1 //===- lli.cpp - LLVM Interpreter / Dynamic compiler ----------------------===//
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 // This utility provides a simple wrapper around the LLVM Execution Engines,
11 // which allow the direct execution of LLVM programs through a Just-In-Time
12 // compiler, or through an interpreter if no JIT is available for this platform.
14 //===----------------------------------------------------------------------===//
16 #include "OrcLazyJIT.h"
17 #include "RemoteJITUtils.h"
18 #include "llvm/IR/LLVMContext.h"
19 #include "llvm/ADT/StringExtras.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/Bitcode/ReaderWriter.h"
22 #include "llvm/CodeGen/LinkAllCodegenComponents.h"
23 #include "llvm/ExecutionEngine/GenericValue.h"
24 #include "llvm/ExecutionEngine/Interpreter.h"
25 #include "llvm/ExecutionEngine/JITEventListener.h"
26 #include "llvm/ExecutionEngine/MCJIT.h"
27 #include "llvm/ExecutionEngine/ObjectCache.h"
28 #include "llvm/ExecutionEngine/OrcMCJITReplacement.h"
29 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
30 #include "llvm/ExecutionEngine/Orc/OrcRemoteTargetClient.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/Type.h"
34 #include "llvm/IR/TypeBuilder.h"
35 #include "llvm/IRReader/IRReader.h"
36 #include "llvm/Object/Archive.h"
37 #include "llvm/Object/ObjectFile.h"
38 #include "llvm/Support/CommandLine.h"
39 #include "llvm/Support/Debug.h"
40 #include "llvm/Support/DynamicLibrary.h"
41 #include "llvm/Support/Format.h"
42 #include "llvm/Support/ManagedStatic.h"
43 #include "llvm/Support/MathExtras.h"
44 #include "llvm/Support/Memory.h"
45 #include "llvm/Support/MemoryBuffer.h"
46 #include "llvm/Support/Path.h"
47 #include "llvm/Support/PluginLoader.h"
48 #include "llvm/Support/PrettyStackTrace.h"
49 #include "llvm/Support/Process.h"
50 #include "llvm/Support/Program.h"
51 #include "llvm/Support/Signals.h"
52 #include "llvm/Support/SourceMgr.h"
53 #include "llvm/Support/TargetSelect.h"
54 #include "llvm/Support/raw_ostream.h"
55 #include "llvm/Transforms/Instrumentation.h"
59 #include <cygwin/version.h>
60 #if defined(CYGWIN_VERSION_DLL_MAJOR) && CYGWIN_VERSION_DLL_MAJOR<1007
61 #define DO_NOTHING_ATEXIT 1
67 #define DEBUG_TYPE "lli"
71 enum class JITKind { MCJIT, OrcMCJITReplacement, OrcLazy };
74 InputFile(cl::desc("<input bitcode>"), cl::Positional, cl::init("-"));
77 InputArgv(cl::ConsumeAfter, cl::desc("<program arguments>..."));
79 cl::opt<bool> ForceInterpreter("force-interpreter",
80 cl::desc("Force interpretation: disable JIT"),
83 cl::opt<JITKind> UseJITKind("jit-kind",
84 cl::desc("Choose underlying JIT kind."),
85 cl::init(JITKind::MCJIT),
87 clEnumValN(JITKind::MCJIT, "mcjit",
89 clEnumValN(JITKind::OrcMCJITReplacement,
91 "Orc-based MCJIT replacement"),
92 clEnumValN(JITKind::OrcLazy,
94 "Orc-based lazy JIT."),
97 // The MCJIT supports building for a target address space separate from
98 // the JIT compilation process. Use a forked process and a copying
99 // memory manager with IPC to execute using this functionality.
100 cl::opt<bool> RemoteMCJIT("remote-mcjit",
101 cl::desc("Execute MCJIT'ed code in a separate process."),
104 // Manually specify the child process for remote execution. This overrides
105 // the simulated remote execution that allocates address space for child
106 // execution. The child process will be executed and will communicate with
107 // lli via stdin/stdout pipes.
109 ChildExecPath("mcjit-remote-process",
110 cl::desc("Specify the filename of the process to launch "
111 "for remote MCJIT execution. If none is specified,"
112 "\n\tremote execution will be simulated in-process."),
113 cl::value_desc("filename"), cl::init(""));
115 // Determine optimization level.
118 cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
119 "(default = '-O2')"),
125 TargetTriple("mtriple", cl::desc("Override target triple for module"));
129 cl::desc("Architecture to generate assembly for (see --version)"));
133 cl::desc("Target a specific cpu type (-mcpu=help for details)"),
134 cl::value_desc("cpu-name"),
137 cl::list<std::string>
140 cl::desc("Target specific attributes (-mattr=help for details)"),
141 cl::value_desc("a1,+a2,-a3,..."));
144 EntryFunc("entry-function",
145 cl::desc("Specify the entry function (default = 'main') "
146 "of the executable"),
147 cl::value_desc("function"),
150 cl::list<std::string>
151 ExtraModules("extra-module",
152 cl::desc("Extra modules to be loaded"),
153 cl::value_desc("input bitcode"));
155 cl::list<std::string>
156 ExtraObjects("extra-object",
157 cl::desc("Extra object files to be loaded"),
158 cl::value_desc("input object"));
160 cl::list<std::string>
161 ExtraArchives("extra-archive",
162 cl::desc("Extra archive files to be loaded"),
163 cl::value_desc("input archive"));
166 EnableCacheManager("enable-cache-manager",
167 cl::desc("Use cache manager to save/load mdoules"),
171 ObjectCacheDir("object-cache-dir",
172 cl::desc("Directory to store cached object files "
173 "(must be user writable)"),
177 FakeArgv0("fake-argv0",
178 cl::desc("Override the 'argv[0]' value passed into the executing"
179 " program"), cl::value_desc("executable"));
182 DisableCoreFiles("disable-core-files", cl::Hidden,
183 cl::desc("Disable emission of core files if possible"));
186 NoLazyCompilation("disable-lazy-compilation",
187 cl::desc("Disable JIT lazy compilation"),
190 cl::opt<Reloc::Model> RelocModel(
191 "relocation-model", cl::desc("Choose relocation model"),
193 clEnumValN(Reloc::Static, "static", "Non-relocatable code"),
194 clEnumValN(Reloc::PIC_, "pic",
195 "Fully relocatable, position independent code"),
196 clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
197 "Relocatable external references, non-relocatable code"),
200 cl::opt<llvm::CodeModel::Model>
201 CMModel("code-model",
202 cl::desc("Choose code model"),
203 cl::init(CodeModel::JITDefault),
204 cl::values(clEnumValN(CodeModel::JITDefault, "default",
205 "Target default JIT code model"),
206 clEnumValN(CodeModel::Small, "small",
208 clEnumValN(CodeModel::Kernel, "kernel",
209 "Kernel code model"),
210 clEnumValN(CodeModel::Medium, "medium",
211 "Medium code model"),
212 clEnumValN(CodeModel::Large, "large",
217 GenerateSoftFloatCalls("soft-float",
218 cl::desc("Generate software floating point library calls"),
221 cl::opt<llvm::FloatABI::ABIType>
222 FloatABIForCalls("float-abi",
223 cl::desc("Choose float ABI type"),
224 cl::init(FloatABI::Default),
226 clEnumValN(FloatABI::Default, "default",
227 "Target default float ABI type"),
228 clEnumValN(FloatABI::Soft, "soft",
229 "Soft float ABI (implied by -soft-float)"),
230 clEnumValN(FloatABI::Hard, "hard",
231 "Hard float ABI (uses FP registers)"),
234 ExitOnError ExitOnErr;
237 //===----------------------------------------------------------------------===//
240 // This object cache implementation writes cached objects to disk to the
241 // directory specified by CacheDir, using a filename provided in the module
242 // descriptor. The cache tries to load a saved object using that path if the
243 // file exists. CacheDir defaults to "", in which case objects are cached
244 // alongside their originating bitcodes.
246 class LLIObjectCache : public ObjectCache {
248 LLIObjectCache(const std::string& CacheDir) : CacheDir(CacheDir) {
249 // Add trailing '/' to cache dir if necessary.
250 if (!this->CacheDir.empty() &&
251 this->CacheDir[this->CacheDir.size() - 1] != '/')
252 this->CacheDir += '/';
254 ~LLIObjectCache() override {}
256 void notifyObjectCompiled(const Module *M, MemoryBufferRef Obj) override {
257 const std::string &ModuleID = M->getModuleIdentifier();
258 std::string CacheName;
259 if (!getCacheFilename(ModuleID, CacheName))
261 if (!CacheDir.empty()) { // Create user-defined cache dir.
262 SmallString<128> dir(sys::path::parent_path(CacheName));
263 sys::fs::create_directories(Twine(dir));
266 raw_fd_ostream outfile(CacheName, EC, sys::fs::F_None);
267 outfile.write(Obj.getBufferStart(), Obj.getBufferSize());
271 std::unique_ptr<MemoryBuffer> getObject(const Module* M) override {
272 const std::string &ModuleID = M->getModuleIdentifier();
273 std::string CacheName;
274 if (!getCacheFilename(ModuleID, CacheName))
276 // Load the object from the cache filename
277 ErrorOr<std::unique_ptr<MemoryBuffer>> IRObjectBuffer =
278 MemoryBuffer::getFile(CacheName.c_str(), -1, false);
279 // If the file isn't there, that's OK.
282 // MCJIT will want to write into this buffer, and we don't want that
283 // because the file has probably just been mmapped. Instead we make
284 // a copy. The filed-based buffer will be released when it goes
286 return MemoryBuffer::getMemBufferCopy(IRObjectBuffer.get()->getBuffer());
290 std::string CacheDir;
292 bool getCacheFilename(const std::string &ModID, std::string &CacheName) {
293 std::string Prefix("file:");
294 size_t PrefixLength = Prefix.length();
295 if (ModID.substr(0, PrefixLength) != Prefix)
297 std::string CacheSubdir = ModID.substr(PrefixLength);
299 // Transform "X:\foo" => "/X\foo" for convenience.
300 if (isalpha(CacheSubdir[0]) && CacheSubdir[1] == ':') {
301 CacheSubdir[1] = CacheSubdir[0];
302 CacheSubdir[0] = '/';
305 CacheName = CacheDir + CacheSubdir;
306 size_t pos = CacheName.rfind('.');
307 CacheName.replace(pos, CacheName.length() - pos, ".o");
312 // On Mingw and Cygwin, an external symbol named '__main' is called from the
313 // generated 'main' function to allow static intialization. To avoid linking
314 // problems with remote targets (because lli's remote target support does not
315 // currently handle external linking) we add a secondary module which defines
316 // an empty '__main' function.
317 static void addCygMingExtraModule(ExecutionEngine &EE, LLVMContext &Context,
318 StringRef TargetTripleStr) {
319 IRBuilder<> Builder(Context);
320 Triple TargetTriple(TargetTripleStr);
322 // Create a new module.
323 std::unique_ptr<Module> M = make_unique<Module>("CygMingHelper", Context);
324 M->setTargetTriple(TargetTripleStr);
326 // Create an empty function named "__main".
328 if (TargetTriple.isArch64Bit()) {
329 Result = Function::Create(
330 TypeBuilder<int64_t(void), false>::get(Context),
331 GlobalValue::ExternalLinkage, "__main", M.get());
333 Result = Function::Create(
334 TypeBuilder<int32_t(void), false>::get(Context),
335 GlobalValue::ExternalLinkage, "__main", M.get());
337 BasicBlock *BB = BasicBlock::Create(Context, "__main", Result);
338 Builder.SetInsertPoint(BB);
340 if (TargetTriple.isArch64Bit())
341 ReturnVal = ConstantInt::get(Context, APInt(64, 0));
343 ReturnVal = ConstantInt::get(Context, APInt(32, 0));
344 Builder.CreateRet(ReturnVal);
346 // Add this new module to the ExecutionEngine.
347 EE.addModule(std::move(M));
350 CodeGenOpt::Level getOptLevel() {
353 errs() << "lli: Invalid optimization level.\n";
355 case '0': return CodeGenOpt::None;
356 case '1': return CodeGenOpt::Less;
358 case '2': return CodeGenOpt::Default;
359 case '3': return CodeGenOpt::Aggressive;
361 llvm_unreachable("Unrecognized opt level.");
364 //===----------------------------------------------------------------------===//
365 // main Driver function
367 int main(int argc, char **argv, char * const *envp) {
368 sys::PrintStackTraceOnErrorSignal(argv[0]);
369 PrettyStackTraceProgram X(argc, argv);
371 atexit(llvm_shutdown); // Call llvm_shutdown() on exit.
374 ExitOnErr.setBanner(std::string(argv[0]) + ": ");
376 // If we have a native target, initialize it to ensure it is linked in and
377 // usable by the JIT.
378 InitializeNativeTarget();
379 InitializeNativeTargetAsmPrinter();
380 InitializeNativeTargetAsmParser();
382 cl::ParseCommandLineOptions(argc, argv,
383 "llvm interpreter & dynamic compiler\n");
385 // If the user doesn't want core files, disable them.
386 if (DisableCoreFiles)
387 sys::Process::PreventCoreFiles();
391 // Load the bitcode...
393 std::unique_ptr<Module> Owner = parseIRFile(InputFile, Err, Context);
394 Module *Mod = Owner.get();
396 Err.print(argv[0], errs());
400 if (UseJITKind == JITKind::OrcLazy)
401 return runOrcLazyJIT(std::move(Owner), argc, argv);
403 if (EnableCacheManager) {
404 std::string CacheName("file:");
405 CacheName.append(InputFile);
406 Mod->setModuleIdentifier(CacheName);
409 // If not jitting lazily, load the whole bitcode file eagerly too.
410 if (NoLazyCompilation) {
411 if (std::error_code EC = Mod->materializeAll()) {
412 errs() << argv[0] << ": bitcode didn't read correctly.\n";
413 errs() << "Reason: " << EC.message() << "\n";
418 std::string ErrorMsg;
419 EngineBuilder builder(std::move(Owner));
420 builder.setMArch(MArch);
421 builder.setMCPU(MCPU);
422 builder.setMAttrs(MAttrs);
423 if (RelocModel.getNumOccurrences())
424 builder.setRelocationModel(RelocModel);
425 builder.setCodeModel(CMModel);
426 builder.setErrorStr(&ErrorMsg);
427 builder.setEngineKind(ForceInterpreter
428 ? EngineKind::Interpreter
430 builder.setUseOrcMCJITReplacement(UseJITKind == JITKind::OrcMCJITReplacement);
432 // If we are supposed to override the target triple, do so now.
433 if (!TargetTriple.empty())
434 Mod->setTargetTriple(Triple::normalize(TargetTriple));
436 // Enable MCJIT if desired.
437 RTDyldMemoryManager *RTDyldMM = nullptr;
438 if (!ForceInterpreter) {
440 RTDyldMM = new ForwardingMemoryManager();
442 RTDyldMM = new SectionMemoryManager();
444 // Deliberately construct a temp std::unique_ptr to pass in. Do not null out
445 // RTDyldMM: We still use it below, even though we don't own it.
446 builder.setMCJITMemoryManager(
447 std::unique_ptr<RTDyldMemoryManager>(RTDyldMM));
448 } else if (RemoteMCJIT) {
449 errs() << "error: Remote process execution does not work with the "
454 builder.setOptLevel(getOptLevel());
456 TargetOptions Options;
457 if (FloatABIForCalls != FloatABI::Default)
458 Options.FloatABIType = FloatABIForCalls;
460 builder.setTargetOptions(Options);
462 std::unique_ptr<ExecutionEngine> EE(builder.create());
464 if (!ErrorMsg.empty())
465 errs() << argv[0] << ": error creating EE: " << ErrorMsg << "\n";
467 errs() << argv[0] << ": unknown error creating EE!\n";
471 std::unique_ptr<LLIObjectCache> CacheManager;
472 if (EnableCacheManager) {
473 CacheManager.reset(new LLIObjectCache(ObjectCacheDir));
474 EE->setObjectCache(CacheManager.get());
477 // Load any additional modules specified on the command line.
478 for (unsigned i = 0, e = ExtraModules.size(); i != e; ++i) {
479 std::unique_ptr<Module> XMod = parseIRFile(ExtraModules[i], Err, Context);
481 Err.print(argv[0], errs());
484 if (EnableCacheManager) {
485 std::string CacheName("file:");
486 CacheName.append(ExtraModules[i]);
487 XMod->setModuleIdentifier(CacheName);
489 EE->addModule(std::move(XMod));
492 for (unsigned i = 0, e = ExtraObjects.size(); i != e; ++i) {
493 Expected<object::OwningBinary<object::ObjectFile>> Obj =
494 object::ObjectFile::createObjectFile(ExtraObjects[i]);
496 // TODO: Actually report errors helpfully.
497 consumeError(Obj.takeError());
498 Err.print(argv[0], errs());
501 object::OwningBinary<object::ObjectFile> &O = Obj.get();
502 EE->addObjectFile(std::move(O));
505 for (unsigned i = 0, e = ExtraArchives.size(); i != e; ++i) {
506 ErrorOr<std::unique_ptr<MemoryBuffer>> ArBufOrErr =
507 MemoryBuffer::getFileOrSTDIN(ExtraArchives[i]);
509 Err.print(argv[0], errs());
512 std::unique_ptr<MemoryBuffer> &ArBuf = ArBufOrErr.get();
514 Expected<std::unique_ptr<object::Archive>> ArOrErr =
515 object::Archive::create(ArBuf->getMemBufferRef());
518 raw_string_ostream OS(Buf);
519 logAllUnhandledErrors(ArOrErr.takeError(), OS, "");
524 std::unique_ptr<object::Archive> &Ar = ArOrErr.get();
526 object::OwningBinary<object::Archive> OB(std::move(Ar), std::move(ArBuf));
528 EE->addArchive(std::move(OB));
531 // If the target is Cygwin/MingW and we are generating remote code, we
532 // need an extra module to help out with linking.
533 if (RemoteMCJIT && Triple(Mod->getTargetTriple()).isOSCygMing()) {
534 addCygMingExtraModule(*EE, Context, Mod->getTargetTriple());
537 // The following functions have no effect if their respective profiling
538 // support wasn't enabled in the build configuration.
539 EE->RegisterJITEventListener(
540 JITEventListener::createOProfileJITEventListener());
541 EE->RegisterJITEventListener(
542 JITEventListener::createIntelJITEventListener());
544 if (!NoLazyCompilation && RemoteMCJIT) {
545 errs() << "warning: remote mcjit does not support lazy compilation\n";
546 NoLazyCompilation = true;
548 EE->DisableLazyCompilation(NoLazyCompilation);
550 // If the user specifically requested an argv[0] to pass into the program,
552 if (!FakeArgv0.empty()) {
553 InputFile = static_cast<std::string>(FakeArgv0);
555 // Otherwise, if there is a .bc suffix on the executable strip it off, it
556 // might confuse the program.
557 if (StringRef(InputFile).endswith(".bc"))
558 InputFile.erase(InputFile.length() - 3);
561 // Add the module's name to the start of the vector of arguments to main().
562 InputArgv.insert(InputArgv.begin(), InputFile);
564 // Call the main function from M as if its signature were:
565 // int main (int argc, char **argv, const char **envp)
566 // using the contents of Args to determine argc & argv, and the contents of
567 // EnvVars to determine envp.
569 Function *EntryFn = Mod->getFunction(EntryFunc);
571 errs() << '\'' << EntryFunc << "\' function not found in module.\n";
575 // Reset errno to zero on entry to main.
580 // Sanity check use of remote-jit: LLI currently only supports use of the
581 // remote JIT on Unix platforms.
584 errs() << "Warning: host does not support external remote targets.\n"
585 << " Defaulting to local execution\n";
588 if (ChildExecPath.empty()) {
589 errs() << "-remote-mcjit requires -mcjit-remote-process.\n";
591 } else if (!sys::fs::can_execute(ChildExecPath)) {
592 errs() << "Unable to find usable child executable: '" << ChildExecPath
600 // If the program doesn't explicitly call exit, we will need the Exit
601 // function later on to make an explicit call, so get the function now.
602 Constant *Exit = Mod->getOrInsertFunction("exit", Type::getVoidTy(Context),
603 Type::getInt32Ty(Context),
606 // Run static constructors.
607 if (!ForceInterpreter) {
608 // Give MCJIT a chance to apply relocations and set page permissions.
609 EE->finalizeObject();
611 EE->runStaticConstructorsDestructors(false);
613 // Trigger compilation separately so code regions that need to be
614 // invalidated will be known.
615 (void)EE->getPointerToFunction(EntryFn);
616 // Clear instruction cache before code will be executed.
618 static_cast<SectionMemoryManager*>(RTDyldMM)->invalidateInstructionCache();
621 Result = EE->runFunctionAsMain(EntryFn, InputArgv, envp);
623 // Run static destructors.
624 EE->runStaticConstructorsDestructors(true);
626 // If the program didn't call exit explicitly, we should call it now.
627 // This ensures that any atexit handlers get called correctly.
628 if (Function *ExitF = dyn_cast<Function>(Exit)) {
629 std::vector<GenericValue> Args;
630 GenericValue ResultGV;
631 ResultGV.IntVal = APInt(32, Result);
632 Args.push_back(ResultGV);
633 EE->runFunction(ExitF, Args);
634 errs() << "ERROR: exit(" << Result << ") returned!\n";
637 errs() << "ERROR: exit defined with wrong prototype!\n";
641 // else == "if (RemoteMCJIT)"
643 // Remote target MCJIT doesn't (yet) support static constructors. No reason
644 // it couldn't. This is a limitation of the LLI implemantation, not the
645 // MCJIT itself. FIXME.
647 // Lanch the remote process and get a channel to it.
648 std::unique_ptr<FDRPCChannel> C = launchRemote();
650 errs() << "Failed to launch remote JIT.\n";
654 // Create a remote target client running over the channel.
655 typedef orc::remote::OrcRemoteTargetClient<orc::remote::RPCChannel> MyRemote;
656 MyRemote R = ExitOnErr(MyRemote::Create(*C));
658 // Create a remote memory manager.
659 std::unique_ptr<MyRemote::RCMemoryManager> RemoteMM;
660 ExitOnErr(R.createRemoteMemoryManager(RemoteMM));
662 // Forward MCJIT's memory manager calls to the remote memory manager.
663 static_cast<ForwardingMemoryManager*>(RTDyldMM)->setMemMgr(
664 std::move(RemoteMM));
666 // Forward MCJIT's symbol resolution calls to the remote.
667 static_cast<ForwardingMemoryManager*>(RTDyldMM)->setResolver(
668 orc::createLambdaResolver(
669 [](const std::string &Name) { return nullptr; },
670 [&](const std::string &Name) {
671 if (auto Addr = ExitOnErr(R.getSymbolAddress(Name)))
672 return RuntimeDyld::SymbolInfo(Addr, JITSymbolFlags::Exported);
673 return RuntimeDyld::SymbolInfo(nullptr);
677 // Grab the target address of the JIT'd main function on the remote and call
679 // FIXME: argv and envp handling.
680 orc::TargetAddress Entry = EE->getFunctionAddress(EntryFn->getName().str());
681 EE->finalizeObject();
682 DEBUG(dbgs() << "Executing '" << EntryFn->getName() << "' at 0x"
683 << format("%llx", Entry) << "\n");
684 Result = ExitOnErr(R.callIntVoid(Entry));
686 // Like static constructors, the remote target MCJIT support doesn't handle
687 // this yet. It could. FIXME.
689 // Delete the EE - we need to tear it down *before* we terminate the session
690 // with the remote, otherwise it'll crash when it tries to release resources
691 // on a remote that has already been disconnected.
694 // Signal the remote target that we're done JITing.
695 ExitOnErr(R.terminateSession());
701 std::unique_ptr<FDRPCChannel> launchRemote() {
703 llvm_unreachable("launchRemote not supported on non-Unix platforms");
709 if (pipe(PipeFD[0]) != 0 || pipe(PipeFD[1]) != 0)
710 perror("Error creating pipe: ");
717 // Close the parent ends of the pipes
722 // Execute the child process.
723 std::unique_ptr<char[]> ChildPath, ChildIn, ChildOut;
725 ChildPath.reset(new char[ChildExecPath.size() + 1]);
726 std::copy(ChildExecPath.begin(), ChildExecPath.end(), &ChildPath[0]);
727 ChildPath[ChildExecPath.size()] = '\0';
728 std::string ChildInStr = utostr(PipeFD[0][0]);
729 ChildIn.reset(new char[ChildInStr.size() + 1]);
730 std::copy(ChildInStr.begin(), ChildInStr.end(), &ChildIn[0]);
731 ChildIn[ChildInStr.size()] = '\0';
732 std::string ChildOutStr = utostr(PipeFD[1][1]);
733 ChildOut.reset(new char[ChildOutStr.size() + 1]);
734 std::copy(ChildOutStr.begin(), ChildOutStr.end(), &ChildOut[0]);
735 ChildOut[ChildOutStr.size()] = '\0';
738 char * const args[] = { &ChildPath[0], &ChildIn[0], &ChildOut[0], nullptr };
739 int rc = execv(ChildExecPath.c_str(), args);
741 perror("Error executing child process: ");
742 llvm_unreachable("Error executing child process");
744 // else we're the parent...
746 // Close the child ends of the pipes
750 // Return an RPC channel connected to our end of the pipes.
751 return llvm::make_unique<FDRPCChannel>(PipeFD[1][0], PipeFD[0][1]);