Work around For and While loop bugs on Intel Mac OSX

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 160
+#define ANGLE_SH_VERSION 161
 
 typedef enum {
     SH_GLES2_SPEC,
@@ -195,6 +195,10 @@ const ShCompileOptions SH_HLSL_GET_DIMENSIONS_IGNORES_BASE_LEVEL = UINT64_C(1) <
 // INTEL drivers. It works by translating texelFetchOffset into texelFetch.
 const ShCompileOptions SH_REWRITE_TEXELFETCHOFFSET_TO_TEXELFETCH = UINT64_C(1) << 24;
 
+// This flag works around condition bug of for and while loops in Intel Mac OSX drivers.
+// Condition calculation is not correct. Rewrite it from "CONDITION" to "CONDITION && true".
+const ShCompileOptions SH_ADD_AND_TRUE_TO_LOOP_CONDITION = UINT64_C(1) << 25;
+
 // Defines alternate strategies for implementing array index clamping.
 typedef enum {
   // Use the clamp intrinsic for array index clamping.

src/compiler.gypi

@@ -22,6 +22,8 @@
             '../include/GLSLANG/ShaderVars.h',
             '../include/KHR/khrplatform.h',
             '../include/angle_gl.h',
+            'compiler/translator/AddAndTrueToLoopCondition.cpp',
+            'compiler/translator/AddAndTrueToLoopCondition.h',
             'compiler/translator/BaseTypes.h',
             'compiler/translator/BuiltInFunctionEmulator.cpp',
             'compiler/translator/BuiltInFunctionEmulator.h',

src/compiler/translator/AddAndTrueToLoopCondition.cpp

+//
+// Copyright (c) 2016 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/AddAndTrueToLoopCondition.h"
+
+#include "compiler/translator/IntermNode.h"
+
+namespace sh
+{
+
+namespace
+{
+
+// An AST traverser that rewrites for and while loops by replacing "condition" with
+// "condition && true" to work around condition bug on Intel Mac.
+class AddAndTrueToLoopConditionTraverser : public TIntermTraverser
+{
+  public:
+    AddAndTrueToLoopConditionTraverser() : TIntermTraverser(true, false, false) {}
+
+    bool visitLoop(Visit, TIntermLoop *loop) override
+    {
+        // do-while loop doesn't have this bug.
+        if (loop->getType() != ELoopFor && loop->getType() != ELoopWhile)
+        {
+            return true;
+        }
+
+        // For loop may not have a condition.
+        if (loop->getCondition() == nullptr)
+        {
+            return true;
+        }
+
+        // Constant true.
+        TConstantUnion *trueConstant = new TConstantUnion();
+        trueConstant->setBConst(true);
+        TIntermTyped *trueValue = new TIntermConstantUnion(trueConstant, TType(EbtBool));
+
+        // CONDITION && true.
+        TIntermBinary *andOp = new TIntermBinary(EOpLogicalAnd, loop->getCondition(), trueValue);
+        loop->setCondition(andOp);
+
+        return true;
+    }
+};
+
+}  // anonymous namespace
+
+void AddAndTrueToLoopCondition(TIntermNode *root)
+{
+    AddAndTrueToLoopConditionTraverser traverser;
+    root->traverse(&traverser);
+}
+
+}  // namespace sh

src/compiler/translator/AddAndTrueToLoopCondition.h

+//
+// Copyright (c) 2016 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.
+//
+
+// Rewrite condition in for and while loops to work around driver bug on Intel Mac.
+
+#ifndef COMPILER_TRANSLATOR_ADDANDTRUETOLOOPCONDITION_H_
+#define COMPILER_TRANSLATOR_ADDANDTRUETOLOOPCONDITION_H_
+
+class TIntermNode;
+namespace sh
+{
+
+void AddAndTrueToLoopCondition(TIntermNode *root);
+
+}  // namespace sh
+
+#endif  // COMPILER_TRANSLATOR_ADDANDTRUETOLOOPCONDITION_H_

src/compiler/translator/Compiler.cpp

@@ -4,6 +4,7 @@
 // found in the LICENSE file.
 //
 
+#include "compiler/translator/AddAndTrueToLoopCondition.h"
 #include "compiler/translator/Cache.h"
 #include "compiler/translator/Compiler.h"
 #include "compiler/translator/CallDAG.h"
@@ -331,6 +332,9 @@ TIntermNode *TCompiler::compileTreeImpl(const char *const shaderStrings[],
         if (success && (compileOptions & SH_REWRITE_DO_WHILE_LOOPS))
             RewriteDoWhile(root, getTemporaryIndex());
 
+        if (success && (compileOptions & SH_ADD_AND_TRUE_TO_LOOP_CONDITION))
+            sh::AddAndTrueToLoopCondition(root);
+
         if (success && (compileOptions & SH_UNFOLD_SHORT_CIRCUIT))
         {
             UnfoldShortCircuitAST unfoldShortCircuit;

src/libANGLE/renderer/gl/ShaderGL.cpp

@@ -55,6 +55,16 @@ ShCompileOptions ShaderGL::prepareSourceAndReturnOptions(std::stringstream *sour
         options |= SH_REWRITE_DO_WHILE_LOOPS;
     }
 
+    if (mWorkarounds.emulateAbsIntFunction)
+    {
+        options |= SH_EMULATE_ABS_INT_FUNCTION;
+    }
+
+    if (mWorkarounds.addAndTrueToLoopCondition)
+    {
+        options |= SH_ADD_AND_TRUE_TO_LOOP_CONDITION;
+    }
+
     return options;
 }
 

src/libANGLE/renderer/gl/WorkaroundsGL.h

@@ -21,7 +21,9 @@ struct WorkaroundsGL
           doWhileGLSLCausesGPUHang(false),
           finishDoesNotCauseQueriesToBeAvailable(false),
           alwaysCallUseProgramAfterLink(false),
-          unpackOverlappingRowsSeparatelyUnpackBuffer(false)
+          unpackOverlappingRowsSeparatelyUnpackBuffer(false),
+          emulateAbsIntFunction(false),
+          addAndTrueToLoopCondition(false)
     {
     }
 
@@ -70,6 +72,14 @@ struct WorkaroundsGL
 
     // During initialization, assign the current vertex attributes to the spec-mandated defaults.
     bool initializeCurrentVertexAttributes;
+
+    // abs(i) where i is an integer returns unexpected result on Intel Mac.
+    // Emulate abs(i) with i * sign(i).
+    bool emulateAbsIntFunction;
+
+    // On Intel Mac, calculation of loop conditions in for and while loop has bug.
+    // Add "&& true" to the end of the condition expression to work around the bug.
+    bool addAndTrueToLoopCondition;
 };
 }
 

src/libANGLE/renderer/gl/renderergl_utils.cpp

@@ -881,6 +881,10 @@ void GenerateWorkarounds(const FunctionsGL *functions, WorkaroundsGL *workaround
     workarounds->rgba4IsNotSupportedForColorRendering =
         functions->standard == STANDARD_GL_DESKTOP && vendor == VENDOR_ID_INTEL;
 
+    workarounds->emulateAbsIntFunction = vendor == VENDOR_ID_INTEL;
+
+    workarounds->addAndTrueToLoopCondition = vendor == VENDOR_ID_INTEL;
+
     workarounds->doesSRGBClearsOnLinearFramebufferAttachments =
         functions->standard == STANDARD_GL_DESKTOP &&
         (vendor == VENDOR_ID_INTEL || vendor == VENDOR_ID_AMD);