tint/ir: Replace Converter with FromProgram() free function

ToProgram() will most likely be conditionally compiled as a separate .h
and .cc file. With just one static method, ir::Converter doesn't make a
lot of sense to be a class. Just replace with a free-function.

Bug: tint:1902
Change-Id: I305bf9cb73082a94848ec5b94129feabdb9b6fe9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/131620
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/tint/BUILD.gn

@@ -1122,8 +1122,8 @@ libtint_source_set("libtint_ir_builder_src") {
   sources = [
     "ir/builder_impl.cc",
     "ir/builder_impl.h",
-    "ir/converter.cc",
-    "ir/converter.h",
+    "ir/from_program.cc",
+    "ir/from_program.h",
   ]
   deps = [
     ":libtint_ast_src",

src/tint/CMakeLists.txt

@@ -727,14 +727,14 @@ if(${TINT_BUILD_IR})
     ir/construct.h
     ir/convert.cc
     ir/convert.h
-    ir/converter.cc
-    ir/converter.h
     ir/debug.cc
     ir/debug.h
     ir/disassembler.cc
     ir/disassembler.h
     ir/discard.cc
     ir/discard.h
+    ir/from_program.cc
+    ir/from_program.h
     ir/flow_node.cc
     ir/flow_node.h
     ir/function.cc

src/tint/cmd/loopy.cc

@@ -19,7 +19,7 @@
 #include "tint/tint.h"
 
 #if TINT_BUILD_IR
-#include "src/tint/ir/converter.h"
+#include "src/tint/ir/from_program.h"
 #include "src/tint/ir/module.h"
 #endif  // TINT_BUILD_IR
 
@@ -378,7 +378,7 @@ int main(int argc, const char** argv) {
             loop_count = options.loop_count;
         }
         for (uint32_t i = 0; i < loop_count; ++i) {
-            auto result = tint::ir::Converter::FromProgram(program.get());
+            auto result = tint::ir::FromProgram(program.get());
             if (!result) {
                 std::cerr << "Failed to build IR from program: " << result.Failure() << std::endl;
             }

src/tint/cmd/main.cc

@@ -49,9 +49,9 @@
 #include "tint/tint.h"
 
 #if TINT_BUILD_IR
-#include "src/tint/ir/converter.h"     // nogncheck
 #include "src/tint/ir/debug.h"         // nogncheck
 #include "src/tint/ir/disassembler.h"  // nogncheck
+#include "src/tint/ir/from_program.h"  // nogncheck
 #include "src/tint/ir/module.h"        // nogncheck
 #endif                                 // TINT_BUILD_IR
 
@@ -1086,7 +1086,7 @@ int main(int argc, const char** argv) {
 
 #if TINT_BUILD_IR
     if (options.dump_ir || options.dump_ir_graph) {
-        auto result = tint::ir::Converter::FromProgram(program.get());
+        auto result = tint::ir::FromProgram(program.get());
         if (!result) {
             std::cerr << "Failed to build IR from program: " << result.Failure() << std::endl;
         } else {

src/tint/ir/converter.h

@@ -1,54 +0,0 @@
-// Copyright 2023 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_TINT_IR_CONVERTER_H_
-#define SRC_TINT_IR_CONVERTER_H_
-
-#include <string>
-
-#include "src/tint/ir/module.h"
-#include "src/tint/utils/result.h"
-
-// Forward Declarations
-namespace tint {
-class Program;
-}  // namespace tint
-
-namespace tint::ir {
-
-/// Class for converting into and out of IR.
-class Converter {
-  public:
-    /// The result type for the FromProgram method.
-    using Result = utils::Result<Module, std::string>;
-
-    /// Builds an ir::Module from the given Program
-    /// @param program the Program to use.
-    /// @returns the `utiils::Result` of generating the IR. The result will contain the `ir::Module`
-    /// on success, otherwise the `std::string` error.
-    ///
-    /// @note this assumes the program |IsValid|, and has had const-eval done so
-    /// any abstract values have been calculated and converted into the relevant
-    /// concrete types.
-    static Result FromProgram(const Program* program);
-
-    /// Converts the module back to a Program
-    /// @returns the resulting program, or nullptr on error
-    ///  (Note, this will probably turn into a utils::Result, just stubbing for now)
-    static const Program* ToProgram();
-};
-
-}  // namespace tint::ir
-
-#endif  // SRC_TINT_IR_CONVERTER_H_

src/tint/ir/from_program.cc

@@ -12,17 +12,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "src/tint/ir/converter.h"
+#include "src/tint/ir/from_program.h"
 
 #include "src/tint/ir/builder_impl.h"
 #include "src/tint/program.h"
 
 namespace tint::ir {
 
-// static
-Converter::Result Converter::FromProgram(const Program* program) {
+utils::Result<Module, std::string> FromProgram(const Program* program) {
     if (!program->IsValid()) {
-        return Result{std::string("input program is not valid")};
+        return std::string("input program is not valid");
     }
 
     BuilderImpl b(program);
@@ -31,12 +30,7 @@ Converter::Result Converter::FromProgram(const Program* program) {
         return b.Diagnostics().str();
     }
 
-    return Result{r.Move()};
-}
-
-// static
-const Program* Converter::ToProgram() {
-    return nullptr;
+    return r.Move();
 }
 
 }  // namespace tint::ir

src/tint/ir/from_program.h

@@ -0,0 +1,42 @@
+// Copyright 2023 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_TINT_IR_FROM_PROGRAM_H_
+#define SRC_TINT_IR_FROM_PROGRAM_H_
+
+#include <string>
+
+#include "src/tint/ir/module.h"
+#include "src/tint/utils/result.h"
+
+// Forward Declarations
+namespace tint {
+class Program;
+}  // namespace tint
+
+namespace tint::ir {
+
+/// Builds an ir::Module from the given Program
+/// @param program the Program to use.
+/// @returns the `utiils::Result` of generating the IR. The result will contain the `ir::Module` on
+/// success, otherwise the `std::string` error.
+///
+/// @note this assumes the `program.IsValid()`, and has had const-eval done so
+/// any abstract values have been calculated and converted into the relevant
+/// concrete types.
+utils::Result<Module, std::string> FromProgram(const Program* program);
+
+}  // namespace tint::ir
+
+#endif  // SRC_TINT_IR_FROM_PROGRAM_H_

src/tint/writer/spirv/generator.cc

@@ -18,7 +18,7 @@
 
 #include "src/tint/writer/spirv/generator_impl.h"
 #if TINT_BUILD_IR
-#include "src/tint/ir/converter.h"                    // nogncheck
+#include "src/tint/ir/from_program.h"                 // nogncheck
 #include "src/tint/writer/spirv/generator_impl_ir.h"  // nogncheck
 #endif                                                // TINT_BUILD_IR
 
@@ -41,7 +41,7 @@ Result Generate(const Program* program, const Options& options) {
 #if TINT_BUILD_IR
     if (options.use_tint_ir) {
         // Convert the AST program to an IR module.
-        auto ir = ir::Converter::FromProgram(program);
+        auto ir = ir::FromProgram(program);
         if (!ir) {
             result.error = "IR converter: " + ir.Failure();
             return result;