[ORC] Remove unneeded __orc_rt_elfnix_tls_get_addr assembly file

[MaskRay]

Summary

In ELF, __tls_get_addr used by general-dynamic/local-dynamic TLS models is a
regular function with C calling convention. Scratch reginsters don't need to be
saved, because the caller will do the right thing.

[lhames]

Hi MaskRay -- The assembly files are placeholders until we have a chance to implement the scheme in https://llvm.org/PR51820. I'd prefer to keep them around for now as scaffolding: they serve as proof-of-concept assembly source components of the ORC runtime (exercising the build system), and a convenient jumping-off point for anyone who might get to https://llvm.org/PR51820 before I do.

compiler-rt/lib/orc/CMakeLists.txt

 # Build for all components of the ORC runtime support library.
 
 # ORC runtime library implementation files.
 set(ORC_SOURCES
   extensible_rtti.cpp
   log_error_to_stderr.cpp
   macho_platform.cpp
   elfnix_platform.cpp
   run_program_wrapper.cpp
   )
 
 # Implementation files for all ORC architectures.
 set(x86_64_SOURCES
 # x86-64 specific assembly files will go here.
   macho_tlv.x86-64.S
-  elfnix_tls.x86-64.S
 )
 
 set(ORC_IMPL_HEADERS
 # Implementation headers will go here.
   adt.h
   c_api.h
   common.h
   compiler.h

compiler-rt/lib/orc/elfnix_platform.cpp

return WrapperFunction<SPSError(SPSELFNixPerObjectSectionsToRegister)>::
              })
           .release();
 }
 
 //------------------------------------------------------------------------------
 //                           TLV support
 //------------------------------------------------------------------------------
 
-ORC_RT_INTERFACE void *__orc_rt_elfnix_tls_get_addr_impl(TLSInfoEntry *D) {
+ORC_RT_INTERFACE void *__orc_rt_elfnix_tls_get_addr(TLSInfoEntry *D) {
   auto *TLVMgr = static_cast<ELFNixPlatformRuntimeTLVManager *>(
       pthread_getspecific(D->Key));
   if (!TLVMgr)
     TLVMgr = new ELFNixPlatformRuntimeTLVManager();
   if (pthread_setspecific(D->Key, TLVMgr)) {
     __orc_rt_log_error("Call to pthread_setspecific failed");
     return nullptr;
   }

compiler-rt/lib/orc/elfnix_tls.x86-64.S

-
-//===-- orc_rt_elfnix_tls_x86-64.s -------------------------------*- ASM -*-===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file is a part of the ORC runtime support library.
-//
-//===----------------------------------------------------------------------===//
-
-#define REGISTER_SAVE_SPACE_SIZE        512
-
-        .text
-
-  // returns address of TLV in %rax, all other registers preserved
-  .globl ___orc_rt_elfnix_tls_get_addr
-___orc_rt_elfnix_tls_get_addr:
-        pushq           %rbp
-        movq            %rsp,        %rbp
-        subq            $REGISTER_SAVE_SPACE_SIZE, %rsp
-        movq            %rcx,    -16(%rbp)
-        movq            %rdx,    -24(%rbp)
-        movq            %rsi,    -32(%rbp)
-        movq            %rdi,    -40(%rbp)
-        movq            %r8,     -48(%rbp)
-        movq            %r9,     -56(%rbp)
-        movq            %r10,    -64(%rbp)
-        movq            %r11,    -72(%rbp)
-  movdqa          %xmm0,  -128(%rbp)
-  movdqa          %xmm1,  -144(%rbp)
-  movdqa          %xmm2,  -160(%rbp)
-  movdqa          %xmm3,  -176(%rbp)
-  movdqa          %xmm4,  -192(%rbp)
-  movdqa          %xmm5,  -208(%rbp)
-  movdqa          %xmm6,  -224(%rbp)
-  movdqa          %xmm7,  -240(%rbp)
-        call           __orc_rt_elfnix_tls_get_addr_impl
-        movq            -16(%rbp),      %rcx
-        movq            -24(%rbp),      %rdx
-        movq            -32(%rbp),      %rsi
-        movq            -40(%rbp),      %rdi
-        movq            -48(%rbp),      %r8
-        movq            -56(%rbp),      %r9
-        movq            -64(%rbp),      %r10
-        movq            -72(%rbp),      %r11
-  movdqa          -128(%rbp),     %xmm0
-  movdqa          -144(%rbp),     %xmm1
-  movdqa          -160(%rbp),     %xmm2
-  movdqa          -176(%rbp),     %xmm3
-  movdqa          -192(%rbp),     %xmm4
-  movdqa          -208(%rbp),     %xmm5
-  movdqa          -224(%rbp),     %xmm6
-  movdqa          -240(%rbp),     %xmm7
-        addq            $REGISTER_SAVE_SPACE_SIZE, %rsp
-        popq            %rbp
-        ret

llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp

Error ELFNixPlatform::ELFNixPlatformPlugin::registerInitSections(
   return MP.registerInitInfo(JD, InitSections);
 }
 
 Error ELFNixPlatform::ELFNixPlatformPlugin::fixTLVSectionsAndEdges(
     jitlink::LinkGraph &G, JITDylib &JD) {
 
   // TODO implement TLV support
   for (auto *Sym : G.external_symbols())
-    if (Sym->getName() == "__tls_get_addr") {
-      Sym->setName("___orc_rt_elfnix_tls_get_addr");
-    }
+    if (Sym->getName() == "__tls_get_addr")
+      Sym->setName("__orc_rt_elfnix_tls_get_addr");
 
   auto *TLSInfoEntrySection = G.findSectionByName("$__TLSINFO");
 
   if (TLSInfoEntrySection) {
     Optional<uint64_t> Key;
     {
       std::lock_guard<std::mutex> Lock(MP.PlatformMutex);
       auto I = MP.JITDylibToPThreadKey.find(&JD);