[dawn] Enable module constant hoisting transform for apple silicon

The module constant hosting code works for apple silicon but has
has issues on Intel/AMD for f16(half). So sadly for now the
module scope hosting code must be conditioned on device.

This new end2end test should go green
https://dawn-review.googlesource.com/c/dawn/+/243854?tab=checks

Bug: 419804339
Change-Id: Iccf18363b0bbc74e876b40fa4dc171d7c2889c64
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/244234
Reviewed-by: James Price <jrprice@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Peter McNeeley <petermcneeley@google.com>

Author: Peter McNeeley

src/dawn/native/Toggles.cpp

@@ -570,6 +570,9 @@ static constexpr ToggleEnumAndInfoList kToggleNameAndInfoList = {{
      {"disable_polyfills_on_integer_div_and_mod",
       "Disable the Tint polyfills on integer division and modulo.", "https://crbug.com/tint/2128",
       ToggleStage::Device}},
+    {Toggle::MetalEnableModuleConstant,
+     {"metal_enable_module_constant_transform", "Enable the module constant transform.",
+      "https://crbug.com/419804339", ToggleStage::Device}},
     {Toggle::EnableImmediateErrorHandling,
      {"enable_immediate_error_handling",
       "Have the uncaptured error callback invoked immediately when an error occurs, rather than "

src/dawn/native/Toggles.h

@@ -138,6 +138,7 @@ enum class Toggle {
     ExposeWGSLTestingFeatures,
     ExposeWGSLExperimentalFeatures,
     DisablePolyfillsOnIntegerDivisonAndModulo,
+    MetalEnableModuleConstant,
     EnableImmediateErrorHandling,
     VulkanUseStorageInputOutput16,
     D3D12DontUseShaderModel66OrHigher,

src/dawn/native/metal/PhysicalDeviceMTL.mm

@@ -29,6 +29,7 @@
 
 #include "dawn/common/CoreFoundationRef.h"
 #include "dawn/common/GPUInfo.h"
+#include "dawn/common/GPUInfo_autogen.h"
 #include "dawn/common/Log.h"
 #include "dawn/common/NSRef.h"
 #include "dawn/common/Platform.h"
@@ -441,6 +442,13 @@ bool IsGPUCounterSupported(id<MTLDevice> device,
         deviceToggles->Default(Toggle::MetalRenderR8RG8UnormSmallMipToTempTexture, true);
     }
 
+    // chromium:419804339: Module constant hoisting is broadly available as a msl transform but
+    // there are execution correction issues with f16 for non apple silicon (Intel/AMD). Therefore
+    // we only enable for apple silicon for now.
+    if (gpu_info::IsApple(vendorId)) {
+        deviceToggles->Default(Toggle::MetalEnableModuleConstant, true);
+    }
+
     // On some Intel GPUs vertex only render pipeline get wrong depth result if no fragment
     // shader provided. Create a placeholder fragment shader module to work around this issue.
     if (gpu_info::IsIntel(vendorId)) {

src/dawn/native/metal/ShaderModuleMTL.mm

@@ -298,6 +298,8 @@
     req.tintOptions.bindings = std::move(bindings);
     req.tintOptions.disable_polyfill_integer_div_mod =
         device->IsToggleEnabled(Toggle::DisablePolyfillsOnIntegerDivisonAndModulo);
+    req.tintOptions.enable_module_constant =
+        device->IsToggleEnabled(Toggle::MetalEnableModuleConstant);
     req.tintOptions.vertex_pulling_config = std::move(vertexPullingTransformConfig);
     req.tintOptions.enable_integer_range_analysis =
         device->IsToggleEnabled(Toggle::EnableIntegerRangeAnalysisInRobustness);

src/tint/lang/msl/writer/common/options.h

@@ -163,6 +163,9 @@ struct Options {
     /// Set to `true` to disable the polyfills on integer division and modulo.
     bool disable_polyfill_integer_div_mod = false;
 
+    /// Set to `true` to enable the module constant transform
+    bool enable_module_constant = false;
+
     /// Emit argument buffers
     bool use_argument_buffers = false;
 
@@ -197,6 +200,7 @@ struct Options {
                  disable_demote_to_helper,
                  emit_vertex_point_size,
                  disable_polyfill_integer_div_mod,
+                 enable_module_constant,
                  use_argument_buffers,
                  buffer_size_ubo_index,
                  fixed_sample_mask,

src/tint/lang/msl/writer/printer/printer.cc

@@ -662,7 +662,9 @@ class Printer : public tint::TextGenerator {
 
         if (current_function_ == nullptr) {
             // program scope let
-            out << "constexpr constant ";
+            // TODO(crbug.com/419804339): This should be 'constexpr constant' but the matrix class
+            // (constructor) in metal is not constexpr.
+            out << "const constant ";
         }
         EmitType(out, l->Result()->Type());
         out << " ";

src/tint/lang/msl/writer/raise/raise.cc

@@ -160,10 +160,7 @@ Result<RaiseResult> Raise(core::ir::Module& module, const Options& options) {
     RUN_TRANSFORM(raise::BinaryPolyfill, module);
     RUN_TRANSFORM(raise::BuiltinPolyfill, module);
 
-    // TODO(crbug.com/419804339): Fix backend compile failures for f16 types related to this
-    // transform
-    constexpr bool kEnabledModuleConstantTransform = false;
-    if (kEnabledModuleConstantTransform) {
+    if (options.enable_module_constant) {
         RUN_TRANSFORM(raise::ModuleConstant, module);
     }