Convert spvc build flag to a runtime toggle

Also moves some of the spirv_cross code into the main library that was
feature guarded, since spvc requires it.

BUG=dawn:281

Change-Id: I482d1d5a5c851956d3815bad90665c52a1ea15bb
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/13860
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

BUILD.gn

@@ -124,15 +124,12 @@ source_set("libdawn_native_sources") {
     ":libdawn_native_headers",
     ":libdawn_native_utils_gen",
     "${dawn_root}/src/common",
+    "${dawn_shaderc_dir}:libshaderc_spvc",
     "${dawn_spirv_tools_dir}:spvtools_val",
     "third_party:spirv_cross",
   ]
-  defines = []
-  if (dawn_use_spvc) {
-    deps += [ "${dawn_shaderc_dir}:libshaderc_spvc" ]
-    defines += [ "DAWN_USE_SPVC" ]
-  }
 
+  defines = []
   configs += [ ":libdawn_native_internal" ]
   libs = []
 

DEPS

@@ -68,7 +68,7 @@ deps = {
     'condition': 'dawn_standalone',
   },
   'third_party/shaderc': {
-    'url': '{chromium_git}/external/github.com/google/shaderc@c7f5cfd07f41c997045d76fd09c934691ff8a6c6',
+    'url': '{chromium_git}/external/github.com/google/shaderc@eca11511a0c09dd599837862c96658a91e927a3a',
     'condition': 'dawn_standalone',
   },
 

scripts/dawn_features.gni

@@ -44,10 +44,6 @@ declare_args() {
   # GLSL/HLSL/MSL compiler. This implicitly pulls in the GLSL
   # compiler, since it is a sub-class of if.
   dawn_enable_cross_reflection = false
-
-  # Enables using spvc for accessing SPIR-V toolchain, instead of
-  # directly accessing it in Dawn.
-  dawn_use_spvc = false
 }
 
 # GN does not allow reading a variable defined in the same declare_args().

src/dawn_native/Toggles.cpp

@@ -82,7 +82,11 @@ namespace dawn_native {
                "versions of Windows prior to build 1809, or when this toggle is turned off, Dawn "
                "will emulate a render pass."}},
              {Toggle::SkipValidation,
-              {"skip_validation", "Skip expensive validation of Dawn commands."}}}};
+              {"skip_validation", "Skip expensive validation of Dawn commands."}},
+             {Toggle::UseSpvc,
+              {"use_spvc",
+               "Enable use of spvc for shader compilation, instead of accessing spirv_cross "
+               "directly."}}}};
     }  // anonymous namespace
 
     void TogglesSet::SetToggle(Toggle toggle, bool enabled) {

src/dawn_native/Toggles.h

@@ -33,7 +33,7 @@ namespace dawn_native {
         UseD3D12ResourceHeapTier2,
         UseD3D12RenderPass,
         SkipValidation,
-
+        UseSpvc,
         EnumCount,
         InvalidEnum = EnumCount,
     };

third_party/BUILD.gn

@@ -50,61 +50,6 @@ static_library("spirv_cross") {
   public_configs = [ ":spirv_cross_public" ]
   configs += [ ":spirv_cross_internal" ]
 
-  sources = [
-    "${spirv_cross_dir}/GLSL.std.450.h",
-    "${spirv_cross_dir}/spirv.hpp",
-    "${spirv_cross_dir}/spirv_cfg.cpp",
-    "${spirv_cross_dir}/spirv_cfg.hpp",
-    "${spirv_cross_dir}/spirv_common.hpp",
-    "${spirv_cross_dir}/spirv_cross.cpp",
-    "${spirv_cross_dir}/spirv_cross.hpp",
-    "${spirv_cross_dir}/spirv_cross_containers.hpp",
-    "${spirv_cross_dir}/spirv_cross_error_handling.hpp",
-    "${spirv_cross_dir}/spirv_cross_parsed_ir.cpp",
-    "${spirv_cross_dir}/spirv_cross_parsed_ir.hpp",
-    "${spirv_cross_dir}/spirv_parser.cpp",
-    "${spirv_cross_dir}/spirv_parser.hpp",
-  ]
-
-  need_glsl_cross =
-      dawn_enable_opengl || dawn_enable_cross_reflection || dawn_use_spvc
-  need_reflection_cross = dawn_enable_cross_reflection || dawn_use_spvc
-
-  if (dawn_enable_d3d12) {
-    sources += [
-      "${spirv_cross_dir}/spirv_hlsl.cpp",
-      "${spirv_cross_dir}/spirv_hlsl.hpp",
-    ]
-    need_glsl_cross = true
-  }
-
-  if (dawn_enable_metal) {
-    sources += [
-      "${spirv_cross_dir}/spirv_msl.cpp",
-      "${spirv_cross_dir}/spirv_msl.hpp",
-    ]
-    need_glsl_cross = true
-  }
-
-  if (need_glsl_cross) {
-    sources += [
-      "${spirv_cross_dir}/spirv_glsl.cpp",
-      "${spirv_cross_dir}/spirv_glsl.hpp",
-    ]
-  }
-
-  if (need_reflection_cross) {
-    sources += [
-      "${spirv_cross_dir}/spirv_reflect.cpp",
-      "${spirv_cross_dir}/spirv_reflect.hpp",
-    ]
-  }
-}
-
-static_library("spirv_cross_full_for_fuzzers") {
-  public_configs = [ ":spirv_cross_public" ]
-  configs += [ ":spirv_cross_internal" ]
-
   sources = [
     "${spirv_cross_dir}/GLSL.std.450.h",
     "${spirv_cross_dir}/spirv.hpp",