Fix initializing bits after bitfields

SpirvShader::InterfaceComponent is used as part of the state that comprises the lookup key for cached Reactor routines. It uses 1-bit bitfields for Boolean values, and the bits following it for padding may be left uninitialized by the compiler. Computing the hash of all the state is done by XORing together the memory, so it shouldn't have any- thing uninitialized. While we memset all of SetupProcessor::State to 0, the InterfaceComponent state copied in still contained the uninitialized bits. Computing a hash from it was detected by MemorySanitizer. Bug chromium:967824 Change-Id: If1676831fc838bf2a6ca869d13e6f6d2052fa6d8 Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/32128 Presubmit-Ready: Nicolas Capens <nicolascapens@google.com> Kokoro-Presubmit: kokoro <noreply+kokoro@google.com> Tested-by: Nicolas Capens <nicolascapens@google.com> Reviewed-by: Alexis Hétu <sugoi@google.com> Reviewed-by: Sean Risser <srisser@google.com>

Fix initializing bits after bitfields
9555830f · Nicolas Capens · Nicolas Capens · 9b627525 · 9555830f
Commit 9555830f authored May 29, 2019 by Nicolas Capens Committed by Nicolas Capens May 29, 2019
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Showing with 13 additions and 4 deletions

SpirvShader.hpp src/Pipeline/SpirvShader.hpp +13 -4

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--- a/src/Pipeline/SpirvShader.hpp
+++ b/src/Pipeline/SpirvShader.hpp
@@ -656,12 +656,21 @@ namespace sw
 		struct InterfaceComponent
 		{
 			AttribType Type;
-			bool Flat : 1;
-			bool Centroid : 1;
+			union
-			bool NoPerspective : 1;
+			{
+				struct
+				{
+					bool Flat : 1;
+					bool Centroid : 1;
+					bool NoPerspective : 1;
+				};
+				uint8_t DecorationBits;
+			};
 			InterfaceComponent()
-					: Type{ATTRIBTYPE_UNUSED}, Flat{false}, Centroid{false}, NoPerspective{false}
+				: Type{ATTRIBTYPE_UNUSED}, DecorationBits{0}
 			{
 			}
 		};