[PATCH] D64304: [X86] -fno-plt: use GOT __tls_get_addr only if GOTPCRELX is enabled
Fangrui Song via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 11 03:11:05 PDT 2019
This revision was automatically updated to reflect the committed changes.
Closed by commit rL365752: [X86] -fno-plt: use GOT __tls_get_addr only if GOTPCRELX is enabled (authored by MaskRay, committed by ).
Repository:
rL LLVM
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D64304/new/
https://reviews.llvm.org/D64304
Files:
llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
llvm/trunk/test/CodeGen/X86/tls-no-plt.ll
Index: llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
+++ llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
@@ -705,7 +705,14 @@
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.
+ // TODO Delete the workaround when GOTPCRELX becomes commonplace.
+ bool UseGot = MMI->getModule()->getRtLibUseGOT() &&
+ Ctx.getAsmInfo()->canRelaxRelocations();
if (Is64Bits) {
bool NeedsPadding = SRVK == MCSymbolRefExpr::VK_TLSGD;
Index: llvm/trunk/test/CodeGen/X86/tls-no-plt.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/tls-no-plt.ll
+++ llvm/trunk/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 @@
; 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 i32* @gd
}
@@ -20,9 +27,11 @@
; 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 i32* @ld
}
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