[tint][bench]: Fix MSL benchmarks

These required binding point remapping so that the @group is always zero.

Also: Use a unique_ptr for the file in ProgramAndFile. Previously the diagnostics were referring to the std::moved file, causing segfaults if the benchmark program errors and printed diagnostics.
Change-Id: Id0e41665b97b3fc73a6cdd5848c5f505cd77e805
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/134280
Kokoro: Ben Clayton <bclayton@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/tint/bench/benchmark.cc

@@ -120,8 +120,8 @@ std::variant<ProgramAndFile, Error> LoadProgram(std::string name) {
     if (auto err = std::get_if<bench::Error>(&res)) {
         return *err;
     }
-    auto& file = std::get<Source::File>(res);
+    auto file = std::make_unique<Source::File>(std::move(std::get<Source::File>(res)));
-    auto program = reader::wgsl::Parse(&file);
+    auto program = reader::wgsl::Parse(file.get());
     if (program.Diagnostics().contains_errors()) {
         return Error{program.Diagnostics().str()};
     }

src/tint/bench/benchmark.h

@@ -36,7 +36,7 @@ struct ProgramAndFile {
     /// The tint program parsed from file.
     Program program;
     /// The source file
-    Source::File file;
+    std::unique_ptr<Source::File> file;
 };
 
 /// LoadInputFile attempts to load a benchmark input file with the given file

src/tint/writer/msl/generator_bench.cc

@@ -14,7 +14,9 @@
 
 #include <string>
 
+#include "src/tint/ast/module.h"
 #include "src/tint/bench/benchmark.h"
+#include "src/tint/sem/variable.h"
 
 namespace tint::writer::msl {
 namespace {
@@ -26,7 +28,7 @@ void GenerateMSL(benchmark::State& state, std::string input_name) {
         return;
     }
     auto& program = std::get<bench::ProgramAndFile>(res).program;
-    for (auto _ : state) {
+
     tint::writer::msl::Options gen_options = {};
     gen_options.array_length_from_uniform.ubo_binding = tint::writer::BindingPoint{0, 30};
     gen_options.array_length_from_uniform.bindpoint_to_size_index.emplace(
@@ -46,6 +48,18 @@ void GenerateMSL(benchmark::State& state, std::string input_name) {
     gen_options.array_length_from_uniform.bindpoint_to_size_index.emplace(
         tint::writer::BindingPoint{0, 7}, 7);
 
+    uint32_t next_binding_point = 0;
+    for (auto* var : program.AST().GlobalVariables()) {
+        if (auto* var_sem = program.Sem().Get(var)->As<sem::GlobalVariable>()) {
+            if (auto bp = var_sem->BindingPoint()) {
+                gen_options.binding_remapper_options.binding_points[*bp] = sem::BindingPoint{
+                    0,                     // group
+                    next_binding_point++,  // binding
+                };
+            }
+        }
+    }
+    for (auto _ : state) {
         auto res = Generate(&program, gen_options);
         if (!res.error.empty()) {
             state.SkipWithError(res.error.c_str());