Add gl_ViewportIndex to the symbol table

src/compiler/translator/Compiler.cpp

@@ -628,11 +628,12 @@ bool TCompiler::InitBuiltInSymbolTable(const ShBuiltInResources &resources)
     compileResources = resources;
     setResourceString();
 
-    assert(symbolTable.isEmpty());
+    ASSERT(symbolTable.isEmpty());
     symbolTable.push();  // COMMON_BUILTINS
     symbolTable.push();  // ESSL1_BUILTINS
     symbolTable.push();  // ESSL3_BUILTINS
     symbolTable.push();  // ESSL3_1_BUILTINS
+    symbolTable.push();  // GLSL_BUILTINS
 
     switch (shaderType)
     {

src/compiler/translator/DeclareAndInitBuiltinsForInstancedMultiview.cpp

@@ -113,7 +113,8 @@ void DeclareGlobalVariable(TIntermBlock *root, TIntermTyped *typedNode)
 // added to the end of the initializers' sequence.
 void SelectViewIndexInVertexShader(TIntermTyped *viewIDSymbol,
                                    TIntermTyped *multiviewBaseViewLayerIndexSymbol,
-                                   TIntermSequence *initializers)
+                                   TIntermSequence *initializers,
+                                   const TSymbolTable &symbolTable)
 {
     // Create an int(ViewID_OVR) node.
     TIntermSequence *viewIDSymbolCastArguments = new TIntermSequence();
@@ -123,7 +124,7 @@ void SelectViewIndexInVertexShader(TIntermTyped *viewIDSymbol,
 
     // Create a gl_ViewportIndex node.
     TIntermSymbol *viewportIndexSymbol =
-        new TIntermSymbol(0, "gl_ViewportIndex", TType(EbtInt, EbpHigh, EvqViewportIndex));
+        ReferenceBuiltInVariable("gl_ViewportIndex", symbolTable, 0);
 
     // Create a { gl_ViewportIndex = int(ViewID_OVR) } node.
     TIntermBlock *viewportIndexInitializerInBlock = new TIntermBlock();
@@ -206,7 +207,7 @@ void DeclareAndInitBuiltinsForInstancedMultiview(TIntermBlock *root,
             // initialization.
             SelectViewIndexInVertexShader(viewIDSymbol->deepCopy(),
                                           multiviewBaseViewLayerIndexSymbol->deepCopy(),
-                                          initializers);
+                                          initializers, *symbolTable);
         }
 
         // Insert initializers at the beginning of main().

src/compiler/translator/Initialize.cpp

@@ -871,11 +871,11 @@ void IdentifyBuiltIns(sh::GLenum type,
                                               "gl_LastFragColorARM",
                                               TType(EbtFloat, EbpMedium, EvqLastFragColor, 4));
             }
-        }
-
-        break;
 
+            break;
+        }
         case GL_VERTEX_SHADER:
+        {
             symbolTable.insertVariable(COMMON_BUILTINS, "gl_Position",
                                        TType(EbtFloat, EbpHigh, EvqPosition, 4));
             symbolTable.insertVariable(COMMON_BUILTINS, "gl_PointSize",
@@ -884,7 +884,12 @@ void IdentifyBuiltIns(sh::GLenum type,
                                        TType(EbtInt, EbpHigh, EvqInstanceID, 1));
             symbolTable.insertVariable(ESSL3_BUILTINS, "gl_VertexID",
                                        TType(EbtInt, EbpHigh, EvqVertexID, 1));
+
+            // For internal use by ANGLE - not exposed to the parser.
+            symbolTable.insertVariable(GLSL_BUILTINS, "gl_ViewportIndex",
+                                       TType(EbtInt, EbpHigh, EvqViewportIndex));
             break;
+        }
         case GL_COMPUTE_SHADER:
         {
             symbolTable.insertVariable(ESSL3_1_BUILTINS, "gl_NumWorkGroups",
@@ -899,15 +904,15 @@ void IdentifyBuiltIns(sh::GLenum type,
                                        TType(EbtUInt, EbpUndefined, EvqGlobalInvocationID, 3));
             symbolTable.insertVariable(ESSL3_1_BUILTINS, "gl_LocalInvocationIndex",
                                        TType(EbtUInt, EbpUndefined, EvqLocalInvocationIndex, 1));
+            break;
         }
-        break;
 
         case GL_GEOMETRY_SHADER_OES:
             // TODO(jiawei.shao@intel.com): add Geometry Shader built-in variables.
             break;
 
         default:
-            assert(false && "Language not supported");
+            UNREACHABLE();
     }
 }
 

src/compiler/translator/IntermNode_util.cpp

@@ -193,7 +193,7 @@ TIntermSymbol *ReferenceBuiltInVariable(const TString &name,
                                         int shaderVersion)
 {
     const TVariable *var =
-        reinterpret_cast<const TVariable *>(symbolTable.findBuiltIn(name, shaderVersion));
+        reinterpret_cast<const TVariable *>(symbolTable.findBuiltIn(name, shaderVersion, true));
     ASSERT(var);
     return new TIntermSymbol(var->getUniqueId(), name, var->getType());
 }

src/compiler/translator/IntermNode_util.h

@@ -35,7 +35,10 @@ TIntermConstantUnion *CreateBoolNode(bool value);
 // If the input node is not a block node, put it inside a block node and return that.
 TIntermBlock *EnsureBlock(TIntermNode *node);
 
+// Should be called from inside Compiler::compileTreeImpl() where the global level is in scope.
 TIntermSymbol *ReferenceGlobalVariable(const TString &name, const TSymbolTable &symbolTable);
+
+// Note: this can access desktop GLSL built-ins that are hidden from the parser.
 TIntermSymbol *ReferenceBuiltInVariable(const TString &name,
                                         const TSymbolTable &symbolTable,
                                         int shaderVersion);

src/compiler/translator/SymbolTable.cpp

@@ -141,6 +141,8 @@ TSymbol *TSymbolTable::find(const TString &name,
 
     do
     {
+        if (level == GLSL_BUILTINS)
+            level--;
         if (level == ESSL3_1_BUILTINS && shaderVersion != 310)
             level--;
         if (level == ESSL3_BUILTINS && shaderVersion < 300)
@@ -167,8 +169,17 @@ TSymbol *TSymbolTable::findGlobal(const TString &name) const
 
 TSymbol *TSymbolTable::findBuiltIn(const TString &name, int shaderVersion) const
 {
+    return findBuiltIn(name, shaderVersion, false);
+}
+
+TSymbol *TSymbolTable::findBuiltIn(const TString &name,
+                                   int shaderVersion,
+                                   bool includeGLSLBuiltins) const
+{
     for (int level = LAST_BUILTIN_LEVEL; level >= 0; level--)
     {
+        if (level == GLSL_BUILTINS && !includeGLSLBuiltins)
+            level--;
         if (level == ESSL3_1_BUILTINS && shaderVersion != 310)
             level--;
         if (level == ESSL3_BUILTINS && shaderVersion < 300)
@@ -182,7 +193,7 @@ TSymbol *TSymbolTable::findBuiltIn(const TString &name, int shaderVersion) const
             return symbol;
     }
 
-    return 0;
+    return nullptr;
 }
 
 TSymbolTable::~TSymbolTable()

src/compiler/translator/SymbolTable.h

@@ -292,8 +292,11 @@ const int COMMON_BUILTINS    = 0;
 const int ESSL1_BUILTINS     = 1;
 const int ESSL3_BUILTINS     = 2;
 const int ESSL3_1_BUILTINS   = 3;
-const int LAST_BUILTIN_LEVEL = ESSL3_1_BUILTINS;
-const int GLOBAL_LEVEL       = 4;
+// GLSL_BUILTINS are desktop GLSL builtins that don't exist in ESSL but are used to implement
+// features in ANGLE's GLSL backend. They're not visible to the parser.
+const int GLSL_BUILTINS      = 4;
+const int LAST_BUILTIN_LEVEL = GLSL_BUILTINS;
+const int GLOBAL_LEVEL       = 5;
 
 class TSymbolTable : angle::NonCopyable
 {
@@ -454,6 +457,8 @@ class TSymbolTable : angle::NonCopyable
 
     TSymbol *findBuiltIn(const TString &name, int shaderVersion) const;
 
+    TSymbol *findBuiltIn(const TString &name, int shaderVersion, bool includeGLSLBuiltins) const;
+
     TSymbolTableLevel *getOuterLevel()
     {
         assert(currentLevel() >= 1);

src/tests/compiler_tests/ShaderValidation_test.cpp

@@ -4401,3 +4401,20 @@ TEST_F(FragmentShaderValidationTest, RedefinedParamInFunctionHeader)
         FAIL() << "Shader compilation succeeded, expecting failure:\n" << mInfoLog;
     }
 }
+
+// Test that using gl_ViewportIndex is not allowed in an ESSL 3.10 shader.
+TEST_F(VertexShaderValidationTest, ViewportIndexInESSL310)
+{
+    const std::string &shaderString =
+        "#version 310 es\n"
+        "precision mediump float;\n"
+        "void main()\n"
+        "{\n"
+        "    gl_Position = vec4(gl_ViewportIndex);\n"
+        "}\n";
+
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure:\n" << mInfoLog;
+    }
+}