[ORC] Set useNamesOnTempLabels as true when emiting object code

[StephenFan]

Summary

As far as I known, In JITLink's linkgraph, every defined symbol must need a name.

In RISCV, some temp symbols will be emitted in object code's symbol table. Because RISCV needs to use these temp symbols to do something like generating dwarf, eh_frame sections... Unfortunately, these temp symbols is unnamed.

To solve this contradiction, I want to set the useNamesOnTempLabels as true in addPassesToEmitMC

[lhames]

Hi Stephen,

JITLink can handle anonymous symbols: Just use LinkGraph::addAnonymousSymbol. It would be better to use this than to change object emission for the sake of JITLink -- we want to be able to load objects not generated by LLVM.

• Lang.

[StephenFan]

In D116438#3214788, @lhames wrote:

Hi Stephen,

JITLink can handle anonymous symbols: Just use LinkGraph::addAnonymousSymbol. It would be better to use this than to change object emission for the sake of JITLink -- we want to be able to load objects not generated by LLVM.

• Lang.

Thanks for your suggestion! @lhames

I have submitted a new patch D116475.

llvm/lib/CodeGen/LLVMTargetMachine.cpp

bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
   if (!PassConfig)
     return true;
   assert(TargetPassConfig::willCompleteCodeGenPipeline() &&
          "Cannot emit MC with limited codegen pipeline");
 
   Ctx = &MMIWP->getMMI().getContext();
   if (Options.MCOptions.MCSaveTempLabels)
     Ctx->setAllowTemporaryLabels(false);
+  Ctx->setUseNamesOnTempLabels(true);
 
   // Create the code emitter for the target if it exists.  If not, .o file
   // emission fails.
   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
   const MCRegisterInfo &MRI = *getMCRegisterInfo();
   MCCodeEmitter *MCE =
       getTarget().createMCCodeEmitter(*getMCInstrInfo(), MRI, *Ctx);
   MCAsmBackend *MAB =