Fix sign-correcting of masked stencil reference.

The stencil test compares the unsigned masked reference value against the unsigned masked stencil value. But because x86 vector instructions only support signed comparison, we have to add 0x80 to both sides. However, this offset was incorrectly added before the masking. Bug b/64683344 Change-Id: I49748e25d8d99e1c2b3c87d3dbe74a9dba75fb1c Reviewed-on: https://swiftshader-review.googlesource.com/12028Tested-by: Nicolas Capens <nicolascapens@google.com> Reviewed-by: Alexis Hétu <sugoi@google.com> Reviewed-by: Nicolas Capens <nicolascapens@google.com>

Fix sign-correcting of masked stencil reference.
a28d04b2 · Nicolas Capens · Nicolas Capens · 660eba9a · a28d04b2
Commit a28d04b2 authored Sep 11, 2017 by Nicolas Capens Committed by Nicolas Capens Sep 11, 2017
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PixelProcessor.hpp src/Renderer/PixelProcessor.hpp +1 -1

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--- a/src/Renderer/PixelProcessor.hpp
+++ b/src/Renderer/PixelProcessor.hpp
@@ -149,7 +149,7 @@ namespace sw
 				writeMaskQ = replicate(writeMask);
 				invWriteMaskQ = ~writeMaskQ;
 				referenceMaskedQ = referenceQ & testMaskQ;
-				referenceMaskedSignedQ = replicate((reference + 0x80) & 0xFF & testMask);
+				referenceMaskedSignedQ = replicate(((reference & testMask) + 0x80) & 0xFF);
 			}

 			static int64_t replicate(int b)