1 //===-- AArch64MachObjectWriter.cpp - ARM Mach Object Writer --------------===//
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 #include "MCTargetDesc/AArch64FixupKinds.h"
11 #include "MCTargetDesc/AArch64MCTargetDesc.h"
12 #include "llvm/ADT/Twine.h"
13 #include "llvm/MC/MCAsmLayout.h"
14 #include "llvm/MC/MCAssembler.h"
15 #include "llvm/MC/MCContext.h"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCFixup.h"
18 #include "llvm/MC/MCMachObjectWriter.h"
19 #include "llvm/MC/MCSectionMachO.h"
20 #include "llvm/MC/MCValue.h"
21 #include "llvm/Support/ErrorHandling.h"
22 #include "llvm/Support/MachO.h"
26 class AArch64MachObjectWriter
: public MCMachObjectTargetWriter
{
27 bool getAArch64FixupKindMachOInfo(const MCFixup
&Fixup
, unsigned &RelocType
,
28 const MCSymbolRefExpr
*Sym
,
29 unsigned &Log2Size
, const MCAssembler
&Asm
);
32 AArch64MachObjectWriter(uint32_t CPUType
, uint32_t CPUSubtype
)
33 : MCMachObjectTargetWriter(true /* is64Bit */, CPUType
, CPUSubtype
,
34 /*UseAggressiveSymbolFolding=*/true) {}
36 void RecordRelocation(MachObjectWriter
*Writer
, const MCAssembler
&Asm
,
37 const MCAsmLayout
&Layout
, const MCFragment
*Fragment
,
38 const MCFixup
&Fixup
, MCValue Target
,
39 uint64_t &FixedValue
) override
;
43 bool AArch64MachObjectWriter::getAArch64FixupKindMachOInfo(
44 const MCFixup
&Fixup
, unsigned &RelocType
, const MCSymbolRefExpr
*Sym
,
45 unsigned &Log2Size
, const MCAssembler
&Asm
) {
46 RelocType
= unsigned(MachO::ARM64_RELOC_UNSIGNED
);
49 switch ((unsigned)Fixup
.getKind()) {
54 Log2Size
= llvm::Log2_32(1);
57 Log2Size
= llvm::Log2_32(2);
60 Log2Size
= llvm::Log2_32(4);
61 if (Sym
->getKind() == MCSymbolRefExpr::VK_GOT
)
62 RelocType
= unsigned(MachO::ARM64_RELOC_POINTER_TO_GOT
);
65 Log2Size
= llvm::Log2_32(8);
66 if (Sym
->getKind() == MCSymbolRefExpr::VK_GOT
)
67 RelocType
= unsigned(MachO::ARM64_RELOC_POINTER_TO_GOT
);
69 case AArch64::fixup_aarch64_add_imm12
:
70 case AArch64::fixup_aarch64_ldst_imm12_scale1
:
71 case AArch64::fixup_aarch64_ldst_imm12_scale2
:
72 case AArch64::fixup_aarch64_ldst_imm12_scale4
:
73 case AArch64::fixup_aarch64_ldst_imm12_scale8
:
74 case AArch64::fixup_aarch64_ldst_imm12_scale16
:
75 Log2Size
= llvm::Log2_32(4);
76 switch (Sym
->getKind()) {
78 llvm_unreachable("Unexpected symbol reference variant kind!");
79 case MCSymbolRefExpr::VK_PAGEOFF
:
80 RelocType
= unsigned(MachO::ARM64_RELOC_PAGEOFF12
);
82 case MCSymbolRefExpr::VK_GOTPAGEOFF
:
83 RelocType
= unsigned(MachO::ARM64_RELOC_GOT_LOAD_PAGEOFF12
);
85 case MCSymbolRefExpr::VK_TLVPPAGEOFF
:
86 RelocType
= unsigned(MachO::ARM64_RELOC_TLVP_LOAD_PAGEOFF12
);
89 case AArch64::fixup_aarch64_pcrel_adrp_imm21
:
90 Log2Size
= llvm::Log2_32(4);
91 // This encompasses the relocation for the whole 21-bit value.
92 switch (Sym
->getKind()) {
94 Asm
.getContext().FatalError(Fixup
.getLoc(),
95 "ADR/ADRP relocations must be GOT relative");
96 case MCSymbolRefExpr::VK_PAGE
:
97 RelocType
= unsigned(MachO::ARM64_RELOC_PAGE21
);
99 case MCSymbolRefExpr::VK_GOTPAGE
:
100 RelocType
= unsigned(MachO::ARM64_RELOC_GOT_LOAD_PAGE21
);
102 case MCSymbolRefExpr::VK_TLVPPAGE
:
103 RelocType
= unsigned(MachO::ARM64_RELOC_TLVP_LOAD_PAGE21
);
107 case AArch64::fixup_aarch64_pcrel_branch26
:
108 case AArch64::fixup_aarch64_pcrel_call26
:
109 Log2Size
= llvm::Log2_32(4);
110 RelocType
= unsigned(MachO::ARM64_RELOC_BRANCH26
);
115 void AArch64MachObjectWriter::RecordRelocation(
116 MachObjectWriter
*Writer
, const MCAssembler
&Asm
, const MCAsmLayout
&Layout
,
117 const MCFragment
*Fragment
, const MCFixup
&Fixup
, MCValue Target
,
118 uint64_t &FixedValue
) {
119 unsigned IsPCRel
= Writer
->isFixupKindPCRel(Asm
, Fixup
.getKind());
122 uint32_t FixupOffset
= Layout
.getFragmentOffset(Fragment
);
123 unsigned Log2Size
= 0;
126 unsigned IsExtern
= 0;
128 unsigned Kind
= Fixup
.getKind();
130 FixupOffset
+= Fixup
.getOffset();
132 // AArch64 pcrel relocation addends do not include the section offset.
134 FixedValue
+= FixupOffset
;
136 // ADRP fixups use relocations for the whole symbol value and only
137 // put the addend in the instruction itself. Clear out any value the
138 // generic code figured out from the sybmol definition.
139 if (Kind
== AArch64::fixup_aarch64_pcrel_adrp_imm21
)
142 // imm19 relocations are for conditional branches, which require
143 // assembler local symbols. If we got here, that's not what we have,
144 // so complain loudly.
145 if (Kind
== AArch64::fixup_aarch64_pcrel_branch19
) {
146 Asm
.getContext().FatalError(Fixup
.getLoc(),
147 "conditional branch requires assembler-local"
149 Target
.getSymA()->getSymbol().getName() +
154 // 14-bit branch relocations should only target internal labels, and so
155 // should never get here.
156 if (Kind
== AArch64::fixup_aarch64_pcrel_branch14
) {
157 Asm
.getContext().FatalError(Fixup
.getLoc(),
158 "Invalid relocation on conditional branch!");
162 if (!getAArch64FixupKindMachOInfo(Fixup
, Type
, Target
.getSymA(), Log2Size
,
164 Asm
.getContext().FatalError(Fixup
.getLoc(), "unknown AArch64 fixup kind!");
168 Value
= Target
.getConstant();
170 if (Target
.isAbsolute()) { // constant
171 // FIXME: Should this always be extern?
172 // SymbolNum of 0 indicates the absolute section.
173 Type
= MachO::ARM64_RELOC_UNSIGNED
;
178 Asm
.getContext().FatalError(Fixup
.getLoc(),
179 "PC relative absolute relocation!");
181 // FIXME: x86_64 sets the type to a branch reloc here. Should we do
182 // something similar?
184 } else if (Target
.getSymB()) { // A - B + constant
185 const MCSymbol
*A
= &Target
.getSymA()->getSymbol();
186 const MCSymbolData
&A_SD
= Asm
.getSymbolData(*A
);
187 const MCSymbolData
*A_Base
= Asm
.getAtom(&A_SD
);
189 const MCSymbol
*B
= &Target
.getSymB()->getSymbol();
190 const MCSymbolData
&B_SD
= Asm
.getSymbolData(*B
);
191 const MCSymbolData
*B_Base
= Asm
.getAtom(&B_SD
);
193 // Check for "_foo@got - .", which comes through here as:
195 // ... _foo@got - Ltmp0
196 if (Target
.getSymA()->getKind() == MCSymbolRefExpr::VK_GOT
&&
197 Target
.getSymB()->getKind() == MCSymbolRefExpr::VK_None
&&
198 Layout
.getSymbolOffset(&B_SD
) ==
199 Layout
.getFragmentOffset(Fragment
) + Fixup
.getOffset()) {
200 // SymB is the PC, so use a PC-rel pointer-to-GOT relocation.
201 Index
= A_Base
->getIndex();
203 Type
= MachO::ARM64_RELOC_POINTER_TO_GOT
;
205 MachO::any_relocation_info MRE
;
206 MRE
.r_word0
= FixupOffset
;
207 MRE
.r_word1
= ((Index
<< 0) | (IsPCRel
<< 24) | (Log2Size
<< 25) |
208 (IsExtern
<< 27) | (Type
<< 28));
209 Writer
->addRelocation(Fragment
->getParent(), MRE
);
211 } else if (Target
.getSymA()->getKind() != MCSymbolRefExpr::VK_None
||
212 Target
.getSymB()->getKind() != MCSymbolRefExpr::VK_None
)
213 // Otherwise, neither symbol can be modified.
214 Asm
.getContext().FatalError(Fixup
.getLoc(),
215 "unsupported relocation of modified symbol");
217 // We don't support PCrel relocations of differences.
219 Asm
.getContext().FatalError(Fixup
.getLoc(),
220 "unsupported pc-relative relocation of "
223 // AArch64 always uses external relocations. If there is no symbol to use as
224 // a base address (a local symbol with no preceding non-local symbol),
227 // FIXME: We should probably just synthesize an external symbol and use
230 Asm
.getContext().FatalError(
232 "unsupported relocation of local symbol '" + A
->getName() +
233 "'. Must have non-local symbol earlier in section.");
235 Asm
.getContext().FatalError(
237 "unsupported relocation of local symbol '" + B
->getName() +
238 "'. Must have non-local symbol earlier in section.");
240 if (A_Base
== B_Base
&& A_Base
)
241 Asm
.getContext().FatalError(Fixup
.getLoc(),
242 "unsupported relocation with identical base");
244 Value
+= (!A_SD
.getFragment() ? 0
245 : Writer
->getSymbolAddress(&A_SD
, Layout
)) -
246 (!A_Base
|| !A_Base
->getFragment()
248 : Writer
->getSymbolAddress(A_Base
, Layout
));
249 Value
-= (!B_SD
.getFragment() ? 0
250 : Writer
->getSymbolAddress(&B_SD
, Layout
)) -
251 (!B_Base
|| !B_Base
->getFragment()
253 : Writer
->getSymbolAddress(B_Base
, Layout
));
255 Index
= A_Base
->getIndex();
257 Type
= MachO::ARM64_RELOC_UNSIGNED
;
259 MachO::any_relocation_info MRE
;
260 MRE
.r_word0
= FixupOffset
;
261 MRE
.r_word1
= ((Index
<< 0) | (IsPCRel
<< 24) | (Log2Size
<< 25) |
262 (IsExtern
<< 27) | (Type
<< 28));
263 Writer
->addRelocation(Fragment
->getParent(), MRE
);
265 Index
= B_Base
->getIndex();
267 Type
= MachO::ARM64_RELOC_SUBTRACTOR
;
268 } else { // A + constant
269 const MCSymbol
*Symbol
= &Target
.getSymA()->getSymbol();
270 const MCSymbolData
&SD
= Asm
.getSymbolData(*Symbol
);
271 const MCSymbolData
*Base
= Asm
.getAtom(&SD
);
272 const MCSectionMachO
&Section
= static_cast<const MCSectionMachO
&>(
273 Fragment
->getParent()->getSection());
275 // If the symbol is a variable and we weren't able to get a Base for it
276 // (i.e., it's not in the symbol table associated with a section) resolve
277 // the relocation based its expansion instead.
278 if (Symbol
->isVariable() && !Base
) {
279 // If the evaluation is an absolute value, just use that directly
280 // to keep things easy.
282 if (SD
.getSymbol().getVariableValue()->EvaluateAsAbsolute(
283 Res
, Layout
, Writer
->getSectionAddressMap())) {
288 // FIXME: Will the Target we already have ever have any data in it
289 // we need to preserve and merge with the new Target? How about
291 if (!Symbol
->getVariableValue()->EvaluateAsRelocatable(Target
, &Layout
,
293 Asm
.getContext().FatalError(Fixup
.getLoc(),
294 "unable to resolve variable '" +
295 Symbol
->getName() + "'");
296 return RecordRelocation(Writer
, Asm
, Layout
, Fragment
, Fixup
, Target
,
300 // Relocations inside debug sections always use local relocations when
301 // possible. This seems to be done because the debugger doesn't fully
302 // understand relocation entries and expects to find values that
303 // have already been fixed up.
304 if (Symbol
->isInSection()) {
305 if (Section
.hasAttribute(MachO::S_ATTR_DEBUG
))
309 // AArch64 uses external relocations as much as possible. For debug
310 // sections, and for pointer-sized relocations (.quad), we allow section
311 // relocations. It's code sections that run into trouble.
313 Index
= Base
->getIndex();
316 // Add the local offset, if needed.
318 Value
+= Layout
.getSymbolOffset(&SD
) - Layout
.getSymbolOffset(Base
);
319 } else if (Symbol
->isInSection()) {
320 // Pointer-sized relocations can use a local relocation. Otherwise,
321 // we have to be in a debug info section.
322 if (!Section
.hasAttribute(MachO::S_ATTR_DEBUG
) && Log2Size
!= 3)
323 Asm
.getContext().FatalError(
325 "unsupported relocation of local symbol '" + Symbol
->getName() +
326 "'. Must have non-local symbol earlier in section.");
327 // Adjust the relocation to be section-relative.
328 // The index is the section ordinal (1-based).
329 const MCSectionData
&SymSD
=
330 Asm
.getSectionData(SD
.getSymbol().getSection());
331 Index
= SymSD
.getOrdinal() + 1;
333 Value
+= Writer
->getSymbolAddress(&SD
, Layout
);
336 Value
-= Writer
->getFragmentAddress(Fragment
, Layout
) +
337 Fixup
.getOffset() + (1ULL << Log2Size
);
339 // Resolve constant variables.
340 if (SD
.getSymbol().isVariable()) {
342 if (SD
.getSymbol().getVariableValue()->EvaluateAsAbsolute(
343 Res
, Layout
, Writer
->getSectionAddressMap())) {
348 Asm
.getContext().FatalError(Fixup
.getLoc(),
349 "unsupported relocation of variable '" +
350 Symbol
->getName() + "'");
354 // If the relocation kind is Branch26, Page21, or Pageoff12, any addend
355 // is represented via an Addend relocation, not encoded directly into
357 if ((Type
== MachO::ARM64_RELOC_BRANCH26
||
358 Type
== MachO::ARM64_RELOC_PAGE21
||
359 Type
== MachO::ARM64_RELOC_PAGEOFF12
) &&
361 assert((Value
& 0xff000000) == 0 && "Added relocation out of range!");
363 MachO::any_relocation_info MRE
;
364 MRE
.r_word0
= FixupOffset
;
365 MRE
.r_word1
= ((Index
<< 0) | (IsPCRel
<< 24) | (Log2Size
<< 25) |
366 (IsExtern
<< 27) | (Type
<< 28));
367 Writer
->addRelocation(Fragment
->getParent(), MRE
);
369 // Now set up the Addend relocation.
370 Type
= MachO::ARM64_RELOC_ADDEND
;
376 // Put zero into the instruction itself. The addend is in the relocation.
380 // If there's any addend left to handle, encode it in the instruction.
383 // struct relocation_info (8 bytes)
384 MachO::any_relocation_info MRE
;
385 MRE
.r_word0
= FixupOffset
;
386 MRE
.r_word1
= ((Index
<< 0) | (IsPCRel
<< 24) | (Log2Size
<< 25) |
387 (IsExtern
<< 27) | (Type
<< 28));
388 Writer
->addRelocation(Fragment
->getParent(), MRE
);
391 MCObjectWriter
*llvm::createAArch64MachObjectWriter(raw_ostream
&OS
,
393 uint32_t CPUSubtype
) {
394 return createMachObjectWriter(
395 new AArch64MachObjectWriter(CPUType
, CPUSubtype
), OS
,
396 /*IsLittleEndian=*/true);