1 //===-- PPCAsmBackend.cpp - PPC Assembler Backend -------------------------===//
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 #include "MCTargetDesc/PPCMCTargetDesc.h"
11 #include "MCTargetDesc/PPCFixupKinds.h"
12 #include "llvm/MC/MCAsmBackend.h"
13 #include "llvm/MC/MCAssembler.h"
14 #include "llvm/MC/MCELFObjectWriter.h"
15 #include "llvm/MC/MCFixupKindInfo.h"
16 #include "llvm/MC/MCMachObjectWriter.h"
17 #include "llvm/MC/MCObjectWriter.h"
18 #include "llvm/MC/MCSectionMachO.h"
19 #include "llvm/MC/MCSymbolELF.h"
20 #include "llvm/MC/MCValue.h"
21 #include "llvm/Support/ELF.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/MachO.h"
24 #include "llvm/Support/TargetRegistry.h"
25 using namespace llvm;
26
adjustFixupValue(unsigned Kind,uint64_t Value)27 static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) {
28 switch (Kind) {
29 default:
30 llvm_unreachable("Unknown fixup kind!");
31 case FK_Data_1:
32 case FK_Data_2:
33 case FK_Data_4:
34 case FK_Data_8:
35 case PPC::fixup_ppc_nofixup:
36 return Value;
37 case PPC::fixup_ppc_brcond14:
38 case PPC::fixup_ppc_brcond14abs:
39 return Value & 0xfffc;
40 case PPC::fixup_ppc_br24:
41 case PPC::fixup_ppc_br24abs:
42 return Value & 0x3fffffc;
43 case PPC::fixup_ppc_half16:
44 return Value & 0xffff;
45 case PPC::fixup_ppc_half16ds:
46 return Value & 0xfffc;
47 }
48 }
49
getFixupKindNumBytes(unsigned Kind)50 static unsigned getFixupKindNumBytes(unsigned Kind) {
51 switch (Kind) {
52 default:
53 llvm_unreachable("Unknown fixup kind!");
54 case FK_Data_1:
55 return 1;
56 case FK_Data_2:
57 case PPC::fixup_ppc_half16:
58 case PPC::fixup_ppc_half16ds:
59 return 2;
60 case FK_Data_4:
61 case PPC::fixup_ppc_brcond14:
62 case PPC::fixup_ppc_brcond14abs:
63 case PPC::fixup_ppc_br24:
64 case PPC::fixup_ppc_br24abs:
65 return 4;
66 case FK_Data_8:
67 return 8;
68 case PPC::fixup_ppc_nofixup:
69 return 0;
70 }
71 }
72
73 namespace {
74
75 class PPCAsmBackend : public MCAsmBackend {
76 const Target &TheTarget;
77 bool IsLittleEndian;
78 public:
PPCAsmBackend(const Target & T,bool isLittle)79 PPCAsmBackend(const Target &T, bool isLittle) : MCAsmBackend(), TheTarget(T),
80 IsLittleEndian(isLittle) {}
81
getNumFixupKinds() const82 unsigned getNumFixupKinds() const override {
83 return PPC::NumTargetFixupKinds;
84 }
85
getFixupKindInfo(MCFixupKind Kind) const86 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override {
87 const static MCFixupKindInfo InfosBE[PPC::NumTargetFixupKinds] = {
88 // name offset bits flags
89 { "fixup_ppc_br24", 6, 24, MCFixupKindInfo::FKF_IsPCRel },
90 { "fixup_ppc_brcond14", 16, 14, MCFixupKindInfo::FKF_IsPCRel },
91 { "fixup_ppc_br24abs", 6, 24, 0 },
92 { "fixup_ppc_brcond14abs", 16, 14, 0 },
93 { "fixup_ppc_half16", 0, 16, 0 },
94 { "fixup_ppc_half16ds", 0, 14, 0 },
95 { "fixup_ppc_nofixup", 0, 0, 0 }
96 };
97 const static MCFixupKindInfo InfosLE[PPC::NumTargetFixupKinds] = {
98 // name offset bits flags
99 { "fixup_ppc_br24", 2, 24, MCFixupKindInfo::FKF_IsPCRel },
100 { "fixup_ppc_brcond14", 2, 14, MCFixupKindInfo::FKF_IsPCRel },
101 { "fixup_ppc_br24abs", 2, 24, 0 },
102 { "fixup_ppc_brcond14abs", 2, 14, 0 },
103 { "fixup_ppc_half16", 0, 16, 0 },
104 { "fixup_ppc_half16ds", 2, 14, 0 },
105 { "fixup_ppc_nofixup", 0, 0, 0 }
106 };
107
108 if (Kind < FirstTargetFixupKind)
109 return MCAsmBackend::getFixupKindInfo(Kind);
110
111 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
112 "Invalid kind!");
113 return (IsLittleEndian? InfosLE : InfosBE)[Kind - FirstTargetFixupKind];
114 }
115
applyFixup(const MCFixup & Fixup,char * Data,unsigned DataSize,uint64_t Value,bool IsPCRel) const116 void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
117 uint64_t Value, bool IsPCRel) const override {
118 Value = adjustFixupValue(Fixup.getKind(), Value);
119 if (!Value) return; // Doesn't change encoding.
120
121 unsigned Offset = Fixup.getOffset();
122 unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
123
124 // For each byte of the fragment that the fixup touches, mask in the bits
125 // from the fixup value. The Value has been "split up" into the appropriate
126 // bitfields above.
127 for (unsigned i = 0; i != NumBytes; ++i) {
128 unsigned Idx = IsLittleEndian ? i : (NumBytes - 1 - i);
129 Data[Offset + i] |= uint8_t((Value >> (Idx * 8)) & 0xff);
130 }
131 }
132
processFixupValue(const MCAssembler & Asm,const MCAsmLayout & Layout,const MCFixup & Fixup,const MCFragment * DF,const MCValue & Target,uint64_t & Value,bool & IsResolved)133 void processFixupValue(const MCAssembler &Asm, const MCAsmLayout &Layout,
134 const MCFixup &Fixup, const MCFragment *DF,
135 const MCValue &Target, uint64_t &Value,
136 bool &IsResolved) override {
137 switch ((PPC::Fixups)Fixup.getKind()) {
138 default: break;
139 case PPC::fixup_ppc_br24:
140 case PPC::fixup_ppc_br24abs:
141 // If the target symbol has a local entry point we must not attempt
142 // to resolve the fixup directly. Emit a relocation and leave
143 // resolution of the final target address to the linker.
144 if (const MCSymbolRefExpr *A = Target.getSymA()) {
145 if (const auto *S = dyn_cast<MCSymbolELF>(&A->getSymbol())) {
146 // The "other" values are stored in the last 6 bits of the second
147 // byte. The traditional defines for STO values assume the full byte
148 // and thus the shift to pack it.
149 unsigned Other = S->getOther() << 2;
150 if ((Other & ELF::STO_PPC64_LOCAL_MASK) != 0)
151 IsResolved = false;
152 }
153 }
154 break;
155 }
156 }
157
mayNeedRelaxation(const MCInst & Inst) const158 bool mayNeedRelaxation(const MCInst &Inst) const override {
159 // FIXME.
160 return false;
161 }
162
fixupNeedsRelaxation(const MCFixup & Fixup,uint64_t Value,const MCRelaxableFragment * DF,const MCAsmLayout & Layout) const163 bool fixupNeedsRelaxation(const MCFixup &Fixup,
164 uint64_t Value,
165 const MCRelaxableFragment *DF,
166 const MCAsmLayout &Layout) const override {
167 // FIXME.
168 llvm_unreachable("relaxInstruction() unimplemented");
169 }
170
relaxInstruction(const MCInst & Inst,const MCSubtargetInfo & STI,MCInst & Res) const171 void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
172 MCInst &Res) const override {
173 // FIXME.
174 llvm_unreachable("relaxInstruction() unimplemented");
175 }
176
writeNopData(uint64_t Count,MCObjectWriter * OW) const177 bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override {
178 uint64_t NumNops = Count / 4;
179 for (uint64_t i = 0; i != NumNops; ++i)
180 OW->write32(0x60000000);
181
182 OW->WriteZeros(Count % 4);
183
184 return true;
185 }
186
getPointerSize() const187 unsigned getPointerSize() const {
188 StringRef Name = TheTarget.getName();
189 if (Name == "ppc64" || Name == "ppc64le") return 8;
190 assert(Name == "ppc32" && "Unknown target name!");
191 return 4;
192 }
193
isLittleEndian() const194 bool isLittleEndian() const {
195 return IsLittleEndian;
196 }
197 };
198 } // end anonymous namespace
199
200
201 // FIXME: This should be in a separate file.
202 namespace {
203 class DarwinPPCAsmBackend : public PPCAsmBackend {
204 public:
DarwinPPCAsmBackend(const Target & T)205 DarwinPPCAsmBackend(const Target &T) : PPCAsmBackend(T, false) { }
206
createObjectWriter(raw_pwrite_stream & OS) const207 MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
208 bool is64 = getPointerSize() == 8;
209 return createPPCMachObjectWriter(
210 OS,
211 /*Is64Bit=*/is64,
212 (is64 ? MachO::CPU_TYPE_POWERPC64 : MachO::CPU_TYPE_POWERPC),
213 MachO::CPU_SUBTYPE_POWERPC_ALL);
214 }
215 };
216
217 class ELFPPCAsmBackend : public PPCAsmBackend {
218 uint8_t OSABI;
219 public:
ELFPPCAsmBackend(const Target & T,bool IsLittleEndian,uint8_t OSABI)220 ELFPPCAsmBackend(const Target &T, bool IsLittleEndian, uint8_t OSABI) :
221 PPCAsmBackend(T, IsLittleEndian), OSABI(OSABI) { }
222
createObjectWriter(raw_pwrite_stream & OS) const223 MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
224 bool is64 = getPointerSize() == 8;
225 return createPPCELFObjectWriter(OS, is64, isLittleEndian(), OSABI);
226 }
227 };
228
229 } // end anonymous namespace
230
createPPCAsmBackend(const Target & T,const MCRegisterInfo & MRI,const Triple & TT,StringRef CPU)231 MCAsmBackend *llvm::createPPCAsmBackend(const Target &T,
232 const MCRegisterInfo &MRI,
233 const Triple &TT, StringRef CPU) {
234 if (TT.isOSDarwin())
235 return new DarwinPPCAsmBackend(T);
236
237 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS());
238 bool IsLittleEndian = TT.getArch() == Triple::ppc64le;
239 return new ELFPPCAsmBackend(T, IsLittleEndian, OSABI);
240 }
241