[MLIR] Add f8E3M4 IEEE 754 type (#101230)

This PR adds `f8E3M4` type to mlir.

`f8E3M4` type  follows IEEE 754 convention

```c
f8E3M4 (IEEE 754)
- Exponent bias: 3
- Maximum stored exponent value: 6 (binary 110)
- Maximum unbiased exponent value: 6 - 3 = 3
- Minimum stored exponent value: 1 (binary 001)
- Minimum unbiased exponent value: 1 − 3 = −2
- Precision specifies the total number of bits used for the significand (mantissa), 
    including implicit leading integer bit = 4 + 1 = 5
- Follows IEEE 754 conventions for representation of special values
- Has Positive and Negative zero
- Has Positive and Negative infinity
- Has NaNs

Additional details:
- Max exp (unbiased): 3
- Min exp (unbiased): -2
- Infinities (+/-): S.111.0000
- Zeros (+/-): S.000.0000
- NaNs: S.111.{0,1}⁴ except S.111.0000
- Max normal number: S.110.1111 = +/-2^(6-3) x (1 + 15/16) = +/-2^3 x 31 x 2^(-4) = +/-15.5
- Min normal number: S.001.0000 = +/-2^(1-3) x (1 + 0) = +/-2^(-2)
- Max subnormal number: S.000.1111 = +/-2^(-2) x 15/16 = +/-2^(-2) x 15 x 2^(-4) = +/-15 x 2^(-6)
- Min subnormal number: S.000.0001 = +/-2^(-2) x 1/16 =  +/-2^(-2) x 2^(-4) = +/-2^(-6)
```

Related PRs:
- [PR-99698](https://github.com/llvm/llvm-project/pull/99698) [APFloat]
Add support for f8E3M4 IEEE 754 type
- [PR-97118](https://github.com/llvm/llvm-project/pull/97118) [MLIR] Add
f8E4M3 IEEE 754 type

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

@@ -120,6 +120,7 @@ __all__ = [
     "F32Type",
     "F64Type",
     "FlatSymbolRefAttr",
+    "Float8E3M4Type",
     "Float8E4M3B11FNUZType",
     "Float8E4M3FNType",
     "Float8E4M3FNUZType",
@@ -1537,6 +1538,19 @@ class FlatSymbolRefAttr(Attribute):
         Returns the value of the FlatSymbolRef attribute as a string
         """
 
+class Float8E3M4Type(FloatType):
+    static_typeid: ClassVar[TypeID]
+    @staticmethod
+    def get(context: Optional[Context] = None) -> Float8E3M4Type:
+        """
+        Create a float8_e3m4 type.
+        """
+    @staticmethod
+    def isinstance(other: Type) -> bool: ...
+    def __init__(self, cast_from_type: Type) -> None: ...
+    @property
+    def typeid(self) -> TypeID: ...
+
 class Float8E4M3B11FNUZType(FloatType):
     static_typeid: ClassVar[TypeID]
     @staticmethod

mlir/python/mlir/extras/types.py

@@ -12,6 +12,7 @@ from ..ir import (
     F16Type,
     F32Type,
     F64Type,
+    Float8E3M4Type,
     Float8E4M3B11FNUZType,
     Float8E4M3FNType,
     Float8E4M3Type,
@@ -72,6 +73,7 @@ f8E5M2 = lambda: Float8E5M2Type.get()
 f8E4M3 = lambda: Float8E4M3Type.get()
 f8E4M3FN = lambda: Float8E4M3FNType.get()
 f8E4M3B11FNUZ = lambda: Float8E4M3B11FNUZType.get()
+f8E3M4 = lambda: Float8E3M4Type.get()
 
 none = lambda: NoneType.get()