internal @f8E8M0FNU_global_as_i8(1.0 : f8E8M0FNU) : i8
+
 // CHECK: @bf16_global_as_i16 = internal global i16 16320
 llvm.mlir.global internal @bf16_global_as_i16(1.5 : bf16) : i16
 

mlir/test/python/ir/builtin_types.py

@@ -133,6 +133,8 @@ def testFloatTypeSubclasses():
     # CHECK: True
     print(isinstance(Type.parse("f8E5M2FNUZ", ctx), FloatType))
     # CHECK: True
+    print(isinstance(Type.parse("f8E8M0FNU", ctx), FloatType))
+    # CHECK: True
     print(isinstance(Type.parse("f16", ctx), FloatType))
     # CHECK: True
     print(isinstance(Type.parse("bf16", ctx), FloatType))
@@ -259,6 +261,8 @@ def testFloatType():
         print("float:", Float8E4M3FNUZType.get())
         # CHECK: float: f8E4M3B11FNUZ
         print("float:", Float8E4M3B11FNUZType.get())
+        # CHECK: float: f8E8M0FNU
+        print("float:", Float8E8M0FNUType.get())
         # CHECK: float: bf16
         print("float:", BF16Type.get())
         # CHECK: float: f16
@@ -631,6 +635,7 @@ def testTypeIDs():
             (Float8E4M3FNUZType, Float8E4M3FNUZType.get()),
             (Float8E4M3B11FNUZType, Float8E4M3B11FNUZType.get()),
             (Float8E5M2FNUZType, Float8E5M2FNUZType.get()),
+            (Float8E8M0FNUType, Float8E8M0FNUType.get()),
             (BF16Type, BF16Type.get()),
             (F16Type, F16Type.get()),
             (F32Type, F32Type.get()),
@@ -659,6 +664,7 @@ def testTypeIDs():
         # CHECK: Float8E4M3FNUZType(f8E4M3FNUZ)
         # CHECK: Float8E4M3B11FNUZType(f8E4M3B11FNUZ)
         # CHECK: Float8E5M2FNUZType(f8E5M2FNUZ)
+        # CHECK: Float8E8M0FNUType(f8E8M0FNU)
         # CHECK: BF16Type(bf16)
         # CHECK: F16Type(f16)
         # CHECK: F32Type(f32)
@@ -761,6 +767,9 @@ def testConcreteTypesRoundTrip():
         # CHECK: Float8E5M2FNUZType
         # CHECK: Float8E5M2FNUZType(f8E5M2FNUZ)
         print_downcasted(Float8E5M2FNUZType.get())
+        # CHECK: Float8E8M0FNUType
+        # CHECK: Float8E8M0FNUType(f8E8M0FNU)
+        print_downcasted(Float8E8M0FNUType.get())
         # CHECK: BF16Type
         # CHECK: BF16Type(bf16)
         print_downcasted(BF16Type.get())

mlir/utils/lldb-scripts/mlirDataFormatters.py

@@ -60,6 +60,7 @@ builtin_attr_type_mnemonics = {
     "mlir::Float8E4M3FNUZType": '"f8E4M3FNUZ"',
     "mlir::Float8E4M3B11FNUZType": '"f8E4M3B11FNUZ"',
     "mlir::Float8E3M4Type": '"f8E3M4"',
+    "mlir::Float8E8M0FNUType": '"f8E8M0FNU"',
     "mlir::BFloat16Type": '"bf16"',
     "mlir::Float16Type": '"f16"',
     "mlir::FloatTF32Type": '"tf32"',

mlir/utils/tree-sitter-mlir/grammar.js

@@ -231,7 +231,8 @@ const common = {
       token(seq(choice('si', 'ui', 'i'), /[1-9]/, repeat(/[0-9]/))),
   float_type : $ => token(
       choice('f16', 'f32', 'f64', 'f80', 'f128', 'bf16', 'f8E3M4', 'f8E4M3FN',
-             'f8E4M3', 'f8E5M2', 'f4E2M1FN', 'f6E2M3FN', 'f6E3M2FN')),
+             'f8E4M3', 'f8E5M2', 'f4E2M1FN', 'f6E2M3FN', 'f6E3M2FN',
+             'f8E8M0FNU')),
   index_type : $ => token('index'),
   none_type : $ => token('none'),
   complex_type : $ => seq(token('complex'), '<', $._prim_type, '>'),