[PATCH] D151335: [AIX][TLS] Generate .extern and .ref references to __tls_get_addr for local-exec accesses.

[Digger Lin via Phabricator via llvm-commits]

DiggerLin added inline comments.


================
Comment at: llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp:2785
+  case PPC::LDtoc:
+  case PPC::LDtocL: {
+    const MachineOperand &MO = MI->getOperand(1);
----------------
I do not think it is efficient to put the code here. if there are a lot of  thread local variables or the variables are reference in a lot of places, the  code run enter  as many time as the the number of  thread local variable reference place.

and each time do the same thing 

 
```
     MCSymbol *TlsGetAddrDescriptor =
          createMCSymbolForTlsGetAddr(OutContext, XCOFF::XMC_DS);
      ExtSymSDNodeSymbols.insert(TlsGetAddrDescriptor);
```

can we do it in the function PPCAIXAsmPrinter::doFinalization() 



  
```
for (auto &I : TOC) {
    // Add a single .ref reference to __tls_get_addr[DS] for the local-exec TLS
    // model on AIX. For TLS models that do not generate calls to TLS functions,
    // this .ref reference to __tls_get_addr helps generate a linker error to
    // an undefined symbol to __tls_get_addr, which indicates to the user that
    // compiling with -pthread is required for programs that use TLS variables.
    if (Subtarget->isPPC64() &&
        (I.first.second == MCSymbolRefExpr::VariantKind::VK_PPC_AIX_TLSLE)) {
      MCSymbol *TlsGetAddrDescriptor =
          createMCSymbolForTlsGetAddr(OutContext, XCOFF::XMC_DS);

      ExtSymSDNodeSymbols.insert(TlsGetAddrDescriptor);

      OutStreamer->emitXCOFFRefDirective(TlsGetAddrDescriptor);
      break;
    }
  }

for (MCSymbol *Sym : ExtSymSDNodeSymbols)
    OutStreamer->emitSymbolAttribute(Sym, MCSA_Extern);
```

it will run only once.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D151335/new/

https://reviews.llvm.org/D151335