Address review comments.

Author: mshahneo

mlir/include/mlir/Conversion/Passes.td

@@ -197,8 +197,9 @@ def ConvertArithToSPIRVPass : Pass<"convert-arith-to-spirv"> {
            "Emulate narrower scalar types with 32-bit ones if not supported by "
            "the target">,
     Option<"emulateUnsupportedFloatTypes", "emulate-unsupported-float-types",
-    "bool", /*default=*/"true",
-    "Emulate unsupported float types by emulating them with integer types of same bit width">
+           "bool", /*default=*/"true",
+           "Emulate unsupported float types by representing them with integer "
+           "types of same bit width">
   ];
 }
 
@@ -421,8 +422,9 @@ def ConvertControlFlowToSPIRVPass : Pass<"convert-cf-to-spirv"> {
            "Emulate narrower scalar types with 32-bit ones if not supported by"
            " the target">,
     Option<"emulateUnsupportedFloatTypes", "emulate-unsupported-float-types",
-    "bool", /*default=*/"true",
-    "Emulate unsupported float types by emulating them with integer types of same bit width">
+           "bool", /*default=*/"true",
+           "Emulate unsupported float types by representing them with integer "
+           "types of same bit width">
   ];
 }
 
@@ -508,8 +510,9 @@ def ConvertFuncToSPIRVPass : Pass<"convert-func-to-spirv"> {
            "Emulate narrower scalar types with 32-bit ones if not supported by"
            " the target">,
     Option<"emulateUnsupportedFloatTypes", "emulate-unsupported-float-types",
-    "bool", /*default=*/"true",
-    "Emulate unsupported float types by emulating them with integer types of same bit width">
+           "bool", /*default=*/"true",
+           "Emulate unsupported float types by representing them with integer "
+           "types of same bit width">
   ];
 }
 
@@ -1174,8 +1177,9 @@ def ConvertTensorToSPIRVPass : Pass<"convert-tensor-to-spirv"> {
            "Emulate narrower scalar types with 32-bit ones if not supported by"
            " the target">,
     Option<"emulateUnsupportedFloatTypes", "emulate-unsupported-float-types",
-    "bool", /*default=*/"true",
-    "Emulate unsupported float types by emulating them with integer types of same bit width">
+           "bool", /*default=*/"true",
+           "Emulate unsupported float types by representing them with integer "
+           "types of same bit width">
   ];
 }
 

mlir/lib/Conversion/ArithToSPIRV/ArithToSPIRV.cpp

@@ -99,9 +99,12 @@ static FloatAttr convertFloatAttr(FloatAttr srcAttr, FloatType dstType,
   return builder.getF32FloatAttr(dstVal.convertToFloat());
 }
 
-// Get IntegerAttr from FloatAttr.
-IntegerAttr getIntegerAttrFromFloatAttr(FloatAttr floatAttr, Type dstType,
-                                        ConversionPatternRewriter &rewriter) {
+// Get in IntegerAttr from FloatAttr while preserving the bits.
+// Useful for converting float constants to integer constants while preserving
+// the bits.
+static IntegerAttr
+getIntegerAttrFromFloatAttr(FloatAttr floatAttr, Type dstType,
+                            ConversionPatternRewriter &rewriter) {
   APFloat floatVal = floatAttr.getValue();
   APInt intVal = floatVal.bitcastToAPInt();
   return rewriter.getIntegerAttr(dstType, intVal);

mlir/lib/Dialect/SPIRV/Transforms/SPIRVConversion.cpp

@@ -169,7 +169,6 @@ static spirv::ScalarType getIndexType(MLIRContext *ctx,
 // SPIR-V dialect. Keeping it local till the use case arises.
 static std::optional<int64_t>
 getTypeNumBytes(const SPIRVConversionOptions &options, Type type) {
-
   if (isa<spirv::ScalarType>(type)) {
     auto bitWidth = type.getIntOrFloatBitWidth();
     // According to the SPIR-V spec:
@@ -188,8 +187,7 @@ getTypeNumBytes(const SPIRVConversionOptions &options, Type type) {
     auto bitWidth = type.getIntOrFloatBitWidth();
     if (bitWidth == 8)
       return bitWidth / 8;
-    else
-      return std::nullopt;
+    return std::nullopt;
   }
 
   if (auto complexType = dyn_cast<ComplexType>(type)) {
@@ -339,7 +337,7 @@ static Type convert8BitFloatType(const SPIRVConversionOptions &options,
           Float8E4M3FNUZType, Float8E4M3B11FNUZType, Float8E3M4Type,
           Float8E8M0FNUType>(type))
     return IntegerType::get(type.getContext(), type.getWidth());
-  LLVM_DEBUG(llvm::dbgs() << "unsupported 8-bit float type\n");
+  LLVM_DEBUG(llvm::dbgs() << "unsupported 8-bit float type: " << type << "\n");
   return nullptr;
 }
 
@@ -351,7 +349,7 @@ convertShaped8BitFloatType(ShapedType type,
                            const SPIRVConversionOptions &options) {
   if (!options.emulateUnsupportedFloatTypes)
     return type;
-  auto srcElementType = type.getElementType();
+  Type srcElementType = type.getElementType();
   Type convertedElementType = nullptr;
   // F8 types are converted to integer types with the same bit width.
   if (isa<Float8E5M2Type, Float8E4M3Type, Float8E4M3FNType, Float8E5M2FNUZType,

mlir/test/Conversion/ArithToSPIRV/arith-to-spirv.mlir

@@ -563,10 +563,16 @@ func.func @constant() {
 func.func @constant_8bit_float() {
   // CHECK: spirv.Constant 56 : i8
   %cst = arith.constant 1.0 : f8E4M3
+  // CHECK: spirv.Constant 56 : i8
+  %cst_i8 = arith.bitcast %cst : f8E4M3 to i8
   // CHECK: spirv.Constant dense<56> : vector<4xi8>
   %cst_vector = arith.constant dense<1.0> : vector<4xf8E4M3>
+  // CHECK: spirv.Constant dense<56> : vector<4xi8>
+  %cst_vector_i8 = arith.bitcast %cst_vector : vector<4xf8E4M3> to vector<4xi8>
   // CHECK: spirv.Constant dense<60> : tensor<4xi8> : !spirv.array<4 x i8>
   %cst_tensor = arith.constant dense<1.0> : tensor<4xf8E5M2>
+  // CHECK: spirv.Constant dense<60> : tensor<4xi8> : !spirv.array<4 x i8>
+  %cst_tensor_i8 = arith.bitcast %cst_tensor : tensor<4xf8E5M2> to tensor<4xi8>
   return
 }