Use atomic operations to specify shared memory access order
TSAN detected many data race errors in the SwiftShader Renderer
class. x86 has a strong memory ordering model which guarantees
that changes are observed in the same order by other threads.
However, C++ does not provide such guarantees unless specified
using atomic operations. In order to fix these, a new AtomicInt
class was added which is a basically a wrapper class for
std::atomic<int> and which only exposes the portion of the API
required by SwiftShader.
Since std::atomic isn't available on older versions of Android,
a fallback class was implemented without using std::atomic, which
is closer to the previous implementation. Both classes appear to
work properly after performing a few dEQP tests. Both also perform
similarly.
A few minor changes were made in order to attempt to reduce the use
of atomic integer operations when possible.
Change-Id: Ife6d3a2b6113346f8f8163b692e79c2a0e03b22f
Reviewed-on: https://swiftshader-review.googlesource.com/12308
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/Renderer/Clipper.cpp b/src/Renderer/Clipper.cpp
index cfd859f..cf3fe3c 100644
--- a/src/Renderer/Clipper.cpp
+++ b/src/Renderer/Clipper.cpp
@@ -60,20 +60,21 @@
if(clipFlagsOr & CLIP_USER)
{
+ int clipFlags = draw.clipFlags;
DrawData &data = *draw.data;
if(polygon.n >= 3) {
- if(draw.clipFlags & CLIP_PLANE0) clipPlane(polygon, data.clipPlane[0]);
+ if(clipFlags & CLIP_PLANE0) clipPlane(polygon, data.clipPlane[0]);
if(polygon.n >= 3) {
- if(draw.clipFlags & CLIP_PLANE1) clipPlane(polygon, data.clipPlane[1]);
+ if(clipFlags & CLIP_PLANE1) clipPlane(polygon, data.clipPlane[1]);
if(polygon.n >= 3) {
- if(draw.clipFlags & CLIP_PLANE2) clipPlane(polygon, data.clipPlane[2]);
+ if(clipFlags & CLIP_PLANE2) clipPlane(polygon, data.clipPlane[2]);
if(polygon.n >= 3) {
- if(draw.clipFlags & CLIP_PLANE3) clipPlane(polygon, data.clipPlane[3]);
+ if(clipFlags & CLIP_PLANE3) clipPlane(polygon, data.clipPlane[3]);
if(polygon.n >= 3) {
- if(draw.clipFlags & CLIP_PLANE4) clipPlane(polygon, data.clipPlane[4]);
+ if(clipFlags & CLIP_PLANE4) clipPlane(polygon, data.clipPlane[4]);
if(polygon.n >= 3) {
- if(draw.clipFlags & CLIP_PLANE5) clipPlane(polygon, data.clipPlane[5]);
+ if(clipFlags & CLIP_PLANE5) clipPlane(polygon, data.clipPlane[5]);
}}}}}}
}
