[llvm] 2679e8b - [X86] Revert -fno-plt __tls_get_addr workaround for old GNU ld

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2022-12-31T22:39:20-08:00
New Revision: 2679e8bba3e166e3174971d040b9457ec7b7d768

URL: https://github.com/llvm/llvm-project/commit/2679e8bba3e166e3174971d040b9457ec7b7d768
DIFF: https://github.com/llvm/llvm-project/commit/2679e8bba3e166e3174971d040b9457ec7b7d768.diff

LOG: [X86] Revert -fno-plt __tls_get_addr workaround for old GNU ld

ENABLE_X86_RELAX_RELOCATIONS has defaulted to on in 2020.
This workaround is not exercised for a long time.

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86MCInstLower.cpp
    llvm/test/CodeGen/X86/tls-no-plt.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86MCInstLower.cpp b/llvm/lib/Target/X86/X86MCInstLower.cpp
index 9fb97df01b081..9f59132d1176e 100644
--- a/llvm/lib/Target/X86/X86MCInstLower.cpp
+++ b/llvm/lib/Target/X86/X86MCInstLower.cpp
@@ -1024,14 +1024,7 @@ void X86AsmPrinter::LowerTlsAddr(X86MCInstLower &MCInstLowering,
 
   const MCSymbolRefExpr *Sym = MCSymbolRefExpr::create(
       MCInstLowering.GetSymbolFromOperand(MI.getOperand(3)), SRVK, Ctx);
-
-  // As of binutils 2.32, ld has a bogus TLS relaxation error when the GD/LD
-  // code sequence using R_X86_64_GOTPCREL (instead of R_X86_64_GOTPCRELX) is
-  // attempted to be relaxed to IE/LE (binutils PR24784). Work around the bug by
-  // only using GOT when GOTPCRELX is enabled.
-  // TODO Delete the workaround when GOTPCRELX becomes commonplace.
-  bool UseGot = MMI->getModule()->getRtLibUseGOT() &&
-                Ctx.getAsmInfo()->canRelaxRelocations();
+  const bool UseGot = MMI->getModule()->getRtLibUseGOT();
 
   if (Is64Bits) {
     bool NeedsPadding = SRVK == MCSymbolRefExpr::VK_TLSGD;

diff  --git a/llvm/test/CodeGen/X86/tls-no-plt.ll b/llvm/test/CodeGen/X86/tls-no-plt.ll
index 5af9eecb838f9..5ca9448e011e3 100644
--- a/llvm/test/CodeGen/X86/tls-no-plt.ll
+++ b/llvm/test/CodeGen/X86/tls-no-plt.ll
@@ -1,10 +1,5 @@
-; RUN: llc < %s -mtriple=i386-linux-musl -relocation-model=pic -relax-elf-relocations=true | FileCheck --check-prefixes=CHECK,X86 %s
-; RUN: llc < %s -mtriple=x86_64-linux-musl -relocation-model=pic -relax-elf-relocations=true | FileCheck --check-prefixes=CHECK,X64 %s
-
-;; If GOTPCRELX is disabled, don't use GOT for __tls_get_addr to work around
-;; a ld.bfd bug (binutils PR24784).
-; RUN: llc < %s -mtriple=i386-linux-musl -relocation-model=pic | FileCheck --check-prefixes=CHECK,X86-PLT %s
-; RUN: llc < %s -mtriple=x86_64-linux-musl -relocation-model=pic | FileCheck --check-prefixes=CHECK,X64-PLT %s
+; RUN: llc < %s -mtriple=i386-linux-musl -relocation-model=pic | FileCheck --check-prefixes=CHECK,X86 %s
+; RUN: llc < %s -mtriple=x86_64-linux-musl -relocation-model=pic | FileCheck --check-prefixes=CHECK,X64 %s
 
 @gd = thread_local global i32 0
 @ld = internal thread_local global i32 0
@@ -14,11 +9,9 @@ entry:
 ; CHECK-LABEL: get_gd:
 ; X86: leal gd at TLSGD(%ebx), %eax
 ; X86: calll *___tls_get_addr at GOT(%ebx)
-; X86-PLT: calll ___tls_get_addr at PLT
 
 ; X64: leaq gd at TLSGD(%rip), %rdi
 ; X64: callq *__tls_get_addr at GOTPCREL(%rip)
-; X64-PLT: callq __tls_get_addr at PLT
   ret ptr @gd
 }
 
@@ -27,11 +20,9 @@ define ptr @get_ld() {
 ; CHECK-LABEL: get_ld:
 ; X86: leal ld at TLSLDM(%ebx), %eax
 ; X86: calll *___tls_get_addr at GOT(%ebx)
-; X86-PLT: calll ___tls_get_addr at PLT
 
 ; X64: leaq ld at TLSLD(%rip), %rdi
 ; X64: callq *__tls_get_addr at GOTPCREL(%rip)
-; X64-PLT: callq __tls_get_addr at PLT
   ret ptr @ld
 }