Merge commit '50d3e596bbe89c95615f96eb71f6bc5be737a1db' into Basilisk-releasev2018.07.18

# Conflicts:
#	browser/app/profile/firefox.js
#	browser/components/preferences/jar.mn

1 files changed, 119 insertions, 241 deletions

diff --git a/gfx/angle/src/libANGLE/renderer/d3d/d3d11/Buffer11.cpp b/gfx/angle/src/libANGLE/renderer/d3d/d3d11/Buffer11.cpp
index 90668b759..107a577e4 100755
--- a/gfx/angle/src/libANGLE/renderer/d3d/d3d11/Buffer11.cpp
+++ b/gfx/angle/src/libANGLE/renderer/d3d/d3d11/Buffer11.cpp
@@ -38,34 +38,12 @@ enum class CopyResult
     NOT_RECREATED,
 };
 
-void CalculateConstantBufferParams(GLintptr offset,
-                                   GLsizeiptr size,
-                                   UINT *outFirstConstant,
-                                   UINT *outNumConstants)
-{
-    // The offset must be aligned to 256 bytes (should have been enforced by glBindBufferRange).
-    ASSERT(offset % 256 == 0);
-
-    // firstConstant and numConstants are expressed in constants of 16-bytes. Furthermore they must
-    // be a multiple of 16 constants.
-    *outFirstConstant = static_cast<UINT>(offset / 16);
-
-    // The GL size is not required to be aligned to a 256 bytes boundary.
-    // Round the size up to a 256 bytes boundary then express the results in constants of 16-bytes.
-    *outNumConstants = static_cast<UINT>(rx::roundUp(size, static_cast<GLsizeiptr>(256)) / 16);
-
-    // Since the size is rounded up, firstConstant + numConstants may be bigger than the actual size
-    // of the buffer. This behaviour is explictly allowed according to the documentation on
-    // ID3D11DeviceContext1::PSSetConstantBuffers1
-    // https://msdn.microsoft.com/en-us/library/windows/desktop/hh404649%28v=vs.85%29.aspx
-}
-
 }  // anonymous namespace
 
 namespace gl_d3d11
 {
 
-D3D11_MAP GetD3DMapTypeFromBits(BufferUsage usage, GLbitfield access)
+D3D11_MAP GetD3DMapTypeFromBits(GLbitfield access)
 {
     bool readBit  = ((access & GL_MAP_READ_BIT) != 0);
     bool writeBit = ((access & GL_MAP_WRITE_BIT) != 0);
@@ -81,8 +59,7 @@ D3D11_MAP GetD3DMapTypeFromBits(BufferUsage usage, GLbitfield access)
     }
     else if (writeBit && !readBit)
     {
-        // Special case for uniform storage - we only allow full buffer updates.
-        return usage == BUFFER_USAGE_UNIFORM ? D3D11_MAP_WRITE_DISCARD : D3D11_MAP_WRITE;
+        return D3D11_MAP_WRITE;
     }
     else if (writeBit && readBit)
     {
@@ -111,7 +88,7 @@ class Buffer11::BufferStorage : angle::NonCopyable
     size_t getSize() const { return mBufferSize; }
     void setDataRevision(DataRevision rev) { mRevision = rev; }
 
-    virtual bool isMappable(GLbitfield access) const = 0;
+    virtual bool isMappable() const = 0;
 
     virtual gl::ErrorOrResult<CopyResult> copyFromStorage(BufferStorage *source,
                                                           size_t sourceOffset,
@@ -146,7 +123,7 @@ class Buffer11::NativeStorage : public Buffer11::BufferStorage
                   const angle::BroadcastChannel *onStorageChanged);
     ~NativeStorage() override;
 
-    bool isMappable(GLbitfield access) const override;
+    bool isMappable() const override { return mUsage == BUFFER_USAGE_STAGING; }
 
     ID3D11Buffer *getNativeStorage() const { return mNativeStorage; }
     gl::ErrorOrResult<CopyResult> copyFromStorage(BufferStorage *source,
@@ -161,18 +138,14 @@ class Buffer11::NativeStorage : public Buffer11::BufferStorage
                   uint8_t **mapPointerOut) override;
     void unmap() override;
 
-    gl::ErrorOrResult<ID3D11ShaderResourceView *> getSRVForFormat(DXGI_FORMAT srvFormat);
-
   private:
-    static void FillBufferDesc(D3D11_BUFFER_DESC *bufferDesc,
+    static void fillBufferDesc(D3D11_BUFFER_DESC *bufferDesc,
                                Renderer11 *renderer,
                                BufferUsage usage,
                                unsigned int bufferSize);
-    void clearSRVs();
 
     ID3D11Buffer *mNativeStorage;
     const angle::BroadcastChannel *mOnStorageChanged;
-    std::map<DXGI_FORMAT, ID3D11ShaderResourceView *> mBufferResourceViews;
 };
 
 // A emulated indexed buffer storage represents an underlying D3D11 buffer for data
@@ -184,7 +157,7 @@ class Buffer11::EmulatedIndexedStorage : public Buffer11::BufferStorage
     EmulatedIndexedStorage(Renderer11 *renderer);
     ~EmulatedIndexedStorage() override;
 
-    bool isMappable(GLbitfield access) const override { return true; }
+    bool isMappable() const override { return true; }
 
     gl::ErrorOrResult<ID3D11Buffer *> getNativeStorage(SourceIndexData *indexInfo,
                                                        const TranslatedAttribute &attribute,
@@ -217,7 +190,7 @@ class Buffer11::PackStorage : public Buffer11::BufferStorage
     explicit PackStorage(Renderer11 *renderer);
     ~PackStorage() override;
 
-    bool isMappable(GLbitfield access) const override { return true; }
+    bool isMappable() const override { return true; }
     gl::ErrorOrResult<CopyResult> copyFromStorage(BufferStorage *source,
                                                   size_t sourceOffset,
                                                   size_t size,
@@ -252,7 +225,7 @@ class Buffer11::SystemMemoryStorage : public Buffer11::BufferStorage
     explicit SystemMemoryStorage(Renderer11 *renderer);
     ~SystemMemoryStorage() override {}
 
-    bool isMappable(GLbitfield access) const override { return true; }
+    bool isMappable() const override { return true; }
     gl::ErrorOrResult<CopyResult> copyFromStorage(BufferStorage *source,
                                                   size_t sourceOffset,
                                                   size_t size,
@@ -271,16 +244,16 @@ class Buffer11::SystemMemoryStorage : public Buffer11::BufferStorage
     MemoryBuffer mSystemCopy;
 };
 
-Buffer11::Buffer11(const gl::BufferState &state, Renderer11 *renderer)
-    : BufferD3D(state, renderer),
+Buffer11::Buffer11(Renderer11 *renderer)
+    : BufferD3D(renderer),
       mRenderer(renderer),
       mSize(0),
       mMappedStorage(nullptr),
-      mBufferStorages({}),
-      mDeallocThresholds({}),
-      mIdleness({}),
+      mBufferStorages(BUFFER_USAGE_COUNT, nullptr),
       mConstantBufferStorageAdditionalSize(0),
-      mMaxConstantBufferLruCount(0)
+      mMaxConstantBufferLruCount(0),
+      mReadUsageCount(0),
+      mSystemMemoryDeallocThreshold(0)
 {
 }
 
@@ -299,10 +272,10 @@ Buffer11::~Buffer11()
     mRenderer->onBufferDelete(this);
 }
 
-gl::Error Buffer11::setData(GLenum target, const void *data, size_t size, GLenum usage)
+gl::Error Buffer11::setData(const void *data, size_t size, GLenum usage)
 {
     updateD3DBufferUsage(usage);
-    ANGLE_TRY(setSubData(target, data, size, 0));
+    ANGLE_TRY(setSubData(data, size, 0));
     return gl::NoError();
 }
 
@@ -311,6 +284,8 @@ gl::Error Buffer11::getData(const uint8_t **outData)
     SystemMemoryStorage *systemMemoryStorage = nullptr;
     ANGLE_TRY_RESULT(getSystemMemoryStorage(), systemMemoryStorage);
 
+    mReadUsageCount = 0;
+
     ASSERT(systemMemoryStorage->getSize() >= mSize);
 
     *outData = systemMemoryStorage->getSystemCopy()->data();
@@ -324,34 +299,16 @@ gl::ErrorOrResult<Buffer11::SystemMemoryStorage *> Buffer11::getSystemMemoryStor
     return GetAs<SystemMemoryStorage>(storage);
 }
 
-gl::Error Buffer11::setSubData(GLenum target, const void *data, size_t size, size_t offset)
+gl::Error Buffer11::setSubData(const void *data, size_t size, size_t offset)
 {
     size_t requiredSize = size + offset;
 
     if (data && size > 0)
     {
         // Use system memory storage for dynamic buffers.
-        // Try using a constant storage for constant buffers
+
         BufferStorage *writeBuffer = nullptr;
-        if (target == GL_UNIFORM_BUFFER)
-        {
-            // If we are a very large uniform buffer, keep system memory storage around so that we
-            // aren't forced to read back from a constant buffer. We also check the workaround for
-            // Intel - this requires us to use system memory so we don't end up having to copy from
-            // a constant buffer to a staging buffer.
-            // TODO(jmadill): Use Context caps.
-            if (offset == 0 && size >= mSize &&
-                size <= static_cast<UINT>(mRenderer->getNativeCaps().maxUniformBlockSize) &&
-                !mRenderer->getWorkarounds().useSystemMemoryForConstantBuffers)
-            {
-                ANGLE_TRY_RESULT(getBufferStorage(BUFFER_USAGE_UNIFORM), writeBuffer);
-            }
-            else
-            {
-                ANGLE_TRY_RESULT(getSystemMemoryStorage(), writeBuffer);
-            }
-        }
-        else if (supportsDirectBinding())
+        if (supportsDirectBinding())
         {
             ANGLE_TRY_RESULT(getStagingStorage(), writeBuffer);
         }
@@ -406,12 +363,11 @@ gl::Error Buffer11::copySubData(BufferImpl *source,
 
     // If copying to/from a pixel pack buffer, we must have a staging or
     // pack buffer partner, because other native buffers can't be mapped
-    if (copyDest->getUsage() == BUFFER_USAGE_PIXEL_PACK && !copySource->isMappable(GL_MAP_READ_BIT))
+    if (copyDest->getUsage() == BUFFER_USAGE_PIXEL_PACK && !copySource->isMappable())
     {
         ANGLE_TRY_RESULT(sourceBuffer->getStagingStorage(), copySource);
     }
-    else if (copySource->getUsage() == BUFFER_USAGE_PIXEL_PACK &&
-             !copyDest->isMappable(GL_MAP_WRITE_BIT))
+    else if (copySource->getUsage() == BUFFER_USAGE_PIXEL_PACK && !copyDest->isMappable())
     {
         ANGLE_TRY_RESULT(getStagingStorage(), copyDest);
     }
@@ -518,81 +474,50 @@ gl::Error Buffer11::markTransformFeedbackUsage()
     return gl::NoError();
 }
 
-void Buffer11::updateDeallocThreshold(BufferUsage usage)
+void Buffer11::updateSystemMemoryDeallocThreshold()
 {
     // The following strategy was tuned on the Oort online benchmark (http://oortonline.gl/)
     // as well as a custom microbenchmark (IndexConversionPerfTest.Run/index_range_d3d11)
 
-    // First readback: 8 unmodified uses before we free buffer memory.
+    // First readback: 8 unmodified uses before we free system memory.
     // After that, double the threshold each time until we reach the max.
-    if (mDeallocThresholds[usage] == 0)
+    if (mSystemMemoryDeallocThreshold == 0)
     {
-        mDeallocThresholds[usage] = 8;
+        mSystemMemoryDeallocThreshold = 8;
     }
-    else if (mDeallocThresholds[usage] < std::numeric_limits<unsigned int>::max() / 2u)
+    else if (mSystemMemoryDeallocThreshold < std::numeric_limits<unsigned int>::max() / 2u)
     {
-        mDeallocThresholds[usage] *= 2u;
+        mSystemMemoryDeallocThreshold *= 2u;
     }
     else
     {
-        mDeallocThresholds[usage] = std::numeric_limits<unsigned int>::max();
+        mSystemMemoryDeallocThreshold = std::numeric_limits<unsigned int>::max();
     }
 }
 
-// Free the storage if we decide it isn't being used very often.
-gl::Error Buffer11::checkForDeallocation(BufferUsage usage)
+gl::Error Buffer11::markBufferUsage()
 {
-    mIdleness[usage]++;
+    mReadUsageCount++;
 
-    BufferStorage *&storage = mBufferStorages[usage];
-    if (storage != nullptr && mIdleness[usage] > mDeallocThresholds[usage])
+    // Free the system memory storage if we decide it isn't being used very often.
+    BufferStorage *&sysMemStorage = mBufferStorages[BUFFER_USAGE_SYSTEM_MEMORY];
+    if (sysMemStorage != nullptr && mReadUsageCount > mSystemMemoryDeallocThreshold)
     {
         BufferStorage *latestStorage = nullptr;
         ANGLE_TRY_RESULT(getLatestBufferStorage(), latestStorage);
-        if (latestStorage != storage)
+        if (latestStorage != sysMemStorage)
         {
-            SafeDelete(storage);
+            SafeDelete(sysMemStorage);
         }
     }
 
     return gl::NoError();
 }
 
-// Keep system memory when we are using it for the canonical version of data.
-bool Buffer11::canDeallocateSystemMemory() const
-{
-    // Must keep system memory on Intel.
-    if (mRenderer->getWorkarounds().useSystemMemoryForConstantBuffers)
-    {
-        return false;
-    }
-
-    return (!mBufferStorages[BUFFER_USAGE_UNIFORM] ||
-            mSize <= mRenderer->getNativeCaps().maxUniformBlockSize);
-}
-
-void Buffer11::markBufferUsage(BufferUsage usage)
-{
-    mIdleness[usage] = 0;
-}
-
-gl::Error Buffer11::garbageCollection(BufferUsage currentUsage)
-{
-    if (currentUsage != BUFFER_USAGE_SYSTEM_MEMORY && canDeallocateSystemMemory())
-    {
-        ANGLE_TRY(checkForDeallocation(BUFFER_USAGE_SYSTEM_MEMORY));
-    }
-
-    if (currentUsage != BUFFER_USAGE_STAGING)
-    {
-        ANGLE_TRY(checkForDeallocation(BUFFER_USAGE_STAGING));
-    }
-
-    return gl::NoError();
-}
-
 gl::ErrorOrResult<ID3D11Buffer *> Buffer11::getBuffer(BufferUsage usage)
 {
+    ANGLE_TRY(markBufferUsage());
+
     BufferStorage *storage = nullptr;
     ANGLE_TRY_RESULT(getBufferStorage(usage), storage);
     return GetAs<NativeStorage>(storage)->getNativeStorage();
@@ -605,6 +530,8 @@ gl::ErrorOrResult<ID3D11Buffer *> Buffer11::getEmulatedIndexedBuffer(
 {
     ASSERT(indexInfo);
 
+    ANGLE_TRY(markBufferUsage());
+
     BufferStorage *untypedStorage = nullptr;
     ANGLE_TRY_RESULT(getBufferStorage(BUFFER_USAGE_EMULATED_INDEXED_VERTEX), untypedStorage);
 
@@ -617,37 +544,64 @@ gl::ErrorOrResult<ID3D11Buffer *> Buffer11::getEmulatedIndexedBuffer(
     return nativeStorage;
 }
 
-gl::Error Buffer11::getConstantBufferRange(GLintptr offset,
-                                           GLsizeiptr size,
-                                           ID3D11Buffer **bufferOut,
-                                           UINT *firstConstantOut,
-                                           UINT *numConstantsOut)
+gl::ErrorOrResult<ID3D11Buffer *> Buffer11::getConstantBufferRange(GLintptr offset, GLsizeiptr size)
 {
+    ANGLE_TRY(markBufferUsage());
+
     BufferStorage *bufferStorage = nullptr;
 
     if (offset == 0 || mRenderer->getRenderer11DeviceCaps().supportsConstantBufferOffsets)
     {
         ANGLE_TRY_RESULT(getBufferStorage(BUFFER_USAGE_UNIFORM), bufferStorage);
-        CalculateConstantBufferParams(offset, size, firstConstantOut, numConstantsOut);
     }
     else
     {
         ANGLE_TRY_RESULT(getConstantBufferRangeStorage(offset, size), bufferStorage);
-        *firstConstantOut = 0;
-        *numConstantsOut  = 0;
     }
 
-    *bufferOut = GetAs<NativeStorage>(bufferStorage)->getNativeStorage();
-
-    return gl::NoError();
+    return GetAs<NativeStorage>(bufferStorage)->getNativeStorage();
 }
 
 gl::ErrorOrResult<ID3D11ShaderResourceView *> Buffer11::getSRV(DXGI_FORMAT srvFormat)
 {
     BufferStorage *storage = nullptr;
     ANGLE_TRY_RESULT(getBufferStorage(BUFFER_USAGE_PIXEL_UNPACK), storage);
-    NativeStorage *nativeStorage = GetAs<NativeStorage>(storage);
-    return nativeStorage->getSRVForFormat(srvFormat);
+    ID3D11Buffer *buffer = GetAs<NativeStorage>(storage)->getNativeStorage();
+
+    auto bufferSRVIt = mBufferResourceViews.find(srvFormat);
+
+    if (bufferSRVIt != mBufferResourceViews.end())
+    {
+        if (bufferSRVIt->second.first == buffer)
+        {
+            return bufferSRVIt->second.second;
+        }
+        else
+        {
+            // The underlying buffer has changed since the SRV was created: recreate the SRV.
+            SafeRelease(bufferSRVIt->second.second);
+        }
+    }
+
+    ID3D11Device *device                = mRenderer->getDevice();
+    ID3D11ShaderResourceView *bufferSRV = nullptr;
+
+    const d3d11::DXGIFormatSize &dxgiFormatInfo = d3d11::GetDXGIFormatSizeInfo(srvFormat);
+
+    D3D11_SHADER_RESOURCE_VIEW_DESC bufferSRVDesc;
+    bufferSRVDesc.Buffer.ElementOffset = 0;
+    bufferSRVDesc.Buffer.ElementWidth =
+        static_cast<unsigned int>(mSize) / dxgiFormatInfo.pixelBytes;
+    bufferSRVDesc.ViewDimension        = D3D11_SRV_DIMENSION_BUFFER;
+    bufferSRVDesc.Format               = srvFormat;
+
+    HRESULT result = device->CreateShaderResourceView(buffer, &bufferSRVDesc, &bufferSRV);
+    UNUSED_ASSERTION_VARIABLE(result);
+    ASSERT(SUCCEEDED(result));
+
+    mBufferResourceViews[srvFormat] = BufferSRVPair(buffer, bufferSRV);
+
+    return bufferSRV;
 }
 
 gl::Error Buffer11::packPixels(const gl::FramebufferAttachment &readAttachment,
@@ -689,31 +643,28 @@ gl::ErrorOrResult<Buffer11::BufferStorage *> Buffer11::getBufferStorage(BufferUs
         newStorage = allocateStorage(usage);
     }
 
-    markBufferUsage(usage);
-
     // resize buffer
     if (newStorage->getSize() < mSize)
     {
         ANGLE_TRY(newStorage->resize(mSize, true));
     }
 
-    ASSERT(newStorage);
-
     ANGLE_TRY(updateBufferStorage(newStorage, 0, mSize));
-    ANGLE_TRY(garbageCollection(usage));
 
     return newStorage;
 }
 
 Buffer11::BufferStorage *Buffer11::allocateStorage(BufferUsage usage)
 {
-    updateDeallocThreshold(usage);
     switch (usage)
     {
         case BUFFER_USAGE_PIXEL_PACK:
             return new PackStorage(mRenderer);
         case BUFFER_USAGE_SYSTEM_MEMORY:
+        {
+            updateSystemMemoryDeallocThreshold();
             return new SystemMemoryStorage(mRenderer);
+        }
         case BUFFER_USAGE_EMULATED_INDEXED_VERTEX:
             return new EmulatedIndexedStorage(mRenderer);
         case BUFFER_USAGE_VERTEX_OR_TRANSFORM_FEEDBACK:
@@ -744,8 +695,6 @@ gl::ErrorOrResult<Buffer11::BufferStorage *> Buffer11::getConstantBufferRangeSto
         newStorage           = cacheEntry->storage;
     }
 
-    markBufferUsage(BUFFER_USAGE_UNIFORM);
-
     if (newStorage->getSize() < static_cast<size_t>(size))
     {
         size_t maximumAllowedAdditionalSize = 2 * getSize();
@@ -780,7 +729,6 @@ gl::ErrorOrResult<Buffer11::BufferStorage *> Buffer11::getConstantBufferRangeSto
     }
 
     ANGLE_TRY(updateBufferStorage(newStorage, offset, size));
-    ANGLE_TRY(garbageCollection(BUFFER_USAGE_UNIFORM));
     return newStorage;
 }
 
@@ -791,8 +739,6 @@ gl::Error Buffer11::updateBufferStorage(BufferStorage *storage,
     BufferStorage *latestBuffer = nullptr;
     ANGLE_TRY_RESULT(getLatestBufferStorage(), latestBuffer);
 
-    ASSERT(storage);
-
     if (latestBuffer && latestBuffer->getDataRevision() > storage->getDataRevision())
     {
         // Copy through a staging buffer if we're copying from or to a non-staging, mappable
@@ -800,7 +746,7 @@ gl::Error Buffer11::updateBufferStorage(BufferStorage *storage,
         // data directly. If we're already using a staging buffer we're fine.
         if (latestBuffer->getUsage() != BUFFER_USAGE_STAGING &&
             storage->getUsage() != BUFFER_USAGE_STAGING &&
-            (!latestBuffer->isMappable(GL_MAP_READ_BIT) || !storage->isMappable(GL_MAP_WRITE_BIT)))
+            (!latestBuffer->isMappable() || !storage->isMappable()))
         {
             NativeStorage *stagingBuffer = nullptr;
             ANGLE_TRY_RESULT(getStagingStorage(), stagingBuffer);
@@ -899,8 +845,6 @@ angle::BroadcastChannel *Buffer11::getDirectBroadcastChannel()
     return &mDirectBroadcastChannel;
 }
 
-// Buffer11::BufferStorage implementation
-
 Buffer11::BufferStorage::BufferStorage(Renderer11 *renderer, BufferUsage usage)
     : mRenderer(renderer), mRevision(0), mUsage(usage), mBufferSize(0)
 {
@@ -908,24 +852,18 @@ Buffer11::BufferStorage::BufferStorage(Renderer11 *renderer, BufferUsage usage)
 
 gl::Error Buffer11::BufferStorage::setData(const uint8_t *data, size_t offset, size_t size)
 {
-    ASSERT(isMappable(GL_MAP_WRITE_BIT));
-
-    // Uniform storage can have a different internal size than the buffer size. Ensure we don't
-    // overflow.
-    size_t mapSize = std::min(size, mBufferSize - offset);
+    ASSERT(isMappable());
 
     uint8_t *writePointer = nullptr;
-    ANGLE_TRY(map(offset, mapSize, GL_MAP_WRITE_BIT, &writePointer));
+    ANGLE_TRY(map(offset, size, GL_MAP_WRITE_BIT, &writePointer));
 
-    memcpy(writePointer, data, mapSize);
+    memcpy(writePointer, data, size);
 
     unmap();
 
     return gl::NoError();
 }
 
-// Buffer11::NativeStorage implementation
-
 Buffer11::NativeStorage::NativeStorage(Renderer11 *renderer,
                                        BufferUsage usage,
                                        const angle::BroadcastChannel *onStorageChanged)
@@ -936,18 +874,6 @@ Buffer11::NativeStorage::NativeStorage(Renderer11 *renderer,
 Buffer11::NativeStorage::~NativeStorage()
 {
     SafeRelease(mNativeStorage);
-    clearSRVs();
-}
-
-bool Buffer11::NativeStorage::isMappable(GLbitfield access) const
-{
-    if ((access & GL_MAP_READ_BIT) != 0)
-    {
-        // Read is more exclusive than write mappability.
-        return (mUsage == BUFFER_USAGE_STAGING);
-    }
-    ASSERT((access & GL_MAP_WRITE_BIT) != 0);
-    return (mUsage == BUFFER_USAGE_STAGING || mUsage == BUFFER_USAGE_UNIFORM);
 }
 
 // Returns true if it recreates the direct buffer
@@ -962,38 +888,45 @@ gl::ErrorOrResult<CopyResult> Buffer11::NativeStorage::copyFromStorage(BufferSto
     bool createBuffer   = !mNativeStorage || mBufferSize < requiredSize;
 
     // (Re)initialize D3D buffer if needed
-    bool preserveData = (destOffset > 0);
     if (createBuffer)
     {
+        bool preserveData = (destOffset > 0);
         resize(requiredSize, preserveData);
     }
 
-    size_t clampedSize = size;
-    if (mUsage == BUFFER_USAGE_UNIFORM)
-    {
-        clampedSize = std::min(clampedSize, mBufferSize - destOffset);
-    }
-
     if (source->getUsage() == BUFFER_USAGE_PIXEL_PACK ||
         source->getUsage() == BUFFER_USAGE_SYSTEM_MEMORY)
     {
-        ASSERT(source->isMappable(GL_MAP_READ_BIT) && isMappable(GL_MAP_WRITE_BIT));
-
-        // Uniform buffers must be mapped with write/discard.
-        ASSERT(!(preserveData && mUsage == BUFFER_USAGE_UNIFORM));
+        ASSERT(source->isMappable());
 
         uint8_t *sourcePointer = nullptr;
-        ANGLE_TRY(source->map(sourceOffset, clampedSize, GL_MAP_READ_BIT, &sourcePointer));
+        ANGLE_TRY(source->map(sourceOffset, size, GL_MAP_READ_BIT, &sourcePointer));
+
+        D3D11_MAPPED_SUBRESOURCE mappedResource;
+        HRESULT hr = context->Map(mNativeStorage, 0, D3D11_MAP_WRITE, 0, &mappedResource);
+        ASSERT(SUCCEEDED(hr));
+        if (FAILED(hr))
+        {
+            source->unmap();
+            return gl::Error(
+                GL_OUT_OF_MEMORY,
+                "Failed to map native storage in Buffer11::NativeStorage::copyFromStorage");
+        }
+
+        uint8_t *destPointer = static_cast<uint8_t *>(mappedResource.pData) + destOffset;
 
-        setData(sourcePointer, destOffset, clampedSize);
+        // Offset bounds are validated at the API layer
+        ASSERT(sourceOffset + size <= destOffset + mBufferSize);
+        memcpy(destPointer, sourcePointer, size);
 
+        context->Unmap(mNativeStorage, 0);
         source->unmap();
     }
     else
     {
         D3D11_BOX srcBox;
         srcBox.left   = static_cast<unsigned int>(sourceOffset);
-        srcBox.right  = static_cast<unsigned int>(sourceOffset + clampedSize);
+        srcBox.right  = static_cast<unsigned int>(sourceOffset + size);
         srcBox.top    = 0;
         srcBox.bottom = 1;
         srcBox.front  = 0;
@@ -1014,7 +947,7 @@ gl::Error Buffer11::NativeStorage::resize(size_t size, bool preserveData)
     ID3D11DeviceContext *context = mRenderer->getDeviceContext();
 
     D3D11_BUFFER_DESC bufferDesc;
-    FillBufferDesc(&bufferDesc, mRenderer, mUsage, static_cast<unsigned int>(size));
+    fillBufferDesc(&bufferDesc, mRenderer, mUsage, static_cast<unsigned int>(size));
 
     ID3D11Buffer *newBuffer;
     HRESULT result = device->CreateBuffer(&bufferDesc, nullptr, &newBuffer);
@@ -1049,9 +982,6 @@ gl::Error Buffer11::NativeStorage::resize(size_t size, bool preserveData)
 
     mBufferSize = bufferDesc.ByteWidth;
 
-    // Free the SRVs.
-    clearSRVs();
-
     // Notify that the storage has changed.
     if (mOnStorageChanged)
     {
@@ -1061,8 +991,7 @@ gl::Error Buffer11::NativeStorage::resize(size_t size, bool preserveData)
     return gl::NoError();
 }
 
-// static
-void Buffer11::NativeStorage::FillBufferDesc(D3D11_BUFFER_DESC *bufferDesc,
+void Buffer11::NativeStorage::fillBufferDesc(D3D11_BUFFER_DESC *bufferDesc,
                                              Renderer11 *renderer,
                                              BufferUsage usage,
                                              unsigned int bufferSize)
@@ -1111,9 +1040,6 @@ void Buffer11::NativeStorage::FillBufferDesc(D3D11_BUFFER_DESC *bufferDesc,
             // Constant buffers must be of a limited size, and aligned to 16 byte boundaries
             // For our purposes we ignore any buffer data past the maximum constant buffer size
             bufferDesc->ByteWidth = roundUp(bufferDesc->ByteWidth, 16u);
-
-            // Note: it seems that D3D11 allows larger buffers on some platforms, but not all.
-            // (Windows 10 seems to allow larger constant buffers, but not Windows 7)
             bufferDesc->ByteWidth =
                 std::min<UINT>(bufferDesc->ByteWidth,
                                static_cast<UINT>(renderer->getNativeCaps().maxUniformBlockSize));
@@ -1129,11 +1055,11 @@ gl::Error Buffer11::NativeStorage::map(size_t offset,
                                        GLbitfield access,
                                        uint8_t **mapPointerOut)
 {
-    ASSERT(isMappable(access));
+    ASSERT(mUsage == BUFFER_USAGE_STAGING);
 
     D3D11_MAPPED_SUBRESOURCE mappedResource;
     ID3D11DeviceContext *context = mRenderer->getDeviceContext();
-    D3D11_MAP d3dMapType         = gl_d3d11::GetD3DMapTypeFromBits(mUsage, access);
+    D3D11_MAP d3dMapType         = gl_d3d11::GetD3DMapTypeFromBits(access);
     UINT d3dMapFlag              = ((access & GL_MAP_UNSYNCHRONIZED_BIT) != 0 ? D3D11_MAP_FLAG_DO_NOT_WAIT : 0);
 
     HRESULT result = context->Map(mNativeStorage, 0, d3dMapType, d3dMapFlag, &mappedResource);
@@ -1150,56 +1076,11 @@ gl::Error Buffer11::NativeStorage::map(size_t offset,
 
 void Buffer11::NativeStorage::unmap()
 {
-    ASSERT(isMappable(GL_MAP_WRITE_BIT) || isMappable(GL_MAP_READ_BIT));
+    ASSERT(mUsage == BUFFER_USAGE_STAGING);
     ID3D11DeviceContext *context = mRenderer->getDeviceContext();
     context->Unmap(mNativeStorage, 0);
 }
 
-gl::ErrorOrResult<ID3D11ShaderResourceView *> Buffer11::NativeStorage::getSRVForFormat(
-    DXGI_FORMAT srvFormat)
-{
-    auto bufferSRVIt = mBufferResourceViews.find(srvFormat);
-
-    if (bufferSRVIt != mBufferResourceViews.end())
-    {
-        return bufferSRVIt->second;
-    }
-
-    ID3D11Device *device                = mRenderer->getDevice();
-    ID3D11ShaderResourceView *bufferSRV = nullptr;
-
-    const d3d11::DXGIFormatSize &dxgiFormatInfo = d3d11::GetDXGIFormatSizeInfo(srvFormat);
-
-    D3D11_SHADER_RESOURCE_VIEW_DESC bufferSRVDesc;
-    bufferSRVDesc.Buffer.ElementOffset = 0;
-    bufferSRVDesc.Buffer.ElementWidth  = static_cast<UINT>(mBufferSize) / dxgiFormatInfo.pixelBytes;
-    bufferSRVDesc.ViewDimension        = D3D11_SRV_DIMENSION_BUFFER;
-    bufferSRVDesc.Format               = srvFormat;
-
-    HRESULT result = device->CreateShaderResourceView(mNativeStorage, &bufferSRVDesc, &bufferSRV);
-    ASSERT(SUCCEEDED(result));
-    if (FAILED(result))
-    {
-        return gl::Error(GL_OUT_OF_MEMORY,
-                         "Error creating buffer SRV in Buffer11::NativeStorage::getSRVForFormat");
-    }
-
-    mBufferResourceViews[srvFormat] = bufferSRV;
-
-    return bufferSRV;
-}
-
-void Buffer11::NativeStorage::clearSRVs()
-{
-    for (auto &srv : mBufferResourceViews)
-    {
-        SafeRelease(srv.second);
-    }
-    mBufferResourceViews.clear();
-}
-
-// Buffer11::EmulatedIndexStorage implementation
-
 Buffer11::EmulatedIndexedStorage::EmulatedIndexedStorage(Renderer11 *renderer)
     : BufferStorage(renderer, BUFFER_USAGE_EMULATED_INDEXED_VERTEX), mNativeStorage(nullptr)
 {
@@ -1334,7 +1215,7 @@ gl::ErrorOrResult<CopyResult> Buffer11::EmulatedIndexedStorage::copyFromStorage(
     size_t size,
     size_t destOffset)
 {
-    ASSERT(source->isMappable(GL_MAP_READ_BIT));
+    ASSERT(source->isMappable());
     uint8_t *sourceData = nullptr;
     ANGLE_TRY(source->map(sourceOffset, size, GL_MAP_READ_BIT, &sourceData));
     ASSERT(destOffset + size <= mMemoryBuffer.size());
@@ -1372,8 +1253,6 @@ void Buffer11::EmulatedIndexedStorage::unmap()
     // No-op
 }
 
-// Buffer11::PackStorage implementation
-
 Buffer11::PackStorage::PackStorage(Renderer11 *renderer)
     : BufferStorage(renderer, BUFFER_USAGE_PIXEL_PACK), mStagingTexture(), mDataModified(false)
 {
@@ -1390,8 +1269,9 @@ gl::ErrorOrResult<CopyResult> Buffer11::PackStorage::copyFromStorage(BufferStora
 {
     ANGLE_TRY(flushQueuedPackCommand());
 
-    // For all use cases of pack buffers, we must copy through a readable buffer.
-    ASSERT(source->isMappable(GL_MAP_READ_BIT));
+    // We copy through a staging buffer when drawing with a pack buffer, or for other cases where we
+    // access the pack buffer
+    ASSERT(source->isMappable() && source->getUsage() == BUFFER_USAGE_STAGING);
     uint8_t *sourceData = nullptr;
     ANGLE_TRY(source->map(sourceOffset, size, GL_MAP_READ_BIT, &sourceData));
     ASSERT(destOffset + size <= mMemoryBuffer.size());
@@ -1504,8 +1384,6 @@ gl::Error Buffer11::PackStorage::flushQueuedPackCommand()
     return gl::NoError();
 }
 
-// Buffer11::SystemMemoryStorage implementation
-
 Buffer11::SystemMemoryStorage::SystemMemoryStorage(Renderer11 *renderer)
     : Buffer11::BufferStorage(renderer, BUFFER_USAGE_SYSTEM_MEMORY)
 {
@@ -1516,7 +1394,7 @@ gl::ErrorOrResult<CopyResult> Buffer11::SystemMemoryStorage::copyFromStorage(Buf
                                                                              size_t size,
                                                                              size_t destOffset)
 {
-    ASSERT(source->isMappable(GL_MAP_READ_BIT));
+    ASSERT(source->isMappable());
     uint8_t *sourceData = nullptr;
     ANGLE_TRY(source->map(sourceOffset, size, GL_MAP_READ_BIT, &sourceData));
     ASSERT(destOffset + size <= mSystemCopy.size());