1//===- lib/MC/GOFFObjectWriter.cpp - GOFF File Writer ---------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements GOFF object file writer information.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/BinaryFormat/GOFF.h"
14#include "llvm/MC/MCAsmBackend.h"
15#include "llvm/MC/MCAssembler.h"
16#include "llvm/MC/MCGOFFAttributes.h"
17#include "llvm/MC/MCGOFFObjectWriter.h"
18#include "llvm/MC/MCObjectWriter.h"
19#include "llvm/MC/MCSectionGOFF.h"
20#include "llvm/MC/MCSymbolGOFF.h"
21#include "llvm/MC/MCValue.h"
22#include "llvm/Support/ConvertEBCDIC.h"
23#include "llvm/Support/Debug.h"
24#include "llvm/Support/Endian.h"
25#include "llvm/Support/raw_ostream.h"
26
27using namespace llvm;
28
29#define DEBUG_TYPE "goff-writer"
30
31namespace {
32// Common flag values on records.
33
34// Flag: This record is continued.
35constexpr uint8_t RecContinued = GOFF::Flags(7, 1, 1);
36
37// Flag: This record is a continuation.
38constexpr uint8_t RecContinuation = GOFF::Flags(6, 1, 1);
39
40// The GOFFOstream is responsible to write the data into the fixed physical
41// records of the format. A user of this class announces the begin of a new
42// logical record. While writing the payload, the physical records are created
43// for the data. Possible fill bytes at the end of a physical record are written
44// automatically. In principle, the GOFFOstream is agnostic of the endianness of
45// the payload. However, it also supports writing data in big endian byte order.
46//
47// The physical records use the flag field to indicate if the there is a
48// successor and predecessor record. To be able to set these flags while
49// writing, the basic implementation idea is to always buffer the last seen
50// physical record.
51class GOFFOstream {
52 /// The underlying raw_pwrite_stream.
53 raw_pwrite_stream &OS;
54
55 /// The number of logical records emitted so far.
56 uint32_t LogicalRecords = 0;
57
58 /// The number of physical records emitted so far.
59 uint32_t PhysicalRecords = 0;
60
61 /// The size of the buffer. Same as the payload size of a physical record.
62 static constexpr uint8_t BufferSize = GOFF::PayloadLength;
63
64 /// Current position in buffer.
65 char *BufferPtr = Buffer;
66
67 /// Static allocated buffer for the stream.
68 char Buffer[BufferSize];
69
70 /// The type of the current logical record, and the flags (aka continued and
71 /// continuation indicators) for the previous (physical) record.
72 uint8_t TypeAndFlags = 0;
73
74public:
75 GOFFOstream(raw_pwrite_stream &OS);
76 ~GOFFOstream();
77
78 raw_pwrite_stream &getOS() { return OS; }
79 size_t getWrittenSize() const { return PhysicalRecords * GOFF::RecordLength; }
80 uint32_t getNumLogicalRecords() { return LogicalRecords; }
81
82 /// Write the specified bytes.
83 void write(const char *Ptr, size_t Size);
84
85 /// Write zeroes, up to a maximum of 16 bytes.
86 void write_zeros(unsigned NumZeros);
87
88 /// Support for endian-specific data.
89 template <typename value_type> void writebe(value_type Value) {
90 Value =
91 support::endian::byte_swap<value_type>(Value, llvm::endianness::big);
92 write(Ptr: (const char *)&Value, Size: sizeof(value_type));
93 }
94
95 /// Begin a new logical record. Implies finalizing the previous record.
96 void newRecord(GOFF::RecordType Type);
97
98 /// Ends a logical record.
99 void finalizeRecord();
100
101private:
102 /// Updates the continued/continuation flags, and writes the record prefix of
103 /// a physical record.
104 void updateFlagsAndWritePrefix(bool IsContinued);
105
106 /// Returns the remaining size in the buffer.
107 size_t getRemainingSize();
108};
109} // namespace
110
111GOFFOstream::GOFFOstream(raw_pwrite_stream &OS) : OS(OS) {}
112
113GOFFOstream::~GOFFOstream() { finalizeRecord(); }
114
115void GOFFOstream::updateFlagsAndWritePrefix(bool IsContinued) {
116 // Update the flags based on the previous state and the flag IsContinued.
117 if (TypeAndFlags & RecContinued)
118 TypeAndFlags |= RecContinuation;
119 if (IsContinued)
120 TypeAndFlags |= RecContinued;
121 else
122 TypeAndFlags &= ~RecContinued;
123
124 OS << static_cast<unsigned char>(GOFF::PTVPrefix) // Record Type
125 << static_cast<unsigned char>(TypeAndFlags) // Continuation
126 << static_cast<unsigned char>(0); // Version
127
128 ++PhysicalRecords;
129}
130
131size_t GOFFOstream::getRemainingSize() {
132 return size_t(&Buffer[BufferSize] - BufferPtr);
133}
134
135void GOFFOstream::write(const char *Ptr, size_t Size) {
136 size_t RemainingSize = getRemainingSize();
137
138 // Data fits into the buffer.
139 if (LLVM_LIKELY(Size <= RemainingSize)) {
140 memcpy(dest: BufferPtr, src: Ptr, n: Size);
141 BufferPtr += Size;
142 return;
143 }
144
145 // Otherwise the buffer is partially filled or full, and data does not fit
146 // into it.
147 updateFlagsAndWritePrefix(/*IsContinued=*/true);
148 OS.write(Ptr: Buffer, Size: size_t(BufferPtr - Buffer));
149 if (RemainingSize > 0) {
150 OS.write(Ptr, Size: RemainingSize);
151 Ptr += RemainingSize;
152 Size -= RemainingSize;
153 }
154
155 while (Size > BufferSize) {
156 updateFlagsAndWritePrefix(/*IsContinued=*/true);
157 OS.write(Ptr, Size: BufferSize);
158 Ptr += BufferSize;
159 Size -= BufferSize;
160 }
161
162 // The remaining bytes fit into the buffer.
163 memcpy(dest: Buffer, src: Ptr, n: Size);
164 BufferPtr = &Buffer[Size];
165}
166
167void GOFFOstream::write_zeros(unsigned NumZeros) {
168 assert(NumZeros <= 16 && "Range for zeros too large");
169
170 // Handle the common case first: all fits in the buffer.
171 size_t RemainingSize = getRemainingSize();
172 if (LLVM_LIKELY(RemainingSize >= NumZeros)) {
173 memset(s: BufferPtr, c: 0, n: NumZeros);
174 BufferPtr += NumZeros;
175 return;
176 }
177
178 // Otherwise some field value is cleared.
179 static char Zeros[16] = {
180 0,
181 };
182 write(Ptr: Zeros, Size: NumZeros);
183}
184
185void GOFFOstream::newRecord(GOFF::RecordType Type) {
186 finalizeRecord();
187 TypeAndFlags = Type << 4;
188 ++LogicalRecords;
189}
190
191void GOFFOstream::finalizeRecord() {
192 if (Buffer == BufferPtr)
193 return;
194 updateFlagsAndWritePrefix(/*IsContinued=*/false);
195 OS.write(Ptr: Buffer, Size: size_t(BufferPtr - Buffer));
196 OS.write_zeros(NumZeros: getRemainingSize());
197 BufferPtr = Buffer;
198}
199
200namespace {
201// A GOFFSymbol holds all the data required for writing an ESD record.
202class GOFFSymbol {
203public:
204 std::string Name;
205 uint32_t EsdId;
206 uint32_t ParentEsdId;
207 uint64_t Offset = 0; // Offset of the symbol into the section. LD only.
208 // Offset is only 32 bit, the larger type is used to
209 // enable error checking.
210 GOFF::ESDSymbolType SymbolType;
211 GOFF::ESDNameSpaceId NameSpace = GOFF::ESD_NS_ProgramManagementBinder;
212
213 GOFF::BehavioralAttributes BehavAttrs;
214 GOFF::SymbolFlags SymbolFlags;
215 uint32_t SortKey = 0;
216 uint32_t SectionLength = 0;
217 uint32_t ADAEsdId = 0;
218 uint32_t EASectionEDEsdId = 0;
219 uint32_t EASectionOffset = 0;
220 uint8_t FillByteValue = 0;
221
222 GOFFSymbol() : EsdId(0), ParentEsdId(0) {}
223
224 GOFFSymbol(StringRef Name, uint32_t EsdID, const GOFF::SDAttr &Attr)
225 : Name(Name.data(), Name.size()), EsdId(EsdID), ParentEsdId(0),
226 SymbolType(GOFF::ESD_ST_SectionDefinition) {
227 BehavAttrs.setTaskingBehavior(Attr.TaskingBehavior);
228 BehavAttrs.setBindingScope(Attr.BindingScope);
229 }
230
231 GOFFSymbol(StringRef Name, uint32_t EsdID, uint32_t ParentEsdID,
232 const GOFF::EDAttr &Attr, GOFF::ESDAlignment Alignment)
233 : Name(Name.data(), Name.size()), EsdId(EsdID), ParentEsdId(ParentEsdID),
234 SymbolType(GOFF::ESD_ST_ElementDefinition) {
235 this->NameSpace = Attr.NameSpace;
236 // We always set a fill byte value.
237 this->FillByteValue = Attr.FillByteValue;
238 SymbolFlags.setFillBytePresence(1);
239 SymbolFlags.setReservedQwords(Attr.ReservedQwords);
240 // TODO Do we need/should set the "mangled" flag?
241 BehavAttrs.setReadOnly(Attr.IsReadOnly);
242 BehavAttrs.setRmode(Attr.Rmode);
243 BehavAttrs.setTextStyle(Attr.TextStyle);
244 BehavAttrs.setBindingAlgorithm(Attr.BindAlgorithm);
245 BehavAttrs.setLoadingBehavior(Attr.LoadBehavior);
246 BehavAttrs.setAlignment(Alignment);
247 }
248
249 GOFFSymbol(StringRef Name, uint32_t EsdID, uint32_t ParentEsdID,
250 GOFF::ESDNameSpaceId NameSpace, const GOFF::LDAttr &Attr)
251 : Name(Name.data(), Name.size()), EsdId(EsdID), ParentEsdId(ParentEsdID),
252 SymbolType(GOFF::ESD_ST_LabelDefinition), NameSpace(NameSpace) {
253 SymbolFlags.setRenameable(Attr.IsRenamable);
254 BehavAttrs.setExecutable(Attr.Executable);
255 BehavAttrs.setBindingStrength(Attr.BindingStrength);
256 BehavAttrs.setLinkageType(Attr.Linkage);
257 BehavAttrs.setAmode(Attr.Amode);
258 BehavAttrs.setBindingScope(Attr.BindingScope);
259 }
260
261 GOFFSymbol(StringRef Name, uint32_t EsdID, uint32_t ParentEsdID,
262 const GOFF::EDAttr &EDAttr, GOFF::ESDAlignment Alignment,
263 const GOFF::PRAttr &Attr)
264 : Name(Name.data(), Name.size()), EsdId(EsdID), ParentEsdId(ParentEsdID),
265 SymbolType(GOFF::ESD_ST_PartReference), NameSpace(EDAttr.NameSpace) {
266 SymbolFlags.setRenameable(Attr.IsRenamable);
267 BehavAttrs.setExecutable(Attr.Executable);
268 BehavAttrs.setLinkageType(Attr.Linkage);
269 BehavAttrs.setBindingScope(Attr.BindingScope);
270 BehavAttrs.setAlignment(Alignment);
271 }
272
273 GOFFSymbol(StringRef Name, uint32_t EsdID, uint32_t ParentEsdID,
274 const GOFF::ERAttr &Attr)
275 : Name(Name.data(), Name.size()), EsdId(EsdID), ParentEsdId(ParentEsdID),
276 SymbolType(GOFF::ESD_ST_ExternalReference),
277 NameSpace(GOFF::ESD_NS_NormalName) {
278 BehavAttrs.setExecutable(Attr.Executable);
279 BehavAttrs.setBindingStrength(Attr.BindingStrength);
280 BehavAttrs.setLinkageType(Attr.Linkage);
281 BehavAttrs.setAmode(Attr.Amode);
282 BehavAttrs.setBindingScope(Attr.BindingScope);
283 BehavAttrs.setIndirectReference(Attr.IsIndirectReference);
284 }
285};
286
287class GOFFWriter {
288 GOFFOstream OS;
289 MCAssembler &Asm;
290 MCSectionGOFF *RootSD;
291
292 /// Saved relocation data collected in recordRelocations().
293 std::vector<GOFFRelocationEntry> &Relocations;
294
295 void writeHeader();
296 void writeSymbol(const GOFFSymbol &Symbol);
297 void writeText(const MCSectionGOFF *MC);
298 void writeRelocations();
299 void writeEnd();
300
301 void defineSectionSymbols(const MCSectionGOFF &Section);
302 void defineLabel(const MCSymbolGOFF &Symbol);
303 void defineExtern(const MCSymbolGOFF &Symbol);
304 void defineSymbols();
305
306public:
307 GOFFWriter(raw_pwrite_stream &OS, MCAssembler &Asm, MCSectionGOFF *RootSD,
308 std::vector<GOFFRelocationEntry> &Relocations);
309 uint64_t writeObject();
310};
311} // namespace
312
313GOFFWriter::GOFFWriter(raw_pwrite_stream &OS, MCAssembler &Asm,
314 MCSectionGOFF *RootSD,
315 std::vector<GOFFRelocationEntry> &Relocations)
316 : OS(OS), Asm(Asm), RootSD(RootSD), Relocations(Relocations) {}
317
318void GOFFWriter::defineSectionSymbols(const MCSectionGOFF &Section) {
319 if (Section.isSD()) {
320 GOFFSymbol SD(Section.getExternalName(), Section.getOrdinal(),
321 Section.getSDAttributes());
322 writeSymbol(Symbol: SD);
323 }
324
325 if (Section.isED()) {
326 GOFFSymbol ED(Section.getExternalName(), Section.getOrdinal(),
327 Section.getParent()->getOrdinal(), Section.getEDAttributes(),
328 Section.getEDAlignment());
329 ED.SectionLength = Asm.getSectionAddressSize(Sec: Section);
330 writeSymbol(Symbol: ED);
331 }
332
333 if (Section.isPR()) {
334 MCSectionGOFF *Parent = Section.getParent();
335 GOFFSymbol PR(Section.getExternalName(), Section.getOrdinal(),
336 Parent->getOrdinal(), Parent->getEDAttributes(),
337 Parent->getEDAlignment(), Section.getPRAttributes());
338 PR.SectionLength = Asm.getSectionAddressSize(Sec: Section);
339 if (Section.requiresNonZeroLength()) {
340 // We cannot have a zero-length section for data. If we do,
341 // artificially inflate it. Use 2 bytes to avoid odd alignments. Note:
342 // if this is ever changed, you will need to update the code in
343 // SystemZAsmPrinter::emitCEEMAIN and SystemZAsmPrinter::emitCELQMAIN to
344 // generate -1 if there is no ADA
345 if (!PR.SectionLength)
346 PR.SectionLength = 2;
347 }
348 writeSymbol(Symbol: PR);
349 }
350}
351
352void GOFFWriter::defineLabel(const MCSymbolGOFF &Symbol) {
353 MCSectionGOFF &Section = static_cast<MCSectionGOFF &>(Symbol.getSection());
354 GOFFSymbol LD(Symbol.getExternalName(), Symbol.getIndex(),
355 Section.getOrdinal(), Section.getEDAttributes().NameSpace,
356 GOFF::LDAttr{.IsRenamable: false, .Executable: Symbol.getCodeData(),
357 .BindingStrength: Symbol.getBindingStrength(), .Linkage: Symbol.getLinkage(),
358 .Amode: GOFF::ESD_AMODE_64, .BindingScope: Symbol.getBindingScope()});
359 if (Symbol.getADA())
360 LD.ADAEsdId = Symbol.getADA()->getOrdinal();
361 LD.Offset = Asm.getSymbolOffset(S: Symbol);
362 writeSymbol(Symbol: LD);
363}
364
365void GOFFWriter::defineExtern(const MCSymbolGOFF &Symbol) {
366 if (Symbol.getCodeData() == GOFF::ESD_EXE_DATA) {
367 MCSectionGOFF *ED = Symbol.getADA()->getParent();
368 GOFFSymbol PR(Symbol.getExternalName(), Symbol.getIndex(), ED->getOrdinal(),
369 ED->getEDAttributes(), ED->getEDAlignment(),
370 GOFF::PRAttr{/*IsRenamable*/ false, .Executable: Symbol.getCodeData(),
371 .Linkage: Symbol.getLinkage(), .BindingScope: Symbol.getBindingScope(),
372 .SortKey: 0});
373 writeSymbol(Symbol: PR);
374 } else {
375 GOFFSymbol ER(Symbol.getExternalName(), Symbol.getIndex(),
376 RootSD->getOrdinal(),
377 GOFF::ERAttr{.IsIndirectReference: Symbol.isIndirect(), .Executable: Symbol.getCodeData(),
378 .BindingStrength: Symbol.getBindingStrength(), .Linkage: Symbol.getLinkage(),
379 .Amode: GOFF::ESD_AMODE_64, .BindingScope: Symbol.getBindingScope()});
380 writeSymbol(Symbol: ER);
381 }
382}
383
384void GOFFWriter::defineSymbols() {
385 unsigned Ordinal = 0;
386 // Process all sections.
387 for (MCSection &S : Asm) {
388 auto &Section = static_cast<MCSectionGOFF &>(S);
389 Section.setOrdinal(++Ordinal);
390 defineSectionSymbols(Section);
391 }
392
393 // Process all symbols
394 for (const MCSymbol &Sym : Asm.symbols()) {
395 if (Sym.isTemporary())
396 continue;
397 auto &Symbol = static_cast<const MCSymbolGOFF &>(Sym);
398 if (!Symbol.isDefined()) {
399 Symbol.setIndex(++Ordinal);
400 defineExtern(Symbol);
401 } else if (Symbol.isInEDSection()) {
402 Symbol.setIndex(++Ordinal);
403 defineLabel(Symbol);
404 } else {
405 // Symbol is in PR section, the symbol refers to the section.
406 Symbol.setIndex(Symbol.getSection().getOrdinal());
407 }
408 }
409}
410
411void GOFFWriter::writeHeader() {
412 OS.newRecord(Type: GOFF::RT_HDR);
413 OS.write_zeros(NumZeros: 1); // Reserved
414 OS.writebe<uint32_t>(Value: 0); // Target Hardware Environment
415 OS.writebe<uint32_t>(Value: 0); // Target Operating System Environment
416 OS.write_zeros(NumZeros: 2); // Reserved
417 OS.writebe<uint16_t>(Value: 0); // CCSID
418 OS.write_zeros(NumZeros: 16); // Character Set name
419 OS.write_zeros(NumZeros: 16); // Language Product Identifier
420 OS.writebe<uint32_t>(Value: 1); // Architecture Level
421 OS.writebe<uint16_t>(Value: 0); // Module Properties Length
422 OS.write_zeros(NumZeros: 6); // Reserved
423}
424
425void GOFFWriter::writeSymbol(const GOFFSymbol &Symbol) {
426 if (Symbol.Offset >= (((uint64_t)1) << 31))
427 report_fatal_error(reason: "ESD offset out of range");
428
429 // All symbol names are in EBCDIC.
430 SmallString<256> Name;
431 ConverterEBCDIC::convertToEBCDIC(Source: Symbol.Name, Result&: Name);
432
433 // Check length here since this number is technically signed but we need uint
434 // for writing to records.
435 if (Name.size() >= GOFF::MaxDataLength)
436 report_fatal_error(reason: "Symbol max name length exceeded");
437 uint16_t NameLength = Name.size();
438
439 OS.newRecord(Type: GOFF::RT_ESD);
440 OS.writebe<uint8_t>(Value: Symbol.SymbolType); // Symbol Type
441 OS.writebe<uint32_t>(Value: Symbol.EsdId); // ESDID
442 OS.writebe<uint32_t>(Value: Symbol.ParentEsdId); // Parent or Owning ESDID
443 OS.writebe<uint32_t>(Value: 0); // Reserved
444 OS.writebe<uint32_t>(
445 Value: static_cast<uint32_t>(Symbol.Offset)); // Offset or Address
446 OS.writebe<uint32_t>(Value: 0); // Reserved
447 OS.writebe<uint32_t>(Value: Symbol.SectionLength); // Length
448 OS.writebe<uint32_t>(Value: Symbol.EASectionEDEsdId); // Extended Attribute ESDID
449 OS.writebe<uint32_t>(Value: Symbol.EASectionOffset); // Extended Attribute Offset
450 OS.writebe<uint32_t>(Value: 0); // Reserved
451 OS.writebe<uint8_t>(Value: Symbol.NameSpace); // Name Space ID
452 OS.writebe<uint8_t>(Value: Symbol.SymbolFlags); // Flags
453 OS.writebe<uint8_t>(Value: Symbol.FillByteValue); // Fill-Byte Value
454 OS.writebe<uint8_t>(Value: 0); // Reserved
455 OS.writebe<uint32_t>(Value: Symbol.ADAEsdId); // ADA ESDID
456 OS.writebe<uint32_t>(Value: Symbol.SortKey); // Sort Priority
457 OS.writebe<uint64_t>(Value: 0); // Reserved
458 for (auto F : Symbol.BehavAttrs.Attr)
459 OS.writebe<uint8_t>(Value: F); // Behavioral Attributes
460 OS.writebe<uint16_t>(Value: NameLength); // Name Length
461 OS.write(Ptr: Name.data(), Size: NameLength); // Name
462}
463
464namespace {
465/// Adapter stream to write a text section.
466class TextStream : public raw_ostream {
467 /// The underlying GOFFOstream.
468 GOFFOstream &OS;
469
470 /// The buffer size is the maximum number of bytes in a TXT section.
471 static constexpr size_t BufferSize = GOFF::MaxDataLength;
472
473 /// Static allocated buffer for the stream, used by the raw_ostream class. The
474 /// buffer is sized to hold the payload of a logical TXT record.
475 char Buffer[BufferSize];
476
477 /// The offset for the next TXT record. This is equal to the number of bytes
478 /// written.
479 size_t Offset;
480
481 /// The Esdid of the GOFF section.
482 const uint32_t EsdId;
483
484 /// The record style.
485 const GOFF::ESDTextStyle RecordStyle;
486
487 /// See raw_ostream::write_impl.
488 void write_impl(const char *Ptr, size_t Size) override;
489
490 uint64_t current_pos() const override { return Offset; }
491
492public:
493 explicit TextStream(GOFFOstream &OS, uint32_t EsdId,
494 GOFF::ESDTextStyle RecordStyle)
495 : OS(OS), Offset(0), EsdId(EsdId), RecordStyle(RecordStyle) {
496 SetBuffer(BufferStart: Buffer, Size: sizeof(Buffer));
497 }
498
499 ~TextStream() override { flush(); }
500};
501} // namespace
502
503void TextStream::write_impl(const char *Ptr, size_t Size) {
504 size_t WrittenLength = 0;
505
506 // We only have signed 32bits of offset.
507 if (Offset + Size > std::numeric_limits<int32_t>::max())
508 report_fatal_error(reason: "TXT section too large");
509
510 while (WrittenLength < Size) {
511 size_t ToWriteLength =
512 std::min(a: Size - WrittenLength, b: size_t(GOFF::MaxDataLength));
513
514 OS.newRecord(Type: GOFF::RT_TXT);
515 OS.writebe<uint8_t>(Value: GOFF::Flags(4, 4, RecordStyle)); // Text Record Style
516 OS.writebe<uint32_t>(Value: EsdId); // Element ESDID
517 OS.writebe<uint32_t>(Value: 0); // Reserved
518 OS.writebe<uint32_t>(Value: static_cast<uint32_t>(Offset)); // Offset
519 OS.writebe<uint32_t>(Value: 0); // Text Field True Length
520 OS.writebe<uint16_t>(Value: 0); // Text Encoding
521 OS.writebe<uint16_t>(Value: ToWriteLength); // Data Length
522 OS.write(Ptr: Ptr + WrittenLength, Size: ToWriteLength); // Data
523
524 WrittenLength += ToWriteLength;
525 Offset += ToWriteLength;
526 }
527}
528
529void GOFFWriter::writeText(const MCSectionGOFF *Section) {
530 // A BSS section contains only zeros, no need to write this.
531 if (Section->isBSS())
532 return;
533
534 TextStream S(OS, Section->getOrdinal(), Section->getTextStyle());
535 Asm.writeSectionData(OS&: S, Section);
536}
537
538namespace {
539// RelocDataItemBuffer provides a static buffer for relocation data items.
540class RelocDataItemBuffer {
541 char Buffer[GOFF::MaxDataLength];
542 char *Ptr;
543
544public:
545 RelocDataItemBuffer() : Ptr(Buffer) {}
546 const char *data() { return Buffer; }
547 size_t size() { return Ptr - Buffer; }
548 void reset() { Ptr = Buffer; }
549 bool fits(size_t S) { return size() + S < GOFF::MaxDataLength; }
550 template <typename T> void writebe(T Val) {
551 assert(fits(sizeof(T)) && "Out-of-bounds write");
552 support::endian::write<T, llvm::endianness::big>(Ptr, Val);
553 Ptr += sizeof(T);
554 }
555};
556} // namespace
557
558void GOFFWriter::writeRelocations() {
559 // Set the IDs in the relocation entries.
560 for (auto &RelocEntry : Relocations) {
561 auto GetRptr = [](const MCSymbolGOFF *Sym) -> uint32_t {
562 if (Sym->isTemporary())
563 return static_cast<MCSectionGOFF &>(Sym->getSection())
564 .getBeginSymbol()
565 ->getIndex();
566 return Sym->getIndex();
567 };
568
569 RelocEntry.PEsdId = RelocEntry.Pptr->getOrdinal();
570 RelocEntry.REsdId = GetRptr(RelocEntry.Rptr);
571 }
572
573 // Sort relocation data items by the P pointer to save space.
574 std::sort(
575 first: Relocations.begin(), last: Relocations.end(),
576 comp: [](const GOFFRelocationEntry &Left, const GOFFRelocationEntry &Right) {
577 return std::tie(args: Left.PEsdId, args: Left.REsdId, args: Left.POffset) <
578 std::tie(args: Right.PEsdId, args: Right.REsdId, args: Right.POffset);
579 });
580
581 // Construct the compressed relocation data items, and write them out.
582 RelocDataItemBuffer Buffer;
583 for (auto I = Relocations.begin(), E = Relocations.end(); I != E;) {
584 Buffer.reset();
585
586 uint32_t PrevResdId = -1;
587 uint32_t PrevPesdId = -1;
588 uint64_t PrevPOffset = -1;
589 for (; I != E; ++I) {
590 const GOFFRelocationEntry &Rel = *I;
591
592 bool SameREsdId = (Rel.REsdId == PrevResdId);
593 bool SamePEsdId = (Rel.PEsdId == PrevPesdId);
594 bool SamePOffset = (Rel.POffset == PrevPOffset);
595 bool EightByteOffset = ((Rel.POffset >> 32) & 0xffffffff);
596
597 // Calculate size of relocation data item, and check if it still fits into
598 // the record.
599 size_t ItemSize = 8; // Smallest size of a relocation data item.
600 if (!SameREsdId)
601 ItemSize += 4;
602 if (!SamePEsdId)
603 ItemSize += 4;
604 if (!SamePOffset)
605 ItemSize += (EightByteOffset ? 8 : 4);
606 if (!Buffer.fits(S: ItemSize))
607 break;
608
609 GOFF::Flags RelocFlags[6];
610 RelocFlags[0].set(BitIndex: 0, Length: 1, NewValue: SameREsdId);
611 RelocFlags[0].set(BitIndex: 1, Length: 1, NewValue: SamePEsdId);
612 RelocFlags[0].set(BitIndex: 2, Length: 1, NewValue: SamePOffset);
613 RelocFlags[0].set(BitIndex: 6, Length: 1, NewValue: EightByteOffset);
614
615 RelocFlags[1].set(BitIndex: 0, Length: 4, NewValue: Rel.ReferenceType);
616 RelocFlags[1].set(BitIndex: 4, Length: 4, NewValue: Rel.ReferentType);
617
618 RelocFlags[2].set(BitIndex: 0, Length: 7, NewValue: Rel.Action);
619 RelocFlags[2].set(BitIndex: 7, Length: 1, NewValue: Rel.FetchStore);
620
621 RelocFlags[4].set(BitIndex: 0, Length: 8, NewValue: Rel.TargetLength);
622
623 for (auto F : RelocFlags)
624 Buffer.writebe<uint8_t>(Val: F);
625 Buffer.writebe<uint16_t>(Val: 0); // Reserved.
626 if (!SameREsdId)
627 Buffer.writebe<uint32_t>(Val: Rel.REsdId);
628 if (!SamePEsdId)
629 Buffer.writebe<uint32_t>(Val: Rel.PEsdId);
630 if (!SamePOffset) {
631 if (EightByteOffset)
632 Buffer.writebe<uint64_t>(Val: Rel.POffset);
633 else
634 Buffer.writebe<uint32_t>(Val: Rel.POffset);
635 }
636
637 PrevResdId = Rel.REsdId;
638 PrevPesdId = Rel.PEsdId;
639 PrevPOffset = Rel.POffset;
640 }
641
642 OS.newRecord(Type: GOFF::RT_RLD);
643 OS.writebe<uint8_t>(Value: 0); // Reserved.
644 OS.writebe<uint16_t>(Value: Buffer.size()); // Length (of the relocation data).
645 OS.write(Ptr: Buffer.data(), Size: Buffer.size()); // Relocation Directory Data Items.
646 }
647}
648
649void GOFFWriter::writeEnd() {
650 uint8_t F = GOFF::END_EPR_None;
651 uint8_t AMODE = 0;
652 uint32_t ESDID = 0;
653
654 // TODO Set Flags/AMODE/ESDID for entry point.
655
656 OS.newRecord(Type: GOFF::RT_END);
657 OS.writebe<uint8_t>(Value: GOFF::Flags(6, 2, F)); // Indicator flags
658 OS.writebe<uint8_t>(Value: AMODE); // AMODE
659 OS.write_zeros(NumZeros: 3); // Reserved
660 // The record count is the number of logical records. In principle, this value
661 // is available as OS.logicalRecords(). However, some tools rely on this field
662 // being zero.
663 OS.writebe<uint32_t>(Value: 0); // Record Count
664 OS.writebe<uint32_t>(Value: ESDID); // ESDID (of entry point)
665}
666
667uint64_t GOFFWriter::writeObject() {
668 writeHeader();
669
670 defineSymbols();
671
672 for (const MCSection &Section : Asm)
673 writeText(Section: static_cast<const MCSectionGOFF *>(&Section));
674
675 writeRelocations();
676
677 writeEnd();
678
679 // Make sure all records are written.
680 OS.finalizeRecord();
681
682 LLVM_DEBUG(dbgs() << "Wrote " << OS.getNumLogicalRecords()
683 << " logical records.");
684
685 return OS.getWrittenSize();
686}
687
688GOFFObjectWriter::GOFFObjectWriter(
689 std::unique_ptr<MCGOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS)
690 : TargetObjectWriter(std::move(MOTW)), OS(OS) {}
691
692GOFFObjectWriter::~GOFFObjectWriter() = default;
693
694void GOFFObjectWriter::reset() {
695 Relocations.clear();
696 RootSD = nullptr;
697 MCObjectWriter::reset();
698}
699
700void GOFFObjectWriter::recordRelocation(const MCFragment &F,
701 const MCFixup &Fixup, MCValue Target,
702 uint64_t &FixedValue) {
703 const MCFixupKindInfo &FKI =
704 Asm->getBackend().getFixupKindInfo(Kind: Fixup.getKind());
705 const uint32_t Length = FKI.TargetSize / 8;
706 assert(FKI.TargetSize % 8 == 0 && "Target Size not multiple of 8");
707 const uint64_t FixupOffset = Asm->getFragmentOffset(F) + Fixup.getOffset();
708
709 unsigned RelocType = TargetObjectWriter->getRelocType(Target, Fixup);
710
711 const MCSectionGOFF *PSection = static_cast<MCSectionGOFF *>(F.getParent());
712 const auto &A = *static_cast<const MCSymbolGOFF *>(Target.getAddSym());
713 const MCSymbolGOFF *B = static_cast<const MCSymbolGOFF *>(Target.getSubSym());
714 if (RelocType == MCGOFFObjectTargetWriter::Reloc_Type_RICon) {
715 if (A.isUndefined()) {
716 Asm->reportError(
717 L: Fixup.getLoc(),
718 Msg: Twine("symbol ")
719 .concat(Suffix: A.getExternalName())
720 .concat(Suffix: " must be defined for a relative immediate relocation"));
721 return;
722 }
723 if (&A.getSection() != PSection) {
724 MCSectionGOFF &GOFFSection = static_cast<MCSectionGOFF &>(A.getSection());
725 Asm->reportError(L: Fixup.getLoc(),
726 Msg: Twine("relative immediate relocation section mismatch: ")
727 .concat(Suffix: GOFFSection.getExternalName())
728 .concat(Suffix: " of symbol ")
729 .concat(Suffix: A.getExternalName())
730 .concat(Suffix: " <-> ")
731 .concat(Suffix: PSection->getExternalName()));
732 return;
733 }
734 if (B) {
735 Asm->reportError(
736 L: Fixup.getLoc(),
737 Msg: Twine("subtractive symbol ")
738 .concat(Suffix: B->getExternalName())
739 .concat(Suffix: " not supported for a relative immediate relocation"));
740 return;
741 }
742 FixedValue = Asm->getSymbolOffset(S: A) - FixupOffset + Target.getConstant();
743 return;
744 }
745 FixedValue = Target.getConstant();
746
747 // The symbol only has a section-relative offset if it is a temporary symbol.
748 FixedValue += A.isTemporary() ? Asm->getSymbolOffset(S: A) : 0;
749 A.setUsedInReloc();
750 if (B) {
751 FixedValue -= B->isTemporary() ? Asm->getSymbolOffset(S: *B) : 0;
752 B->setUsedInReloc();
753 }
754
755 // UseQCon causes class offsets versus absolute addresses to be used. This
756 // is analogous to using QCONs in older OBJ object file format.
757 bool UseQCon = RelocType == MCGOFFObjectTargetWriter::Reloc_Type_QCon;
758
759 GOFF::RLDFetchStore FetchStore =
760 (RelocType == MCGOFFObjectTargetWriter::Reloc_Type_RCon ||
761 RelocType == MCGOFFObjectTargetWriter::Reloc_Type_VCon)
762 ? GOFF::RLDFetchStore::RLD_FS_Store
763 : GOFF::RLDFetchStore::RLD_FS_Fetch;
764 assert((FetchStore == GOFF::RLDFetchStore::RLD_FS_Fetch || B == nullptr) &&
765 "No dependent relocations expected");
766
767 enum GOFF::RLDReferenceType ReferenceType = GOFF::RLD_RT_RAddress;
768 enum GOFF::RLDReferentType ReferentType = GOFF::RLD_RO_Label;
769 if (UseQCon) {
770 ReferenceType = GOFF::RLD_RT_ROffset;
771 ReferentType = GOFF::RLD_RO_Class;
772 }
773 if (RelocType == MCGOFFObjectTargetWriter::Reloc_Type_RCon)
774 ReferenceType = GOFF::RLD_RT_RTypeConstant;
775
776 auto DumpReloc = [&PSection, &ReferenceType, &FixupOffset,
777 &FixedValue](const char *N, const MCSymbolGOFF *Sym) {
778 const char *Con;
779 switch (ReferenceType) {
780 case GOFF::RLDReferenceType::RLD_RT_RAddress:
781 Con = "ACon";
782 break;
783 case GOFF::RLDReferenceType::RLD_RT_ROffset:
784 Con = "QCon";
785 break;
786 case GOFF::RLDReferenceType::RLD_RT_RTypeConstant:
787 Con = "VCon";
788 break;
789 default:
790 Con = "(unknown)";
791 }
792 dbgs() << "Reloc " << N << ": " << Con
793 << " Rptr: " << Sym->getExternalName()
794 << " Pptr: " << PSection->getExternalName()
795 << " Offset: " << FixupOffset << " Fixed Imm: " << FixedValue
796 << "\n";
797 };
798 (void)DumpReloc;
799
800 // Save relocation data for later writing.
801 LLVM_DEBUG(DumpReloc("A", &A));
802 Relocations.emplace_back(args&: PSection, args: &A, args&: ReferenceType, args&: ReferentType,
803 args: GOFF::RLD_ACT_Add, args&: FetchStore, args: FixupOffset, args: Length);
804 if (B) {
805 LLVM_DEBUG(DumpReloc("B", B));
806 Relocations.emplace_back(
807 args&: PSection, args&: B, args&: ReferenceType, args&: ReferentType, args: GOFF::RLD_ACT_Subtract,
808 args: GOFF::RLDFetchStore::RLD_FS_Fetch, args: FixupOffset, args: Length);
809 }
810}
811
812uint64_t GOFFObjectWriter::writeObject() {
813 uint64_t Size = GOFFWriter(OS, *Asm, RootSD, Relocations).writeObject();
814 return Size;
815}
816
817std::unique_ptr<MCObjectWriter>
818llvm::createGOFFObjectWriter(std::unique_ptr<MCGOFFObjectTargetWriter> MOTW,
819 raw_pwrite_stream &OS) {
820 return std::make_unique<GOFFObjectWriter>(args: std::move(MOTW), args&: OS);
821}
822