[hlsl-writer] Scaffold the HLSL backend.

This CL adds the scaffolding for the HLSL backend.

Bug: tint:7
Change-Id: Iaf9f5159bc409f3ac71fcec281229258bdfa021b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/25000
Reviewed-by: David Neto <dneto@google.com>

src/CMakeLists.txt

@@ -260,6 +260,15 @@ if(${TINT_BUILD_MSL_WRITER})
   )
 endif()
 
+if(${TINT_BUILD_HLSL_WRITER})
+  list(APPEND TINT_LIB_SRCS
+    writer/hlsl/generator.cc
+    writer/hlsl/generator.h
+    writer/hlsl/generator_impl.cc
+    writer/hlsl/generator_impl.h
+  )
+endif()
+
 set(TINT_TEST_SRCS
   ast/array_accessor_expression_test.cc
   ast/as_expression_test.cc
@@ -524,6 +533,12 @@ if(${TINT_BUILD_MSL_WRITER})
   )
 endif()
 
+if (${TINT_BUILD_HLSL_WRITER})
+  list(APPEND TINT_TEST_SRCS
+    writer/hlsl/generator_impl_test.cc
+  )
+endif()
+
 add_executable(tint_unittests ${TINT_TEST_SRCS})
 
 if(NOT MSVC)

src/writer/hlsl/generator.cc

@@ -0,0 +1,45 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/writer/hlsl/generator.h"
+
+#include <utility>
+
+namespace tint {
+namespace writer {
+namespace hlsl {
+
+Generator::Generator(ast::Module module) : Text(std::move(module)) {}
+
+Generator::~Generator() = default;
+
+bool Generator::Generate() {
+  auto ret = impl_.Generate(module_);
+  if (!ret) {
+    error_ = impl_.error();
+  }
+  return ret;
+}
+
+std::string Generator::result() const {
+  return impl_.result();
+}
+
+std::string Generator::error() const {
+  return impl_.error();
+}
+
+}  // namespace hlsl
+}  // namespace writer
+}  // namespace tint

src/writer/hlsl/generator.h

@@ -0,0 +1,53 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_WRITER_HLSL_GENERATOR_H_
+#define SRC_WRITER_HLSL_GENERATOR_H_
+
+#include <string>
+
+#include "src/writer/hlsl/generator_impl.h"
+#include "src/writer/text.h"
+
+namespace tint {
+namespace writer {
+namespace hlsl {
+
+/// Class to generate HLSL source
+class Generator : public Text {
+ public:
+  /// Constructor
+  /// @param module the module to convert
+  explicit Generator(ast::Module module);
+  ~Generator() override;
+
+  /// Generates the result data
+  /// @returns true on successful generation; false otherwise
+  bool Generate() override;
+
+  /// @returns the result data
+  std::string result() const override;
+
+  /// @returns the error
+  std::string error() const;
+
+ private:
+  GeneratorImpl impl_;
+};
+
+}  // namespace hlsl
+}  // namespace writer
+}  // namespace tint
+
+#endif  // SRC_WRITER_HLSL_GENERATOR_H_

src/writer/hlsl/generator_impl.cc

@@ -0,0 +1,31 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/writer/hlsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace hlsl {
+
+GeneratorImpl::GeneratorImpl() = default;
+
+GeneratorImpl::~GeneratorImpl() = default;
+
+bool GeneratorImpl::Generate(const ast::Module&) {
+  return true;
+}
+
+}  // namespace hlsl
+}  // namespace writer
+}  // namespace tint

src/writer/hlsl/generator_impl.h

@@ -0,0 +1,42 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_WRITER_HLSL_GENERATOR_IMPL_H_
+#define SRC_WRITER_HLSL_GENERATOR_IMPL_H_
+
+#include "src/ast/module.h"
+#include "src/writer/text_generator.h"
+
+namespace tint {
+namespace writer {
+namespace hlsl {
+
+/// Implementation class for HLSL generator
+class GeneratorImpl : public TextGenerator {
+ public:
+  /// Constructor
+  GeneratorImpl();
+  ~GeneratorImpl();
+
+  /// Generates the result data
+  /// @param module the module to generate
+  /// @returns true on successful generation; false otherwise
+  bool Generate(const ast::Module& module);
+};
+
+}  // namespace hlsl
+}  // namespace writer
+}  // namespace tint
+
+#endif  // SRC_WRITER_HLSL_GENERATOR_IMPL_H_

src/writer/hlsl/generator_impl_test.cc

@@ -0,0 +1,53 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/writer/hlsl/generator_impl.h"
+
+#include <memory>
+
+#include "gtest/gtest.h"
+#include "src/ast/entry_point.h"
+#include "src/ast/function.h"
+#include "src/ast/module.h"
+#include "src/ast/type/void_type.h"
+
+namespace tint {
+namespace writer {
+namespace hlsl {
+namespace {
+
+using HlslGeneratorImplTest = testing::Test;
+
+TEST_F(HlslGeneratorImplTest, DISABLED_Generate) {
+  ast::type::VoidType void_type;
+  ast::Module m;
+  m.AddFunction(std::make_unique<ast::Function>("my_func", ast::VariableList{},
+                                                &void_type));
+  m.AddEntryPoint(std::make_unique<ast::EntryPoint>(
+      ast::PipelineStage::kFragment, "my_func", ""));
+
+  GeneratorImpl g;
+
+  ASSERT_TRUE(g.Generate(m)) << g.error();
+  EXPECT_EQ(g.result(), R"(#import <metal_lib>
+
+void my_func() {
+}
+)");
+}
+
+}  // namespace
+}  // namespace hlsl
+}  // namespace writer
+}  // namespace tint

src/writer/msl/generator.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace writer {
 namespace msl {
 
-/// Class to generate WGSL source from a WGSL module
+/// Class to generate MSL source
 class Generator : public Text {
  public:
   /// Constructor

src/writer/msl/generator_impl.h

@@ -32,7 +32,7 @@ namespace tint {
 namespace writer {
 namespace msl {
 
-/// Implementation class for WGSL generator
+/// Implementation class for MSL generator
 class GeneratorImpl : public TextGenerator {
  public:
   /// Constructor

src/writer/wgsl/generator.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace writer {
 namespace wgsl {
 
-/// Class to generate WGSL source from a WGSL module
+/// Class to generate WGSL source
 class Generator : public Text {
  public:
   /// Constructor