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[PPC32] Emit R_PPC_GOT_TPREL16 instead R_PPC_GOT_TPREL16_LO 

Unlike ppc64, which has ADDISgotTprelHA+LDgotTprelL pairs,
ppc32 just uses LDgotTprelL32, so it does not make lots of sense to use
_LO without a paired _HA.

Emit R_PPC_GOT_TPREL16 instead R_PPC_GOT_TPREL16_LO to match GCC, and
get better linker relocation check. Note, R_PPC_GOT_TPREL16_{HA,LO}
don't have good linker support:

(a) lld does not support R_PPC_GOT_TPREL16_{HA,LO}.
(b) Top of tree ld.bfd does not support R_PPC_GOT_REL16_HA Initial-Exec -> Local-Exec relaxation:

  // a.o
  addis 3, 3, tsd_tls@got@tprel@ha
  lwz 3, tsd_tls@got@tprel@l(3)
  add 3, 3, tsd_tls@tls
  // b.o
  .section .tdata,"awT"; .globl tsd_tls; tsd_tls:

  // ld/ld-new a.o b.o
  internal error, aborting at ../../bfd/elf32-ppc.c:7952 in ppc_elf_relocate_section

Reviewed By: adalava

Differential Revision: https://reviews.llvm.org/D66925

llvm-svn: 370426
This commit is contained in:
Fangrui Song 2019-08-30 02:20:49 +00:00
parent ca4216abde
commit 7704b54389
2 changed files with 6 additions and 4 deletions
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6
llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
View File

@ -870,8 +870,10 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
const GlobalValue *GValue = MO.getGlobal();
MCSymbol *MOSymbol = getSymbol(GValue);
const MCExpr *Exp =
MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO,
OutContext);
MCSymbolRefExpr::create(MOSymbol,
isPPC64 ? MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO
: MCSymbolRefExpr::VK_PPC_GOT_TPREL,
OutContext);
TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
EmitToStreamer(*OutStreamer, TmpInst);
return;

4
llvm/test/CodeGen/PowerPC/tls.ll
View File

@ -43,7 +43,7 @@ entry:
;OPT0-PPC32-LABEL: main2:
;OPT0-PPC32: li [[REG1:[0-9]+]], _GLOBAL_OFFSET_TABLE_@l
;OPT0-PPC32: addis [[REG1]], [[REG1]], _GLOBAL_OFFSET_TABLE_@ha
;OPT0-PPC32: lwz [[REG2:[0-9]+]], a2@got@tprel@l([[REG1]])
;OPT0-PPC32: lwz [[REG2:[0-9]+]], a2@got@tprel([[REG1]])
;OPT0-PPC32: add 3, [[REG2]], a2@tls
;OPT0-PPC32-PIC-LABEL: main2:
@ -51,4 +51,4 @@ entry:
;OPT0-PPC32-PIC-NOT: li {{[0-9]+}}, _GLOBAL_OFFSET_TABLE_@l
;OPT0-PPC32-PIC-NOT: addis {{[0-9]+}}, {{[0-9+]}}, _GLOBAL_OFFSET_TABLE_@ha
;OPT0-PPC32-PIC-NOT: bl __tls_get_addr(a2@tlsgd)@PLT
;OPT0-PPC32-PIC: lwz {{[0-9]+}}, a2@got@tprel@l({{[0-9]+}})
;OPT0-PPC32-PIC: lwz {{[0-9]+}}, a2@got@tprel({{[0-9]+}})