[MLIR][SPIRVToLLVM] Added Bitcast conversion pattern

[georgemitenkov]

Summary

Added conversion pattern and tests for spv.Bitcast op. This one has a direct mapping in LLVM dialect so DirectConversionPattern was used.

mlir/lib/Conversion/SPIRVToLLVM/ConvertSPIRVToLLVM.cpp

patterns.insert<
       DirectConversionPattern<spirv::BitCountOp, LLVM::CtPopOp>,
       DirectConversionPattern<spirv::BitReverseOp, LLVM::BitReverseOp>,
       DirectConversionPattern<spirv::BitwiseAndOp, LLVM::AndOp>,
       DirectConversionPattern<spirv::BitwiseOrOp, LLVM::OrOp>,
       DirectConversionPattern<spirv::BitwiseXorOp, LLVM::XOrOp>,
       NotPattern<spirv::NotOp>,
 
       // Cast ops
+      DirectConversionPattern<spirv::BitcastOp, LLVM::BitcastOp>,
       DirectConversionPattern<spirv::ConvertFToSOp, LLVM::FPToSIOp>,
       DirectConversionPattern<spirv::ConvertFToUOp, LLVM::FPToUIOp>,
       DirectConversionPattern<spirv::ConvertSToFOp, LLVM::SIToFPOp>,
       DirectConversionPattern<spirv::ConvertUToFOp, LLVM::UIToFPOp>,
       IndirectCastPattern<spirv::FConvertOp, LLVM::FPExtOp, LLVM::FPTruncOp>,
       IndirectCastPattern<spirv::SConvertOp, LLVM::SExtOp, LLVM::TruncOp>,
       IndirectCastPattern<spirv::UConvertOp, LLVM::ZExtOp, LLVM::TruncOp>,
 

mlir/test/Conversion/SPIRVToLLVM/cast-ops-to-llvm.mlir

 // RUN: mlir-opt -convert-spirv-to-llvm %s | FileCheck %s
 
 //===----------------------------------------------------------------------===//
+// spv.Bitcast
+//===----------------------------------------------------------------------===//
+
+func @bitcast_float_to_integer_scalar(%arg0 : f32) {
+  // CHECK: {{.*}} = llvm.bitcast {{.*}} : !llvm.float to !llvm.i32
+  %0 = spv.Bitcast %arg0: f32 to i32
+  return
+}
+
+func @bitcast_float_to_integer_vector(%arg0 : vector<3xf32>) {
+  // CHECK: {{.*}} = llvm.bitcast {{.*}} : !llvm<"<3 x float>"> to !llvm<"<3 x i32>">
+  %0 = spv.Bitcast %arg0: vector<3xf32> to vector<3xi32>
+  return
+}
+
+func @bitcast_vector_to_scalar(%arg0 : vector<2xf32>) {
+  // CHECK: {{.*}} = llvm.bitcast {{.*}} : !llvm<"<2 x float>"> to !llvm.i64
+  %0 = spv.Bitcast %arg0: vector<2xf32> to i64
+  return
+}
+
+func @bitcast_scalar_to_vector(%arg0 : f64) {
+  // CHECK: {{.*}} = llvm.bitcast {{.*}} : !llvm.double to !llvm<"<2 x i32>">
+  %0 = spv.Bitcast %arg0: f64 to vector<2xi32>
+  return
+}
+
+func @bitcast_vector_to_vector(%arg0 : vector<4xf32>) {
+  // CHECK: {{.*}} = llvm.bitcast {{.*}} : !llvm<"<4 x float>"> to !llvm<"<2 x i64>">
+  %0 = spv.Bitcast %arg0: vector<4xf32> to vector<2xi64>
+  return
+}
+
+//===----------------------------------------------------------------------===//
 // spv.ConvertFToS
 //===----------------------------------------------------------------------===//
 
 func @convert_float_to_signed_scalar(%arg0: f32) {
   // CHECK: %{{.*}} = llvm.fptosi %{{.*}} : !llvm.float to !llvm.i32
     %0 = spv.ConvertFToS %arg0: f32 to i32
   return
 }