commit 5c407bb7c90acabe3d2c85666ba00ad07dcb31ba
author Olli Etuaho <oetuaho@nvidia.com> Mon Jun 01 12:20:39 2015 +0300
committer Olli Etuaho <oetuaho@nvidia.com> Tue Jun 02 10:40:42 2015 +0000
tree 797fae52e5ded5924167351c81f26e513f03a25b
parent 6bef4ff7e9eeaf3a3b5058dbc8f156735c25ce93

Work around pow() issue in NVIDIA 331.x drivers

pow(x, y) when y is a certain kind of a constant vector can cause issues on
NVIDIA 331 series drivers. Add an option to replace pow(x, y) with
exp2(y * log2(x)) when y is a constant to work around this issue.

This is done with an AST traverser instead of BuiltInFunctionEmulator, since
there's no mechanism in BuiltInFunctionEmulator to apply the replacements
only to calls where the second parameter is constant.

TEST=WebGL conformance tests
BUG=chromium:477306

Change-Id: Ifb327d72659fca36868439f24705203014b3ce53
Reviewed-on: https://chromium-review.googlesource.com/274279
Tested-by: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>

src/compiler/translator/Compiler.cpp

diff --git a/src/compiler/translator/Compiler.cpp b/src/compiler/translator/Compiler.cpp
index 721e297..911a8f2 100644
--- a/src/compiler/translator/Compiler.cpp
+++ b/src/compiler/translator/Compiler.cpp
@@ -13,6 +13,7 @@
 #include "compiler/translator/ParseContext.h"
 #include "compiler/translator/PruneEmptyDeclarations.h"
 #include "compiler/translator/RegenerateStructNames.h"
+#include "compiler/translator/RemovePow.h"
 #include "compiler/translator/RenameFunction.h"
 #include "compiler/translator/ScalarizeVecAndMatConstructorArgs.h"
 #include "compiler/translator/UnfoldShortCircuitAST.h"
@@ -312,6 +313,11 @@
             unfoldShortCircuit.updateTree();
         }
 
+        if (success && (compileOptions & SH_REMOVE_POW_WITH_CONSTANT_EXPONENT))
+        {
+            RemovePow(root);
+        }
+
         if (success && (compileOptions & SH_VARIABLES))
         {
             collectVariables(root);