1 //===-- MipsASMBackend.cpp - Mips Asm Backend ----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the MipsAsmBackend and MipsELFObjectWriter classes.
12 //===----------------------------------------------------------------------===//
15 #include "MipsBaseInfo.h"
16 #include "MipsFixupKinds.h"
17 #include "MCTargetDesc/MipsMCTargetDesc.h"
18 #include "llvm/MC/MCAsmBackend.h"
19 #include "llvm/MC/MCAssembler.h"
20 #include "llvm/MC/MCDirectives.h"
21 #include "llvm/MC/MCELFObjectWriter.h"
22 #include "llvm/MC/MCFixupKindInfo.h"
23 #include "llvm/MC/MCObjectWriter.h"
24 #include "llvm/MC/MCSubtargetInfo.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/raw_ostream.h"
30 // Prepare value for the target space for it
31 static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
33 // Add/subtract and shift
39 case Mips::fixup_Mips_LO16:
41 case Mips::fixup_Mips_PC16:
42 // So far we are only using this type for branches.
43 // For branches we start 1 instruction after the branch
44 // so the displacement will be one instruction size less.
46 // The displacement is then divided by 4 to give us an 18 bit
50 case Mips::fixup_Mips_26:
51 // So far we are only using this type for jumps.
52 // The displacement is then divided by 4 to give us an 28 bit
56 case Mips::fixup_Mips_HI16:
57 case Mips::fixup_Mips_GOT_Local:
58 // Get the higher 16-bits. Also add 1 if bit 15 is 1.
59 Value = ((Value + 0x8000) >> 16) & 0xffff;
67 class MipsAsmBackend : public MCAsmBackend {
68 Triple::OSType OSType;
69 bool IsLittle; // Big or little endian
70 bool Is64Bit; // 32 or 64 bit words
73 MipsAsmBackend(const Target &T, Triple::OSType _OSType,
74 bool _isLittle, bool _is64Bit)
75 :MCAsmBackend(), OSType(_OSType), IsLittle(_isLittle), Is64Bit(_is64Bit) {}
77 MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
78 return createMipsELFObjectWriter(OS, OSType, IsLittle, Is64Bit);
81 /// ApplyFixup - Apply the \arg Value for given \arg Fixup into the provided
82 /// data fragment, at the offset specified by the fixup and following the
83 /// fixup kind as appropriate.
84 void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
85 uint64_t Value) const {
86 MCFixupKind Kind = Fixup.getKind();
87 Value = adjustFixupValue((unsigned)Kind, Value);
88 int64_t SymOffset = MipsGetSymAndOffset(Fixup).second;
90 if (!Value && !SymOffset)
91 return; // Doesn't change encoding.
93 // Where do we start in the object
94 unsigned Offset = Fixup.getOffset();
95 // Number of bytes we need to fixup
96 unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8;
97 // Used to point to big endian bytes
100 switch ((unsigned)Kind) {
101 case Mips::fixup_Mips_16:
104 case Mips::fixup_Mips_64:
112 // Grab current value, if any, from bits.
115 for (unsigned i = 0; i != NumBytes; ++i) {
116 unsigned Idx = IsLittle ? i : (FullSize - 1 - i);
117 CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i*8);
120 uint64_t Mask = ((uint64_t)(-1) >> (64 - getFixupKindInfo(Kind).TargetSize));
121 CurVal |= (Value + SymOffset) & Mask;
123 // Write out the fixed up bytes back to the code/data bits.
124 for (unsigned i = 0; i != NumBytes; ++i) {
125 unsigned Idx = IsLittle ? i : (FullSize - 1 - i);
126 Data[Offset + Idx] = (uint8_t)((CurVal >> (i*8)) & 0xff);
130 unsigned getNumFixupKinds() const { return Mips::NumTargetFixupKinds; }
132 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const {
133 const static MCFixupKindInfo Infos[Mips::NumTargetFixupKinds] = {
134 // This table *must* be in same the order of fixup_* kinds in
137 // name offset bits flags
138 { "fixup_Mips_16", 0, 16, 0 },
139 { "fixup_Mips_32", 0, 32, 0 },
140 { "fixup_Mips_REL32", 0, 32, 0 },
141 { "fixup_Mips_26", 0, 26, 0 },
142 { "fixup_Mips_HI16", 0, 16, 0 },
143 { "fixup_Mips_LO16", 0, 16, 0 },
144 { "fixup_Mips_GPREL16", 0, 16, 0 },
145 { "fixup_Mips_LITERAL", 0, 16, 0 },
146 { "fixup_Mips_GOT_Global", 0, 16, 0 },
147 { "fixup_Mips_GOT_Local", 0, 16, 0 },
148 { "fixup_Mips_PC16", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
149 { "fixup_Mips_CALL16", 0, 16, 0 },
150 { "fixup_Mips_GPREL32", 0, 32, 0 },
151 { "fixup_Mips_SHIFT5", 6, 5, 0 },
152 { "fixup_Mips_SHIFT6", 6, 5, 0 },
153 { "fixup_Mips_64", 0, 64, 0 },
154 { "fixup_Mips_TLSGD", 0, 16, 0 },
155 { "fixup_Mips_GOTTPREL", 0, 16, 0 },
156 { "fixup_Mips_TPREL_HI", 0, 16, 0 },
157 { "fixup_Mips_TPREL_LO", 0, 16, 0 },
158 { "fixup_Mips_TLSLDM", 0, 16, 0 },
159 { "fixup_Mips_DTPREL_HI", 0, 16, 0 },
160 { "fixup_Mips_DTPREL_LO", 0, 16, 0 },
161 { "fixup_Mips_Branch_PCRel", 0, 16, MCFixupKindInfo::FKF_IsPCRel }
164 if (Kind < FirstTargetFixupKind)
165 return MCAsmBackend::getFixupKindInfo(Kind);
167 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
169 return Infos[Kind - FirstTargetFixupKind];
172 /// @name Target Relaxation Interfaces
175 /// MayNeedRelaxation - Check whether the given instruction may need
178 /// \param Inst - The instruction to test.
179 bool mayNeedRelaxation(const MCInst &Inst) const {
183 /// fixupNeedsRelaxation - Target specific predicate for whether a given
184 /// fixup requires the associated instruction to be relaxed.
185 bool fixupNeedsRelaxation(const MCFixup &Fixup,
187 const MCInstFragment *DF,
188 const MCAsmLayout &Layout) const {
190 assert(0 && "RelaxInstruction() unimplemented");
194 /// RelaxInstruction - Relax the instruction in the given fragment
195 /// to the next wider instruction.
197 /// \param Inst - The instruction to relax, which may be the same
199 /// \parm Res [output] - On return, the relaxed instruction.
200 void relaxInstruction(const MCInst &Inst, MCInst &Res) const {
205 /// WriteNopData - Write an (optimal) nop sequence of Count bytes
206 /// to the given output. If the target cannot generate such a sequence,
207 /// it should return an error.
209 /// \return - True on success.
210 bool writeNopData(uint64_t Count, MCObjectWriter *OW) const {
213 }; // class MipsAsmBackend
218 MCAsmBackend *llvm::createMipsAsmBackendEL32(const Target &T, StringRef TT) {
219 return new MipsAsmBackend(T, Triple(TT).getOS(),
220 /*IsLittle*/true, /*Is64Bit*/false);
223 MCAsmBackend *llvm::createMipsAsmBackendEB32(const Target &T, StringRef TT) {
224 return new MipsAsmBackend(T, Triple(TT).getOS(),
225 /*IsLittle*/false, /*Is64Bit*/false);
228 MCAsmBackend *llvm::createMipsAsmBackendEL64(const Target &T, StringRef TT) {
229 return new MipsAsmBackend(T, Triple(TT).getOS(),
230 /*IsLittle*/true, /*Is64Bit*/true);
233 MCAsmBackend *llvm::createMipsAsmBackendEB64(const Target &T, StringRef TT) {
234 return new MipsAsmBackend(T, Triple(TT).getOS(),
235 /*IsLittle*/false, /*Is64Bit*/true);