Apply -fno-plt __tls_get_addr fix

Taken from https://reviews.llvm.org/D64304.
rust-lang · Jul 8, 2019 · f714d96 · f714d96
1 parent 2f4d367
commit f714d96
Show file tree

Hide file tree

Showing 2 changed files with 18 additions and 3 deletions.
diff --git a/llvm/lib/Target/X86/X86MCInstLower.cpp b/llvm/lib/Target/X86/X86MCInstLower.cpp
@@ -705,7 +705,13 @@ void X86AsmPrinter::LowerTlsAddr(X86MCInstLower &MCInstLowering,
 
   const MCSymbolRefExpr *Sym = MCSymbolRefExpr::create(
       MCInstLowering.GetSymbolFromOperand(MI.getOperand(3)), SRVK, Ctx);
-  bool UseGot = MMI->getModule()->getRtLibUseGOT();
+
+  // 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.
+  bool UseGot = MMI->getModule()->getRtLibUseGOT() &&
+                Ctx.getAsmInfo()->canRelaxRelocations();
 
   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
@@ -1,5 +1,10 @@
-; 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
+; 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
 
 @gd = thread_local global i32 0
 @ld = internal thread_local global i32 0
@@ -9,9 +14,11 @@ entry:
 ; CHECK-LABEL: get_gd:
 ; X86: leal gd@TLSGD(%ebx), %eax
 ; X86: calll *___tls_get_addr@GOT(%ebx)
+; X86-PLT: calll ___tls_get_addr@PLT
 
 ; X64: leaq gd@TLSGD(%rip), %rdi
 ; X64: callq *__tls_get_addr@GOTPCREL(%rip)
+; X64-PLT: callq __tls_get_addr@PLT
   ret i32* @gd
 }
 
@@ -20,9 +27,11 @@ define i32* @get_ld() {
 ; CHECK-LABEL: get_ld:
 ; X86: leal ld@TLSLDM(%ebx), %eax
 ; X86: calll *___tls_get_addr@GOT(%ebx)
+; X86-PLT: calll ___tls_get_addr@PLT
 
 ; X64: leaq ld@TLSLD(%rip), %rdi
 ; X64: callq *__tls_get_addr@GOTPCREL(%rip)
+; X64-PLT: callq __tls_get_addr@PLT
   ret i32* @ld
 }