lib/Target/X86/X86InstrBuilder.h

   1 //===-- X86InstrBuilder.h - Functions to aid building x86 insts -*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file exposes functions that may be used with BuildMI from the
  11 // MachineInstrBuilder.h file to handle X86'isms in a clean way.
  12 //
  13 // The BuildMem function may be used with the BuildMI function to add entire
  14 // memory references in a single, typed, function call.  X86 memory references
  15 // can be very complex expressions (described in the README), so wrapping them
  16 // up behind an easier to use interface makes sense.  Descriptions of the
  17 // functions are included below.
  18 //
  19 // For reference, the order of operands for memory references is:
  20 // (Operand), Base, Scale, Index, Displacement.
  21 //
  22 //===----------------------------------------------------------------------===//
  23
  24 #ifndef X86INSTRBUILDER_H
  25 #define X86INSTRBUILDER_H
  26
  27 #include "llvm/CodeGen/MachineFrameInfo.h"
  28 #include "llvm/CodeGen/MachineInstrBuilder.h"
  29 #include "llvm/CodeGen/PseudoSourceValue.h"
  30
  31 namespace llvm {
  32
  33 /// X86AddressMode - This struct holds a generalized full x86 address mode.
  34 /// The base register can be a frame index, which will eventually be replaced
  35 /// with BP or SP and Disp being offsetted accordingly.  The displacement may
  36 /// also include the offset of a global value.
  37 struct X86AddressMode {
  38   enum {
  39     RegBase,
  40     FrameIndexBase
  41   } BaseType;
  42
  43   union {
  44     unsigned Reg;
  45     int FrameIndex;
  46   } Base;
  47
  48   unsigned Scale;
  49   unsigned IndexReg;
  50   unsigned Disp;
  51   GlobalValue *GV;
  52
  53   X86AddressMode() : BaseType(RegBase), Scale(1), IndexReg(0), Disp(0), GV(0) {
  54     Base.Reg = 0;
  55   }
  56 };
  57
  58 /// addDirectMem - This function is used to add a direct memory reference to the
  59 /// current instruction -- that is, a dereference of an address in a register,
  60 /// with no scale, index or displacement. An example is: DWORD PTR [EAX].
  61 ///
  62 inline const MachineInstrBuilder &addDirectMem(const MachineInstrBuilder &MIB,
  63                                                unsigned Reg) {
  64   // Because memory references are always represented with four
  65   // values, this adds: Reg, [1, NoReg, 0] to the instruction.
  66   return MIB.addReg(Reg).addImm(1).addReg(0).addImm(0);
  67 }
  68
  69 inline const MachineInstrBuilder &addLeaOffset(const MachineInstrBuilder &MIB,
  70                                             int Offset) {
  71   return MIB.addImm(1).addReg(0).addImm(Offset);
  72 }
  73
  74 inline const MachineInstrBuilder &addOffset(const MachineInstrBuilder &MIB,
  75                                             int Offset) {
  76   return addLeaOffset(MIB, Offset).addReg(0);
  77 }
  78
  79 /// addRegOffset - This function is used to add a memory reference of the form
  80 /// [Reg + Offset], i.e., one with no scale or index, but with a
  81 /// displacement. An example is: DWORD PTR [EAX + 4].
  82 ///
  83 inline const MachineInstrBuilder &addRegOffset(const MachineInstrBuilder &MIB,
  84                                                unsigned Reg, bool isKill,
  85                                                int Offset) {
  86   return addOffset(MIB.addReg(Reg, false, false, isKill), Offset);
  87 }
  88
  89 inline const MachineInstrBuilder &addLeaRegOffset(const MachineInstrBuilder &MIB,
  90                                                   unsigned Reg, bool isKill,
  91                                                   int Offset) {
  92   return addLeaOffset(MIB.addReg(Reg, false, false, isKill), Offset);
  93 }
  94
  95 /// addRegReg - This function is used to add a memory reference of the form:
  96 /// [Reg + Reg].
  97 inline const MachineInstrBuilder &addRegReg(const MachineInstrBuilder &MIB,
  98                                             unsigned Reg1, bool isKill1,
  99                                             unsigned Reg2, bool isKill2) {
 100   return MIB.addReg(Reg1, false, false, isKill1).addImm(1)
 101     .addReg(Reg2, false, false, isKill2).addImm(0);
 102 }
 103
 104 inline const MachineInstrBuilder &addLeaAddress(const MachineInstrBuilder &MIB,
 105                                                 const X86AddressMode &AM) {
 106   assert (AM.Scale == 1 || AM.Scale == 2 || AM.Scale == 4 || AM.Scale == 8);
 107
 108   if (AM.BaseType == X86AddressMode::RegBase)
 109     MIB.addReg(AM.Base.Reg);
 110   else if (AM.BaseType == X86AddressMode::FrameIndexBase)
 111     MIB.addFrameIndex(AM.Base.FrameIndex);
 112   else
 113     assert (0);
 114   MIB.addImm(AM.Scale).addReg(AM.IndexReg);
 115   if (AM.GV)
 116     return MIB.addGlobalAddress(AM.GV, AM.Disp);
 117   else
 118     return MIB.addImm(AM.Disp);
 119 }
 120
 121 inline const MachineInstrBuilder &addFullAddress(const MachineInstrBuilder &MIB,
 122                                                  const X86AddressMode &AM) {
 123   return addLeaAddress(MIB, AM).addReg(0);
 124 }
 125
 126 /// addFrameReference - This function is used to add a reference to the base of
 127 /// an abstract object on the stack frame of the current function.  This
 128 /// reference has base register as the FrameIndex offset until it is resolved.
 129 /// This allows a constant offset to be specified as well...
 130 ///
 131 inline const MachineInstrBuilder &
 132 addFrameReference(const MachineInstrBuilder &MIB, int FI, int Offset = 0) {
 133   MachineInstr *MI = MIB;
 134   MachineFunction &MF = *MI->getParent()->getParent();
 135   MachineFrameInfo &MFI = *MF.getFrameInfo();
 136   const TargetInstrDesc &TID = MI->getDesc();
 137   unsigned Flags = 0;
 138   if (TID.mayLoad())
 139     Flags |= MachineMemOperand::MOLoad;
 140   if (TID.mayStore())
 141     Flags |= MachineMemOperand::MOStore;
 142   MachineMemOperand MMO(PseudoSourceValue::getFixedStack(FI),
 143                         Flags,
 144                         MFI.getObjectOffset(FI) + Offset,
 145                         MFI.getObjectSize(FI),
 146                         MFI.getObjectAlignment(FI));
 147   return addOffset(MIB.addFrameIndex(FI), Offset)
 148             .addMemOperand(MMO);
 149 }
 150
 151 /// addConstantPoolReference - This function is used to add a reference to the
 152 /// base of a constant value spilled to the per-function constant pool.  The
 153 /// reference uses the abstract ConstantPoolIndex which is retained until
 154 /// either machine code emission or assembly output. In PIC mode on x86-32,
 155 /// the GlobalBaseReg parameter can be used to make this a
 156 /// GlobalBaseReg-relative reference.
 157 ///
 158 inline const MachineInstrBuilder &
 159 addConstantPoolReference(const MachineInstrBuilder &MIB, unsigned CPI,
 160                          unsigned GlobalBaseReg = 0) {
 161   //FIXME: factor this
 162   return MIB.addReg(GlobalBaseReg).addImm(1).addReg(0)
 163     .addConstantPoolIndex(CPI).addReg(0);
 164 }
 165
 166 } // End llvm namespace
 167
 168 #endif