1 files changed, 113 insertions, 0 deletions
diff --git a/gfx/angle/src/compiler/translator/PruneEmptyDeclarations.cpp b/gfx/angle/src/compiler/translator/PruneEmptyDeclarations.cpp
new file mode 100755
index 000000000..7ec434796
--- /dev/null
+++ b/gfx/angle/src/compiler/translator/PruneEmptyDeclarations.cpp
@@ -0,0 +1,113 @@
+//
+// Copyright (c) 2002-2015 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.
+//
+// The PruneEmptyDeclarations function prunes unnecessary empty declarations and declarators from the AST.
+
+#include "compiler/translator/PruneEmptyDeclarations.h"
+
+#include "compiler/translator/IntermNode.h"
+
+namespace sh
+{
+
+namespace
+{
+
+class PruneEmptyDeclarationsTraverser : private TIntermTraverser
+{
+  public:
+    static void apply(TIntermNode *root);
+  private:
+    PruneEmptyDeclarationsTraverser();
+    bool visitDeclaration(Visit, TIntermDeclaration *node) override;
+};
+
+void PruneEmptyDeclarationsTraverser::apply(TIntermNode *root)
+{
+    PruneEmptyDeclarationsTraverser prune;
+    root->traverse(&prune);
+    prune.updateTree();
+}
+
+PruneEmptyDeclarationsTraverser::PruneEmptyDeclarationsTraverser()
+    : TIntermTraverser(true, false, false)
+{
+}
+
+bool PruneEmptyDeclarationsTraverser::visitDeclaration(Visit, TIntermDeclaration *node)
+{
+    TIntermSequence *sequence = node->getSequence();
+    if (sequence->size() >= 1)
+    {
+        TIntermSymbol *sym = sequence->front()->getAsSymbolNode();
+        // Prune declarations without a variable name, unless it's an interface block declaration.
+        if (sym != nullptr && sym->getSymbol() == "" && !sym->isInterfaceBlock())
+        {
+            if (sequence->size() > 1)
+            {
+                // Generate a replacement that will remove the empty declarator in the beginning of
+                // a declarator list. Example of a declaration that will be changed:
+                // float, a;
+                // will be changed to
+                // float a;
+                // This applies also to struct declarations.
+                TIntermSequence emptyReplacement;
+                mMultiReplacements.push_back(
+                    NodeReplaceWithMultipleEntry(node, sym, emptyReplacement));
+            }
+            else if (sym->getBasicType() != EbtStruct)
+            {
+                // Single struct declarations may just declare the struct type and no variables, so
+                // they should not be pruned. All other single empty declarations can be pruned
+                // entirely. Example of an empty declaration that will be pruned:
+                // float;
+                TIntermSequence emptyReplacement;
+                TIntermBlock *parentAsBlock = getParentNode()->getAsBlock();
+                // The declaration may be inside a block or in a loop init expression.
+                ASSERT(parentAsBlock != nullptr || getParentNode()->getAsLoopNode() != nullptr);
+                if (parentAsBlock)
+                {
+                    mMultiReplacements.push_back(
+                        NodeReplaceWithMultipleEntry(parentAsBlock, node, emptyReplacement));
+                }
+                else
+                {
+                    queueReplacement(node, nullptr, OriginalNode::IS_DROPPED);
+                }
+            }
+            else if (sym->getType().getQualifier() != EvqGlobal &&
+                     sym->getType().getQualifier() != EvqTemporary)
+            {
+                // We've hit an empty struct declaration with a qualifier, for example like
+                // this:
+                // const struct a { int i; };
+                // NVIDIA GL driver version 367.27 doesn't accept this kind of declarations, so
+                // we convert the declaration to a regular struct declaration. This is okay,
+                // since ESSL 1.00 spec section 4.1.8 says about structs that "The optional
+                // qualifiers only apply to any declarators, and are not part of the type being
+                // defined for name."
+
+                if (mInGlobalScope)
+                {
+                    sym->getTypePointer()->setQualifier(EvqGlobal);
+                }
+                else
+                {
+                    sym->getTypePointer()->setQualifier(EvqTemporary);
+                }
+            }
+        }
+    }
+    return false;
+}
+
+} // namespace
+
+void PruneEmptyDeclarations(TIntermNode *root)
+{
+    PruneEmptyDeclarationsTraverser::apply(root);
+}
+
+}  // namespace sh