commit 85769f0d6133c034bce3bb6d5eb490da8e024f9b
author Jinyoung Hur <hurims@gmail.com> Tue Oct 20 17:08:44 2015 -0400
committer Jamie Madill <jmadill@chromium.org> Wed Oct 21 14:14:18 2015 +0000
tree d9343742dab98904d35accd0a6147a6c6be70f99
parent 1220bbbd564adcf82df042318006831efeec4502

Re-land "Only require that the stencil masks are same as many effective bits set"

It seems reasonable to validate the equality between stencilWriteMask
and stencilBackWriteMask only by comparing the effective bits.
An existing dEQP test[1] and a WebGL test[2] also use the max size of
stencil bits for checking the stencil mask values.

[1] StencilWriteMaskSeparateTestCase (gles3/functional/
es3fIntegerStateQueryTests.cpp)
[2] https://www.khronos.org/registry/webgl/sdk/tests/conformance/state/
gl-get-calls.html (Search for "minimumRequiredStencilMask ")

Re-land with fix for Clang warning.

Change-Id: I4cadaffced04ca55fa6daf7ac6a462368e0cfeec
Reviewed-on: https://chromium-review.googlesource.com/307530
Reviewed-by: Jinyoung Hur <hurims@gmail.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>

src/libANGLE/validationES.cpp

diff --git a/src/libANGLE/validationES.cpp b/src/libANGLE/validationES.cpp
index 7ee2183..8a59c06 100644
--- a/src/libANGLE/validationES.cpp
+++ b/src/libANGLE/validationES.cpp
@@ -1500,10 +1500,16 @@
 
     if (context->getLimitations().noSeparateStencilRefsAndMasks)
     {
-        const gl::DepthStencilState &depthStencilState = state.getDepthStencilState();
-        if (depthStencilState.stencilWritemask != depthStencilState.stencilBackWritemask ||
+        const Framebuffer *framebuffer             = context->getState().getDrawFramebuffer();
+        const FramebufferAttachment *stencilBuffer = framebuffer->getStencilbuffer();
+        GLuint stencilBits                         = stencilBuffer ? stencilBuffer->getStencilSize() : 0;
+        GLuint minimumRequiredStencilMask          = (1 << stencilBits) - 1;
+        const DepthStencilState &depthStencilState = state.getDepthStencilState();
+        if ((depthStencilState.stencilWritemask & minimumRequiredStencilMask) !=
+                (depthStencilState.stencilBackWritemask & minimumRequiredStencilMask) ||
             state.getStencilRef() != state.getStencilBackRef() ||
-            depthStencilState.stencilMask != depthStencilState.stencilBackMask)
+            (depthStencilState.stencilMask & minimumRequiredStencilMask) !=
+                (depthStencilState.stencilBackMask & minimumRequiredStencilMask))
         {
             // Note: these separate values are not supported in WebGL, due to D3D's limitations. See
             // Section 6.10 of the WebGL 1.0 spec