我想按照编译器实现教程来生成目标代码。但是当我调用createTargetMachine()时，出现了段错误。这似乎是与为什么LLVM在尝试生成目标代码时会出现段错误？不同的问题。
这是我的代码，没有头文件，与上面的代码基本相同：
using namespace llvm;
using namespace llvm::sys;
static LLVMContext TheContext;
static IRBuilder<> Builder(TheContext);
static std::unique_ptr<Module> TheModule;
static std::map<std::string, AllocaInst *> NamedValues;
int main() {
TheModule = llvm::make_unique<llvm::Module>("module", TheContext);
Function *f = Function::Create(
FunctionType::get(llvm::Type::getVoidTy(TheContext), std::vector<llvm::Type*>(), false),
Function::ExternalLinkage,
"test",
TheModule.get()
);
BasicBlock *BB = BasicBlock::Create(TheContext, "entry", f);
Builder.SetInsertPoint(BB);
Builder.CreateRetVoid();
if( verifyFunction(*f, &errs()) )
return 1;
InitializeAllTargetInfos();
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmParsers();
InitializeAllAsmPrinters();
auto TargetTriple = sys::getDefaultTargetTriple();
TheModule->setTargetTriple(TargetTriple);
std::string Error;
auto Target = TargetRegistry::lookupTarget(TargetTriple, Error);
if (!Target)
{
errs() << Error;
return 1;
}
auto CPU = "generic";
auto Features = "";
TargetOptions opt;
auto RM = Optional<Reloc::Model>();
/***********Crash Here**************/
auto TheTargetMachine =
Target->createTargetMachine(TargetTriple, CPU, Features, opt, RM); //Crash
/***********************************/
TheModule->setDataLayout(TheTargetMachine->createDataLayout());
llvm::verifyModule(*TheModule, &errs());
auto Filename = "output.o";
std::error_code EC;
raw_fd_ostream dest(Filename, EC, sys::fs::F_None);
if (EC)
{
errs() << "Could not open file: " << EC.message();
return 1;
}
legacy::PassManager pass;
auto FileType = TargetMachine::CGFT_ObjectFile;
if (TheTargetMachine->addPassesToEmitFile(pass, dest, nullptr, FileType))
{
errs() << "TheTargetMachine can't emit a file of this type";
return 1;
}
pass.run(*TheModule);
dest.flush();
outs() << "Wrote " << Filename << "\n";
return 0;
}
这是编译命令，clang++和LLVM版本均为7.0.1。
clang++ -g main.cpp `llvm-config --cxxflags --ldflags --system-libs --libs all` -Wall -fexceptions -o toy`
这里是lldb信息：
Process 26460 stopped
* thread #1, name = 'toy', stop reason = step over
frame #0: 0x000055555555869b toy`main [inlined] llvm::Target::createTargetMachine(this=0x00007ffff7f9bcc0, TT=(Data = "x86_64-pc-linux-gnu", Length = 19), CPU=(Data = <no value available>, Length = 7), Features=(Data = <no value available>, Length = 0), Options=<unavailable>, RM=Optional<llvm::Reloc::Model> @ scalar, CM=Optional<llvm::CodeModel::Model> @ scalar, OL=Default, JIT=false) const at TargetRegistry.h:397
394 bool JIT = false) const {
395 if (!TargetMachineCtorFn)
396 return nullptr;
-> 397 return TargetMachineCtorFn(*this, Triple(TT), CPU, Features, Options, RM,
398 CM, OL, JIT);
399 }
400
(lldb) s
Process 26460 stopped
* thread #1, name = 'toy', stop reason = signal SIGSEGV: invalid address (fault address: 0x4)
frame #0: 0x00007ffff691806a libLLVM-7.so`___lldb_unnamed_symbol27390$$libLLVM-7.so + 74
libLLVM-7.so`___lldb_unnamed_symbol27390$$libLLVM-7.so:
-> 0x7ffff691806a <+74>: movzbl 0x4(%rcx), %eax
0x7ffff691806e <+78>: movb %al, 0x1c(%rsp)
0x7ffff6918072 <+82>: testb %al, %al
0x7ffff6918074 <+84>: je 0x7ffff691807c ; <+92>
(lldb) bt
* thread #1, name = 'toy', stop reason = signal SIGSEGV: invalid address (fault address: 0x4)
* frame #0: 0x00007ffff691806a libLLVM-7.so`___lldb_unnamed_symbol27390$$libLLVM-7.so + 74
frame #1: 0x00005555555586e5 toy`main [inlined] llvm::Target::createTargetMachine(this=0x00007ffff7f9bcc0, TT=(Data = "x86_64-pc-linux-gnu", Length = 19), CPU=<unavailable>, Features=<unavailable>, Options=0x00000000ffff0000, RM=Optional<llvm::Reloc::Model> @ scalar, CM=Optional<llvm::CodeModel::Model> @ scalar, OL=Default, JIT=false) const at TargetRegistry.h:397
frame #2: 0x0000555555558673 toy`main at main.cpp:73
frame #3: 0x00007ffff3afe223 libc.so.6`__libc_start_main + 243
frame #4: 0x00005555555581ae toy`_start + 46