Add transform to substitute overrides with const expressions.

This CL adds a SubstituteOverride transform which will convert
an `override` into a `const`. The transform is provided a map of
(string, double) which matches what the WebGPU API accepts as
data for overrides.

Bug: tint:1582
Change-Id: I6e6bf51b98ce4d4746f8de55128666c36735e585
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/96760
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

include/tint/tint.h

@@ -31,6 +31,7 @@
 #include "src/tint/transform/renamer.h"
 #include "src/tint/transform/robustness.h"
 #include "src/tint/transform/single_entry_point.h"
+#include "src/tint/transform/substitute_override.h"
 #include "src/tint/transform/vertex_pulling.h"
 #include "src/tint/writer/flatten_bindings.h"
 #include "src/tint/writer/writer.h"

src/tint/BUILD.gn

@@ -287,9 +287,9 @@ libtint_source_set("libtint_core_all_src") {
     "ast/module.h",
     "ast/multisampled_texture.cc",
     "ast/multisampled_texture.h",
-    "ast/node_id.h",
     "ast/node.cc",
     "ast/node.h",
+    "ast/node_id.h",
     "ast/override.cc",
     "ast/override.h",
     "ast/parameter.cc",
@@ -529,6 +529,8 @@ libtint_source_set("libtint_core_all_src") {
     "transform/single_entry_point.h",
     "transform/spirv_atomic.cc",
     "transform/spirv_atomic.h",
+    "transform/substitute_override.cc",
+    "transform/substitute_override.h",
     "transform/transform.cc",
     "transform/transform.h",
     "transform/unshadow.cc",
@@ -1034,6 +1036,7 @@ if (tint_build_unittests) {
       "ast/module_clone_test.cc",
       "ast/module_test.cc",
       "ast/multisampled_texture_test.cc",
+      "ast/override_test.cc",
       "ast/phony_expression_test.cc",
       "ast/pointer_test.cc",
       "ast/return_statement_test.cc",
@@ -1197,6 +1200,7 @@ if (tint_build_unittests) {
       "transform/simplify_pointers_test.cc",
       "transform/single_entry_point_test.cc",
       "transform/spirv_atomic_test.cc",
+      "transform/substitute_override_test.cc",
       "transform/test_helper.h",
       "transform/transform_test.cc",
       "transform/unshadow_test.cc",

src/tint/CMakeLists.txt

@@ -441,6 +441,8 @@ set(TINT_LIB_SRCS
   transform/single_entry_point.h
   transform/spirv_atomic.cc
   transform/spirv_atomic.h
+  transform/substitute_override.cc
+  transform/substitute_override.h
   transform/transform.cc
   transform/transform.h
   transform/unshadow.cc
@@ -730,6 +732,7 @@ if(TINT_BUILD_TESTS)
     ast/module_clone_test.cc
     ast/module_test.cc
     ast/multisampled_texture_test.cc
+    ast/override_test.cc
     ast/phony_expression_test.cc
     ast/pointer_test.cc
     ast/return_statement_test.cc
@@ -1109,6 +1112,7 @@ if(TINT_BUILD_TESTS)
       transform/simplify_pointers_test.cc
       transform/single_entry_point_test.cc
       transform/spirv_atomic_test.cc
+      transform/substitute_override_test.cc
       transform/test_helper.h
       transform/unshadow_test.cc
       transform/unwind_discard_functions_test.cc

src/tint/ast/override.cc

@@ -46,4 +46,11 @@ const Override* Override::Clone(CloneContext* ctx) const {
     return ctx->dst->create<Override>(src, sym, ty, ctor, attrs);
 }
 
+std::string Override::Identifier(const SymbolTable& symbols) const {
+    if (auto* id = ast::GetAttribute<ast::IdAttribute>(attributes)) {
+        return std::to_string(id->value);
+    }
+    return symbols.NameFor(symbol);
+}
+
 }  // namespace tint::ast

src/tint/ast/override.h

@@ -15,6 +15,8 @@
 #ifndef SRC_TINT_AST_OVERRIDE_H_
 #define SRC_TINT_AST_OVERRIDE_H_
 
+#include <string>
+
 #include "src/tint/ast/variable.h"
 
 namespace tint::ast {
@@ -60,6 +62,12 @@ class Override final : public Castable<Override, Variable> {
     /// @param ctx the clone context
     /// @return the newly cloned node
     const Override* Clone(CloneContext* ctx) const override;
+
+    /// @param symbols the symbol table to retrieve the name from
+    /// @returns the identifier string for the override. If the override has
+    /// an ID attribute, the string is the id-stringified. Otherwise, the ID
+    /// is the symbol.
+    std::string Identifier(const SymbolTable& symbols) const;
 };
 
 }  // namespace tint::ast

src/tint/ast/override_test.cc

@@ -0,0 +1,35 @@
+// Copyright 2022 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/tint/ast/override.h"
+
+#include "src/tint/ast/test_helper.h"
+
+namespace tint::ast {
+namespace {
+
+using OverrideTest = TestHelper;
+
+TEST_F(OverrideTest, Identifier_NoId) {
+    auto* o = Override("o", nullptr, Expr(f32(1.0)));
+    EXPECT_EQ(std::string("o"), o->Identifier(Symbols()));
+}
+
+TEST_F(OverrideTest, Identifier_WithId) {
+    auto* o = Override("o", nullptr, Expr(f32(1.0)), {Id(4u)});
+    EXPECT_EQ(std::string("4"), o->Identifier(Symbols()));
+}
+
+}  // namespace
+}  // namespace tint::ast

src/tint/cmd/main.cc

@@ -20,6 +20,7 @@
 #include <optional>
 #include <sstream>
 #include <string>
+#include <unordered_map>
 #include <vector>
 
 #if TINT_BUILD_GLSL_WRITER
@@ -86,7 +87,7 @@ struct Options {
     bool use_fxc = false;
     std::string dxc_path;
     std::string xcrun_path;
-    std::vector<std::string> overrides;
+    std::unordered_map<std::string, double> overrides;
     std::optional<tint::sem::BindingPoint> hlsl_root_constant_binding_point;
 };
 
@@ -126,7 +127,8 @@ ${transforms}
                                When specified, automatically enables --validate
   --xcrun                   -- Path to xcrun executable, used to validate MSL output.
                                When specified, automatically enables --validate
-  --overrides               -- Pipeline overrides as NAME=VALUE, comma-separated.)";
+  --overrides               -- Override values as IDENTIFIER=VALUE, comma-separated.
+)";
 
 Format parse_format(const std::string& fmt) {
     (void)fmt;
@@ -215,18 +217,26 @@ Format infer_format(const std::string& filename) {
     return Format::kNone;
 }
 
-std::vector<std::string> split_on_comma(std::string list) {
+std::vector<std::string> split_on_char(std::string list, char c) {
     std::vector<std::string> res;
 
     std::stringstream str(list);
     while (str.good()) {
         std::string substr;
-        getline(str, substr, ',');
+        getline(str, substr, c);
         res.push_back(substr);
     }
     return res;
 }
 
+std::vector<std::string> split_on_comma(std::string list) {
+    return split_on_char(list, ',');
+}
+
+std::vector<std::string> split_on_equal(std::string list) {
+    return split_on_char(list, '=');
+}
+
 std::optional<uint64_t> parse_unsigned_number(std::string number) {
     for (char c : number) {
         if (!std::isdigit(c)) {
@@ -429,7 +439,10 @@ bool ParseArgs(const std::vector<std::string>& args, Options* opts) {
                 std::cerr << "Missing value for " << arg << std::endl;
                 return false;
             }
-            opts->overrides = split_on_comma(args[i]);
+            for (const auto& o : split_on_comma(args[i])) {
+                auto parts = split_on_equal(o);
+                opts->overrides.insert({parts[0], std::stod(parts[1])});
+            }
         } else if (arg == "--hlsl-root-constant-binding-point") {
             ++i;
             if (i >= args.size()) {
@@ -792,7 +805,7 @@ bool GenerateHlsl(const tint::Program* program, const Options& options) {
         tint::val::Result res;
         if (options.use_fxc) {
 #ifdef _WIN32
-            res = tint::val::HlslUsingFXC(result.hlsl, result.entry_points, options.overrides);
+            res = tint::val::HlslUsingFXC(result.hlsl, result.entry_points);
 #else
             res.failed = true;
             res.output = "FXC can only be used on Windows. Sorry :X";
@@ -801,8 +814,7 @@ bool GenerateHlsl(const tint::Program* program, const Options& options) {
             auto dxc =
                 tint::utils::Command::LookPath(options.dxc_path.empty() ? "dxc" : options.dxc_path);
             if (dxc.Found()) {
-                res = tint::val::HlslUsingDXC(dxc.Path(), result.hlsl, result.entry_points,
+                res = tint::val::HlslUsingDXC(dxc.Path(), result.hlsl, result.entry_points);
-                                              options.overrides);
             } else {
                 res.failed = true;
                 res.output = "DXC executable not found. Cannot validate";
@@ -947,6 +959,14 @@ int main(int argc, const char** argv) {
                        tint::transform::DataMap&) { m.Add<tint::transform::Renamer>(); }},
         {"robustness", [](tint::transform::Manager& m,
                           tint::transform::DataMap&) { m.Add<tint::transform::Robustness>(); }},
+        {"substitute_override",
+         [&](tint::transform::Manager& m, tint::transform::DataMap& i) {
+             tint::transform::SubstituteOverride::Config cfg;
+             cfg.map = options.overrides;
+
+             i.Add<tint::transform::SubstituteOverride::Config>(cfg);
+             m.Add<tint::transform::SubstituteOverride>();
+         }},
     };
     auto transform_names = [&] {
         std::stringstream names;
@@ -1078,6 +1098,17 @@ int main(int argc, const char** argv) {
 
     tint::transform::Manager transform_manager;
     tint::transform::DataMap transform_inputs;
+
+    // If overrides are provided, add the SubstituteOverride transform.
+    if (!options.overrides.empty()) {
+        for (auto& t : transforms) {
+            if (t.name == std::string("substitute_override")) {
+                t.make(transform_manager, transform_inputs);
+                break;
+            }
+        }
+    }
+
     for (const auto& name : options.transforms) {
         // TODO(dsinclair): The vertex pulling transform requires setup code to
         // be run that needs user input. Should we find a way to support that here

src/tint/transform/substitute_override.cc

@@ -0,0 +1,96 @@
+// Copyright 2022 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/tint/transform/substitute_override.h"
+
+#include <functional>
+
+#include "src/tint/program_builder.h"
+#include "src/tint/sem/variable.h"
+
+TINT_INSTANTIATE_TYPEINFO(tint::transform::SubstituteOverride);
+TINT_INSTANTIATE_TYPEINFO(tint::transform::SubstituteOverride::Config);
+
+namespace tint::transform {
+
+SubstituteOverride::SubstituteOverride() = default;
+
+SubstituteOverride::~SubstituteOverride() = default;
+
+bool SubstituteOverride::ShouldRun(const Program* program, const DataMap&) const {
+    for (auto* node : program->AST().GlobalVariables()) {
+        if (node->Is<ast::Override>()) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void SubstituteOverride::Run(CloneContext& ctx, const DataMap& config, DataMap&) const {
+    const auto* data = config.Get<Config>();
+    if (!data) {
+        ctx.dst->Diagnostics().add_error(diag::System::Transform,
+                                         "Missing override substitution data");
+        return;
+    }
+
+    ctx.ReplaceAll([&](const ast::Override* w) -> const ast::Const* {
+        auto ident = w->Identifier(ctx.src->Symbols());
+
+        auto src = ctx.Clone(w->source);
+        auto sym = ctx.Clone(w->symbol);
+        auto* ty = ctx.Clone(w->type);
+
+        // No replacement provided, just clone the override node as a const.
+        auto iter = data->map.find(ident);
+        if (iter == data->map.end()) {
+            if (!w->constructor) {
+                ctx.dst->Diagnostics().add_error(
+                    diag::System::Transform,
+                    "Initializer not provided for override, and override not overridden.");
+                return nullptr;
+            }
+            return ctx.dst->Const(src, sym, ty, ctx.Clone(w->constructor));
+        }
+
+        auto value = iter->second;
+        auto* ctor = Switch(
+            ctx.src->Sem().Get(w)->Type(),
+            [&](const sem::Bool*) { return ctx.dst->Expr(!std::equal_to<double>()(value, 0.0)); },
+            [&](const sem::I32*) { return ctx.dst->Expr(i32(value)); },
+            [&](const sem::U32*) { return ctx.dst->Expr(u32(value)); },
+            [&](const sem::F32*) { return ctx.dst->Expr(f32(value)); },
+            [&](const sem::F16*) { return ctx.dst->Expr(f16(value)); });
+
+        if (!ctor) {
+            ctx.dst->Diagnostics().add_error(diag::System::Transform,
+                                             "Failed to create override expression");
+            return nullptr;
+        }
+
+        return ctx.dst->Const(src, sym, ty, ctor);
+    });
+
+    ctx.Clone();
+}
+
+SubstituteOverride::Config::Config() = default;
+
+SubstituteOverride::Config::Config(const Config&) = default;
+
+SubstituteOverride::Config::~Config() = default;
+
+SubstituteOverride::Config& SubstituteOverride::Config::operator=(const Config&) = default;
+
+}  // namespace tint::transform

src/tint/transform/substitute_override.h

@@ -0,0 +1,89 @@
+// Copyright 2022 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_TRANSFORM_SUBSTITUTE_OVERRIDE_H_
+#define SRC_TINT_TRANSFORM_SUBSTITUTE_OVERRIDE_H_
+
+#include <string>
+#include <unordered_map>
+
+#include "src/tint/transform/transform.h"
+
+namespace tint::transform {
+
+/// A transform that replaces overrides with the constant values provided.
+///
+/// # Example
+/// ```
+/// override width: f32;
+/// @id(1) override height: i32 = 4;
+/// override depth = 1i;
+/// ```
+///
+/// When transformed with `width` -> 1, `1` -> 22, `depth` -> 42
+///
+/// ```
+/// const width: f32 = 1f;
+/// const height: i32 = 22i;
+/// const depth = 42i;
+/// ```
+///
+/// @see crbug.com/tint/1582
+class SubstituteOverride final : public Castable<SubstituteOverride, Transform> {
+  public:
+    /// Configuration options for the transform
+    struct Config final : public Castable<Config, Data> {
+        /// Constructor
+        Config();
+
+        /// Copy constructor
+        Config(const Config&);
+
+        /// Destructor
+        ~Config() override;
+
+        /// Assignment operator
+        /// @returns this Config
+        Config& operator=(const Config&);
+
+        /// The map of override name (either the identifier or id) to value.
+        /// The value is always a double coming into the transform and will be
+        /// converted to the correct type through and initializer.
+        std::unordered_map<std::string, double> map;
+    };
+
+    /// Constructor
+    SubstituteOverride();
+
+    /// Destructor
+    ~SubstituteOverride() override;
+
+    /// @param program the program to inspect
+    /// @param data optional extra transform-specific input data
+    /// @returns true if this transform should be run for the given program
+    bool ShouldRun(const Program* program, const DataMap& data = {}) const override;
+
+  protected:
+    /// Runs the transform using the CloneContext built for transforming a
+    /// program. Run() is responsible for calling Clone() on the CloneContext.
+    /// @param ctx the CloneContext primed with the input program and
+    /// ProgramBuilder
+    /// @param inputs optional extra transform-specific input data
+    /// @param outputs optional extra transform-specific output data
+    void Run(CloneContext& ctx, const DataMap& inputs, DataMap& outputs) const override;
+};
+
+}  // namespace tint::transform
+
+#endif  // SRC_TINT_TRANSFORM_SUBSTITUTE_OVERRIDE_H_

src/tint/transform/substitute_override_test.cc

@@ -0,0 +1,243 @@
+// Copyright 2022 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/tint/transform/substitute_override.h"
+
+#include "src/tint/transform/test_helper.h"
+
+namespace tint::transform {
+namespace {
+
+using SubstituteOverrideTest = TransformTest;
+
+TEST_F(SubstituteOverrideTest, Error_NoData) {
+    auto* src = R"(
+override width: i32;
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    auto* expect = "error: Missing override substitution data";
+
+    DataMap data;
+    auto got = Run<SubstituteOverride>(src, data);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(SubstituteOverrideTest, Error_NoOverrideValue) {
+    auto* src = R"(
+override width: i32;
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    auto* expect = "error: Initializer not provided for override, and override not overridden.";
+
+    SubstituteOverride::Config cfg;
+    DataMap data;
+    data.Add<SubstituteOverride::Config>(cfg);
+
+    auto got = Run<SubstituteOverride>(src, data);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(SubstituteOverrideTest, Module_NoOverrides) {
+    auto* src = R"(
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    auto* expect = R"(
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    SubstituteOverride::Config cfg;
+
+    DataMap data;
+    data.Add<SubstituteOverride::Config>(cfg);
+    auto got = Run<SubstituteOverride>(src, data);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(SubstituteOverrideTest, Identifier) {
+    auto* src = R"(
+override i_width: i32;
+override i_height = 1i;
+
+override f_width: f32;
+override f_height = 1.f;
+
+// TODO(crbug.com/tint/1473)
+// override h_width: f16;
+// override h_height = 1.h;
+
+override b_width: bool;
+override b_height = true;
+
+override o_width = 2i;
+
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    auto* expect = R"(
+const i_width : i32 = 42i;
+
+const i_height = 11i;
+
+const f_width : f32 = 22.299999237f;
+
+const f_height = 12.399999619f;
+
+const b_width : bool = true;
+
+const b_height = false;
+
+const o_width = 2i;
+
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    SubstituteOverride::Config cfg;
+    cfg.map.insert({"i_width", 42.0});
+    cfg.map.insert({"i_height", 11.0});
+    cfg.map.insert({"f_width", 22.3});
+    cfg.map.insert({"f_height", 12.4});
+    cfg.map.insert({"h_width", 9.4});
+    cfg.map.insert({"h_height", 3.4});
+    cfg.map.insert({"b_width", 1.0});
+    cfg.map.insert({"b_height", 0.0});
+
+    DataMap data;
+    data.Add<SubstituteOverride::Config>(cfg);
+    auto got = Run<SubstituteOverride>(src, data);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(SubstituteOverrideTest, Id) {
+    auto* src = R"(
+enable f16;
+
+@id(0) override i_width: i32;
+@id(10) override i_height = 1i;
+
+@id(1) override f_width: f32;
+@id(9) override f_height = 1.f;
+
+// TODO(crbug.com/tint/1473)
+// @id(2) override h_width: f16;
+// @id(8) override h_height = 1.h;
+
+@id(3) override b_width: bool;
+@id(7) override b_height = true;
+
+@id(5) override o_width = 2i;
+
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    auto* expect = R"(
+enable f16;
+
+const i_width : i32 = 42i;
+
+const i_height = 11i;
+
+const f_width : f32 = 22.299999237f;
+
+const f_height = 12.399999619f;
+
+const b_width : bool = true;
+
+const b_height = false;
+
+const o_width = 2i;
+
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    SubstituteOverride::Config cfg;
+    cfg.map.insert({"0", 42.0});
+    cfg.map.insert({"10", 11.0});
+    cfg.map.insert({"1", 22.3});
+    cfg.map.insert({"9", 12.4});
+    cfg.map.insert({"2", 9.4});
+    cfg.map.insert({"8", 3.4});
+    cfg.map.insert({"3", 1.0});
+    cfg.map.insert({"7", 0.0});
+    // No effect because an @id is set for o_width
+    cfg.map.insert({"o_width", 13});
+
+    DataMap data;
+    data.Add<SubstituteOverride::Config>(cfg);
+    auto got = Run<SubstituteOverride>(src, data);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(SubstituteOverrideTest, Identifier_Expression) {
+    auto* src = R"(
+override i_height = ~2i;
+
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    auto* expect = R"(
+const i_height = 11i;
+
+@vertex
+fn main() -> @builtin(position) vec4<f32> {
+  return vec4<f32>();
+}
+)";
+
+    SubstituteOverride::Config cfg;
+    cfg.map.insert({"i_height", 11.0});
+
+    DataMap data;
+    data.Add<SubstituteOverride::Config>(cfg);
+    auto got = Run<SubstituteOverride>(src, data);
+
+    EXPECT_EQ(expect, str(got));
+}
+
+}  // namespace
+}  // namespace tint::transform

src/tint/val/hlsl.cc

@@ -30,8 +30,7 @@ namespace tint::val {
 
 Result HlslUsingDXC(const std::string& dxc_path,
                     const std::string& source,
-                    const EntryPointList& entry_points,
+                    const EntryPointList& entry_points) {
-                    const std::vector<std::string>& overrides) {
     Result result;
 
     auto dxc = utils::Command(dxc_path);
@@ -70,13 +69,7 @@ Result HlslUsingDXC(const std::string& dxc_path,
             "/Zpr "  // D3DCOMPILE_PACK_MATRIX_ROW_MAJOR
             "/Gis";  // D3DCOMPILE_IEEE_STRICTNESS
 
-        std::string defs;
+        auto res = dxc(profile, "-E " + ep.first, compileFlags, file.Path());
-        defs.reserve(overrides.size() * 20);
-        for (auto& o : overrides) {
-            defs += "/D" + o + " ";
-        }
-
-        auto res = dxc(profile, "-E " + ep.first, compileFlags, file.Path(), defs);
         if (!res.out.empty()) {
             if (!result.output.empty()) {
                 result.output += "\n";
@@ -102,9 +95,7 @@ Result HlslUsingDXC(const std::string& dxc_path,
 }
 
 #ifdef _WIN32
-Result HlslUsingFXC(const std::string& source,
+Result HlslUsingFXC(const std::string& source, const EntryPointList& entry_points) {
-                    const EntryPointList& entry_points,
-                    const std::vector<std::string>& overrides) {
     Result result;
 
     // This library leaks if an error happens in this function, but it is ok
@@ -148,26 +139,12 @@ Result HlslUsingFXC(const std::string& source,
         UINT compileFlags = D3DCOMPILE_OPTIMIZATION_LEVEL0 | D3DCOMPILE_PACK_MATRIX_ROW_MAJOR |
                             D3DCOMPILE_IEEE_STRICTNESS;
 
-        auto overrides_copy = overrides;  // Copy so that we can replace '=' with '\0'
-        std::vector<D3D_SHADER_MACRO> macros;
-        macros.reserve(overrides_copy.size() * 2);
-        for (auto& o : overrides_copy) {
-            if (auto sep = o.find_first_of('='); sep != std::string::npos) {
-                // Replace '=' with '\0' so we can point directly into the allocated string buffer
-                o[sep] = '\0';
-                macros.push_back(D3D_SHADER_MACRO{&o[0], &o[sep + 1]});
-            } else {
-                macros.emplace_back(D3D_SHADER_MACRO{o.c_str(), NULL});
-            }
-        }
-        macros.emplace_back(D3D_SHADER_MACRO{NULL, NULL});
-
         ComPtr<ID3DBlob> compiledShader;
         ComPtr<ID3DBlob> errors;
         HRESULT cr = d3dCompile(source.c_str(),    // pSrcData
                                 source.length(),   // SrcDataSize
                                 nullptr,           // pSourceName
-                                macros.data(),     // pDefines
+                                nullptr,           // pDefines
                                 nullptr,           // pInclude
                                 ep.first.c_str(),  // pEntrypoint
                                 profile,           // pTarget

src/tint/val/val.h

@@ -43,23 +43,18 @@ struct Result {
 /// @param dxc_path path to DXC
 /// @param source the generated HLSL source
 /// @param entry_points the list of entry points to validate
-/// @param overrides optional list of pipeline overrides
 /// @return the result of the compile
 Result HlslUsingDXC(const std::string& dxc_path,
                     const std::string& source,
-                    const EntryPointList& entry_points,
+                    const EntryPointList& entry_points);
-                    const std::vector<std::string>& overrides);
 
 #ifdef _WIN32
 /// Hlsl attempts to compile the shader with FXC, verifying that the shader
 /// compiles successfully.
 /// @param source the generated HLSL source
 /// @param entry_points the list of entry points to validate
-/// @param overrides optional list of pipeline overrides
 /// @return the result of the compile
-Result HlslUsingFXC(const std::string& source,
+Result HlslUsingFXC(const std::string& source, const EntryPointList& entry_points);
-                    const EntryPointList& entry_points,
-                    const std::vector<std::string>& overrides);
 #endif  // _WIN32
 
 /// Msl attempts to compile the shader with the Metal Shader Compiler,

test/tint/var/override/named/no_init/bool.wgsl

@@ -1,7 +1,10 @@
-// flags: --overrides WGSL_SPEC_CONSTANT_0=0
+// flags: --overrides o=0,j=1
 override o : bool;
+override j : bool;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o && j {
+        _ = 1;
+    }
 }

test/tint/var/override/named/no_init/bool.wgsl.expected.glsl

@@ -1,12 +1,12 @@
-SKIP: FAILED
-
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-const bool o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  bool tint_tmp = false;
+  if (tint_tmp) {
+    tint_tmp = true;
+  }
+  if ((tint_tmp)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
@@ -14,11 +14,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: '#error' : spec constant required for constant id 0  
-ERROR: 0:5: '' : missing #endif 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/var/override/named/no_init/bool.wgsl.expected.hlsl

@@ -1,9 +1,10 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-static const bool o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  bool tint_tmp = false;
+  if (tint_tmp) {
+    tint_tmp = true;
+  }
+  if ((tint_tmp)) {
+  }
   return;
 }

test/tint/var/override/named/no_init/bool.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant bool o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((false && true)) {
+  }
   return;
 }
 

test/tint/var/override/named/no_init/bool.wgsl.expected.spvasm

@@ -1,20 +1,30 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 13
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-       %bool = OpTypeBool
-          %o = OpSpecConstantFalse %bool
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+       %bool = OpTypeBool
-          %6 = OpLabel
+          %6 = OpConstantNull %bool
+       %true = OpConstantTrue %bool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+               OpSelectionMerge %7 None
+               OpBranchConditional %6 %8 %7
+          %8 = OpLabel
+               OpBranch %7
+          %7 = OpLabel
+         %10 = OpPhi %bool %6 %4 %true %8
+               OpSelectionMerge %11 None
+               OpBranchConditional %10 %12 %11
+         %12 = OpLabel
+               OpBranch %11
+         %11 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/no_init/bool.wgsl.expected.wgsl

@@ -1,6 +1,10 @@
-override o : bool;
+const o : bool = false;
+
+const j : bool = true;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o && j)) {
+    _ = 1;
+  }
 }

test/tint/var/override/named/no_init/f32.wgsl

@@ -1,7 +1,9 @@
-// flags: --overrides WGSL_SPEC_CONSTANT_0=0
+// flags: --overrides o=0
 override o : f32;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 0.0 {
+        _ = 1;
+    }
 }

test/tint/var/override/named/no_init/f32.wgsl.expected.glsl

@@ -1,12 +1,8 @@
-SKIP: FAILED
-
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-const float o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
@@ -14,11 +10,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: '#error' : spec constant required for constant id 0  
-ERROR: 0:5: '' : missing #endif 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/var/override/named/no_init/f32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-static const float o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }

test/tint/var/override/named/no_init/f32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant float o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }
 

test/tint/var/override/named/no_init/f32.wgsl.expected.spvasm

@@ -1,20 +1,25 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 11
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-      %float = OpTypeFloat 32
-          %o = OpSpecConstant %float 0
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+      %float = OpTypeFloat 32
-          %6 = OpLabel
+          %6 = OpConstantNull %float
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %7 = OpFOrdEqual %bool %6 %6
+               OpSelectionMerge %9 None
+               OpBranchConditional %7 %10 %9
+         %10 = OpLabel
+               OpBranch %9
+          %9 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/no_init/f32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : f32;
+const o : f32 = 0.0f;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 0.0)) {
+    _ = 1;
+  }
 }

test/tint/var/override/named/no_init/i32.wgsl

@@ -1,7 +1,9 @@
-// flags: --overrides WGSL_SPEC_CONSTANT_0=0
+// flags: --overrides o=0
 override o : i32;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 1 {
+        _ = o;
+    }
 }

test/tint/var/override/named/no_init/i32.wgsl.expected.glsl

@@ -1,12 +1,8 @@
-SKIP: FAILED
-
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-const int o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0 == 1)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
@@ -14,11 +10,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: '#error' : spec constant required for constant id 0  
-ERROR: 0:5: '' : missing #endif 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/var/override/named/no_init/i32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-static const int o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0 == 1)) {
+  }
   return;
 }

test/tint/var/override/named/no_init/i32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant int o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0 == 1)) {
+  }
   return;
 }
 

test/tint/var/override/named/no_init/i32.wgsl.expected.spvasm

@@ -1,20 +1,26 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-        %int = OpTypeInt 32 1
-          %o = OpSpecConstant %int 0
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+        %int = OpTypeInt 32 1
-          %6 = OpLabel
+          %6 = OpConstantNull %int
+      %int_1 = OpConstant %int 1
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %8 = OpIEqual %bool %6 %int_1
+               OpSelectionMerge %10 None
+               OpBranchConditional %8 %11 %10
+         %11 = OpLabel
+               OpBranch %10
+         %10 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/no_init/i32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : i32;
+const o : i32 = 0i;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 1)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/no_init/u32.wgsl

@@ -1,7 +1,9 @@
-// flags: --overrides WGSL_SPEC_CONSTANT_0=0
+// flags: --overrides o=0
 override o : u32;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 1 {
+        _ = o;
+    }
 }

test/tint/var/override/named/no_init/u32.wgsl.expected.glsl

@@ -1,12 +1,8 @@
-SKIP: FAILED
-
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-const uint o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0u == 1u)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
@@ -14,11 +10,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: '#error' : spec constant required for constant id 0  
-ERROR: 0:5: '' : missing #endif 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/var/override/named/no_init/u32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#error spec constant required for constant id 0
-#endif
-static const uint o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0u == 1u)) {
+  }
   return;
 }

test/tint/var/override/named/no_init/u32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant uint o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0u == 1u)) {
+  }
   return;
 }
 

test/tint/var/override/named/no_init/u32.wgsl.expected.spvasm

@@ -1,20 +1,26 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-       %uint = OpTypeInt 32 0
-          %o = OpSpecConstant %uint 0
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+       %uint = OpTypeInt 32 0
-          %6 = OpLabel
+          %6 = OpConstantNull %uint
+     %uint_1 = OpConstant %uint 1
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %8 = OpIEqual %bool %6 %uint_1
+               OpSelectionMerge %10 None
+               OpBranchConditional %8 %11 %10
+         %11 = OpLabel
+               OpBranch %10
+         %10 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/no_init/u32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : u32;
+const o : u32 = 0u;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 1)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/val_init/bool.wgsl

@@ -1,6 +1,10 @@
+// flags: --overrides o=0,j=1
 override o : bool = true;
+override j : bool = false;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o && j {
+        _ = o;
+    }
 }

test/tint/var/override/named/val_init/bool.wgsl.expected.glsl

@@ -1,10 +1,12 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 true
-#endif
-const bool o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  bool tint_tmp = false;
+  if (tint_tmp) {
+    tint_tmp = true;
+  }
+  if ((tint_tmp)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/val_init/bool.wgsl.expected.hlsl

@@ -1,9 +1,10 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 true
-#endif
-static const bool o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  bool tint_tmp = false;
+  if (tint_tmp) {
+    tint_tmp = true;
+  }
+  if ((tint_tmp)) {
+  }
   return;
 }

test/tint/var/override/named/val_init/bool.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant bool o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((false && true)) {
+  }
   return;
 }
 

test/tint/var/override/named/val_init/bool.wgsl.expected.spvasm

@@ -1,20 +1,30 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 13
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-       %bool = OpTypeBool
-          %o = OpSpecConstantTrue %bool
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+       %bool = OpTypeBool
-          %6 = OpLabel
+          %6 = OpConstantNull %bool
+       %true = OpConstantTrue %bool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+               OpSelectionMerge %7 None
+               OpBranchConditional %6 %8 %7
+          %8 = OpLabel
+               OpBranch %7
+          %7 = OpLabel
+         %10 = OpPhi %bool %6 %4 %true %8
+               OpSelectionMerge %11 None
+               OpBranchConditional %10 %12 %11
+         %12 = OpLabel
+               OpBranch %11
+         %11 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/val_init/bool.wgsl.expected.wgsl

@@ -1,6 +1,10 @@
-override o : bool = true;
+const o : bool = false;
+
+const j : bool = true;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o && j)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/val_init/f32.wgsl

@@ -1,6 +1,9 @@
+// flags: --overrides o=0
 override o : f32 = 1.0;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 0.0 {
+        _ = o;
+    }
 }

test/tint/var/override/named/val_init/f32.wgsl.expected.glsl

@@ -1,10 +1,8 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 1.0f
-#endif
-const float o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/val_init/f32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 1.0f
-#endif
-static const float o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }

test/tint/var/override/named/val_init/f32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant float o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }
 

test/tint/var/override/named/val_init/f32.wgsl.expected.spvasm

@@ -1,20 +1,25 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 11
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-      %float = OpTypeFloat 32
-          %o = OpSpecConstant %float 1
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+      %float = OpTypeFloat 32
-          %6 = OpLabel
+          %6 = OpConstantNull %float
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %7 = OpFOrdEqual %bool %6 %6
+               OpSelectionMerge %9 None
+               OpBranchConditional %7 %10 %9
+         %10 = OpLabel
+               OpBranch %9
+          %9 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/val_init/f32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : f32 = 1.0;
+const o : f32 = 0.0f;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 0.0)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/val_init/i32.wgsl

@@ -1,6 +1,9 @@
+// flags: --overrides o=0
 override o : i32 = 1;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 2 {
+        _ = o;
+    }
 }

test/tint/var/override/named/val_init/i32.wgsl.expected.glsl

@@ -1,10 +1,8 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 1
-#endif
-const int o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0 == 2)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/val_init/i32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 1
-#endif
-static const int o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0 == 2)) {
+  }
   return;
 }

test/tint/var/override/named/val_init/i32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant int o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0 == 2)) {
+  }
   return;
 }
 

test/tint/var/override/named/val_init/i32.wgsl.expected.spvasm

@@ -1,20 +1,26 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-        %int = OpTypeInt 32 1
-          %o = OpSpecConstant %int 1
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+        %int = OpTypeInt 32 1
-          %6 = OpLabel
+          %6 = OpConstantNull %int
+      %int_2 = OpConstant %int 2
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %8 = OpIEqual %bool %6 %int_2
+               OpSelectionMerge %10 None
+               OpBranchConditional %8 %11 %10
+         %11 = OpLabel
+               OpBranch %10
+         %10 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/val_init/i32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : i32 = 1;
+const o : i32 = 0i;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 2)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/val_init/u32.wgsl

@@ -1,6 +1,9 @@
+// flags: --overrides o=0
 override o : u32 = 1u;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 2 {
+        _ = o;
+    }
 }

test/tint/var/override/named/val_init/u32.wgsl.expected.glsl

@@ -1,10 +1,8 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 1u
-#endif
-const uint o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0u == 2u)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/val_init/u32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 1u
-#endif
-static const uint o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0u == 2u)) {
+  }
   return;
 }

test/tint/var/override/named/val_init/u32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant uint o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0u == 2u)) {
+  }
   return;
 }
 

test/tint/var/override/named/val_init/u32.wgsl.expected.spvasm

@@ -1,20 +1,26 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-       %uint = OpTypeInt 32 0
-          %o = OpSpecConstant %uint 1
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+       %uint = OpTypeInt 32 0
-          %6 = OpLabel
+          %6 = OpConstantNull %uint
+     %uint_2 = OpConstant %uint 2
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %8 = OpIEqual %bool %6 %uint_2
+               OpSelectionMerge %10 None
+               OpBranchConditional %8 %11 %10
+         %11 = OpLabel
+               OpBranch %10
+         %10 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/val_init/u32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : u32 = 1u;
+const o : u32 = 0u;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 2)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/zero_init/bool.wgsl

@@ -1,6 +1,10 @@
+// flags: --overrides o=0,j=1
 override o : bool = bool();
+override j : bool = bool();
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o && j {
+        _ = o;
+    }
 }

test/tint/var/override/named/zero_init/bool.wgsl.expected.glsl

@@ -1,10 +1,12 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 false
-#endif
-const bool o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  bool tint_tmp = false;
+  if (tint_tmp) {
+    tint_tmp = true;
+  }
+  if ((tint_tmp)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/zero_init/bool.wgsl.expected.hlsl

@@ -1,9 +1,10 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 false
-#endif
-static const bool o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  bool tint_tmp = false;
+  if (tint_tmp) {
+    tint_tmp = true;
+  }
+  if ((tint_tmp)) {
+  }
   return;
 }

test/tint/var/override/named/zero_init/bool.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant bool o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((false && true)) {
+  }
   return;
 }
 

test/tint/var/override/named/zero_init/bool.wgsl.expected.spvasm

@@ -1,20 +1,30 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 13
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-       %bool = OpTypeBool
-          %o = OpSpecConstantFalse %bool
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+       %bool = OpTypeBool
-          %6 = OpLabel
+          %6 = OpConstantNull %bool
+       %true = OpConstantTrue %bool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+               OpSelectionMerge %7 None
+               OpBranchConditional %6 %8 %7
+          %8 = OpLabel
+               OpBranch %7
+          %7 = OpLabel
+         %10 = OpPhi %bool %6 %4 %true %8
+               OpSelectionMerge %11 None
+               OpBranchConditional %10 %12 %11
+         %12 = OpLabel
+               OpBranch %11
+         %11 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/zero_init/bool.wgsl.expected.wgsl

@@ -1,6 +1,10 @@
-override o : bool = bool();
+const o : bool = false;
+
+const j : bool = true;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o && j)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/zero_init/f32.wgsl

@@ -1,6 +1,9 @@
+// flags: --overrides o=0
 override o : f32 = f32();
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 0.0 {
+        _ = o;
+    }
 }

test/tint/var/override/named/zero_init/f32.wgsl.expected.glsl

@@ -1,10 +1,8 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 0.0f
-#endif
-const float o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/zero_init/f32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 0.0f
-#endif
-static const float o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }

test/tint/var/override/named/zero_init/f32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant float o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }
 

test/tint/var/override/named/zero_init/f32.wgsl.expected.spvasm

@@ -1,20 +1,25 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 11
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-      %float = OpTypeFloat 32
-          %o = OpSpecConstant %float 0
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+      %float = OpTypeFloat 32
-          %6 = OpLabel
+          %6 = OpConstantNull %float
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %7 = OpFOrdEqual %bool %6 %6
+               OpSelectionMerge %9 None
+               OpBranchConditional %7 %10 %9
+         %10 = OpLabel
+               OpBranch %9
+          %9 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/zero_init/f32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : f32 = f32();
+const o : f32 = 0.0f;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 0.0)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/zero_init/i32.wgsl

@@ -1,6 +1,9 @@
+// flags: --overrides o=0
 override o : i32 = i32();
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 2 {
+        _ = o;
+    }
 }

test/tint/var/override/named/zero_init/i32.wgsl.expected.glsl

@@ -1,10 +1,8 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 0
-#endif
-const int o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0 == 2)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/zero_init/i32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 0
-#endif
-static const int o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0 == 2)) {
+  }
   return;
 }

test/tint/var/override/named/zero_init/i32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant int o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0 == 2)) {
+  }
   return;
 }
 

test/tint/var/override/named/zero_init/i32.wgsl.expected.spvasm

@@ -1,20 +1,26 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-        %int = OpTypeInt 32 1
-          %o = OpSpecConstant %int 0
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+        %int = OpTypeInt 32 1
-          %6 = OpLabel
+          %6 = OpConstantNull %int
+      %int_2 = OpConstant %int 2
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %8 = OpIEqual %bool %6 %int_2
+               OpSelectionMerge %10 None
+               OpBranchConditional %8 %11 %10
+         %11 = OpLabel
+               OpBranch %10
+         %10 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/zero_init/i32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : i32 = i32();
+const o : i32 = 0i;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 2)) {
+    _ = o;
+  }
 }

test/tint/var/override/named/zero_init/u32.wgsl

@@ -1,6 +1,9 @@
+// flags: --overrides o=0
 override o : u32 = u32();
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 2 {
+        _ = o;
+    }
 }

test/tint/var/override/named/zero_init/u32.wgsl.expected.glsl

@@ -1,10 +1,8 @@
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 0u
-#endif
-const uint o = WGSL_SPEC_CONSTANT_0;
 void tint_symbol() {
+  if ((0u == 2u)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

test/tint/var/override/named/zero_init/u32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_0
-#define WGSL_SPEC_CONSTANT_0 0u
-#endif
-static const uint o = WGSL_SPEC_CONSTANT_0;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0u == 2u)) {
+  }
   return;
 }

test/tint/var/override/named/zero_init/u32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant uint o [[function_constant(0)]];
-
 kernel void tint_symbol() {
+  if ((0u == 2u)) {
+  }
   return;
 }
 

test/tint/var/override/named/zero_init/u32.wgsl.expected.spvasm

@@ -1,20 +1,26 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 0
-       %uint = OpTypeInt 32 0
-          %o = OpSpecConstant %uint 0
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+       %uint = OpTypeInt 32 0
-          %6 = OpLabel
+          %6 = OpConstantNull %uint
+     %uint_2 = OpConstant %uint 2
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %8 = OpIEqual %bool %6 %uint_2
+               OpSelectionMerge %10 None
+               OpBranchConditional %8 %11 %10
+         %11 = OpLabel
+               OpBranch %10
+         %10 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/named/zero_init/u32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-override o : u32 = u32();
+const o : u32 = 0u;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 2)) {
+    _ = o;
+  }
 }

test/tint/var/override/numbered/no_init/bool.wgsl

@@ -1,7 +1,9 @@
-// flags: --overrides WGSL_SPEC_CONSTANT_1234=0
+// flags: --overrides 1234=0
 @id(1234) override o : bool;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o {
+        _ = o;
+    }
 }

test/tint/var/override/numbered/no_init/bool.wgsl.expected.glsl

@@ -1,12 +1,8 @@
-SKIP: FAILED
-
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_1234
-#error spec constant required for constant id 1234
-#endif
-const bool o = WGSL_SPEC_CONSTANT_1234;
 void tint_symbol() {
+  if (false) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
@@ -14,11 +10,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: '#error' : spec constant required for constant id 1234  
-ERROR: 0:5: '' : missing #endif 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/var/override/numbered/no_init/bool.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_1234
-#error spec constant required for constant id 1234
-#endif
-static const bool o = WGSL_SPEC_CONSTANT_1234;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if (false) {
+  }
   return;
 }

test/tint/var/override/numbered/no_init/bool.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant bool o [[function_constant(1234)]];
-
 kernel void tint_symbol() {
+  if (false) {
+  }
   return;
 }
 

test/tint/var/override/numbered/no_init/bool.wgsl.expected.spvasm

@@ -1,20 +1,23 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 9
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 1234
-       %bool = OpTypeBool
-          %o = OpSpecConstantFalse %bool
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+       %bool = OpTypeBool
-          %6 = OpLabel
+          %6 = OpConstantNull %bool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+               OpSelectionMerge %7 None
+               OpBranchConditional %6 %8 %7
+          %8 = OpLabel
+               OpBranch %7
+          %7 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/numbered/no_init/bool.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-@id(1234) override o : bool;
+const o : bool = false;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if (o) {
+    _ = o;
+  }
 }

test/tint/var/override/numbered/no_init/f32.wgsl

@@ -1,7 +1,9 @@
-// flags: --overrides WGSL_SPEC_CONSTANT_1234=0
+// flags: --overrides 1234=0
 @id(1234) override o : f32;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 0.0 {
+        _ = o;
+    }
 }

test/tint/var/override/numbered/no_init/f32.wgsl.expected.glsl

@@ -1,12 +1,8 @@
-SKIP: FAILED
-
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_1234
-#error spec constant required for constant id 1234
-#endif
-const float o = WGSL_SPEC_CONSTANT_1234;
 void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
@@ -14,11 +10,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: '#error' : spec constant required for constant id 1234  
-ERROR: 0:5: '' : missing #endif 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/var/override/numbered/no_init/f32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_1234
-#error spec constant required for constant id 1234
-#endif
-static const float o = WGSL_SPEC_CONSTANT_1234;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }

test/tint/var/override/numbered/no_init/f32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant float o [[function_constant(1234)]];
-
 kernel void tint_symbol() {
+  if ((0.0f == 0.0f)) {
+  }
   return;
 }
 

test/tint/var/override/numbered/no_init/f32.wgsl.expected.spvasm

@@ -1,20 +1,25 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 7
+; Bound: 11
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
                OpEntryPoint GLCompute %main "main"
                OpExecutionMode %main LocalSize 1 1 1
-               OpName %o "o"
                OpName %main "main"
-               OpDecorate %o SpecId 1234
-      %float = OpTypeFloat 32
-          %o = OpSpecConstant %float 0
        %void = OpTypeVoid
-          %3 = OpTypeFunction %void
+          %1 = OpTypeFunction %void
-       %main = OpFunction %void None %3
+      %float = OpTypeFloat 32
-          %6 = OpLabel
+          %6 = OpConstantNull %float
+       %bool = OpTypeBool
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+          %7 = OpFOrdEqual %bool %6 %6
+               OpSelectionMerge %9 None
+               OpBranchConditional %7 %10 %9
+         %10 = OpLabel
+               OpBranch %9
+          %9 = OpLabel
                OpReturn
                OpFunctionEnd

test/tint/var/override/numbered/no_init/f32.wgsl.expected.wgsl

@@ -1,6 +1,8 @@
-@id(1234) override o : f32;
+const o : f32 = 0.0f;
 
 @compute @workgroup_size(1)
 fn main() {
-  _ = o;
+  if ((o == 0.0)) {
+    _ = o;
+  }
 }

test/tint/var/override/numbered/no_init/i32.wgsl

@@ -1,7 +1,9 @@
-// flags: --overrides WGSL_SPEC_CONSTANT_1234=0
+// flags: --overrides 1234=0
 @id(1234) override o : i32;
 
 @compute @workgroup_size(1)
 fn main() {
-    _ = o;
+    if o == 0 {
+        _ = o;
+    }
 }

test/tint/var/override/numbered/no_init/i32.wgsl.expected.glsl

@@ -1,12 +1,8 @@
-SKIP: FAILED
-
 #version 310 es
 
-#ifndef WGSL_SPEC_CONSTANT_1234
-#error spec constant required for constant id 1234
-#endif
-const int o = WGSL_SPEC_CONSTANT_1234;
 void tint_symbol() {
+  if ((0 == 0)) {
+  }
 }
 
 layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
@@ -14,11 +10,3 @@ void main() {
   tint_symbol();
   return;
 }
-Error parsing GLSL shader:
-ERROR: 0:4: '#error' : spec constant required for constant id 1234  
-ERROR: 0:5: '' : missing #endif 
-ERROR: 0:5: '' : compilation terminated 
-ERROR: 3 compilation errors.  No code generated.
-
-
-

test/tint/var/override/numbered/no_init/i32.wgsl.expected.hlsl

@@ -1,9 +1,6 @@
-#ifndef WGSL_SPEC_CONSTANT_1234
-#error spec constant required for constant id 1234
-#endif
-static const int o = WGSL_SPEC_CONSTANT_1234;
-
 [numthreads(1, 1, 1)]
 void main() {
+  if ((0 == 0)) {
+  }
   return;
 }

test/tint/var/override/numbered/no_init/i32.wgsl.expected.msl

@@ -1,9 +1,9 @@
 #include <metal_stdlib>
 
 using namespace metal;
-constant int o [[function_constant(1234)]];
-
 kernel void tint_symbol() {
+  if ((0 == 0)) {
+  }
   return;
 }