Resolve Bad Binary Link Failures

src/libANGLE/BlobCache.cpp

@@ -147,8 +147,7 @@ bool BlobCache::getAt(size_t index, const BlobCache::Key **keyOut, BlobCache::Va
 
 void BlobCache::remove(const BlobCache::Key &key)
 {
-    bool result = mBlobCache.eraseByKey(key);
-    ASSERT(result);
+    mBlobCache.eraseByKey(key);
 }
 
 void BlobCache::setBlobCacheFuncs(EGLSetBlobFuncANDROID set, EGLGetBlobFuncANDROID get)

src/libANGLE/Program.cpp

@@ -1865,12 +1865,41 @@ angle::Result Program::loadBinary(const Context *context,
         mDirtyBits.set(uniformBlockIndex);
     }
 
-    mLinkingState.reset(new LinkingState());
-    mLinkingState->linkingFromBinary = true;
-    mLinkingState->linkEvent         = mProgram->load(context, &stream, infoLog);
+    // The rx::LinkEvent returned from ProgramImpl::load is a base class with multiple
+    // implementations. In some implementations, a background thread is used to compile the
+    // shaders. Any calls to the LinkEvent object, therefore, are racy and may interfere with
+    // the operation.
+
+    // We do not want to call LinkEvent::wait because that will cause the background thread
+    // to finish its task before returning, thus defeating the purpose of background compilation.
+    // We need to defer waiting on background compilation until the very last minute when we
+    // absolutely need the results, such as when the developer binds the program or queries
+    // for the completion status.
+
+    // If load returns nullptr, we know for sure that the binary is not compatible with the backend.
+    // The loaded binary could have been read from the on-disk shader cache and be corrupted or
+    // serialized with different revision and subsystem id than the currently loaded backend.
+    // Returning 'Incomplete' to the caller results in link happening using the original shader
+    // sources.
+    angle::Result result;
+    std::unique_ptr<LinkingState> linkingState;
+    std::unique_ptr<rx::LinkEvent> linkEvent = mProgram->load(context, &stream, infoLog);
+    if (linkEvent)
+    {
+        linkingState                    = std::make_unique<LinkingState>();
+        linkingState->linkingFromBinary = true;
+        linkingState->linkEvent         = std::move(linkEvent);
+        result                          = angle::Result::Continue;
         mLinkResolved                   = false;
+    }
+    else
+    {
+        result        = angle::Result::Incomplete;
+        mLinkResolved = true;
+    }
+    mLinkingState = std::move(linkingState);
 
-    return angle::Result::Continue;
+    return result;
 #endif  // #if ANGLE_PROGRAM_BINARY_LOAD == ANGLE_ENABLED
 }
 

src/libANGLE/SizedMRUCache.h

@@ -75,7 +75,7 @@ class SizedMRUCache final : angle::NonCopyable
         mCurrentSize = 0;
     }
 
-    bool eraseByKey(const Key &key)
+    void eraseByKey(const Key &key)
     {
         // Check for existing key.
         auto existing = mStore.Peek(key);
@@ -83,10 +83,7 @@ class SizedMRUCache final : angle::NonCopyable
         {
             mCurrentSize -= existing->second.size;
             mStore.Erase(existing);
-            return true;
         }
-
-        return false;
     }
 
     size_t entryCount() const { return mStore.size(); }

src/libANGLE/renderer/d3d/ProgramD3D.cpp

@@ -963,14 +963,14 @@ std::unique_ptr<rx::LinkEvent> ProgramD3D::load(const gl::Context *context,
     if (memcmp(&identifier, &binaryDeviceIdentifier, sizeof(DeviceIdentifier)) != 0)
     {
         infoLog << "Invalid program binary, device configuration has changed.";
-        return std::make_unique<LinkEventDone>(angle::Result::Incomplete);
+        return nullptr;
     }
 
     int compileFlags = stream->readInt<int>();
     if (compileFlags != ANGLE_COMPILE_OPTIMIZATION_LEVEL)
     {
         infoLog << "Mismatched compilation flags.";
-        return std::make_unique<LinkEventDone>(angle::Result::Incomplete);
+        return nullptr;
     }
 
     for (int &index : mAttribLocationToD3DSemantic)
@@ -1033,7 +1033,7 @@ std::unique_ptr<rx::LinkEvent> ProgramD3D::load(const gl::Context *context,
     if (stream->error())
     {
         infoLog << "Invalid program binary.";
-        return std::make_unique<LinkEventDone>(angle::Result::Incomplete);
+        return nullptr;
     }
 
     ASSERT(mD3DShaderStorageBlocks.empty());
@@ -1051,7 +1051,7 @@ std::unique_ptr<rx::LinkEvent> ProgramD3D::load(const gl::Context *context,
     if (stream->error())
     {
         infoLog << "Invalid program binary.";
-        return std::make_unique<LinkEventDone>(angle::Result::Incomplete);
+        return nullptr;
     }
 
     ASSERT(mImage2DUniforms.empty());
@@ -1073,7 +1073,7 @@ std::unique_ptr<rx::LinkEvent> ProgramD3D::load(const gl::Context *context,
     if (stream->error())
     {
         infoLog << "Invalid program binary.";
-        return std::make_unique<LinkEventDone>(angle::Result::Incomplete);
+        return nullptr;
     }
 
     const auto &linkedUniforms = mState.getUniforms();
@@ -1100,7 +1100,7 @@ std::unique_ptr<rx::LinkEvent> ProgramD3D::load(const gl::Context *context,
     if (stream->error())
     {
         infoLog << "Invalid program binary.";
-        return std::make_unique<LinkEventDone>(angle::Result::Incomplete);
+        return nullptr;
     }
 
     ASSERT(mD3DUniformBlocks.empty());