1 //===-- CodeGen/MachineConstantPool.h - Abstract Constant Pool --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // The MachineConstantPool class keeps track of constants referenced by a
11 // function which must be spilled to memory. This is used for constants which
12 // are unable to be used directly as operands to instructions, which typically
13 // include floating point and large integer constants.
15 // Instructions reference the address of these constant pool constants through
16 // the use of MO_ConstantPoolIndex values. When emitting assembly or machine
17 // code, these virtual address references are converted to refer to the
18 // address of the function constant pool values.
20 //===----------------------------------------------------------------------===//
22 #ifndef LLVM_CODEGEN_MACHINECONSTANTPOOL_H
23 #define LLVM_CODEGEN_MACHINECONSTANTPOOL_H
33 /// MachineConstantPoolEntry - One entry in the constant pool.
35 struct MachineConstantPoolEntry {
36 /// Val - The constant itself.
38 /// Alignment - The alignment of the constant.
41 MachineConstantPoolEntry(Constant *V, unsigned A) : Val(V), Alignment(A) {}
44 class MachineConstantPool {
45 std::vector<MachineConstantPoolEntry> Constants;
47 /// getConstantPoolIndex - Create a new entry in the constant pool or return
48 /// an existing one. User must specify an alignment in bytes for the object.
50 unsigned getConstantPoolIndex(Constant *C, unsigned Alignment) {
51 assert(Alignment && "Alignment must be specified!");
53 // Check to see if we already have this constant.
55 // FIXME, this could be made much more efficient for large constant pools.
56 for (unsigned i = 0, e = Constants.size(); i != e; ++i)
57 if (Constants[i].Val == C && Constants[i].Alignment >= Alignment)
59 Constants.push_back(MachineConstantPoolEntry(C, Alignment));
60 return Constants.size()-1;
63 /// isEmpty - Return true if this constant pool contains no constants.
65 bool isEmpty() const { return Constants.empty(); }
67 const std::vector<MachineConstantPoolEntry> &getConstants() const {
71 /// print - Used by the MachineFunction printer to print information about
72 /// stack objects. Implemented in MachineFunction.cpp
74 void print(std::ostream &OS) const;
76 /// dump - Call print(std::cerr) to be called from the debugger.
80 } // End llvm namespace