[PowerPC][JITLink] Support R_PPC64_GOT_TLSGD_PCREL34

[bzEq]

R_PPC64_GOT_TLSGD_PCREL34 is generated for pwr10+.

[bzEq]

Since we don't have pwr10 buildbot, I don't add test in compiler-rt. Here's the simple example I create and runs on pwr10 machine successfully.

#include <stdio.h>
#include <iostream>
#include <thread>
#include <vector>

_Thread_local int id;

int main() {
  std::vector<std::thread> vt;
  for (int i = 0; i < 8; ++i) {
    vt.emplace_back([&]() {
        std::cout << &id << std::endl;
      });
  }
  for (auto &t : vt) t.join();
  return 0;
}

~/llvm/community/build/bin/clang++ -c -O3 -mcpu=pwr10 -fPIC -ftls-model=global-dynamic tls.cc
~/llvm/community/build/bin/llvm-objdump -r tls.o|grep TLS
0000000000000564 R_PPC64_GOT_TLSGD_PCREL34 id
000000000000056c R_PPC64_TLSGD            id

~/llvm/community/build/bin/llvm-jitlink tls.o --orc-runtime=$HOME/llvm/community/build/lib/clang/18/lib/powerpc64le-unknown-linux-gnu/liborc_rt.a
0x760540000c70
0x760538000c70
0x760538000c90
0x760530000c70
0x760530000c90
0x760530000be0
0x760530000c70
0x760530000c90

[vgvassilev]

This looks good to me and our use case in cms-sw/cmssw#41658. I'd wait for one more reviewer to approve it. @lhames ping.

[lhames]

Are you able to add a testcase that runs locally? If so then I think it make sense to include one even if there's no builedbot to run it, since at least PPC developers could run it locally.

LGTM though -- if you're not able to add a testcase please go ahead and land anyway.

[bzEq]

Added TLS test for pwr10. Since requiring different PLT stubs for the same external symbol is rare(need __attribute__((target(...)))), I currently mark it as FIXME.

[lhames]

Thanks very much for adding the testcase!