Remove invariant declaration in vertex shader for translation from ESSL 3.00 to GLSL <= 4.1

This is a follow-up patch of
https://chromium-review.googlesource.com/408569. This CL removes
invariant declaration in ESSL 3.00 vertex shader, such like:
"
out vec4 foo;
invariant foo;
"

This CL also adds the workarounds in libANGLE.

BUG=chromium:639760
TEST=webgl2_conformance

Change-Id: I568ab51a9a2f5da10d1aff0b63aae8805097e081
Reviewed-on: https://chromium-review.googlesource.com/409157
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

include/GLSLANG/ShaderLang.h

@@ -49,7 +49,7 @@ typedef unsigned int GLenum;
 
 // Version number for shader translation API.
 // It is incremented every time the API changes.
-#define ANGLE_SH_VERSION 166
+#define ANGLE_SH_VERSION 167
 
 enum ShShaderSpec
 {
@@ -226,8 +226,7 @@ const ShCompileOptions SH_DONT_REMOVE_INVARIANT_FOR_FRAGMENT_INPUT = UINT64_C(1)
 // TODO(zmo): This is not a good long-term solution. Simply dropping these qualifiers may break some
 // developers' content. A more complex workaround of dynamically generating, compiling, and
 // re-linking shaders that use these qualifiers should be implemented.
-const ShCompileOptions SH_REMOVE_INVARIANT_FOR_ESSL3 = UINT64_C(1) << 30;
-const ShCompileOptions SH_REMOVE_CENTROID_FOR_ESSL3 = UINT64_C(1) << 31;
+const ShCompileOptions SH_REMOVE_INVARIANT_AND_CENTROID_FOR_ESSL3 = UINT64_C(1) << 30;
 
 // Defines alternate strategies for implementing array index clamping.
 enum ShArrayIndexClampingStrategy

src/compiler/translator/Compiler.cpp

@@ -103,6 +103,22 @@ bool IsGLSL410OrOlder(ShShaderOutput output)
             output == SH_GLSL_400_CORE_OUTPUT || output == SH_GLSL_410_CORE_OUTPUT);
 }
 
+bool RemoveInvariant(sh::GLenum shaderType,
+                     int shaderVersion,
+                     ShShaderOutput outputType,
+                     ShCompileOptions compileOptions)
+{
+    if ((compileOptions & SH_DONT_REMOVE_INVARIANT_FOR_FRAGMENT_INPUT) == 0 &&
+        shaderType == GL_FRAGMENT_SHADER && IsGLSL420OrNewer(outputType))
+        return true;
+
+    if ((compileOptions & SH_REMOVE_INVARIANT_AND_CENTROID_FOR_ESSL3) != 0 &&
+        shaderVersion >= 300 && shaderType == GL_VERTEX_SHADER && IsGLSL410OrOlder(outputType))
+        return true;
+
+    return false;
+}
+
 size_t GetGlobalMaxTokenSize(ShShaderSpec spec)
 {
     // WebGL defines a max token legnth of 256, while ES2 leaves max token
@@ -394,8 +410,7 @@ TIntermBlock *TCompiler::compileTreeImpl(const char *const shaderStrings[],
              (outputType == SH_GLSL_COMPATIBILITY_OUTPUT)))
             initializeGLPosition(root);
 
-        if (success && !(compileOptions & SH_DONT_REMOVE_INVARIANT_FOR_FRAGMENT_INPUT) &&
-            shaderType == GL_FRAGMENT_SHADER && IsGLSL420OrNewer(outputType))
+        if (success && RemoveInvariant(shaderType, shaderVersion, outputType, compileOptions))
             sh::RemoveInvariantDeclaration(root);
 
         // This pass might emit short circuits so keep it before the short circuit unfolding

src/compiler/translator/Compiler.h

@@ -44,6 +44,14 @@ bool IsGLSL130OrNewer(ShShaderOutput output);
 bool IsGLSL420OrNewer(ShShaderOutput output);
 bool IsGLSL410OrOlder(ShShaderOutput output);
 
+//
+// Helper function to check if the invariant qualifier can be removed.
+//
+bool RemoveInvariant(sh::GLenum shaderType,
+                     int shaderVersion,
+                     ShShaderOutput outputType,
+                     ShCompileOptions compileOptions);
+
 //
 // The base class used to back handles returned to the driver.
 //

src/compiler/translator/OutputESSL.cpp

@@ -14,6 +14,7 @@ TOutputESSL::TOutputESSL(TInfoSinkBase &objSink,
                          ShHashFunction64 hashFunction,
                          NameMap &nameMap,
                          TSymbolTable &symbolTable,
+                         sh::GLenum shaderType,
                          int shaderVersion,
                          bool forceHighp,
                          ShCompileOptions compileOptions)
@@ -22,6 +23,7 @@ TOutputESSL::TOutputESSL(TInfoSinkBase &objSink,
                       hashFunction,
                       nameMap,
                       symbolTable,
+                      shaderType,
                       shaderVersion,
                       SH_ESSL_OUTPUT,
                       compileOptions),

src/compiler/translator/OutputESSL.h

@@ -14,20 +14,21 @@ namespace sh
 
 class TOutputESSL : public TOutputGLSLBase
 {
-public:
-    TOutputESSL(TInfoSinkBase& objSink,
+  public:
+    TOutputESSL(TInfoSinkBase &objSink,
                 ShArrayIndexClampingStrategy clampingStrategy,
                 ShHashFunction64 hashFunction,
-                NameMap& nameMap,
-                TSymbolTable& symbolTable,
+                NameMap &nameMap,
+                TSymbolTable &symbolTable,
+                sh::GLenum shaderType,
                 int shaderVersion,
                 bool forceHighp,
                 ShCompileOptions compileOptions);
 
-protected:
-  bool writeVariablePrecision(TPrecision precision) override;
+  protected:
+    bool writeVariablePrecision(TPrecision precision) override;
 
-private:
+  private:
     bool mForceHighp;
 };
 

src/compiler/translator/OutputGLSL.cpp

@@ -9,11 +9,12 @@
 namespace sh
 {
 
-TOutputGLSL::TOutputGLSL(TInfoSinkBase& objSink,
+TOutputGLSL::TOutputGLSL(TInfoSinkBase &objSink,
                          ShArrayIndexClampingStrategy clampingStrategy,
                          ShHashFunction64 hashFunction,
-                         NameMap& nameMap,
-                         TSymbolTable& symbolTable,
+                         NameMap &nameMap,
+                         TSymbolTable &symbolTable,
+                         sh::GLenum shaderType,
                          int shaderVersion,
                          ShShaderOutput output,
                          ShCompileOptions compileOptions)
@@ -22,6 +23,7 @@ TOutputGLSL::TOutputGLSL(TInfoSinkBase& objSink,
                       hashFunction,
                       nameMap,
                       symbolTable,
+                      shaderType,
                       shaderVersion,
                       output,
                       compileOptions)

src/compiler/translator/OutputGLSL.h

@@ -15,11 +15,12 @@ namespace sh
 class TOutputGLSL : public TOutputGLSLBase
 {
   public:
-    TOutputGLSL(TInfoSinkBase& objSink,
+    TOutputGLSL(TInfoSinkBase &objSink,
                 ShArrayIndexClampingStrategy clampingStrategy,
                 ShHashFunction64 hashFunction,
-                NameMap& nameMap,
-                TSymbolTable& symbolTable,
+                NameMap &nameMap,
+                TSymbolTable &symbolTable,
+                sh::GLenum shaderType,
                 int shaderVersion,
                 ShShaderOutput output,
                 ShCompileOptions compileOptions);

src/compiler/translator/OutputGLSLBase.cpp

@@ -85,6 +85,7 @@ TOutputGLSLBase::TOutputGLSLBase(TInfoSinkBase &objSink,
                                  ShHashFunction64 hashFunction,
                                  NameMap &nameMap,
                                  TSymbolTable &symbolTable,
+                                 sh::GLenum shaderType,
                                  int shaderVersion,
                                  ShShaderOutput output,
                                  ShCompileOptions compileOptions)
@@ -95,6 +96,7 @@ TOutputGLSLBase::TOutputGLSLBase(TInfoSinkBase &objSink,
       mHashFunction(hashFunction),
       mNameMap(nameMap),
       mSymbolTable(symbolTable),
+      mShaderType(shaderType),
       mShaderVersion(shaderVersion),
       mOutput(output),
       mCompileOptions(compileOptions)
@@ -103,11 +105,7 @@ TOutputGLSLBase::TOutputGLSLBase(TInfoSinkBase &objSink,
 
 void TOutputGLSLBase::writeInvariantQualifier(const TType &type)
 {
-    bool removeInvariant = ((type.getQualifier() == EvqVaryingIn && sh::IsGLSL420OrNewer(mOutput) &&
-                             !(mCompileOptions & SH_DONT_REMOVE_INVARIANT_FOR_FRAGMENT_INPUT)) ||
-                            (sh::IsGLSL410OrOlder(mOutput) && mShaderVersion >= 300 &&
-                             !!(mCompileOptions & SH_REMOVE_INVARIANT_FOR_ESSL3)));
-    if (!removeInvariant)
+    if (!sh::RemoveInvariant(mShaderType, mShaderVersion, mOutput, mCompileOptions))
     {
         TInfoSinkBase &out = objSink();
         out << "invariant ";
@@ -165,7 +163,7 @@ void TOutputGLSLBase::writeLayoutQualifier(const TType &type)
 const char *TOutputGLSLBase::mapQualifierToString(TQualifier qualifier)
 {
     if (sh::IsGLSL410OrOlder(mOutput) && mShaderVersion >= 300 &&
-        !!(mCompileOptions & SH_REMOVE_CENTROID_FOR_ESSL3))
+        (mCompileOptions & SH_REMOVE_INVARIANT_AND_CENTROID_FOR_ESSL3) != 0)
     {
         switch (qualifier)
         {
@@ -960,8 +958,7 @@ bool TOutputGLSLBase::visitAggregate(Visit visit, TIntermAggregate *node)
             ASSERT(sequence && sequence->size() == 1);
             const TIntermSymbol *symbol = sequence->front()->getAsSymbolNode();
             ASSERT(symbol);
-            writeInvariantQualifier(symbol->getType());
-            out << hashVariableName(symbol->getName());
+            out << "invariant " << hashVariableName(symbol->getName());
         }
         visitChildren = false;
         break;

src/compiler/translator/OutputGLSLBase.h

@@ -23,7 +23,8 @@ class TOutputGLSLBase : public TIntermTraverser
                     ShArrayIndexClampingStrategy clampingStrategy,
                     ShHashFunction64 hashFunction,
                     NameMap &nameMap,
-                    TSymbolTable& symbolTable,
+                    TSymbolTable &symbolTable,
+                    sh::GLenum shaderType,
                     int shaderVersion,
                     ShShaderOutput output,
                     ShCompileOptions compileOptions);
@@ -102,6 +103,8 @@ class TOutputGLSLBase : public TIntermTraverser
 
     TSymbolTable &mSymbolTable;
 
+    sh::GLenum mShaderType;
+
     const int mShaderVersion;
 
     ShShaderOutput mOutput;

src/compiler/translator/RemoveInvariantDeclaration.cpp

@@ -15,7 +15,7 @@ namespace
 {
 
 // An AST traverser that removes invariant declaration for input in fragment shader
-// when GLSL >= 4.20.
+// when GLSL >= 4.20 and for output in vertex shader when GLSL < 4.2.
 class RemoveInvariantDeclarationTraverser : public TIntermTraverser
 {
   public:
@@ -26,17 +26,10 @@ class RemoveInvariantDeclarationTraverser : public TIntermTraverser
     {
         if (node->getOp() == EOpInvariantDeclaration)
         {
-            for (TIntermNode *&child : *node->getSequence())
-            {
-                TIntermTyped *typed = child->getAsTyped();
-                if (typed && typed->getQualifier() == EvqVaryingIn)
-                {
-                    TIntermSequence emptyReplacement;
-                    mMultiReplacements.push_back(NodeReplaceWithMultipleEntry(
-                        getParentNode()->getAsBlock(), node, emptyReplacement));
-                    return false;
-                }
-            }
+            TIntermSequence emptyReplacement;
+            mMultiReplacements.push_back(NodeReplaceWithMultipleEntry(getParentNode()->getAsBlock(),
+                                                                      node, emptyReplacement));
+            return false;
         }
         return true;
     }

src/compiler/translator/TranslatorESSL.cpp

@@ -81,7 +81,8 @@ void TranslatorESSL::translate(TIntermNode *root, ShCompileOptions compileOption
 
     // Write translated shader.
     TOutputESSL outputESSL(sink, getArrayIndexClampingStrategy(), getHashFunction(), getNameMap(),
-                           getSymbolTable(), shaderVer, precisionEmulation, compileOptions);
+                           getSymbolTable(), getShaderType(), shaderVer, precisionEmulation,
+                           compileOptions);
     root->traverse(&outputESSL);
 }
 

src/compiler/translator/TranslatorGLSL.cpp

@@ -188,13 +188,8 @@ void TranslatorGLSL::translate(TIntermNode *root, ShCompileOptions compileOption
     }
 
     // Write translated shader.
-    TOutputGLSL outputGLSL(sink,
-                           getArrayIndexClampingStrategy(),
-                           getHashFunction(),
-                           getNameMap(),
-                           getSymbolTable(),
-                           getShaderVersion(),
-                           getOutputType(),
+    TOutputGLSL outputGLSL(sink, getArrayIndexClampingStrategy(), getHashFunction(), getNameMap(),
+                           getSymbolTable(), getShaderType(), getShaderVersion(), getOutputType(),
                            compileOptions);
     root->traverse(&outputGLSL);
 }

src/libANGLE/renderer/gl/ShaderGL.cpp

@@ -80,6 +80,11 @@ ShCompileOptions ShaderGL::prepareSourceAndReturnOptions(std::stringstream *sour
         options |= SH_DONT_REMOVE_INVARIANT_FOR_FRAGMENT_INPUT;
     }
 
+    if (mWorkarounds.removeInvariantAndCentroidForESSL3)
+    {
+        options |= SH_REMOVE_INVARIANT_AND_CENTROID_FOR_ESSL3;
+    }
+
     return options;
 }
 

src/libANGLE/renderer/gl/WorkaroundsGL.h

@@ -26,7 +26,8 @@ struct WorkaroundsGL
           addAndTrueToLoopCondition(false),
           emulateIsnanFloat(false),
           useUnusedBlocksWithStandardOrSharedLayout(false),
-          dontRemoveInvariantForFragmentInput(false)
+          dontRemoveInvariantForFragmentInput(false),
+          removeInvariantAndCentroidForESSL3(false)
     {
     }
 
@@ -116,6 +117,9 @@ struct WorkaroundsGL
     // This flag will keep invariant declaration for input in fragment shader for GLSL >=4.20
     // on AMD.
     bool dontRemoveInvariantForFragmentInput;
+
+    // This flag is used to fix spec difference between GLSL 4.1 or lower and ESSL3.
+    bool removeInvariantAndCentroidForESSL3;
 };
 }
 

src/libANGLE/renderer/gl/renderergl_utils.cpp

@@ -944,6 +944,8 @@ void GenerateWorkarounds(const FunctionsGL *functions, WorkaroundsGL *workaround
     workarounds->unpackLastRowSeparatelyForPaddingInclusion = IsNvidia(vendor);
     workarounds->packLastRowSeparatelyForPaddingInclusion   = IsNvidia(vendor);
 #endif
+
+    workarounds->removeInvariantAndCentroidForESSL3 = functions->isAtMostGL(gl::Version(4, 1));
 }
 
 }