[metal-writer] Emit functions

This Cl adds the code to emit functions from the metal writer. Note,
this does not handle entry points yet.

Bug: tint:8
Change-Id: Ie665771169261f6839de5eb1b66dc511bf47616a
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/23704
Reviewed-by: David Neto <dneto@google.com>

BUILD.gn

@@ -885,6 +885,7 @@ source_set("tint_unittests_wgsl_writer_src") {
 
 source_set("tint_unittests_msl_writer_src") {
   sources = [
+    "src/writer/msl/generator_impl_function_test.cc",
     "src/writer/msl/generator_impl_identifier_test.cc",
     "src/writer/msl/generator_impl_return_test.cc",
     "src/writer/msl/generator_impl_test.cc",

src/CMakeLists.txt

@@ -493,6 +493,7 @@ endif()
 
 if(${TINT_BUILD_MSL_WRITER})
   list(APPEND TINT_TEST_SRCS
+    writer/msl/generator_impl_function_test.cc
     writer/msl/generator_impl_identifier_test.cc
     writer/msl/generator_impl_return_test.cc
     writer/msl/generator_impl_test.cc

src/writer/msl/generator_impl.cc

@@ -14,6 +14,7 @@
 
 #include "src/writer/msl/generator_impl.h"
 
+#include "src/ast/function.h"
 #include "src/ast/identifier_expression.h"
 #include "src/ast/return_statement.h"
 #include "src/ast/type/alias_type.h"
@@ -36,7 +37,13 @@ GeneratorImpl::GeneratorImpl() = default;
 
 GeneratorImpl::~GeneratorImpl() = default;
 
-bool GeneratorImpl::Generate(const ast::Module&) {
+bool GeneratorImpl::Generate(const ast::Module& module) {
+  for (const auto& func : module.functions()) {
+    if (!EmitFunction(func.get())) {
+      return false;
+    }
+    out_ << std::endl;
+  }
   return true;
 }
 
@@ -49,6 +56,35 @@ bool GeneratorImpl::EmitExpression(ast::Expression* expr) {
   return false;
 }
 
+bool GeneratorImpl::EmitFunction(ast::Function* func) {
+  make_indent();
+
+  if (!EmitType(func->return_type(), "")) {
+    return false;
+  }
+
+  out_ << " " << func->name() << "(";
+
+  bool first = true;
+  for (const auto& v : func->params()) {
+    if (!first) {
+      out_ << ", ";
+    }
+    first = false;
+
+    if (!EmitType(v->type(), v->name())) {
+      return false;
+    }
+    // Array name is output as part of the type
+    if (!v->type()->IsArray()) {
+      out_ << " " << v->name();
+    }
+  }
+  out_ << ")";
+
+  return EmitStatementBlockAndNewline(func->body());
+}
+
 bool GeneratorImpl::EmitIdentifier(ast::IdentifierExpression* expr) {
   auto* ident = expr->AsIdentifier();
   if (ident->has_path()) {

src/writer/msl/generator_impl.h

@@ -41,6 +41,10 @@ class GeneratorImpl : public TextGenerator {
   /// @param expr the expression
   /// @returns true if the expression was emitted
   bool EmitExpression(ast::Expression* expr);
+  /// Handles generating a function
+  /// @param func the function to generate
+  /// @returns true if the function was emitted
+  bool EmitFunction(ast::Function* func);
   /// Handles generating an identifier expression
   /// @param expr the identifier expression
   /// @returns true if the identifeir was emitted

src/writer/msl/generator_impl_function_test.cc

@@ -0,0 +1,111 @@
+// 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/function.h"
+#include "src/ast/return_statement.h"
+#include "src/ast/type/array_type.h"
+#include "src/ast/type/f32_type.h"
+#include "src/ast/type/i32_type.h"
+#include "src/ast/type/void_type.h"
+#include "src/ast/variable.h"
+#include "src/writer/msl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace msl {
+namespace {
+
+using MslGeneratorImplTest = testing::Test;
+
+TEST_F(MslGeneratorImplTest, Emit_Function) {
+  ast::type::VoidType void_type;
+
+  ast::Function func("my_func", {}, &void_type);
+
+  ast::StatementList body;
+  body.push_back(std::make_unique<ast::ReturnStatement>());
+  func.set_body(std::move(body));
+
+  GeneratorImpl g;
+  g.increment_indent();
+
+  ASSERT_TRUE(g.EmitFunction(&func));
+  EXPECT_EQ(g.result(), R"(  void my_func() {
+    return;
+  }
+)");
+}
+
+TEST_F(MslGeneratorImplTest, Emit_Function_WithParams) {
+  ast::type::F32Type f32;
+  ast::type::I32Type i32;
+
+  ast::VariableList params;
+  params.push_back(
+      std::make_unique<ast::Variable>("a", ast::StorageClass::kNone, &f32));
+  params.push_back(
+      std::make_unique<ast::Variable>("b", ast::StorageClass::kNone, &i32));
+
+  ast::type::VoidType void_type;
+  ast::Function func("my_func", std::move(params), &void_type);
+
+  ast::StatementList body;
+  body.push_back(std::make_unique<ast::ReturnStatement>());
+  func.set_body(std::move(body));
+
+  GeneratorImpl g;
+  g.increment_indent();
+
+  ASSERT_TRUE(g.EmitFunction(&func));
+  EXPECT_EQ(g.result(), R"(  void my_func(float a, int b) {
+    return;
+  }
+)");
+}
+
+TEST_F(MslGeneratorImplTest, Emit_Function_WithArrayParams) {
+  ast::type::F32Type f32;
+  ast::type::ArrayType ary(&f32, 5);
+
+  ast::VariableList params;
+  params.push_back(
+      std::make_unique<ast::Variable>("a", ast::StorageClass::kNone, &ary));
+
+  ast::type::VoidType void_type;
+  auto func =
+      std::make_unique<ast::Function>("my_func", std::move(params), &void_type);
+
+  ast::StatementList body;
+  body.push_back(std::make_unique<ast::ReturnStatement>());
+  func->set_body(std::move(body));
+
+  ast::Module m;
+  m.AddFunction(std::move(func));
+
+  GeneratorImpl g;
+  g.increment_indent();
+
+  ASSERT_TRUE(g.Generate(m)) << g.error();
+  EXPECT_EQ(g.result(), R"(  void my_func(float a[5]) {
+    return;
+  }
+
+)");
+}
+
+}  // namespace
+}  // namespace msl
+}  // namespace writer
+}  // namespace tint