MCFixup.h revision 1f6efa3996dd1929fbc129203ce5009b620e6969
173c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar//===-- llvm/MC/MCFixup.h - Instruction Relocation and Patching -*- C++ -*-===// 273c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar// 373c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar// The LLVM Compiler Infrastructure 473c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar// 573c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar// This file is distributed under the University of Illinois Open Source 673c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar// License. See LICENSE.TXT for details. 773c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar// 873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar//===----------------------------------------------------------------------===// 973c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 1073c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar#ifndef LLVM_MC_MCFIXUP_H 1173c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar#define LLVM_MC_MCFIXUP_H 1273c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 131f6efa3996dd1929fbc129203ce5009b620e6969Michael J. Spencer#include "llvm/Support/DataTypes.h" 1473c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar#include <cassert> 1573c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 1673c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbarnamespace llvm { 175d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbarclass MCExpr; 1873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 1973c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// MCFixupKind - Extensible enumeration to represent the type of a fixup. 2073c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbarenum MCFixupKind { 2173c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar FK_Data_1 = 0, ///< A one-byte fixup. 2273c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar FK_Data_2, ///< A two-byte fixup. 2373c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar FK_Data_4, ///< A four-byte fixup. 2473c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar FK_Data_8, ///< A eight-byte fixup. 25e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola FK_PCRel_1, ///< A one-byte pc relative fixup. 26e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola FK_PCRel_2, ///< A two-byte pc relative fixup. 27e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola FK_PCRel_4, ///< A four-byte pc relative fixup. 2873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 290dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar FirstTargetFixupKind = 128, 3073c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 310dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar // Limit range of target fixups, in case we want to pack more efficiently 320dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar // later. 330dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar MaxTargetFixupKind = (1 << 8) 3473c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar}; 3573c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 360dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar/// MCFixup - Encode information on a single operation to perform on a byte 3773c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// sequence (e.g., an encoded instruction) which requires assemble- or run- 3873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// time patching. 3973c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// 4073c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// Fixups are used any time the target instruction encoder needs to represent 4173c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// some value in an instruction which is not yet concrete. The encoder will 4273c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// encode the instruction assuming the value is 0, and emit a fixup which 4373c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// communicates to the assembler backend how it should rewrite the encoded 4473c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// value. 4573c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// 4673c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// During the process of relaxation, the assembler will apply fixups as 4773c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// symbolic values become concrete. When relaxation is complete, any remaining 4873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// fixups become relocations in the object file (or errors, if the fixup cannot 4973c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar/// be encoded on the target). 5073c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbarclass MCFixup { 515d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbar /// The value to put into the fixup location. The exact interpretation of the 520dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar /// expression is target dependent, usually it will be one of the operands to 530dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar /// an instruction or an assembler directive. 545d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbar const MCExpr *Value; 555d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbar 5673c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar /// The byte index of start of the relocation inside the encoded instruction. 570dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar uint32_t Offset; 5873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 5973c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar /// The target dependent kind of fixup item this is. The kind is used to 6073c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar /// determine how the operand value should be encoded into the instruction. 610dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar unsigned Kind; 6273c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 6373c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbarpublic: 640dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar static MCFixup Create(uint32_t Offset, const MCExpr *Value, 655d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbar MCFixupKind Kind) { 660dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar assert(unsigned(Kind) < MaxTargetFixupKind && "Kind out of range!"); 6773c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar MCFixup FI; 685d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbar FI.Value = Value; 6973c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar FI.Offset = Offset; 7073c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar FI.Kind = unsigned(Kind); 7173c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar return FI; 7273c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar } 7373c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 745d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbar MCFixupKind getKind() const { return MCFixupKind(Kind); } 7573c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 760dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar uint32_t getOffset() const { return Offset; } 770dd0c941c9eb4adc13319ed7adcaffe58a68d294Daniel Dunbar void setOffset(uint32_t Value) { Offset = Value; } 7873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 795d5a1e13a129e18ee6031fe6354acd2ab4d39f37Daniel Dunbar const MCExpr *getValue() const { return Value; } 802be2fd073003c0988723d2894dfb117ad90be11bDaniel Dunbar 812be2fd073003c0988723d2894dfb117ad90be11bDaniel Dunbar /// getKindForSize - Return the generic fixup kind for a value with the given 822be2fd073003c0988723d2894dfb117ad90be11bDaniel Dunbar /// size. It is an error to pass an unsupported size. 83e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola static MCFixupKind getKindForSize(unsigned Size, bool isPCRel) { 842be2fd073003c0988723d2894dfb117ad90be11bDaniel Dunbar switch (Size) { 852be2fd073003c0988723d2894dfb117ad90be11bDaniel Dunbar default: assert(0 && "Invalid generic fixup size!"); 86e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola case 1: return isPCRel ? FK_PCRel_1 : FK_Data_1; 87e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola case 2: return isPCRel ? FK_PCRel_2 : FK_Data_2; 88e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola case 4: return isPCRel ? FK_PCRel_4 : FK_Data_4; 89e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola case 8: 90e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola assert(!isPCRel && "8 byte pc relative fixup is not supported."); 91e04ed7e45f194f14a7b28bbf3f55694d8e2bcf80Rafael Espindola return FK_Data_8; 922be2fd073003c0988723d2894dfb117ad90be11bDaniel Dunbar } 932be2fd073003c0988723d2894dfb117ad90be11bDaniel Dunbar } 9473c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar}; 9573c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 9673c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar} // End llvm namespace 9773c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar 9873c557458c0e28899f37c557bcaf36c2b6701260Daniel Dunbar#endif 99