[mlir][spirv][vector] Support converting vector.from_elements to SPIR-V (llvm#118540)

Closes llvm#118098.

Author: andfau-amd

mlir/lib/Conversion/VectorToSPIRV/VectorToSPIRV.cpp

@@ -220,6 +220,32 @@ struct VectorFmaOpConvert final : public OpConversionPattern<vector::FMAOp> {
   }
 };
 
+struct VectorFromElementsOpConvert final
+    : public OpConversionPattern<vector::FromElementsOp> {
+  using OpConversionPattern::OpConversionPattern;
+
+  LogicalResult
+  matchAndRewrite(vector::FromElementsOp op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    Type resultType = getTypeConverter()->convertType(op.getType());
+    if (!resultType)
+      return failure();
+    OperandRange elements = op.getElements();
+    if (isa<spirv::ScalarType>(resultType)) {
+      // In the case with a single scalar operand / single-element result,
+      // pass through the scalar.
+      rewriter.replaceOp(op, elements[0]);
+      return success();
+    }
+    // SPIRVTypeConverter rejects vectors with rank > 1, so multi-dimensional
+    // vector.from_elements cases should not need to be handled, only 1d.
+    assert(cast<VectorType>(resultType).getRank() == 1);
+    rewriter.replaceOpWithNewOp<spirv::CompositeConstructOp>(op, resultType,
+                                                             elements);
+    return success();
+  }
+};
+
 struct VectorInsertOpConvert final
     : public OpConversionPattern<vector::InsertOp> {
   using OpConversionPattern::OpConversionPattern;
@@ -952,8 +978,9 @@ void mlir::populateVectorToSPIRVPatterns(
       VectorBitcastConvert, VectorBroadcastConvert,
       VectorExtractElementOpConvert, VectorExtractOpConvert,
       VectorExtractStridedSliceOpConvert, VectorFmaOpConvert<spirv::GLFmaOp>,
-      VectorFmaOpConvert<spirv::CLFmaOp>, VectorInsertElementOpConvert,
-      VectorInsertOpConvert, VectorReductionPattern<GL_INT_MAX_MIN_OPS>,
+      VectorFmaOpConvert<spirv::CLFmaOp>, VectorFromElementsOpConvert,
+      VectorInsertElementOpConvert, VectorInsertOpConvert,
+      VectorReductionPattern<GL_INT_MAX_MIN_OPS>,
       VectorReductionPattern<CL_INT_MAX_MIN_OPS>,
       VectorReductionFloatMinMax<CL_FLOAT_MAX_MIN_OPS>,
       VectorReductionFloatMinMax<GL_FLOAT_MAX_MIN_OPS>, VectorShapeCast,

mlir/test/Conversion/VectorToSPIRV/vector-to-spirv.mlir

@@ -217,6 +217,35 @@ func.func @extract_dynamic_cst(%arg0 : vector<4xf32>) -> f32 {
 
 // -----
 
+// CHECK-LABEL: @from_elements_0d
+//  CHECK-SAME: %[[ARG0:.+]]: f32
+//       CHECK:   %[[RETVAL:.+]] = builtin.unrealized_conversion_cast %[[ARG0]]
+//       CHECK:   return %[[RETVAL]]
+func.func @from_elements_0d(%arg0 : f32) -> vector<f32> {
+  %0 = vector.from_elements %arg0 : vector<f32>
+  return %0: vector<f32>
+}
+
+// CHECK-LABEL: @from_elements_1x
+//  CHECK-SAME: %[[ARG0:.+]]: f32
+//       CHECK:   %[[RETVAL:.+]] = builtin.unrealized_conversion_cast %[[ARG0]]
+//       CHECK:   return %[[RETVAL]]
+func.func @from_elements_1x(%arg0 : f32) -> vector<1xf32> {
+  %0 = vector.from_elements %arg0 : vector<1xf32>
+  return %0: vector<1xf32>
+}
+
+// CHECK-LABEL: @from_elements_3x
+//  CHECK-SAME: %[[ARG0:.+]]: f32, %[[ARG1:.+]]: f32, %[[ARG2:.+]]: f32
+//       CHECK:   %[[RETVAL:.+]] = spirv.CompositeConstruct %[[ARG0]], %[[ARG1]], %[[ARG2]] : (f32, f32, f32) -> vector<3xf32>
+//       CHECK:   return %[[RETVAL]]
+func.func @from_elements_3x(%arg0 : f32, %arg1 : f32, %arg2 : f32) -> vector<3xf32> {
+  %0 = vector.from_elements %arg0, %arg1, %arg2 : vector<3xf32>
+  return %0: vector<3xf32>
+}
+
+// -----
+
 // CHECK-LABEL: @insert
 //  CHECK-SAME: %[[V:.*]]: vector<4xf32>, %[[S:.*]]: f32
 //       CHECK:   spirv.CompositeInsert %[[S]], %[[V]][2 : i32] : f32 into vector<4xf32>