From eaf039a94b6a84035735109165f9e262e36f054b Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 18 Oct 2001 20:05:30 +0000
Subject: [PATCH] Initial Checkin

llvm-svn: 896
---
 .../llvm/Transforms/IPO/ConstantMerge.h       | 58 +++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 llvm/include/llvm/Transforms/IPO/ConstantMerge.h

diff --git a/llvm/include/llvm/Transforms/IPO/ConstantMerge.h b/llvm/include/llvm/Transforms/IPO/ConstantMerge.h
new file mode 100644
index 000000000000..e98e375f084e
--- /dev/null
+++ b/llvm/include/llvm/Transforms/IPO/ConstantMerge.h
@@ -0,0 +1,58 @@
+//===- llvm/Transforms/ConstantMerge.h - Merge duplicate consts --*- C++ -*--=//
+//
+// 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 they duplicate an existing string.
+//
+// Algorithm: ConstantMerge is designed to build up a map of available constants
+// and elminate duplicates when it is initialized.
+//
+// The DynamicConstantMerge method is a superset of the ConstantMerge algorithm
+// that checks for each method to see if constants have been added to the
+// constant pool since it was last run... if so, it processes them.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_CONSTANTMERGE_H
+#define LLVM_TRANSFORMS_CONSTANTMERGE_H
+
+#include "llvm/Transforms/Pass.h"
+#include <map>
+class ConstPoolVal;
+class GlobalVariable;
+
+class ConstantMerge : public Pass {
+protected:
+  map<ConstPoolVal*, GlobalVariable*> Constants;
+  unsigned LastConstantSeen;
+public:
+  inline ConstantMerge() : LastConstantSeen(0) {}
+
+  // mergeDuplicateConstants - Static accessor for clients that don't want to
+  // deal with passes.
+  //
+  static bool mergeDuplicateConstants(Module *M);
+
+  // doPassInitialization - For this pass, process all of the globals in the
+  // module, eliminating duplicate constants.
+  //
+  bool doPassInitialization(Module *M);
+
+  // doPassFinalization - Clean up internal state for this module
+  //
+  bool doPassFinalization(Module *M) {
+    LastConstantSeen = 0;
+    Constants.clear();
+    return false;
+  }
+};
+
+struct DynamicConstantMerge : public ConstantMerge {
+  // doPerMethodWork - Check to see if any globals have been added to the 
+  // global list for the module.  If so, eliminate them.
+  //
+  bool doPerMethodWork(Method *M);
+};
+
+#endif