Add a zero-filled scratch buffer to Context.

src/common/MemoryBuffer.cpp

@@ -108,6 +108,20 @@ ScratchBuffer::~ScratchBuffer()
 
 bool ScratchBuffer::get(size_t requestedSize, MemoryBuffer **memoryBufferOut)
 {
+    return getImpl(requestedSize, memoryBufferOut, Optional<uint8_t>::Invalid());
+}
+
+bool ScratchBuffer::getInitialized(size_t requestedSize,
+                                   MemoryBuffer **memoryBufferOut,
+                                   uint8_t initValue)
+{
+    return getImpl(requestedSize, memoryBufferOut, Optional<uint8_t>(initValue));
+}
+
+bool ScratchBuffer::getImpl(size_t requestedSize,
+                            MemoryBuffer **memoryBufferOut,
+                            Optional<uint8_t> initValue)
+{
     if (mScratchMemory.size() == requestedSize)
     {
         mResetCounter    = mLifetime;
@@ -128,6 +142,10 @@ bool ScratchBuffer::get(size_t requestedSize, MemoryBuffer **memoryBufferOut)
             return false;
         }
         mResetCounter = mLifetime;
+        if (initValue.valid())
+        {
+            mScratchMemory.fill(initValue.value());
+        }
     }
 
     ASSERT(mScratchMemory.size() >= requestedSize);

src/common/MemoryBuffer.h

@@ -7,6 +7,7 @@
 #ifndef COMMON_MEMORYBUFFER_H_
 #define COMMON_MEMORYBUFFER_H_
 
+#include "common/Optional.h"
 #include "common/angleutils.h"
 
 #include <stdint.h>
@@ -50,12 +51,17 @@ class ScratchBuffer final : NonCopyable
     // Returns true with a memory buffer of the requested size, or false on failure.
     bool get(size_t requestedSize, MemoryBuffer **memoryBufferOut);
 
+    // Same as get, but ensures new values are initialized to a fixed constant.
+    bool getInitialized(size_t requestedSize, MemoryBuffer **memoryBufferOut, uint8_t initValue);
+
     // Ticks the release counter for the scratch buffer. Also done implicitly in get().
     void tick();
 
     void clear();
 
   private:
+    bool getImpl(size_t requestedSize, MemoryBuffer **memoryBufferOut, Optional<uint8_t> initValue);
+
     const uint32_t mLifetime;
     uint32_t mResetCounter;
     MemoryBuffer mScratchMemory;

src/libANGLE/Buffer.cpp

@@ -75,8 +75,7 @@ Error Buffer::bufferData(const Context *context,
     if (context && context->getGLState().isRobustResourceInitEnabled() && !data && size > 0)
     {
         angle::MemoryBuffer *scratchBuffer = nullptr;
-        ANGLE_TRY(context->getScratchBuffer(static_cast<size_t>(size), &scratchBuffer));
-        std::fill(scratchBuffer->data(), scratchBuffer->data() + size, static_cast<uint8_t>(0));
+        ANGLE_TRY(context->getZeroFilledBuffer(static_cast<size_t>(size), &scratchBuffer));
         dataForImpl = scratchBuffer->data();
     }
 

src/libANGLE/Context.cpp

@@ -272,7 +272,8 @@ Context::Context(rx::EGLImplFactory *implFactory,
       mSurfacelessFramebuffer(nullptr),
       mWebGLContext(GetWebGLContext(attribs)),
       mMemoryProgramCache(memoryProgramCache),
-      mScratchBuffer(1000u)
+      mScratchBuffer(1000u),
+      mZeroFilledBuffer(1000u)
 {
     if (mRobustAccess)
     {
@@ -4171,9 +4172,20 @@ void Context::setFramebufferParameteri(GLenum target, GLenum pname, GLint param)
     SetFramebufferParameteri(framebuffer, pname, param);
 }
 
-Error Context::getScratchBuffer(size_t requestedSize, angle::MemoryBuffer **scratchBufferOut) const
+Error Context::getScratchBuffer(size_t requstedSizeBytes,
+                                angle::MemoryBuffer **scratchBufferOut) const
 {
-    if (!mScratchBuffer.get(requestedSize, scratchBufferOut))
+    if (!mScratchBuffer.get(requstedSizeBytes, scratchBufferOut))
+    {
+        return OutOfMemory() << "Failed to allocate internal buffer.";
+    }
+    return NoError();
+}
+
+Error Context::getZeroFilledBuffer(size_t requstedSizeBytes,
+                                   angle::MemoryBuffer **zeroBufferOut) const
+{
+    if (!mZeroFilledBuffer.getInitialized(requstedSizeBytes, zeroBufferOut, 0))
     {
         return OutOfMemory() << "Failed to allocate internal buffer.";
     }

src/libANGLE/Context.h

@@ -793,7 +793,8 @@ class Context final : public ValidationContext
     void getFramebufferParameteriv(GLenum target, GLenum pname, GLint *params);
     void setFramebufferParameteri(GLenum target, GLenum pname, GLint param);
 
-    Error getScratchBuffer(size_t requestedSize, angle::MemoryBuffer **scratchBufferOut) const;
+    Error getScratchBuffer(size_t requestedSizeBytes, angle::MemoryBuffer **scratchBufferOut) const;
+    Error getZeroFilledBuffer(size_t requstedSizeBytes, angle::MemoryBuffer **zeroBufferOut) const;
 
     void dispatchCompute(GLuint numGroupsX, GLuint numGroupsY, GLuint numGroupsZ);
 
@@ -915,6 +916,7 @@ class Context final : public ValidationContext
 
     // Not really a property of context state. The size and contexts change per-api-call.
     mutable angle::ScratchBuffer mScratchBuffer;
+    mutable angle::ScratchBuffer mZeroFilledBuffer;
 };
 
 template <EntryPoint EP, typename... ArgsT>

src/libANGLE/renderer/d3d/TextureD3D.cpp

@@ -888,9 +888,8 @@ gl::Error TextureD3D_2D::copyImage(const gl::Context *context,
         !mRenderer->isRobustResourceInitEnabled())
     {
         angle::MemoryBuffer *zero;
-        ANGLE_TRY(context->getScratchBuffer(
+        ANGLE_TRY(context->getZeroFilledBuffer(
             origSourceArea.width * origSourceArea.height * internalFormatInfo.pixelBytes, &zero));
-        zero->fill(0);
         setImage(context, target, imageLevel, internalFormat, sourceExtents,
                  internalFormatInfo.format, internalFormatInfo.type, gl::PixelUnpackState(1, 0),
                  zero->data());

src/libANGLE/renderer/gl/TextureGL.cpp

@@ -575,9 +575,8 @@ gl::Error TextureGL::copyImage(const gl::Context *context,
         GLuint pixelBytes =
             gl::GetInternalFormatInfo(copyTexImageFormat.internalFormat, type).pixelBytes;
         angle::MemoryBuffer *zero;
-        ANGLE_TRY(context->getScratchBuffer(
+        ANGLE_TRY(context->getZeroFilledBuffer(
             origSourceArea.width * origSourceArea.height * pixelBytes, &zero));
-        zero->fill(0);
         mStateManager->setPixelUnpackState(gl::PixelUnpackState(1, 0));
         mFunctions->texImage2D(target, static_cast<GLint>(level), copyTexImageFormat.internalFormat,
                                origSourceArea.width, origSourceArea.height, 0,