1 files changed, 97 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/tree_ops/gl/RewriteRepeatedAssignToSwizzled.cpp b/gfx/angle/checkout/src/compiler/translator/tree_ops/gl/RewriteRepeatedAssignToSwizzled.cpp
new file mode 100644
index 0000000000..83a0f029b8
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/tree_ops/gl/RewriteRepeatedAssignToSwizzled.cpp
@@ -0,0 +1,97 @@
+//
+// Copyright 2018 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// RewriteRepeatedAssignToSwizzled.cpp: Rewrite expressions that assign an assignment to a swizzled
+// vector, like:
+//     v.x = z = expression;
+// to:
+//     z = expression;
+//     v.x = z;
+//
+// Note that this doesn't handle some corner cases: expressions nested inside other expressions,
+// inside loop headers, or inside if conditions.
+
+#include "compiler/translator/tree_ops/gl/RewriteRepeatedAssignToSwizzled.h"
+
+#include "compiler/translator/tree_util/IntermNode_util.h"
+#include "compiler/translator/tree_util/IntermTraverse.h"
+
+namespace sh
+{
+
+namespace
+{
+
+class RewriteAssignToSwizzledTraverser : public TIntermTraverser
+{
+  public:
+    [[nodiscard]] static bool rewrite(TCompiler *compiler, TIntermBlock *root);
+
+  private:
+    RewriteAssignToSwizzledTraverser();
+
+    bool visitBinary(Visit, TIntermBinary *node) override;
+
+    void nextIteration();
+
+    bool didRewrite() { return mDidRewrite; }
+
+    bool mDidRewrite;
+};
+
+// static
+bool RewriteAssignToSwizzledTraverser::rewrite(TCompiler *compiler, TIntermBlock *root)
+{
+    RewriteAssignToSwizzledTraverser rewrite;
+    do
+    {
+        rewrite.nextIteration();
+        root->traverse(&rewrite);
+        if (!rewrite.updateTree(compiler, root))
+        {
+            return false;
+        }
+    } while (rewrite.didRewrite());
+
+    return true;
+}
+
+RewriteAssignToSwizzledTraverser::RewriteAssignToSwizzledTraverser()
+    : TIntermTraverser(true, false, false), mDidRewrite(false)
+{}
+
+void RewriteAssignToSwizzledTraverser::nextIteration()
+{
+    mDidRewrite = false;
+}
+
+bool RewriteAssignToSwizzledTraverser::visitBinary(Visit, TIntermBinary *node)
+{
+    TIntermBinary *rightBinary = node->getRight()->getAsBinaryNode();
+    TIntermBlock *parentBlock  = getParentNode()->getAsBlock();
+    if (parentBlock && node->isAssignment() && node->getLeft()->getAsSwizzleNode() && rightBinary &&
+        rightBinary->isAssignment())
+    {
+        TIntermSequence replacements;
+        replacements.push_back(rightBinary);
+        TIntermTyped *rightAssignmentTargetCopy = rightBinary->getLeft()->deepCopy();
+        TIntermBinary *lastAssign =
+            new TIntermBinary(EOpAssign, node->getLeft(), rightAssignmentTargetCopy);
+        replacements.push_back(lastAssign);
+        mMultiReplacements.emplace_back(parentBlock, node, std::move(replacements));
+        mDidRewrite = true;
+        return false;
+    }
+    return true;
+}
+
+}  // anonymous namespace
+
+bool RewriteRepeatedAssignToSwizzled(TCompiler *compiler, TIntermBlock *root)
+{
+    return RewriteAssignToSwizzledTraverser::rewrite(compiler, root);
+}
+
+}  // namespace sh