1 files changed, 116 insertions, 0 deletions
diff --git a/src/3rdparty/angle/src/compiler/translator/RemoveNoOpCasesFromEndOfSwitchStatements.cpp b/src/3rdparty/angle/src/compiler/translator/RemoveNoOpCasesFromEndOfSwitchStatements.cpp
new file mode 100644
index 0000000000..b86d64d7a3
--- /dev/null
+++ b/src/3rdparty/angle/src/compiler/translator/RemoveNoOpCasesFromEndOfSwitchStatements.cpp
@@ -0,0 +1,116 @@
+//
+// Copyright (c) 2017 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.
+//
+// RemoveNoOpCasesFromEndOfSwitchStatements.cpp: Clean up cases from the end of a switch statement
+// that only contain no-ops.
+
+#include "compiler/translator/RemoveNoOpCasesFromEndOfSwitchStatements.h"
+
+#include "compiler/translator/IntermNode.h"
+#include "compiler/translator/IntermNode_util.h"
+#include "compiler/translator/IntermTraverse.h"
+#include "compiler/translator/SymbolTable.h"
+
+namespace sh
+{
+
+namespace
+{
+
+bool AreEmptyBlocks(TIntermSequence *statements, size_t i);
+
+bool IsEmptyBlock(TIntermNode *node)
+{
+    TIntermBlock *asBlock = node->getAsBlock();
+    if (asBlock)
+    {
+        if (asBlock->getSequence()->empty())
+        {
+            return true;
+        }
+        return AreEmptyBlocks(asBlock->getSequence(), 0u);
+    }
+    // Empty declarations should have already been pruned, otherwise they would need to be handled
+    // here. Note that declarations for struct types do contain a nameless child node.
+    ASSERT(node->getAsDeclarationNode() == nullptr ||
+           !node->getAsDeclarationNode()->getSequence()->empty());
+    // Pure literal statements should also already be pruned.
+    ASSERT(node->getAsConstantUnion() == nullptr);
+    return false;
+}
+
+// Return true if all statements in "statements" starting from index i consist only of empty blocks
+// and no-op statements. Returns true also if there are no statements.
+bool AreEmptyBlocks(TIntermSequence *statements, size_t i)
+{
+    for (; i < statements->size(); ++i)
+    {
+        if (!IsEmptyBlock(statements->at(i)))
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+void RemoveNoOpCasesFromEndOfStatementList(TIntermBlock *statementList, TSymbolTable *symbolTable)
+{
+    TIntermSequence *statements = statementList->getSequence();
+
+    bool foundDeadCase = false;
+    do
+    {
+        if (statements->empty())
+        {
+            return;
+        }
+
+        // Find the last case label.
+        size_t i = statements->size();
+        while (i > 0u && !(*statements)[i - 1]->getAsCaseNode())
+        {
+            --i;
+        }
+        // Now i is the index of the first statement following the last label inside the switch
+        // statement.
+        ASSERT(i > 0u);
+
+        foundDeadCase = AreEmptyBlocks(statements, i);
+        if (foundDeadCase)
+        {
+            statements->erase(statements->begin() + (i - 1u), statements->end());
+        }
+    } while (foundDeadCase);
+}
+
+class RemoveNoOpCasesFromEndOfSwitchTraverser : public TIntermTraverser
+{
+  public:
+    RemoveNoOpCasesFromEndOfSwitchTraverser(TSymbolTable *symbolTable)
+        : TIntermTraverser(true, false, false, symbolTable)
+    {
+    }
+
+    bool visitSwitch(Visit visit, TIntermSwitch *node) override;
+};
+
+bool RemoveNoOpCasesFromEndOfSwitchTraverser::visitSwitch(Visit visit, TIntermSwitch *node)
+{
+    // Here we may mutate the statement list, but it's safe since traversal has not yet reached
+    // there.
+    RemoveNoOpCasesFromEndOfStatementList(node->getStatementList(), mSymbolTable);
+    // Handle also nested switch statements.
+    return true;
+}
+
+}  // anonymous namespace
+
+void RemoveNoOpCasesFromEndOfSwitchStatements(TIntermBlock *root, TSymbolTable *symbolTable)
+{
+    RemoveNoOpCasesFromEndOfSwitchTraverser traverser(symbolTable);
+    root->traverse(&traverser);
+}
+
+}  // namespace sh