Reland "Vulkan:Include precision qualifier in GLSL"

Currently still ignoring precision qualifiers for Vulkan shaders by
default, but have added feature "enablePrecisionQualifiers" that can be
enabled in order to include precision qualifiers.

With this initial implementation, it's possible to get precision
qualifier mis-matches in the generated GLSL 4.50. According to the
spec this is allowed. From GLSLangSpec 4.50 section 4.7 "Precision and
Precision Qualifiers":

For the purposes of determining if an output from one shader stage
matches an input of the next stage, the precision qualifier need not
match.

However, when converted to SPIR-V and run through the shader validation
any mismatches will cause shader validation errors. Initially just
ignoring those errors with this commit.

Bug: angleproject:3078
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2057749
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tobin Ehlis <tobine@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>
Commit-Queue: Tobin Ehlis <tobine@google.com>
Change-Id: Ieecca604bb2c834c9b1c2bcab85279d1f8755dfa
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2086280

include/GLSLANG/ShaderLang.h

@@ -333,6 +333,9 @@ const ShCompileOptions SH_DISABLE_ARB_TEXTURE_RECTANGLE = UINT64_C(1) << 52;
 // as column-major in ESSL 3.00 and greater shaders.
 const ShCompileOptions SH_REWRITE_ROW_MAJOR_MATRICES = UINT64_C(1) << 53;
 
+// Drop any explicit precision qualifiers from shader.
+const ShCompileOptions SH_IGNORE_PRECISION_QUALIFIERS = UINT64_C(1) << 54;
+
 // Defines alternate strategies for implementing array index clamping.
 enum ShArrayIndexClampingStrategy
 {

include/platform/FeaturesVk.h

@@ -263,6 +263,11 @@ struct FeaturesVk : FeatureSetBase
     Feature enableFramebufferVkCache = {
         "enable_framebuffer_vk_cache", FeatureCategory::VulkanFeatures,
         "Enable FramebufferVk objects to be cached", &members, "http://anglebug.com/4442"};
+
+    // Enable precision qualifiers for shaders generated by Vulkan backend http://anglebug.com/3078
+    Feature enablePrecisionQualifiers = {
+        "enable_precision_qualifiers", FeatureCategory::VulkanFeatures,
+        "Enable precision qualifiers in shaders", &members, "http://anglebug.com/3078"};
 };
 
 inline FeaturesVk::FeaturesVk()  = default;

src/compiler/translator/OutputVulkanGLSL.cpp

@@ -27,6 +27,8 @@ TOutputVulkanGLSL::TOutputVulkanGLSL(TInfoSinkBase &objSink,
                                      sh::GLenum shaderType,
                                      int shaderVersion,
                                      ShShaderOutput output,
+                                     bool forceHighp,
+                                     bool enablePrecision,
                                      ShCompileOptions compileOptions)
     : TOutputGLSL(objSink,
                   clampingStrategy,
@@ -39,7 +41,9 @@ TOutputVulkanGLSL::TOutputVulkanGLSL(TInfoSinkBase &objSink,
                   compileOptions),
       mNextUnusedBinding(0),
       mNextUnusedInputLocation(0),
-      mNextUnusedOutputLocation(0)
+      mNextUnusedOutputLocation(0),
+      mForceHighp(forceHighp),
+      mEnablePrecision(enablePrecision)
 {}
 
 void TOutputVulkanGLSL::writeLayoutQualifier(TIntermTyped *variable)
@@ -168,4 +172,17 @@ void TOutputVulkanGLSL::writeStructType(const TStructure *structure)
     }
 }
 
+bool TOutputVulkanGLSL::writeVariablePrecision(TPrecision precision)
+{
+    if ((precision == EbpUndefined) || !mEnablePrecision)
+        return false;
+
+    TInfoSinkBase &out = objSink();
+    if (mForceHighp)
+        out << getPrecisionString(EbpHigh);
+    else
+        out << getPrecisionString(precision);
+    return true;
+}
+
 }  // namespace sh

src/compiler/translator/OutputVulkanGLSL.h

@@ -25,6 +25,8 @@ class TOutputVulkanGLSL : public TOutputGLSL
                       sh::GLenum shaderType,
                       int shaderVersion,
                       ShShaderOutput output,
+                      bool forceHighp,
+                      bool enablePrecision,
                       ShCompileOptions compileOptions);
 
     void writeStructType(const TStructure *structure);
@@ -48,6 +50,7 @@ class TOutputVulkanGLSL : public TOutputGLSL
     void writeVariableType(const TType &type,
                            const TSymbol *symbol,
                            bool isFunctionArgument) override;
+    bool writeVariablePrecision(TPrecision) override;
 
     // Every resource that requires set & binding layout qualifiers is assigned set 0 and an
     // arbitrary binding when outputting GLSL.  Every input/output that requires a location
@@ -57,6 +60,10 @@ class TOutputVulkanGLSL : public TOutputGLSL
     uint32_t mNextUnusedBinding;
     uint32_t mNextUnusedInputLocation;
     uint32_t mNextUnusedOutputLocation;
+
+  private:
+    bool mForceHighp;
+    bool mEnablePrecision;
 };
 
 }  // namespace sh

src/compiler/translator/OutputVulkanGLSLForMetal.mm

@@ -71,6 +71,8 @@ TOutputVulkanGLSLForMetal::TOutputVulkanGLSLForMetal(TInfoSinkBase &objSink,
                         shaderType,
                         shaderVersion,
                         output,
+                        false,
+                        true,
                         compileOptions)
 {}
 

src/compiler/translator/TranslatorMetal.cpp

@@ -67,9 +67,10 @@ bool TranslatorMetal::translate(TIntermBlock *root,
                                 PerformanceDiagnostics *perfDiagnostics)
 {
     TInfoSinkBase &sink = getInfoSink().obj;
+
     TOutputVulkanGLSL outputGLSL(sink, getArrayIndexClampingStrategy(), getHashFunction(),
                                  getNameMap(), &getSymbolTable(), getShaderType(),
-                                 getShaderVersion(), getOutputType(), compileOptions);
+                                 getShaderVersion(), getOutputType(), false, true, compileOptions);
 
     const TVariable *driverUniforms = nullptr;
     if (!TranslatorVulkan::translateImpl(root, compileOptions, perfDiagnostics, &driverUniforms,

src/compiler/translator/TranslatorVulkan.cpp

@@ -1043,9 +1043,17 @@ bool TranslatorVulkan::translate(TIntermBlock *root,
 {
 
     TInfoSinkBase &sink = getInfoSink().obj;
+
+    bool precisionEmulation = false;
+    if (!emulatePrecisionIfNeeded(root, sink, &precisionEmulation, SH_GLSL_VULKAN_OUTPUT))
+        return false;
+
+    bool enablePrecision = ((compileOptions & SH_IGNORE_PRECISION_QUALIFIERS) == 0);
+
     TOutputVulkanGLSL outputGLSL(sink, getArrayIndexClampingStrategy(), getHashFunction(),
                                  getNameMap(), &getSymbolTable(), getShaderType(),
-                                 getShaderVersion(), getOutputType(), compileOptions);
+                                 getShaderVersion(), getOutputType(), precisionEmulation,
+                                 enablePrecision, compileOptions);
 
     if (!translateImpl(root, compileOptions, perfDiagnostics, nullptr, &outputGLSL))
     {

src/libANGLE/renderer/vulkan/RendererVk.cpp

@@ -124,9 +124,9 @@ constexpr const char *kSkippedMessages[] = {
     "VUID-vkDestroySemaphore-semaphore-parameter",
     // http://anglebug.com/4063
     "VUID-VkDeviceCreateInfo-pNext-pNext",
-    "VUID-VkPipelineRasterizationStateCreateInfo-pNext-pNext",
-    "VUID_Undefined",
-};
+    "VUID-VkPipelineRasterizationStateCreateInfo-pNext-pNext", "VUID_Undefined",
+    // http://anglebug.com/3078
+    "UNASSIGNED-CoreValidation-Shader-InterfaceTypeMismatch"};
 
 // Suppress validation errors that are known
 //  return "true" if given code/prefix/message is known, else return "false"
@@ -1673,6 +1673,9 @@ void RendererVk::initFeatures(DisplayVk *displayVk, const ExtensionNameList &dev
     // Currently disable FramebufferVk cache on Apple: http://anglebug.com/4442
     ANGLE_FEATURE_CONDITION((&mFeatures), enableFramebufferVkCache, !IsApple());
 
+    // Currently disabled by default: http://anglebug.com/3078
+    ANGLE_FEATURE_CONDITION((&mFeatures), enablePrecisionQualifiers, false);
+
     angle::PlatformMethods *platform = ANGLEPlatformCurrent();
     platform->overrideFeaturesVk(platform, &mFeatures);
 

src/libANGLE/renderer/vulkan/ShaderVk.cpp

@@ -55,6 +55,11 @@ std::shared_ptr<WaitableCompileEvent> ShaderVk::compile(const gl::Context *conte
         compileOptions |= SH_USE_OLD_REWRITE_STRUCT_SAMPLERS;
     }
 
+    if (!contextVk->getFeatures().enablePrecisionQualifiers.enabled)
+    {
+        compileOptions |= SH_IGNORE_PRECISION_QUALIFIERS;
+    }
+
     return compileImpl(context, compilerInstance, mData.getSource(), compileOptions | options);
 }