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gerrit-public.fairphone.software / platform / external / llvm / 7609785d2b9b79b9aafc3b3afabcb691cfc8afa5 / . / lib / Target / ARM / MCTargetDesc / ARMELFObjectWriter.cpp
blob: 0cea32bfbb54dca9b5570d7dcbe27467a3d7f4b2 [file] [log] [blame]
Rafael Espindola76097852011-12-22 01:06:53 +0000[diff] [blame^]1//===-- ARMELFObjectWriter.cpp - ARM ELF Writer ---------------------------===//
Rafael Espindola69bbda02011-12-22 00:37:50 +0000[diff] [blame]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/ARMFixupKinds.h"
11#include "MCTargetDesc/ARMMCTargetDesc.h"
12#include "llvm/Support/Debug.h"
13#include "llvm/Support/ErrorHandling.h"
14#include "llvm/ADT/Statistic.h"
15#include "llvm/ADT/StringSwitch.h"
16#include "llvm/MC/MCELFObjectWriter.h"
17#include "llvm/MC/MCExpr.h"
18#include "llvm/MC/MCSectionELF.h"
19#include "llvm/MC/MCValue.h"
20
21using namespace llvm;
22
23namespace {
24 class ARMELFObjectWriter : public MCELFObjectTargetWriter {
25 enum { DefaultEABIVersion = 0x05000000U };
26
27 const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
28 const MCValue &Target,
29 const MCFragment &F,
30 const MCFixup &Fixup,
31 bool IsPCRel) const;
32 unsigned GetRelocTypeInner(const MCValue &Target,
33 const MCFixup &Fixup,
34 bool IsPCRel) const;
35
36
37 public:
38 ARMELFObjectWriter(uint8_t OSABI);
39
40 virtual ~ARMELFObjectWriter();
41 protected:
42 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
43 bool IsPCRel, bool IsRelocWithSymbol,
44 int64_t Addend) const;
45 virtual unsigned getEFlags() const;
46 };
47}
48
49ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI)
50 : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI,
51 ELF::EM_ARM,
52 /*HasRelocationAddend*/ false) {}
53
54ARMELFObjectWriter::~ARMELFObjectWriter() {}
55
56// FIXME: get the real EABI Version from the Triple.
57unsigned ARMELFObjectWriter::getEFlags() const {
58 return ELF::EF_ARM_EABIMASK & DefaultEABIVersion;
59}
60
61// In ARM, _MergedGlobals and other most symbols get emitted directly.
62// I.e. not as an offset to a section symbol.
63// This code is an approximation of what ARM/gcc does.
64
65STATISTIC(PCRelCount, "Total number of PIC Relocations");
66STATISTIC(NonPCRelCount, "Total number of non-PIC relocations");
67
68const MCSymbol *ARMELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm,
69 const MCValue &Target,
70 const MCFragment &F,
71 const MCFixup &Fixup,
72 bool IsPCRel) const {
73 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
74 bool EmitThisSym = false;
75
76 const MCSectionELF &Section =
77 static_cast<const MCSectionELF&>(Symbol.getSection());
78 bool InNormalSection = true;
79 unsigned RelocType = 0;
80 RelocType = GetRelocTypeInner(Target, Fixup, IsPCRel);
81
82 DEBUG(
83 const MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
84 MCSymbolRefExpr::VariantKind Kind2;
85 Kind2 = Target.getSymB() ? Target.getSymB()->getKind() :
86 MCSymbolRefExpr::VK_None;
87 dbgs() << "considering symbol "
88 << Section.getSectionName() << "/"
89 << Symbol.getName() << "/"
90 << " Rel:" << (unsigned)RelocType
91 << " Kind: " << (int)Kind << "/" << (int)Kind2
92 << " Tmp:"
93 << Symbol.isAbsolute() << "/" << Symbol.isDefined() << "/"
94 << Symbol.isVariable() << "/" << Symbol.isTemporary()
95 << " Counts:" << PCRelCount << "/" << NonPCRelCount << "\n");
96
97 if (IsPCRel) { ++PCRelCount;
98 switch (RelocType) {
99 default:
100 // Most relocation types are emitted as explicit symbols
101 InNormalSection =
102 StringSwitch<bool>(Section.getSectionName())
103 .Case(".data.rel.ro.local", false)
104 .Case(".data.rel", false)
105 .Case(".bss", false)
106 .Default(true);
107 EmitThisSym = true;
108 break;
109 case ELF::R_ARM_ABS32:
110 // But things get strange with R_ARM_ABS32
111 // In this case, most things that go in .rodata show up
112 // as section relative relocations
113 InNormalSection =
114 StringSwitch<bool>(Section.getSectionName())
115 .Case(".data.rel.ro.local", false)
116 .Case(".data.rel", false)
117 .Case(".rodata", false)
118 .Case(".bss", false)
119 .Default(true);
120 EmitThisSym = false;
121 break;
122 }
123 } else {
124 NonPCRelCount++;
125 InNormalSection =
126 StringSwitch<bool>(Section.getSectionName())
127 .Case(".data.rel.ro.local", false)
128 .Case(".rodata", false)
129 .Case(".data.rel", false)
130 .Case(".bss", false)
131 .Default(true);
132
133 switch (RelocType) {
134 default: EmitThisSym = true; break;
135 case ELF::R_ARM_ABS32: EmitThisSym = false; break;
136 }
137 }
138
139 if (EmitThisSym)
140 return &Symbol;
141 if (! Symbol.isTemporary() && InNormalSection) {
142 return &Symbol;
143 }
144 return NULL;
145}
146
147// Need to examine the Fixup when determining whether to
148// emit the relocation as an explicit symbol or as a section relative
149// offset
150unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
151 const MCFixup &Fixup,
152 bool IsPCRel,
153 bool IsRelocWithSymbol,
154 int64_t Addend) const {
155 return GetRelocTypeInner(Target, Fixup, IsPCRel);
156}
157
158unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
159 const MCFixup &Fixup,
160 bool IsPCRel) const {
161 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
162 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
163
164 unsigned Type = 0;
165 if (IsPCRel) {
166 switch ((unsigned)Fixup.getKind()) {
167 default: assert(0 && "Unimplemented");
168 case FK_Data_4:
169 switch (Modifier) {
170 default: llvm_unreachable("Unsupported Modifier");
171 case MCSymbolRefExpr::VK_None:
172 Type = ELF::R_ARM_REL32;
173 break;
174 case MCSymbolRefExpr::VK_ARM_TLSGD:
175 assert(0 && "unimplemented");
176 break;
177 case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
178 Type = ELF::R_ARM_TLS_IE32;
179 break;
180 }
181 break;
182 case ARM::fixup_arm_uncondbranch:
183 switch (Modifier) {
184 case MCSymbolRefExpr::VK_ARM_PLT:
185 Type = ELF::R_ARM_PLT32;
186 break;
187 default:
188 Type = ELF::R_ARM_CALL;
189 break;
190 }
191 break;
192 case ARM::fixup_arm_condbranch:
193 Type = ELF::R_ARM_JUMP24;
194 break;
195 case ARM::fixup_arm_movt_hi16:
196 case ARM::fixup_arm_movt_hi16_pcrel:
197 Type = ELF::R_ARM_MOVT_PREL;
198 break;
199 case ARM::fixup_arm_movw_lo16:
200 case ARM::fixup_arm_movw_lo16_pcrel:
201 Type = ELF::R_ARM_MOVW_PREL_NC;
202 break;
203 case ARM::fixup_t2_movt_hi16:
204 case ARM::fixup_t2_movt_hi16_pcrel:
205 Type = ELF::R_ARM_THM_MOVT_PREL;
206 break;
207 case ARM::fixup_t2_movw_lo16:
208 case ARM::fixup_t2_movw_lo16_pcrel:
209 Type = ELF::R_ARM_THM_MOVW_PREL_NC;
210 break;
211 case ARM::fixup_arm_thumb_bl:
212 case ARM::fixup_arm_thumb_blx:
213 switch (Modifier) {
214 case MCSymbolRefExpr::VK_ARM_PLT:
215 Type = ELF::R_ARM_THM_CALL;
216 break;
217 default:
218 Type = ELF::R_ARM_NONE;
219 break;
220 }
221 break;
222 }
223 } else {
224 switch ((unsigned)Fixup.getKind()) {
225 default: llvm_unreachable("invalid fixup kind!");
226 case FK_Data_4:
227 switch (Modifier) {
228 default: llvm_unreachable("Unsupported Modifier"); break;
229 case MCSymbolRefExpr::VK_ARM_GOT:
230 Type = ELF::R_ARM_GOT_BREL;
231 break;
232 case MCSymbolRefExpr::VK_ARM_TLSGD:
233 Type = ELF::R_ARM_TLS_GD32;
234 break;
235 case MCSymbolRefExpr::VK_ARM_TPOFF:
236 Type = ELF::R_ARM_TLS_LE32;
237 break;
238 case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
239 Type = ELF::R_ARM_TLS_IE32;
240 break;
241 case MCSymbolRefExpr::VK_None:
242 Type = ELF::R_ARM_ABS32;
243 break;
244 case MCSymbolRefExpr::VK_ARM_GOTOFF:
245 Type = ELF::R_ARM_GOTOFF32;
246 break;
247 }
248 break;
249 case ARM::fixup_arm_ldst_pcrel_12:
250 case ARM::fixup_arm_pcrel_10:
251 case ARM::fixup_arm_adr_pcrel_12:
252 case ARM::fixup_arm_thumb_bl:
253 case ARM::fixup_arm_thumb_cb:
254 case ARM::fixup_arm_thumb_cp:
255 case ARM::fixup_arm_thumb_br:
256 assert(0 && "Unimplemented");
257 break;
258 case ARM::fixup_arm_uncondbranch:
259 Type = ELF::R_ARM_CALL;
260 break;
261 case ARM::fixup_arm_condbranch:
262 Type = ELF::R_ARM_JUMP24;
263 break;
264 case ARM::fixup_arm_movt_hi16:
265 Type = ELF::R_ARM_MOVT_ABS;
266 break;
267 case ARM::fixup_arm_movw_lo16:
268 Type = ELF::R_ARM_MOVW_ABS_NC;
269 break;
270 case ARM::fixup_t2_movt_hi16:
271 Type = ELF::R_ARM_THM_MOVT_ABS;
272 break;
273 case ARM::fixup_t2_movw_lo16:
274 Type = ELF::R_ARM_THM_MOVW_ABS_NC;
275 break;
276 }
277 }
278
279 return Type;
280}
281
282MCObjectWriter *llvm::createARMELFObjectWriter(raw_ostream &OS,
283 uint8_t OSABI) {
284 MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI);
285 return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);
286}