JumpTable support! What this represents is working asm and jit support for

x86 and ppc for 100% dense switch statements when relocations are non-PIC.
This support will be extended and enhanced in the coming days to support
PIC, and less dense forms of jump tables.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27947 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineJumpTableInfo.h

@@ -0,0 +1,73 @@
+//===-- CodeGen/MachineJumpTableInfo.h - Abstract Jump Tables  --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Nate Begeman and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The MachineJumpTableInfo class keeps track of jump tables referenced by
+// lowered switch instructions in the MachineFunction.
+//
+// Instructions reference the address of these jump tables through the use of 
+// MO_JumpTableIndex values.  When emitting assembly or machine code, these 
+// virtual address references are converted to refer to the address of the 
+// function jump tables.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H
+#define LLVM_CODEGEN_MACHINEJUMPTABLEINFO_H
+
+#include "llvm/Target/TargetData.h"
+#include <vector>
+#include <iosfwd>
+
+namespace llvm {
+
+class MachineBasicBlock;
+
+/// MachineJumpTableEntry - One jump table in the jump table info.
+///
+struct MachineJumpTableEntry {
+  /// MBBs - The vector of basic blocks from which to create the jump table.
+  std::vector<MachineBasicBlock*> MBBs;
+  
+  MachineJumpTableEntry(std::vector<MachineBasicBlock*> &M) : MBBs(M) {}
+};
+  
+class MachineJumpTableInfo {
+  const TargetData &TD;
+  std::vector<MachineJumpTableEntry> JumpTables;
+public:
+  MachineJumpTableInfo(const TargetData &td) : TD(td) {}
+    
+  /// getJumpTableIndex - Create a new jump table or return an existing one.
+  ///
+  unsigned getJumpTableIndex(std::vector<MachineBasicBlock*> &DestBBs);
+  
+  /// isEmpty - Return true if there are no jump tables.
+  ///
+  bool isEmpty() const { return JumpTables.empty(); }
+
+  const std::vector<MachineJumpTableEntry> &getJumpTables() const {
+    return JumpTables;
+  }
+  
+  unsigned getEntrySize() const { return TD.getPointerSize(); }
+  unsigned getAlignment() const { return TD.getPointerAlignment(); }
+  
+  /// print - Used by the MachineFunction printer to print information about
+  /// jump tables.  Implemented in MachineFunction.cpp
+  ///
+  void print(std::ostream &OS) const;
+
+  /// dump - Call print(std::cerr) to be called from the debugger.
+  ///
+  void dump() const;
+};
+
+} // End llvm namespace
+
+#endif