commit e708fc023362f7d66a59795d467486e41f0fcffa
author Jamie Madill <jmadill@chromium.org> Mon Mar 17 10:23:18 2014 -0400
committer Jamie Madill <jmadill@chromium.org> Tue Mar 18 13:50:26 2014 +0000
tree b0202ea2b2602ea01c5b675684c3604d13b9ed55
parent 0c66720a14bb41c9161874b8940675616703ef40

Only use map-write instead of map-write-discard.

In D3D11, map-discard is reserved for DYNAMIC usage buffer,
which are resources that live on the GPU. Staging buffers
don't have the notion of map-discard, and using them with
discard gives a D3D11 error.

This patch fixes crashes in dEQP buffer.map.write.invalidate.

BUG=angle:587

Change-Id: Ie225e72d4e226c69e73826c9fb67bbb940bbc466
Reviewed-on: https://chromium-review.googlesource.com/190072
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>

src/libGLESv2/renderer/d3d11/BufferStorage11.cpp

diff --git a/src/libGLESv2/renderer/d3d11/BufferStorage11.cpp b/src/libGLESv2/renderer/d3d11/BufferStorage11.cpp
index 2429696..86b8e30 100644
--- a/src/libGLESv2/renderer/d3d11/BufferStorage11.cpp
+++ b/src/libGLESv2/renderer/d3d11/BufferStorage11.cpp
@@ -22,18 +22,19 @@
 {
     bool readBit = ((access & GL_MAP_READ_BIT) != 0);
     bool writeBit = ((access & GL_MAP_WRITE_BIT) != 0);
-    bool discardBit = ((access & (GL_MAP_INVALIDATE_BUFFER_BIT)) != 0);
 
-    ASSERT(!readBit || !discardBit);
     ASSERT(readBit || writeBit);
 
+    // Note : we ignore the discard bit, because in D3D11, staging buffers
+    //  don't accept the map-discard flag (discard only works for DYNAMIC usage)
+
     if (readBit && !writeBit)
     {
         return D3D11_MAP_READ;
     }
     else if (writeBit && !readBit)
     {
-        return (discardBit ? D3D11_MAP_WRITE_DISCARD : D3D11_MAP_WRITE);
+        return D3D11_MAP_WRITE;
     }
     else if (writeBit && readBit)
     {