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>
diff --git a/src/compiler/translator/RemovePow.h b/src/compiler/translator/RemovePow.h
new file mode 100644
index 0000000..40f9d67
--- /dev/null
+++ b/src/compiler/translator/RemovePow.h
@@ -0,0 +1,18 @@
+//
+// 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.
+//
+// RemovePow is an AST traverser to convert pow(x, y) built-in calls where y is a
+// constant to exp2(y * log2(x)). This works around an issue in NVIDIA 311 series
+// OpenGL drivers.
+//
+
+#ifndef COMPILER_TRANSLATOR_REMOVEPOW_H_
+#define COMPILER_TRANSLATOR_REMOVEPOW_H_
+
+class TIntermNode;
+
+void RemovePow(TIntermNode *root);
+
+#endif // COMPILER_TRANSLATOR_REMOVEPOW_H_