1 //===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization ------===//
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 // This is a gold plugin for LLVM. It provides an LLVM implementation of the
11 // interface described in http://gcc.gnu.org/wiki/whopr/driver .
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/ADT/Statistic.h"
16 #include "llvm/Bitcode/BitcodeReader.h"
17 #include "llvm/Bitcode/BitcodeWriter.h"
18 #include "llvm/CodeGen/CommandFlags.inc"
19 #include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
20 #include "llvm/IR/Constants.h"
21 #include "llvm/IR/DiagnosticPrinter.h"
22 #include "llvm/LTO/Caching.h"
23 #include "llvm/LTO/LTO.h"
24 #include "llvm/Object/Error.h"
25 #include "llvm/Support/CachePruning.h"
26 #include "llvm/Support/CommandLine.h"
27 #include "llvm/Support/FileSystem.h"
28 #include "llvm/Support/ManagedStatic.h"
29 #include "llvm/Support/MemoryBuffer.h"
30 #include "llvm/Support/Path.h"
31 #include "llvm/Support/TargetSelect.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include <list>
34 #include <map>
35 #include <plugin-api.h>
36 #include <string>
37 #include <system_error>
38 #include <utility>
39 #include <vector>
40
41 // FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
42 // Precise and Debian Wheezy (binutils 2.23 is required)
43 #define LDPO_PIE 3
44
45 #define LDPT_GET_SYMBOLS_V3 28
46
47 // FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
48 // required version.
49 #define LDPT_GET_WRAP_SYMBOLS 32
50
51 using namespace llvm;
52 using namespace lto;
53
54 // FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
55 // required version.
56 typedef enum ld_plugin_status (*ld_plugin_get_wrap_symbols)(
57 uint64_t *num_symbols, const char ***wrap_symbol_list);
58
59 static ld_plugin_status discard_message(int level, const char *format, ...) {
60 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
61 // callback in the transfer vector. This should never be called.
62 abort();
63 }
64
65 static ld_plugin_release_input_file release_input_file = nullptr;
66 static ld_plugin_get_input_file get_input_file = nullptr;
67 static ld_plugin_message message = discard_message;
68 static ld_plugin_get_wrap_symbols get_wrap_symbols = nullptr;
69
70 namespace {
71 struct claimed_file {
72 void *handle;
73 void *leader_handle;
74 std::vector<ld_plugin_symbol> syms;
75 off_t filesize;
76 std::string name;
77 };
78
79 /// RAII wrapper to manage opening and releasing of a ld_plugin_input_file.
80 struct PluginInputFile {
81 void *Handle;
82 std::unique_ptr<ld_plugin_input_file> File;
83
PluginInputFile__anon598391230111::PluginInputFile84 PluginInputFile(void *Handle) : Handle(Handle) {
85 File = llvm::make_unique<ld_plugin_input_file>();
86 if (get_input_file(Handle, File.get()) != LDPS_OK)
87 message(LDPL_FATAL, "Failed to get file information");
88 }
~PluginInputFile__anon598391230111::PluginInputFile89 ~PluginInputFile() {
90 // File would have been reset to nullptr if we moved this object
91 // to a new owner.
92 if (File)
93 if (release_input_file(Handle) != LDPS_OK)
94 message(LDPL_FATAL, "Failed to release file information");
95 }
96
file__anon598391230111::PluginInputFile97 ld_plugin_input_file &file() { return *File; }
98
99 PluginInputFile(PluginInputFile &&RHS) = default;
100 PluginInputFile &operator=(PluginInputFile &&RHS) = default;
101 };
102
103 struct ResolutionInfo {
104 bool CanOmitFromDynSym = true;
105 bool DefaultVisibility = true;
106 bool CanInline = true;
107 bool IsUsedInRegularObj = false;
108 };
109
110 }
111
112 static ld_plugin_add_symbols add_symbols = nullptr;
113 static ld_plugin_get_symbols get_symbols = nullptr;
114 static ld_plugin_add_input_file add_input_file = nullptr;
115 static ld_plugin_set_extra_library_path set_extra_library_path = nullptr;
116 static ld_plugin_get_view get_view = nullptr;
117 static bool IsExecutable = false;
118 static bool SplitSections = true;
119 static Optional<Reloc::Model> RelocationModel = None;
120 static std::string output_name = "";
121 static std::list<claimed_file> Modules;
122 static DenseMap<int, void *> FDToLeaderHandle;
123 static StringMap<ResolutionInfo> ResInfo;
124 static std::vector<std::string> Cleanup;
125
126 namespace options {
127 enum OutputType {
128 OT_NORMAL,
129 OT_DISABLE,
130 OT_BC_ONLY,
131 OT_SAVE_TEMPS
132 };
133 static OutputType TheOutputType = OT_NORMAL;
134 static unsigned OptLevel = 2;
135 // Default parallelism of 0 used to indicate that user did not specify.
136 // Actual parallelism default value depends on implementation.
137 // Currently only affects ThinLTO, where the default is
138 // llvm::heavyweight_hardware_concurrency.
139 static unsigned Parallelism = 0;
140 // Default regular LTO codegen parallelism (number of partitions).
141 static unsigned ParallelCodeGenParallelismLevel = 1;
142 #ifdef NDEBUG
143 static bool DisableVerify = true;
144 #else
145 static bool DisableVerify = false;
146 #endif
147 static std::string obj_path;
148 static std::string extra_library_path;
149 static std::string triple;
150 static std::string mcpu;
151 // When the thinlto plugin option is specified, only read the function
152 // the information from intermediate files and write a combined
153 // global index for the ThinLTO backends.
154 static bool thinlto = false;
155 // If false, all ThinLTO backend compilations through code gen are performed
156 // using multiple threads in the gold-plugin, before handing control back to
157 // gold. If true, write individual backend index files which reflect
158 // the import decisions, and exit afterwards. The assumption is
159 // that the build system will launch the backend processes.
160 static bool thinlto_index_only = false;
161 // If non-empty, holds the name of a file in which to write the list of
162 // oject files gold selected for inclusion in the link after symbol
163 // resolution (i.e. they had selected symbols). This will only be non-empty
164 // in the thinlto_index_only case. It is used to identify files, which may
165 // have originally been within archive libraries specified via
166 // --start-lib/--end-lib pairs, that should be included in the final
167 // native link process (since intervening function importing and inlining
168 // may change the symbol resolution detected in the final link and which
169 // files to include out of --start-lib/--end-lib libraries as a result).
170 static std::string thinlto_linked_objects_file;
171 // If true, when generating individual index files for distributed backends,
172 // also generate a "${bitcodefile}.imports" file at the same location for each
173 // bitcode file, listing the files it imports from in plain text. This is to
174 // support distributed build file staging.
175 static bool thinlto_emit_imports_files = false;
176 // Option to control where files for a distributed backend (the individual
177 // index files and optional imports files) are created.
178 // If specified, expects a string of the form "oldprefix:newprefix", and
179 // instead of generating these files in the same directory path as the
180 // corresponding bitcode file, will use a path formed by replacing the
181 // bitcode file's path prefix matching oldprefix with newprefix.
182 static std::string thinlto_prefix_replace;
183 // Option to control the name of modules encoded in the individual index
184 // files for a distributed backend. This enables the use of minimized
185 // bitcode files for the thin link, assuming the name of the full bitcode
186 // file used in the backend differs just in some part of the file suffix.
187 // If specified, expects a string of the form "oldsuffix:newsuffix".
188 static std::string thinlto_object_suffix_replace;
189 // Optional path to a directory for caching ThinLTO objects.
190 static std::string cache_dir;
191 // Optional pruning policy for ThinLTO caches.
192 static std::string cache_policy;
193 // Additional options to pass into the code generator.
194 // Note: This array will contain all plugin options which are not claimed
195 // as plugin exclusive to pass to the code generator.
196 static std::vector<const char *> extra;
197 // Sample profile file path
198 static std::string sample_profile;
199 // New pass manager
200 static bool new_pass_manager = false;
201 // Debug new pass manager
202 static bool debug_pass_manager = false;
203 // Directory to store the .dwo files.
204 static std::string dwo_dir;
205 /// Statistics output filename.
206 static std::string stats_file;
207
208 // Optimization remarks filename and hotness options
209 static std::string OptRemarksFilename;
210 static bool OptRemarksWithHotness = false;
211
process_plugin_option(const char * opt_)212 static void process_plugin_option(const char *opt_)
213 {
214 if (opt_ == nullptr)
215 return;
216 llvm::StringRef opt = opt_;
217
218 if (opt.startswith("mcpu=")) {
219 mcpu = opt.substr(strlen("mcpu="));
220 } else if (opt.startswith("extra-library-path=")) {
221 extra_library_path = opt.substr(strlen("extra_library_path="));
222 } else if (opt.startswith("mtriple=")) {
223 triple = opt.substr(strlen("mtriple="));
224 } else if (opt.startswith("obj-path=")) {
225 obj_path = opt.substr(strlen("obj-path="));
226 } else if (opt == "emit-llvm") {
227 TheOutputType = OT_BC_ONLY;
228 } else if (opt == "save-temps") {
229 TheOutputType = OT_SAVE_TEMPS;
230 } else if (opt == "disable-output") {
231 TheOutputType = OT_DISABLE;
232 } else if (opt == "thinlto") {
233 thinlto = true;
234 } else if (opt == "thinlto-index-only") {
235 thinlto_index_only = true;
236 } else if (opt.startswith("thinlto-index-only=")) {
237 thinlto_index_only = true;
238 thinlto_linked_objects_file = opt.substr(strlen("thinlto-index-only="));
239 } else if (opt == "thinlto-emit-imports-files") {
240 thinlto_emit_imports_files = true;
241 } else if (opt.startswith("thinlto-prefix-replace=")) {
242 thinlto_prefix_replace = opt.substr(strlen("thinlto-prefix-replace="));
243 if (thinlto_prefix_replace.find(';') == std::string::npos)
244 message(LDPL_FATAL, "thinlto-prefix-replace expects 'old;new' format");
245 } else if (opt.startswith("thinlto-object-suffix-replace=")) {
246 thinlto_object_suffix_replace =
247 opt.substr(strlen("thinlto-object-suffix-replace="));
248 if (thinlto_object_suffix_replace.find(';') == std::string::npos)
249 message(LDPL_FATAL,
250 "thinlto-object-suffix-replace expects 'old;new' format");
251 } else if (opt.startswith("cache-dir=")) {
252 cache_dir = opt.substr(strlen("cache-dir="));
253 } else if (opt.startswith("cache-policy=")) {
254 cache_policy = opt.substr(strlen("cache-policy="));
255 } else if (opt.size() == 2 && opt[0] == 'O') {
256 if (opt[1] < '0' || opt[1] > '3')
257 message(LDPL_FATAL, "Optimization level must be between 0 and 3");
258 OptLevel = opt[1] - '0';
259 } else if (opt.startswith("jobs=")) {
260 if (StringRef(opt_ + 5).getAsInteger(10, Parallelism))
261 message(LDPL_FATAL, "Invalid parallelism level: %s", opt_ + 5);
262 } else if (opt.startswith("lto-partitions=")) {
263 if (opt.substr(strlen("lto-partitions="))
264 .getAsInteger(10, ParallelCodeGenParallelismLevel))
265 message(LDPL_FATAL, "Invalid codegen partition level: %s", opt_ + 5);
266 } else if (opt == "disable-verify") {
267 DisableVerify = true;
268 } else if (opt.startswith("sample-profile=")) {
269 sample_profile= opt.substr(strlen("sample-profile="));
270 } else if (opt == "new-pass-manager") {
271 new_pass_manager = true;
272 } else if (opt == "debug-pass-manager") {
273 debug_pass_manager = true;
274 } else if (opt.startswith("dwo_dir=")) {
275 dwo_dir = opt.substr(strlen("dwo_dir="));
276 } else if (opt.startswith("opt-remarks-filename=")) {
277 OptRemarksFilename = opt.substr(strlen("opt-remarks-filename="));
278 } else if (opt == "opt-remarks-with-hotness") {
279 OptRemarksWithHotness = true;
280 } else if (opt.startswith("stats-file=")) {
281 stats_file = opt.substr(strlen("stats-file="));
282 } else {
283 // Save this option to pass to the code generator.
284 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily
285 // add that.
286 if (extra.empty())
287 extra.push_back("LLVMgold");
288
289 extra.push_back(opt_);
290 }
291 }
292 }
293
294 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
295 int *claimed);
296 static ld_plugin_status all_symbols_read_hook(void);
297 static ld_plugin_status cleanup_hook(void);
298
299 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
onload(ld_plugin_tv * tv)300 ld_plugin_status onload(ld_plugin_tv *tv) {
301 InitializeAllTargetInfos();
302 InitializeAllTargets();
303 InitializeAllTargetMCs();
304 InitializeAllAsmParsers();
305 InitializeAllAsmPrinters();
306
307 // We're given a pointer to the first transfer vector. We read through them
308 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
309 // contain pointers to functions that we need to call to register our own
310 // hooks. The others are addresses of functions we can use to call into gold
311 // for services.
312
313 bool registeredClaimFile = false;
314 bool RegisteredAllSymbolsRead = false;
315
316 for (; tv->tv_tag != LDPT_NULL; ++tv) {
317 // Cast tv_tag to int to allow values not in "enum ld_plugin_tag", like, for
318 // example, LDPT_GET_SYMBOLS_V3 when building against an older plugin-api.h
319 // header.
320 switch (static_cast<int>(tv->tv_tag)) {
321 case LDPT_OUTPUT_NAME:
322 output_name = tv->tv_u.tv_string;
323 break;
324 case LDPT_LINKER_OUTPUT:
325 switch (tv->tv_u.tv_val) {
326 case LDPO_REL: // .o
327 IsExecutable = false;
328 SplitSections = false;
329 break;
330 case LDPO_DYN: // .so
331 IsExecutable = false;
332 RelocationModel = Reloc::PIC_;
333 break;
334 case LDPO_PIE: // position independent executable
335 IsExecutable = true;
336 RelocationModel = Reloc::PIC_;
337 break;
338 case LDPO_EXEC: // .exe
339 IsExecutable = true;
340 RelocationModel = Reloc::Static;
341 break;
342 default:
343 message(LDPL_ERROR, "Unknown output file type %d", tv->tv_u.tv_val);
344 return LDPS_ERR;
345 }
346 break;
347 case LDPT_OPTION:
348 options::process_plugin_option(tv->tv_u.tv_string);
349 break;
350 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
351 ld_plugin_register_claim_file callback;
352 callback = tv->tv_u.tv_register_claim_file;
353
354 if (callback(claim_file_hook) != LDPS_OK)
355 return LDPS_ERR;
356
357 registeredClaimFile = true;
358 } break;
359 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
360 ld_plugin_register_all_symbols_read callback;
361 callback = tv->tv_u.tv_register_all_symbols_read;
362
363 if (callback(all_symbols_read_hook) != LDPS_OK)
364 return LDPS_ERR;
365
366 RegisteredAllSymbolsRead = true;
367 } break;
368 case LDPT_REGISTER_CLEANUP_HOOK: {
369 ld_plugin_register_cleanup callback;
370 callback = tv->tv_u.tv_register_cleanup;
371
372 if (callback(cleanup_hook) != LDPS_OK)
373 return LDPS_ERR;
374 } break;
375 case LDPT_GET_INPUT_FILE:
376 get_input_file = tv->tv_u.tv_get_input_file;
377 break;
378 case LDPT_RELEASE_INPUT_FILE:
379 release_input_file = tv->tv_u.tv_release_input_file;
380 break;
381 case LDPT_ADD_SYMBOLS:
382 add_symbols = tv->tv_u.tv_add_symbols;
383 break;
384 case LDPT_GET_SYMBOLS_V2:
385 // Do not override get_symbols_v3 with get_symbols_v2.
386 if (!get_symbols)
387 get_symbols = tv->tv_u.tv_get_symbols;
388 break;
389 case LDPT_GET_SYMBOLS_V3:
390 get_symbols = tv->tv_u.tv_get_symbols;
391 break;
392 case LDPT_ADD_INPUT_FILE:
393 add_input_file = tv->tv_u.tv_add_input_file;
394 break;
395 case LDPT_SET_EXTRA_LIBRARY_PATH:
396 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
397 break;
398 case LDPT_GET_VIEW:
399 get_view = tv->tv_u.tv_get_view;
400 break;
401 case LDPT_MESSAGE:
402 message = tv->tv_u.tv_message;
403 break;
404 case LDPT_GET_WRAP_SYMBOLS:
405 // FIXME: When binutils 2.31 (containing gold 1.16) is the minimum
406 // required version, this should be changed to:
407 // get_wrap_symbols = tv->tv_u.tv_get_wrap_symbols;
408 get_wrap_symbols =
409 (ld_plugin_get_wrap_symbols)tv->tv_u.tv_message;
410 break;
411 default:
412 break;
413 }
414 }
415
416 if (!registeredClaimFile) {
417 message(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
418 return LDPS_ERR;
419 }
420 if (!add_symbols) {
421 message(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
422 return LDPS_ERR;
423 }
424
425 if (!RegisteredAllSymbolsRead)
426 return LDPS_OK;
427
428 if (!get_input_file) {
429 message(LDPL_ERROR, "get_input_file not passed to LLVMgold.");
430 return LDPS_ERR;
431 }
432 if (!release_input_file) {
433 message(LDPL_ERROR, "release_input_file not passed to LLVMgold.");
434 return LDPS_ERR;
435 }
436
437 return LDPS_OK;
438 }
439
diagnosticHandler(const DiagnosticInfo & DI)440 static void diagnosticHandler(const DiagnosticInfo &DI) {
441 std::string ErrStorage;
442 {
443 raw_string_ostream OS(ErrStorage);
444 DiagnosticPrinterRawOStream DP(OS);
445 DI.print(DP);
446 }
447 ld_plugin_level Level;
448 switch (DI.getSeverity()) {
449 case DS_Error:
450 message(LDPL_FATAL, "LLVM gold plugin has failed to create LTO module: %s",
451 ErrStorage.c_str());
452 case DS_Warning:
453 Level = LDPL_WARNING;
454 break;
455 case DS_Note:
456 case DS_Remark:
457 Level = LDPL_INFO;
458 break;
459 }
460 message(Level, "LLVM gold plugin: %s", ErrStorage.c_str());
461 }
462
check(Error E,std::string Msg="LLVM gold plugin")463 static void check(Error E, std::string Msg = "LLVM gold plugin") {
464 handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) -> Error {
465 message(LDPL_FATAL, "%s: %s", Msg.c_str(), EIB.message().c_str());
466 return Error::success();
467 });
468 }
469
check(Expected<T> E)470 template <typename T> static T check(Expected<T> E) {
471 if (E)
472 return std::move(*E);
473 check(E.takeError());
474 return T();
475 }
476
477 /// Called by gold to see whether this file is one that our plugin can handle.
478 /// We'll try to open it and register all the symbols with add_symbol if
479 /// possible.
claim_file_hook(const ld_plugin_input_file * file,int * claimed)480 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
481 int *claimed) {
482 MemoryBufferRef BufferRef;
483 std::unique_ptr<MemoryBuffer> Buffer;
484 if (get_view) {
485 const void *view;
486 if (get_view(file->handle, &view) != LDPS_OK) {
487 message(LDPL_ERROR, "Failed to get a view of %s", file->name);
488 return LDPS_ERR;
489 }
490 BufferRef =
491 MemoryBufferRef(StringRef((const char *)view, file->filesize), "");
492 } else {
493 int64_t offset = 0;
494 // Gold has found what might be IR part-way inside of a file, such as
495 // an .a archive.
496 if (file->offset) {
497 offset = file->offset;
498 }
499 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
500 MemoryBuffer::getOpenFileSlice(file->fd, file->name, file->filesize,
501 offset);
502 if (std::error_code EC = BufferOrErr.getError()) {
503 message(LDPL_ERROR, EC.message().c_str());
504 return LDPS_ERR;
505 }
506 Buffer = std::move(BufferOrErr.get());
507 BufferRef = Buffer->getMemBufferRef();
508 }
509
510 *claimed = 1;
511
512 Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
513 if (!ObjOrErr) {
514 handleAllErrors(ObjOrErr.takeError(), [&](const ErrorInfoBase &EI) {
515 std::error_code EC = EI.convertToErrorCode();
516 if (EC == object::object_error::invalid_file_type ||
517 EC == object::object_error::bitcode_section_not_found)
518 *claimed = 0;
519 else
520 message(LDPL_FATAL,
521 "LLVM gold plugin has failed to create LTO module: %s",
522 EI.message().c_str());
523 });
524
525 return *claimed ? LDPS_ERR : LDPS_OK;
526 }
527
528 std::unique_ptr<InputFile> Obj = std::move(*ObjOrErr);
529
530 Modules.emplace_back();
531 claimed_file &cf = Modules.back();
532
533 cf.handle = file->handle;
534 // Keep track of the first handle for each file descriptor, since there are
535 // multiple in the case of an archive. This is used later in the case of
536 // ThinLTO parallel backends to ensure that each file is only opened and
537 // released once.
538 auto LeaderHandle =
539 FDToLeaderHandle.insert(std::make_pair(file->fd, file->handle)).first;
540 cf.leader_handle = LeaderHandle->second;
541 // Save the filesize since for parallel ThinLTO backends we can only
542 // invoke get_input_file once per archive (only for the leader handle).
543 cf.filesize = file->filesize;
544 // In the case of an archive library, all but the first member must have a
545 // non-zero offset, which we can append to the file name to obtain a
546 // unique name.
547 cf.name = file->name;
548 if (file->offset)
549 cf.name += ".llvm." + std::to_string(file->offset) + "." +
550 sys::path::filename(Obj->getSourceFileName()).str();
551
552 for (auto &Sym : Obj->symbols()) {
553 cf.syms.push_back(ld_plugin_symbol());
554 ld_plugin_symbol &sym = cf.syms.back();
555 sym.version = nullptr;
556 StringRef Name = Sym.getName();
557 sym.name = strdup(Name.str().c_str());
558
559 ResolutionInfo &Res = ResInfo[Name];
560
561 Res.CanOmitFromDynSym &= Sym.canBeOmittedFromSymbolTable();
562
563 sym.visibility = LDPV_DEFAULT;
564 GlobalValue::VisibilityTypes Vis = Sym.getVisibility();
565 if (Vis != GlobalValue::DefaultVisibility)
566 Res.DefaultVisibility = false;
567 switch (Vis) {
568 case GlobalValue::DefaultVisibility:
569 break;
570 case GlobalValue::HiddenVisibility:
571 sym.visibility = LDPV_HIDDEN;
572 break;
573 case GlobalValue::ProtectedVisibility:
574 sym.visibility = LDPV_PROTECTED;
575 break;
576 }
577
578 if (Sym.isUndefined()) {
579 sym.def = LDPK_UNDEF;
580 if (Sym.isWeak())
581 sym.def = LDPK_WEAKUNDEF;
582 } else if (Sym.isCommon())
583 sym.def = LDPK_COMMON;
584 else if (Sym.isWeak())
585 sym.def = LDPK_WEAKDEF;
586 else
587 sym.def = LDPK_DEF;
588
589 sym.size = 0;
590 sym.comdat_key = nullptr;
591 int CI = Sym.getComdatIndex();
592 if (CI != -1) {
593 StringRef C = Obj->getComdatTable()[CI];
594 sym.comdat_key = strdup(C.str().c_str());
595 }
596
597 sym.resolution = LDPR_UNKNOWN;
598 }
599
600 if (!cf.syms.empty()) {
601 if (add_symbols(cf.handle, cf.syms.size(), cf.syms.data()) != LDPS_OK) {
602 message(LDPL_ERROR, "Unable to add symbols!");
603 return LDPS_ERR;
604 }
605 }
606
607 // Handle any --wrap options passed to gold, which are than passed
608 // along to the plugin.
609 if (get_wrap_symbols) {
610 const char **wrap_symbols;
611 uint64_t count = 0;
612 if (get_wrap_symbols(&count, &wrap_symbols) != LDPS_OK) {
613 message(LDPL_ERROR, "Unable to get wrap symbols!");
614 return LDPS_ERR;
615 }
616 for (uint64_t i = 0; i < count; i++) {
617 StringRef Name = wrap_symbols[i];
618 ResolutionInfo &Res = ResInfo[Name];
619 ResolutionInfo &WrapRes = ResInfo["__wrap_" + Name.str()];
620 ResolutionInfo &RealRes = ResInfo["__real_" + Name.str()];
621 // Tell LTO not to inline symbols that will be overwritten.
622 Res.CanInline = false;
623 RealRes.CanInline = false;
624 // Tell LTO not to eliminate symbols that will be used after renaming.
625 Res.IsUsedInRegularObj = true;
626 WrapRes.IsUsedInRegularObj = true;
627 }
628 }
629
630 return LDPS_OK;
631 }
632
freeSymName(ld_plugin_symbol & Sym)633 static void freeSymName(ld_plugin_symbol &Sym) {
634 free(Sym.name);
635 free(Sym.comdat_key);
636 Sym.name = nullptr;
637 Sym.comdat_key = nullptr;
638 }
639
640 /// Helper to get a file's symbols and a view into it via gold callbacks.
getSymbolsAndView(claimed_file & F)641 static const void *getSymbolsAndView(claimed_file &F) {
642 ld_plugin_status status = get_symbols(F.handle, F.syms.size(), F.syms.data());
643 if (status == LDPS_NO_SYMS)
644 return nullptr;
645
646 if (status != LDPS_OK)
647 message(LDPL_FATAL, "Failed to get symbol information");
648
649 const void *View;
650 if (get_view(F.handle, &View) != LDPS_OK)
651 message(LDPL_FATAL, "Failed to get a view of file");
652
653 return View;
654 }
655
656 /// Parse the thinlto-object-suffix-replace option into the \p OldSuffix and
657 /// \p NewSuffix strings, if it was specified.
getThinLTOOldAndNewSuffix(std::string & OldSuffix,std::string & NewSuffix)658 static void getThinLTOOldAndNewSuffix(std::string &OldSuffix,
659 std::string &NewSuffix) {
660 assert(options::thinlto_object_suffix_replace.empty() ||
661 options::thinlto_object_suffix_replace.find(";") != StringRef::npos);
662 StringRef SuffixReplace = options::thinlto_object_suffix_replace;
663 std::tie(OldSuffix, NewSuffix) = SuffixReplace.split(';');
664 }
665
666 /// Given the original \p Path to an output file, replace any filename
667 /// suffix matching \p OldSuffix with \p NewSuffix.
getThinLTOObjectFileName(StringRef Path,StringRef OldSuffix,StringRef NewSuffix)668 static std::string getThinLTOObjectFileName(StringRef Path, StringRef OldSuffix,
669 StringRef NewSuffix) {
670 if (OldSuffix.empty() && NewSuffix.empty())
671 return Path;
672 StringRef NewPath = Path;
673 NewPath.consume_back(OldSuffix);
674 std::string NewNewPath = NewPath;
675 NewNewPath += NewSuffix;
676 return NewNewPath;
677 }
678
679 // Returns true if S is valid as a C language identifier.
isValidCIdentifier(StringRef S)680 static bool isValidCIdentifier(StringRef S) {
681 return !S.empty() && (isAlpha(S[0]) || S[0] == '_') &&
682 std::all_of(S.begin() + 1, S.end(),
683 [](char C) { return C == '_' || isAlnum(C); });
684 }
685
isUndefined(ld_plugin_symbol & Sym)686 static bool isUndefined(ld_plugin_symbol &Sym) {
687 return Sym.def == LDPK_UNDEF || Sym.def == LDPK_WEAKUNDEF;
688 }
689
addModule(LTO & Lto,claimed_file & F,const void * View,StringRef Filename)690 static void addModule(LTO &Lto, claimed_file &F, const void *View,
691 StringRef Filename) {
692 MemoryBufferRef BufferRef(StringRef((const char *)View, F.filesize),
693 Filename);
694 Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
695
696 if (!ObjOrErr)
697 message(LDPL_FATAL, "Could not read bitcode from file : %s",
698 toString(ObjOrErr.takeError()).c_str());
699
700 unsigned SymNum = 0;
701 std::unique_ptr<InputFile> Input = std::move(ObjOrErr.get());
702 auto InputFileSyms = Input->symbols();
703 assert(InputFileSyms.size() == F.syms.size());
704 std::vector<SymbolResolution> Resols(F.syms.size());
705 for (ld_plugin_symbol &Sym : F.syms) {
706 const InputFile::Symbol &InpSym = InputFileSyms[SymNum];
707 SymbolResolution &R = Resols[SymNum++];
708
709 ld_plugin_symbol_resolution Resolution =
710 (ld_plugin_symbol_resolution)Sym.resolution;
711
712 ResolutionInfo &Res = ResInfo[Sym.name];
713
714 switch (Resolution) {
715 case LDPR_UNKNOWN:
716 llvm_unreachable("Unexpected resolution");
717
718 case LDPR_RESOLVED_IR:
719 case LDPR_RESOLVED_EXEC:
720 case LDPR_RESOLVED_DYN:
721 case LDPR_PREEMPTED_IR:
722 case LDPR_PREEMPTED_REG:
723 case LDPR_UNDEF:
724 break;
725
726 case LDPR_PREVAILING_DEF_IRONLY:
727 R.Prevailing = !isUndefined(Sym);
728 break;
729
730 case LDPR_PREVAILING_DEF:
731 R.Prevailing = !isUndefined(Sym);
732 R.VisibleToRegularObj = true;
733 break;
734
735 case LDPR_PREVAILING_DEF_IRONLY_EXP:
736 R.Prevailing = !isUndefined(Sym);
737 if (!Res.CanOmitFromDynSym)
738 R.VisibleToRegularObj = true;
739 break;
740 }
741
742 // If the symbol has a C identifier section name, we need to mark
743 // it as visible to a regular object so that LTO will keep it around
744 // to ensure the linker generates special __start_<secname> and
745 // __stop_<secname> symbols which may be used elsewhere.
746 if (isValidCIdentifier(InpSym.getSectionName()))
747 R.VisibleToRegularObj = true;
748
749 if (Resolution != LDPR_RESOLVED_DYN && Resolution != LDPR_UNDEF &&
750 (IsExecutable || !Res.DefaultVisibility))
751 R.FinalDefinitionInLinkageUnit = true;
752
753 if (!Res.CanInline)
754 R.LinkerRedefined = true;
755
756 if (Res.IsUsedInRegularObj)
757 R.VisibleToRegularObj = true;
758
759 freeSymName(Sym);
760 }
761
762 check(Lto.add(std::move(Input), Resols),
763 std::string("Failed to link module ") + F.name);
764 }
765
recordFile(const std::string & Filename,bool TempOutFile)766 static void recordFile(const std::string &Filename, bool TempOutFile) {
767 if (add_input_file(Filename.c_str()) != LDPS_OK)
768 message(LDPL_FATAL,
769 "Unable to add .o file to the link. File left behind in: %s",
770 Filename.c_str());
771 if (TempOutFile)
772 Cleanup.push_back(Filename);
773 }
774
775 /// Return the desired output filename given a base input name, a flag
776 /// indicating whether a temp file should be generated, and an optional task id.
777 /// The new filename generated is returned in \p NewFilename.
getOutputFileName(StringRef InFilename,bool TempOutFile,SmallString<128> & NewFilename,int TaskID)778 static int getOutputFileName(StringRef InFilename, bool TempOutFile,
779 SmallString<128> &NewFilename, int TaskID) {
780 int FD = -1;
781 if (TempOutFile) {
782 std::error_code EC =
783 sys::fs::createTemporaryFile("lto-llvm", "o", FD, NewFilename);
784 if (EC)
785 message(LDPL_FATAL, "Could not create temporary file: %s",
786 EC.message().c_str());
787 } else {
788 NewFilename = InFilename;
789 if (TaskID > 0)
790 NewFilename += utostr(TaskID);
791 std::error_code EC =
792 sys::fs::openFileForWrite(NewFilename, FD, sys::fs::CD_CreateAlways);
793 if (EC)
794 message(LDPL_FATAL, "Could not open file %s: %s", NewFilename.c_str(),
795 EC.message().c_str());
796 }
797 return FD;
798 }
799
getCGOptLevel()800 static CodeGenOpt::Level getCGOptLevel() {
801 switch (options::OptLevel) {
802 case 0:
803 return CodeGenOpt::None;
804 case 1:
805 return CodeGenOpt::Less;
806 case 2:
807 return CodeGenOpt::Default;
808 case 3:
809 return CodeGenOpt::Aggressive;
810 }
811 llvm_unreachable("Invalid optimization level");
812 }
813
814 /// Parse the thinlto_prefix_replace option into the \p OldPrefix and
815 /// \p NewPrefix strings, if it was specified.
getThinLTOOldAndNewPrefix(std::string & OldPrefix,std::string & NewPrefix)816 static void getThinLTOOldAndNewPrefix(std::string &OldPrefix,
817 std::string &NewPrefix) {
818 StringRef PrefixReplace = options::thinlto_prefix_replace;
819 assert(PrefixReplace.empty() || PrefixReplace.find(";") != StringRef::npos);
820 std::tie(OldPrefix, NewPrefix) = PrefixReplace.split(';');
821 }
822
823 /// Creates instance of LTO.
824 /// OnIndexWrite is callback to let caller know when LTO writes index files.
825 /// LinkedObjectsFile is an output stream to write the list of object files for
826 /// the final ThinLTO linking. Can be nullptr.
createLTO(IndexWriteCallback OnIndexWrite,raw_fd_ostream * LinkedObjectsFile)827 static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
828 raw_fd_ostream *LinkedObjectsFile) {
829 Config Conf;
830 ThinBackend Backend;
831
832 Conf.CPU = options::mcpu;
833 Conf.Options = InitTargetOptionsFromCodeGenFlags();
834
835 // Disable the new X86 relax relocations since gold might not support them.
836 // FIXME: Check the gold version or add a new option to enable them.
837 Conf.Options.RelaxELFRelocations = false;
838
839 // Toggle function/data sections.
840 Conf.Options.FunctionSections = SplitSections;
841 Conf.Options.DataSections = SplitSections;
842
843 Conf.MAttrs = MAttrs;
844 Conf.RelocModel = RelocationModel;
845 Conf.CodeModel = getCodeModel();
846 Conf.CGOptLevel = getCGOptLevel();
847 Conf.DisableVerify = options::DisableVerify;
848 Conf.OptLevel = options::OptLevel;
849 if (options::Parallelism)
850 Backend = createInProcessThinBackend(options::Parallelism);
851 if (options::thinlto_index_only) {
852 std::string OldPrefix, NewPrefix;
853 getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
854 Backend = createWriteIndexesThinBackend(OldPrefix, NewPrefix,
855 options::thinlto_emit_imports_files,
856 LinkedObjectsFile, OnIndexWrite);
857 }
858
859 Conf.OverrideTriple = options::triple;
860 Conf.DefaultTriple = sys::getDefaultTargetTriple();
861
862 Conf.DiagHandler = diagnosticHandler;
863
864 switch (options::TheOutputType) {
865 case options::OT_NORMAL:
866 break;
867
868 case options::OT_DISABLE:
869 Conf.PreOptModuleHook = [](size_t Task, const Module &M) { return false; };
870 break;
871
872 case options::OT_BC_ONLY:
873 Conf.PostInternalizeModuleHook = [](size_t Task, const Module &M) {
874 std::error_code EC;
875 raw_fd_ostream OS(output_name, EC, sys::fs::OpenFlags::F_None);
876 if (EC)
877 message(LDPL_FATAL, "Failed to write the output file.");
878 WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ false);
879 return false;
880 };
881 break;
882
883 case options::OT_SAVE_TEMPS:
884 check(Conf.addSaveTemps(output_name + ".",
885 /* UseInputModulePath */ true));
886 break;
887 }
888
889 if (!options::sample_profile.empty())
890 Conf.SampleProfile = options::sample_profile;
891
892 Conf.DwoDir = options::dwo_dir;
893
894 // Set up optimization remarks handling.
895 Conf.RemarksFilename = options::OptRemarksFilename;
896 Conf.RemarksWithHotness = options::OptRemarksWithHotness;
897
898 // Use new pass manager if set in driver
899 Conf.UseNewPM = options::new_pass_manager;
900 // Debug new pass manager if requested
901 Conf.DebugPassManager = options::debug_pass_manager;
902
903 Conf.StatsFile = options::stats_file;
904 return llvm::make_unique<LTO>(std::move(Conf), Backend,
905 options::ParallelCodeGenParallelismLevel);
906 }
907
908 // Write empty files that may be expected by a distributed build
909 // system when invoked with thinlto_index_only. This is invoked when
910 // the linker has decided not to include the given module in the
911 // final link. Frequently the distributed build system will want to
912 // confirm that all expected outputs are created based on all of the
913 // modules provided to the linker.
914 // If SkipModule is true then .thinlto.bc should contain just
915 // SkipModuleByDistributedBackend flag which requests distributed backend
916 // to skip the compilation of the corresponding module and produce an empty
917 // object file.
writeEmptyDistributedBuildOutputs(const std::string & ModulePath,const std::string & OldPrefix,const std::string & NewPrefix,bool SkipModule)918 static void writeEmptyDistributedBuildOutputs(const std::string &ModulePath,
919 const std::string &OldPrefix,
920 const std::string &NewPrefix,
921 bool SkipModule) {
922 std::string NewModulePath =
923 getThinLTOOutputFile(ModulePath, OldPrefix, NewPrefix);
924 std::error_code EC;
925 {
926 raw_fd_ostream OS(NewModulePath + ".thinlto.bc", EC,
927 sys::fs::OpenFlags::F_None);
928 if (EC)
929 message(LDPL_FATAL, "Failed to write '%s': %s",
930 (NewModulePath + ".thinlto.bc").c_str(), EC.message().c_str());
931
932 if (SkipModule) {
933 ModuleSummaryIndex Index(/*HaveGVs*/ false);
934 Index.setSkipModuleByDistributedBackend();
935 WriteIndexToFile(Index, OS, nullptr);
936 }
937 }
938 if (options::thinlto_emit_imports_files) {
939 raw_fd_ostream OS(NewModulePath + ".imports", EC,
940 sys::fs::OpenFlags::F_None);
941 if (EC)
942 message(LDPL_FATAL, "Failed to write '%s': %s",
943 (NewModulePath + ".imports").c_str(), EC.message().c_str());
944 }
945 }
946
947 // Creates and returns output stream with a list of object files for final
948 // linking of distributed ThinLTO.
CreateLinkedObjectsFile()949 static std::unique_ptr<raw_fd_ostream> CreateLinkedObjectsFile() {
950 if (options::thinlto_linked_objects_file.empty())
951 return nullptr;
952 assert(options::thinlto_index_only);
953 std::error_code EC;
954 auto LinkedObjectsFile = llvm::make_unique<raw_fd_ostream>(
955 options::thinlto_linked_objects_file, EC, sys::fs::OpenFlags::F_None);
956 if (EC)
957 message(LDPL_FATAL, "Failed to create '%s': %s",
958 options::thinlto_linked_objects_file.c_str(), EC.message().c_str());
959 return LinkedObjectsFile;
960 }
961
962 /// Runs LTO and return a list of pairs <FileName, IsTemporary>.
runLTO()963 static std::vector<std::pair<SmallString<128>, bool>> runLTO() {
964 // Map to own RAII objects that manage the file opening and releasing
965 // interfaces with gold. This is needed only for ThinLTO mode, since
966 // unlike regular LTO, where addModule will result in the opened file
967 // being merged into a new combined module, we need to keep these files open
968 // through Lto->run().
969 DenseMap<void *, std::unique_ptr<PluginInputFile>> HandleToInputFile;
970
971 // Owns string objects and tells if index file was already created.
972 StringMap<bool> ObjectToIndexFileState;
973
974 std::unique_ptr<raw_fd_ostream> LinkedObjects = CreateLinkedObjectsFile();
975 std::unique_ptr<LTO> Lto = createLTO(
976 [&ObjectToIndexFileState](const std::string &Identifier) {
977 ObjectToIndexFileState[Identifier] = true;
978 },
979 LinkedObjects.get());
980
981 std::string OldPrefix, NewPrefix;
982 if (options::thinlto_index_only)
983 getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
984
985 std::string OldSuffix, NewSuffix;
986 getThinLTOOldAndNewSuffix(OldSuffix, NewSuffix);
987
988 for (claimed_file &F : Modules) {
989 if (options::thinlto && !HandleToInputFile.count(F.leader_handle))
990 HandleToInputFile.insert(std::make_pair(
991 F.leader_handle, llvm::make_unique<PluginInputFile>(F.handle)));
992 // In case we are thin linking with a minimized bitcode file, ensure
993 // the module paths encoded in the index reflect where the backends
994 // will locate the full bitcode files for compiling/importing.
995 std::string Identifier =
996 getThinLTOObjectFileName(F.name, OldSuffix, NewSuffix);
997 auto ObjFilename = ObjectToIndexFileState.insert({Identifier, false});
998 assert(ObjFilename.second);
999 if (const void *View = getSymbolsAndView(F))
1000 addModule(*Lto, F, View, ObjFilename.first->first());
1001 else if (options::thinlto_index_only) {
1002 ObjFilename.first->second = true;
1003 writeEmptyDistributedBuildOutputs(Identifier, OldPrefix, NewPrefix,
1004 /* SkipModule */ true);
1005 }
1006 }
1007
1008 SmallString<128> Filename;
1009 // Note that getOutputFileName will append a unique ID for each task
1010 if (!options::obj_path.empty())
1011 Filename = options::obj_path;
1012 else if (options::TheOutputType == options::OT_SAVE_TEMPS)
1013 Filename = output_name + ".o";
1014 bool SaveTemps = !Filename.empty();
1015
1016 size_t MaxTasks = Lto->getMaxTasks();
1017 std::vector<std::pair<SmallString<128>, bool>> Files(MaxTasks);
1018
1019 auto AddStream =
1020 [&](size_t Task) -> std::unique_ptr<lto::NativeObjectStream> {
1021 Files[Task].second = !SaveTemps;
1022 int FD = getOutputFileName(Filename, /* TempOutFile */ !SaveTemps,
1023 Files[Task].first, Task);
1024 return llvm::make_unique<lto::NativeObjectStream>(
1025 llvm::make_unique<llvm::raw_fd_ostream>(FD, true));
1026 };
1027
1028 auto AddBuffer = [&](size_t Task, std::unique_ptr<MemoryBuffer> MB) {
1029 *AddStream(Task)->OS << MB->getBuffer();
1030 };
1031
1032 NativeObjectCache Cache;
1033 if (!options::cache_dir.empty())
1034 Cache = check(localCache(options::cache_dir, AddBuffer));
1035
1036 check(Lto->run(AddStream, Cache));
1037
1038 // Write empty output files that may be expected by the distributed build
1039 // system.
1040 if (options::thinlto_index_only)
1041 for (auto &Identifier : ObjectToIndexFileState)
1042 if (!Identifier.getValue())
1043 writeEmptyDistributedBuildOutputs(Identifier.getKey(), OldPrefix,
1044 NewPrefix, /* SkipModule */ false);
1045
1046 return Files;
1047 }
1048
1049 /// gold informs us that all symbols have been read. At this point, we use
1050 /// get_symbols to see if any of our definitions have been overridden by a
1051 /// native object file. Then, perform optimization and codegen.
allSymbolsReadHook()1052 static ld_plugin_status allSymbolsReadHook() {
1053 if (Modules.empty())
1054 return LDPS_OK;
1055
1056 if (unsigned NumOpts = options::extra.size())
1057 cl::ParseCommandLineOptions(NumOpts, &options::extra[0]);
1058
1059 std::vector<std::pair<SmallString<128>, bool>> Files = runLTO();
1060
1061 if (options::TheOutputType == options::OT_DISABLE ||
1062 options::TheOutputType == options::OT_BC_ONLY)
1063 return LDPS_OK;
1064
1065 if (options::thinlto_index_only) {
1066 llvm_shutdown();
1067 cleanup_hook();
1068 exit(0);
1069 }
1070
1071 for (const auto &F : Files)
1072 if (!F.first.empty())
1073 recordFile(F.first.str(), F.second);
1074
1075 if (!options::extra_library_path.empty() &&
1076 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK)
1077 message(LDPL_FATAL, "Unable to set the extra library path.");
1078
1079 return LDPS_OK;
1080 }
1081
all_symbols_read_hook(void)1082 static ld_plugin_status all_symbols_read_hook(void) {
1083 ld_plugin_status Ret = allSymbolsReadHook();
1084 llvm_shutdown();
1085
1086 if (options::TheOutputType == options::OT_BC_ONLY ||
1087 options::TheOutputType == options::OT_DISABLE) {
1088 if (options::TheOutputType == options::OT_DISABLE) {
1089 // Remove the output file here since ld.bfd creates the output file
1090 // early.
1091 std::error_code EC = sys::fs::remove(output_name);
1092 if (EC)
1093 message(LDPL_ERROR, "Failed to delete '%s': %s", output_name.c_str(),
1094 EC.message().c_str());
1095 }
1096 exit(0);
1097 }
1098
1099 return Ret;
1100 }
1101
cleanup_hook(void)1102 static ld_plugin_status cleanup_hook(void) {
1103 for (std::string &Name : Cleanup) {
1104 std::error_code EC = sys::fs::remove(Name);
1105 if (EC)
1106 message(LDPL_ERROR, "Failed to delete '%s': %s", Name.c_str(),
1107 EC.message().c_str());
1108 }
1109
1110 // Prune cache
1111 if (!options::cache_dir.empty()) {
1112 CachePruningPolicy policy = check(parseCachePruningPolicy(options::cache_policy));
1113 pruneCache(options::cache_dir, policy);
1114 }
1115
1116 return LDPS_OK;
1117 }
1118