LLVM API Documentation
00001 //===-- X86InstrBuilder.h - Functions to aid building x86 insts -*- C++ -*-===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This file exposes functions that may be used with BuildMI from the 00011 // MachineInstrBuilder.h file to handle X86'isms in a clean way. 00012 // 00013 // The BuildMem function may be used with the BuildMI function to add entire 00014 // memory references in a single, typed, function call. X86 memory references 00015 // can be very complex expressions (described in the README), so wrapping them 00016 // up behind an easier to use interface makes sense. Descriptions of the 00017 // functions are included below. 00018 // 00019 // For reference, the order of operands for memory references is: 00020 // (Operand), Base, Scale, Index, Displacement. 00021 // 00022 //===----------------------------------------------------------------------===// 00023 00024 #ifndef X86INSTRBUILDER_H 00025 #define X86INSTRBUILDER_H 00026 00027 #include "llvm/CodeGen/MachineInstrBuilder.h" 00028 00029 namespace llvm { 00030 00031 /// X86AddressMode - This struct holds a generalized full x86 address mode. 00032 /// The base register can be a frame index, which will eventually be replaced 00033 /// with BP or SP and Disp being offsetted accordingly. The displacement may 00034 /// also include the offset of a global value. 00035 struct X86AddressMode { 00036 enum { 00037 RegBase, 00038 FrameIndexBase 00039 } BaseType; 00040 00041 union { 00042 unsigned Reg; 00043 int FrameIndex; 00044 } Base; 00045 00046 unsigned Scale; 00047 unsigned IndexReg; 00048 unsigned Disp; 00049 GlobalValue *GV; 00050 00051 X86AddressMode() : BaseType(RegBase), Scale(1), IndexReg(0), Disp(0), GV(0) { 00052 Base.Reg = 0; 00053 } 00054 }; 00055 00056 /// addDirectMem - This function is used to add a direct memory reference to the 00057 /// current instruction -- that is, a dereference of an address in a register, 00058 /// with no scale, index or displacement. An example is: DWORD PTR [EAX]. 00059 /// 00060 inline const MachineInstrBuilder &addDirectMem(const MachineInstrBuilder &MIB, 00061 unsigned Reg) { 00062 // Because memory references are always represented with four 00063 // values, this adds: Reg, [1, NoReg, 0] to the instruction. 00064 return MIB.addReg(Reg).addImm(1).addReg(0).addImm(0); 00065 } 00066 00067 00068 /// addRegOffset - This function is used to add a memory reference of the form 00069 /// [Reg + Offset], i.e., one with no scale or index, but with a 00070 /// displacement. An example is: DWORD PTR [EAX + 4]. 00071 /// 00072 inline const MachineInstrBuilder &addRegOffset(const MachineInstrBuilder &MIB, 00073 unsigned Reg, int Offset) { 00074 return MIB.addReg(Reg).addImm(1).addReg(0).addImm(Offset); 00075 } 00076 00077 /// addRegReg - This function is used to add a memory reference of the form: 00078 /// [Reg + Reg]. 00079 inline const MachineInstrBuilder &addRegReg(const MachineInstrBuilder &MIB, 00080 unsigned Reg1, unsigned Reg2) { 00081 return MIB.addReg(Reg1).addImm(1).addReg(Reg2).addImm(0); 00082 } 00083 00084 inline const MachineInstrBuilder &addFullAddress(const MachineInstrBuilder &MIB, 00085 const X86AddressMode &AM) { 00086 assert (AM.Scale == 1 || AM.Scale == 2 || AM.Scale == 4 || AM.Scale == 8); 00087 00088 if (AM.BaseType == X86AddressMode::RegBase) 00089 MIB.addReg(AM.Base.Reg); 00090 else if (AM.BaseType == X86AddressMode::FrameIndexBase) 00091 MIB.addFrameIndex(AM.Base.FrameIndex); 00092 else 00093 assert (0); 00094 MIB.addImm(AM.Scale).addReg(AM.IndexReg); 00095 if (AM.GV) 00096 return MIB.addGlobalAddress(AM.GV, AM.Disp); 00097 else 00098 return MIB.addImm(AM.Disp); 00099 } 00100 00101 /// addFrameReference - This function is used to add a reference to the base of 00102 /// an abstract object on the stack frame of the current function. This 00103 /// reference has base register as the FrameIndex offset until it is resolved. 00104 /// This allows a constant offset to be specified as well... 00105 /// 00106 inline const MachineInstrBuilder & 00107 addFrameReference(const MachineInstrBuilder &MIB, int FI, int Offset = 0) { 00108 return MIB.addFrameIndex(FI).addImm(1).addReg(0).addImm(Offset); 00109 } 00110 00111 /// addConstantPoolReference - This function is used to add a reference to the 00112 /// base of a constant value spilled to the per-function constant pool. The 00113 /// reference has base register ConstantPoolIndex offset which is retained until 00114 /// either machine code emission or assembly output. This allows an optional 00115 /// offset to be added as well. 00116 /// 00117 inline const MachineInstrBuilder & 00118 addConstantPoolReference(const MachineInstrBuilder &MIB, unsigned CPI, 00119 int Offset = 0) { 00120 return MIB.addConstantPoolIndex(CPI).addImm(1).addReg(0).addImm(Offset); 00121 } 00122 00123 } // End llvm namespace 00124 00125 #endif