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Apply -fno-plt __tls_get_addr fix
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nikic committed Jul 8, 2019
1 parent 2f4d367 commit f714d96
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Showing 2 changed files with 18 additions and 3 deletions.
8 changes: 7 additions & 1 deletion llvm/lib/Target/X86/X86MCInstLower.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -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;
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13 changes: 11 additions & 2 deletions llvm/test/CodeGen/X86/tls-no-plt.ll
Original file line number Diff line number Diff line change
@@ -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
Expand All @@ -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
}

Expand All @@ -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
}

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