Add Kill, Nop and Fallthrough to WGSL writer

This CL adds the Kill, Nop and Fallthrough statements to the WGSL
writer.

Bug: tint:4
Change-Id: Ic0c635cfa7ca4c3195c593b119f9436ffeb1f9dc
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/17201
Reviewed-by: David Neto <dneto@google.com>

src/CMakeLists.txt

@@ -414,10 +414,13 @@ if(${TINT_BUILD_WGSL_WRITER})
     writer/wgsl/generator_impl_cast_test.cc
     writer/wgsl/generator_impl_continue_test.cc
     writer/wgsl/generator_impl_entry_point_test.cc
+    writer/wgsl/generator_impl_fallthrough_test.cc
     writer/wgsl/generator_impl_identifier_test.cc
     writer/wgsl/generator_impl_import_test.cc
     writer/wgsl/generator_impl_initializer_test.cc
+    writer/wgsl/generator_impl_kill_test.cc
     writer/wgsl/generator_impl_member_accessor_test.cc
+    writer/wgsl/generator_impl_nop_test.cc
     writer/wgsl/generator_impl_relational_test.cc
     writer/wgsl/generator_impl_type_test.cc
     writer/wgsl/generator_impl_unary_derivative_test.cc

src/writer/wgsl/generator_impl.cc

@@ -660,6 +660,15 @@ bool GeneratorImpl::EmitStatement(ast::Statement* stmt) {
   if (stmt->IsContinue()) {
     return EmitContinue(stmt->AsContinue());
   }
+  if (stmt->IsFallthrough()) {
+    return EmitFallthrough(stmt->AsFallthrough());
+  }
+  if (stmt->IsKill()) {
+    return EmitKill(stmt->AsKill());
+  }
+  if (stmt->IsNop()) {
+    return EmitNop(stmt->AsNop());
+  }
 
   error_ = "unknown statement type";
   return false;
@@ -762,6 +771,24 @@ bool GeneratorImpl::EmitContinue(ast::ContinueStatement* stmt) {
   return true;
 }
 
+bool GeneratorImpl::EmitFallthrough(ast::FallthroughStatement*) {
+  make_indent();
+  out_ << "fallthrough;" << std::endl;
+  return true;
+}
+
+bool GeneratorImpl::EmitKill(ast::KillStatement*) {
+  make_indent();
+  out_ << "kill;" << std::endl;
+  return true;
+}
+
+bool GeneratorImpl::EmitNop(ast::NopStatement*) {
+  make_indent();
+  out_ << "nop;" << std::endl;
+  return true;
+}
+
 }  // namespace wgsl
 }  // namespace writer
 }  // namespace tint

src/writer/wgsl/generator_impl.h

@@ -114,6 +114,10 @@ class GeneratorImpl {
   /// @param expr the expression
   /// @returns true if the expression was emitted
   bool EmitExpression(ast::Expression* expr);
+  /// Handles generating a fallthrough statement
+  /// @param stmt the fallthrough statement
+  /// @returns true if the statement was successfully emitted
+  bool EmitFallthrough(ast::FallthroughStatement* stmt);
   /// Handles generating an identifier expression
   /// @param expr the identifier expression
   /// @returns true if the identifeir was emitted
@@ -126,6 +130,10 @@ class GeneratorImpl {
   /// @param expr the initializer expression
   /// @returns true if the expression was emitted
   bool EmitInitializer(ast::InitializerExpression* expr);
+  /// Handles generating a kill statement
+  /// @param stmt the kill statement
+  /// @returns true if the statement was successfully emitted
+  bool EmitKill(ast::KillStatement* stmt);
   /// Handles a literal
   /// @param lit the literal to emit
   /// @returns true if the literal was successfully emitted
@@ -134,6 +142,10 @@ class GeneratorImpl {
   /// @param expr the member accessor expression
   /// @returns true if the member accessor was emitted
   bool EmitMemberAccessor(ast::MemberAccessorExpression* expr);
+  /// Handles generating a nop statement
+  /// @param stmt the nop statement
+  /// @returns true if the statement was successfully emitted
+  bool EmitNop(ast::NopStatement* stmt);
   /// Handles generating a relational expression
   /// @param expr the relational expression
   /// @returns true if the expression was emitted, false otherwise

src/writer/wgsl/generator_impl_fallthrough_test.cc

@@ -0,0 +1,39 @@
+// 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 "gtest/gtest.h"
+#include "src/ast/fallthrough_statement.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, Emit_Fallthrough) {
+  ast::FallthroughStatement f;
+
+  GeneratorImpl g;
+  g.increment_indent();
+
+  ASSERT_TRUE(g.EmitStatement(&f)) << g.error();
+  EXPECT_EQ(g.result(), "  fallthrough;\n");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint

src/writer/wgsl/generator_impl_kill_test.cc

@@ -0,0 +1,39 @@
+// 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 "gtest/gtest.h"
+#include "src/ast/kill_statement.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, Emit_kill) {
+  ast::KillStatement k;
+
+  GeneratorImpl g;
+  g.increment_indent();
+
+  ASSERT_TRUE(g.EmitStatement(&k)) << g.error();
+  EXPECT_EQ(g.result(), "  kill;\n");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint

src/writer/wgsl/generator_impl_nop_test.cc

@@ -0,0 +1,39 @@
+// 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 "gtest/gtest.h"
+#include "src/ast/nop_statement.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, Emit_Nop) {
+  ast::NopStatement n;
+
+  GeneratorImpl g;
+  g.increment_indent();
+
+  ASSERT_TRUE(g.EmitStatement(&n)) << g.error();
+  EXPECT_EQ(g.result(), "  nop;\n");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint