Validate global initializer qualifiers

src/compiler.gypi

@@ -99,6 +99,8 @@
             'compiler/translator/Types.h',
             'compiler/translator/UnfoldShortCircuitAST.cpp',
             'compiler/translator/UnfoldShortCircuitAST.h',
+            'compiler/translator/ValidateGlobalInitializer.cpp',
+            'compiler/translator/ValidateGlobalInitializer.h',
             'compiler/translator/ValidateLimitations.cpp',
             'compiler/translator/ValidateLimitations.h',
             'compiler/translator/ValidateOutputs.cpp',

src/compiler/translator/ParseContext.cpp

@@ -12,6 +12,7 @@
 #include "compiler/preprocessor/SourceLocation.h"
 #include "compiler/translator/glslang.h"
 #include "compiler/translator/ValidateSwitch.h"
+#include "compiler/translator/ValidateGlobalInitializer.h"
 #include "compiler/translator/util.h"
 
 ///////////////////////////////////////////////////////////////////////
@@ -1110,6 +1111,20 @@ bool TParseContext::executeInitializer(const TSourceLoc &line, const TString &id
         return true;
     }
 
+    bool globalInitWarning = false;
+    if (symbolTable.atGlobalLevel() && !ValidateGlobalInitializer(initializer, this, &globalInitWarning))
+    {
+        // Error message does not completely match behavior with ESSL 1.00, but
+        // we want to steer developers towards only using constant expressions.
+        error(line, "global variable initializers must be constant expressions", "=");
+        return true;
+    }
+    if (globalInitWarning)
+    {
+        warning(line, "global variable initializers should be constant expressions "
+                "(uniforms and globals are allowed in global initializers for legacy compatibility)", "=");
+    }
+
     //
     // identifier must be of type constant, a global, or a temporary
     //

src/compiler/translator/ValidateGlobalInitializer.cpp

+//
+// Copyright (c) 2002-2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+#include "compiler/translator/ValidateGlobalInitializer.h"
+
+#include "compiler/translator/ParseContext.h"
+
+namespace
+{
+
+class ValidateGlobalInitializerTraverser : public TIntermTraverser
+{
+  public:
+    ValidateGlobalInitializerTraverser(const TParseContext *context);
+
+    void visitSymbol(TIntermSymbol *node) override;
+
+    bool isValid() const { return mIsValid; }
+    bool issueWarning() const { return mIssueWarning; }
+
+  private:
+    const TParseContext *mContext;
+    bool mIsValid;
+    bool mIssueWarning;
+};
+
+void ValidateGlobalInitializerTraverser::visitSymbol(TIntermSymbol *node)
+{
+    const TSymbol *sym = mContext->symbolTable.find(node->getSymbol(), mContext->getShaderVersion());
+    if (sym->isVariable())
+    {
+        // ESSL 1.00 section 4.3 (or ESSL 3.00 section 4.3):
+        // Global initializers must be constant expressions.
+        const TVariable *var = static_cast<const TVariable *>(sym);
+        switch (var->getType().getQualifier())
+        {
+          case EvqConst:
+            break;
+          case EvqGlobal:
+          case EvqTemporary:
+          case EvqUniform:
+            // We allow these cases to be compatible with legacy ESSL 1.00 content.
+            // Implement stricter rules for ESSL 3.00 since there's no legacy content to deal with.
+            if (mContext->getShaderVersion() >= 300)
+            {
+                mIsValid = false;
+            }
+            else
+            {
+                mIssueWarning = true;
+            }
+            break;
+          default:
+            mIsValid = false;
+        }
+    }
+}
+
+ValidateGlobalInitializerTraverser::ValidateGlobalInitializerTraverser(const TParseContext *context)
+    : TIntermTraverser(true, false, false),
+      mContext(context),
+      mIsValid(true),
+      mIssueWarning(false)
+{
+}
+
+} // namespace
+
+bool ValidateGlobalInitializer(TIntermTyped *initializer, const TParseContext *context, bool *warning)
+{
+    ValidateGlobalInitializerTraverser validate(context);
+    initializer->traverse(&validate);
+    ASSERT(warning != nullptr);
+    *warning = validate.issueWarning();
+    return validate.isValid();
+}
+

src/compiler/translator/ValidateGlobalInitializer.h

+//
+// Copyright (c) 2002-2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+#ifndef COMPILER_TRANSLATOR_VALIDATEGLOBALINITIALIZER_H_
+#define COMPILER_TRANSLATOR_VALIDATEGLOBALINITIALIZER_H_
+
+class TIntermTyped;
+struct TParseContext;
+
+// Returns true if the initializer is valid.
+bool ValidateGlobalInitializer(TIntermTyped *initializer, const TParseContext *context, bool *warning);
+
+#endif // COMPILER_TRANSLATOR_VALIDATEGLOBALINITIALIZER_H_

src/tests/compiler_tests/MalformedShader_test.cpp

@@ -42,6 +42,11 @@ class MalformedShaderTest : public testing::Test
         return compilationSuccess;
     }
 
+    bool hasWarning() const
+    {
+        return mInfoLog.find("WARNING: ") != std::string::npos;
+    }
+
   protected:
     std::string mInfoLog;
 
@@ -441,3 +446,102 @@ TEST_F(MalformedShaderTest, AssignArrayLengthToUnsigned)
         FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
     }
 }
+
+// Global variable initializers need to be constant expressions (ESSL 1.00 section 4.3)
+// Initializing with a varying should be an error.
+TEST_F(MalformedShaderTest, AssignVaryingToGlobal)
+{
+    const std::string &shaderString =
+        "precision mediump float;\n"
+        "varying float a;\n"
+        "float b = a * 2.0;\n"
+        "void main() {\n"
+        "   gl_FragColor = vec4(b);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}
+
+// Global variable initializers need to be constant expressions (ESSL 3.00 section 4.3)
+// Initializing with an uniform should be an error.
+TEST_F(MalformedShaderTest, AssignUniformToGlobalESSL3)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "uniform float a;\n"
+        "float b = a * 2.0;\n"
+        "out vec4 my_FragColor;\n"
+        "void main() {\n"
+        "   my_FragColor = vec4(b);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}
+
+// Global variable initializers need to be constant expressions (ESSL 1.00 section 4.3)
+// Initializing with an uniform should generate a warning
+// (we don't generate an error on ESSL 1.00 because of legacy compatibility)
+TEST_F(MalformedShaderTest, AssignUniformToGlobalESSL1)
+{
+    const std::string &shaderString =
+        "precision mediump float;\n"
+        "uniform float a;\n"
+        "float b = a * 2.0;\n"
+        "void main() {\n"
+        "   gl_FragColor = vec4(b);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        if (!hasWarning())
+        {
+            FAIL() << "Shader compilation succeeded without warnings, expecting warning " << mInfoLog;
+        }
+    }
+    else
+    {
+        FAIL() << "Shader compilation failed, expecting success with warning " << mInfoLog;
+    }
+}
+
+// Global variable initializers need to be constant expressions (ESSL 3.00 section 4.3)
+// Initializing with a non-constant global should be an error.
+TEST_F(MalformedShaderTest, AssignNonConstGlobalToGlobal)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "float a = 1.0;\n"
+        "float b = a * 2.0;\n"
+        "out vec4 my_FragColor;\n"
+        "void main() {\n"
+        "   my_FragColor = vec4(b);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}
+
+// Global variable initializers need to be constant expressions (ESSL 3.00 section 4.3)
+// Initializing with a constant global should be fine.
+TEST_F(MalformedShaderTest, AssignConstGlobalToGlobal)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "const float a = 1.0;\n"
+        "float b = a * 2.0;\n"
+        "out vec4 my_FragColor;\n"
+        "void main() {\n"
+        "   my_FragColor = vec4(b);\n"
+        "}\n";
+    if (!compile(shaderString))
+    {
+        FAIL() << "Shader compilation failed, expecting success " << mInfoLog;
+    }
+}