sem: Add atomic type

Bug: tint:892
Change-Id: I4826b71e5911c7f66019a956685675e9504551cf
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/54646
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: James Price <jrprice@google.com>

src/BUILD.gn

@@ -487,6 +487,8 @@ libtint_source_set("libtint_core_all_src") {
     "resolver/resolver.h",
     "scope_stack.h",
     "sem/array.h",
+    "sem/atomic_type.cc",
+    "sem/atomic_type.h",
     "sem/binding_point.h",
     "sem/bool_type.cc",
     "sem/bool_type.h",

src/CMakeLists.txt

@@ -235,6 +235,8 @@ set(TINT_LIB_SRCS
   scope_stack.h
   sem/array.cc
   sem/array.h
+  sem/atomic_type.cc
+  sem/atomic_type.h
   sem/binding_point.h
   sem/block_statement.cc
   sem/block_statement.h
@@ -624,6 +626,7 @@ if(${TINT_BUILD_TESTS})
     symbol_test.cc
     transform/transform_test.cc
     test_main.cc
+    sem/atomic_type_test.cc
     sem/bool_type_test.cc
     sem/depth_texture_type_test.cc
     sem/external_texture_type_test.cc

src/sem/atomic_type.cc

@@ -0,0 +1,46 @@
+// Copyright 2021 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/sem/atomic_type.h"
+
+#include "src/program_builder.h"
+#include "src/sem/reference_type.h"
+
+TINT_INSTANTIATE_TYPEINFO(tint::sem::Atomic);
+
+namespace tint {
+namespace sem {
+
+Atomic::Atomic(const sem::Type* subtype) : subtype_(subtype) {
+  TINT_ASSERT(!subtype->Is<Reference>());
+}
+
+std::string Atomic::type_name() const {
+  std::ostringstream out;
+  out << "__atomic" << subtype_->type_name();
+  return out.str();
+}
+
+std::string Atomic::FriendlyName(const SymbolTable& symbols) const {
+  std::ostringstream out;
+  out << "atomic<" << subtype_->FriendlyName(symbols) << ">";
+  return out.str();
+}
+
+Atomic::Atomic(Atomic&&) = default;
+
+Atomic::~Atomic() = default;
+
+}  // namespace sem
+}  // namespace tint

src/sem/atomic_type.h

@@ -0,0 +1,54 @@
+// Copyright 2021 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_SEM_ATOMIC_TYPE_H_
+#define SRC_SEM_ATOMIC_TYPE_H_
+
+#include <string>
+
+#include "src/sem/type.h"
+
+namespace tint {
+namespace sem {
+
+/// A atomic type.
+class Atomic : public Castable<Atomic, Type> {
+ public:
+  /// Constructor
+  /// @param subtype the atomic type
+  explicit Atomic(const sem::Type* subtype);
+
+  /// Move constructor
+  Atomic(Atomic&&);
+  ~Atomic() override;
+
+  /// @returns the atomic type
+  const sem::Type* Type() const { return subtype_; }
+
+  /// @returns the name for this type
+  std::string type_name() const override;
+
+  /// @param symbols the program's symbol table
+  /// @returns the name for this type that closely resembles how it would be
+  /// declared in WGSL.
+  std::string FriendlyName(const SymbolTable& symbols) const override;
+
+ private:
+  sem::Type const* const subtype_;
+};
+
+}  // namespace sem
+}  // namespace tint
+
+#endif  // SRC_SEM_ATOMIC_TYPE_H_

src/sem/atomic_type_test.cc

@@ -0,0 +1,42 @@
+// Copyright 2021 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/sem/atomic_type.h"
+
+#include "src/sem/test_helper.h"
+
+namespace tint {
+namespace sem {
+namespace {
+
+using AtomicTest = TestHelper;
+
+TEST_F(AtomicTest, Creation) {
+  auto* a = create<Atomic>(create<I32>());
+  EXPECT_TRUE(a->Type()->Is<sem::I32>());
+}
+
+TEST_F(AtomicTest, TypeName) {
+  auto* a = create<Atomic>(create<I32>());
+  EXPECT_EQ(a->type_name(), "__atomic__i32");
+}
+
+TEST_F(AtomicTest, FriendlyName) {
+  auto* a = create<Atomic>(create<I32>());
+  EXPECT_EQ(a->FriendlyName(Symbols()), "atomic<i32>");
+}
+
+}  // namespace
+}  // namespace sem
+}  // namespace tint

test/BUILD.gn

@@ -251,6 +251,7 @@ tint_unittests_source_set("tint_unittests_core_src") {
     "../src/resolver/var_let_test.cc",
     "../src/resolver/var_let_validation_test.cc",
     "../src/scope_stack_test.cc",
+    "../src/sem/atomic_type_test.cc",
     "../src/sem/bool_type_test.cc",
     "../src/sem/depth_texture_type_test.cc",
     "../src/sem/external_texture_type_test.cc",