Vendor import of llvm release_39 branch r276489:vendor/llvm/llvm-release_39-r276489

https://llvm.org/svn/llvm-project/llvm/branches/release_39@276489

1 files changed, 35 insertions, 0 deletions

diff --git a/include/llvm/Transforms/IPO/ConstantMerge.h b/include/llvm/Transforms/IPO/ConstantMerge.h
new file mode 100644
index 000000000000..1d4da43f6a7b
--- /dev/null
+++ b/include/llvm/Transforms/IPO/ConstantMerge.h
@@ -0,0 +1,35 @@
+//===- ConstantMerge.h - Merge duplicate global constants -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the interface to a pass that merges duplicate global
+// constants together into a single constant that is shared.  This is useful
+// because some passes (ie TraceValues) insert a lot of string constants into
+// the program, regardless of whether or not an existing string is available.
+//
+// Algorithm: ConstantMerge is designed to build up a map of available constants
+// and eliminate duplicates when it is initialized.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_IPO_CONSTANTMERGE_H
+#define LLVM_TRANSFORMS_IPO_CONSTANTMERGE_H
+
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// A pass that merges duplicate global constants into a single constant.
+class ConstantMergePass : public PassInfoMixin<ConstantMergePass> {
+public:
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &);
+};
+}
+
+#endif // LLVM_TRANSFORMS_IPO_CONSTANTMERGE_H