[llvm] r370426 - [PPC32] Emit R_PPC_GOT_TPREL16 instead R_PPC_GOT_TPREL16_LO

[Fangrui Song via llvm-commits]

Author: maskray
Date: Thu Aug 29 19:20:49 2019
New Revision: 370426

URL: http://llvm.org/viewvc/llvm-project?rev=370426&view=rev
Log:
[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 at got@tprel at ha
  lwz 3, tsd_tls at got@tprel at l(3)
  add 3, 3, tsd_tls at 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

Modified:
    llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp
    llvm/trunk/test/CodeGen/PowerPC/tls.ll

Modified: llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp?rev=370426&r1=370425&r2=370426&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCAsmPrinter.cpp Thu Aug 29 19:20:49 2019
@@ -870,8 +870,10 @@ void PPCAsmPrinter::EmitInstruction(cons
     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;

Modified: llvm/trunk/test/CodeGen/PowerPC/tls.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/tls.ll?rev=370426&r1=370425&r2=370426&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/tls.ll (original)
+++ llvm/trunk/test/CodeGen/PowerPC/tls.ll Thu Aug 29 19:20:49 2019
@@ -43,7 +43,7 @@ entry:
 ;OPT0-PPC32-LABEL:    main2:
 ;OPT0-PPC32:       li [[REG1:[0-9]+]], _GLOBAL_OFFSET_TABLE_ at l
 ;OPT0-PPC32:       addis [[REG1]], [[REG1]], _GLOBAL_OFFSET_TABLE_ at ha
-;OPT0-PPC32:       lwz [[REG2:[0-9]+]], a2 at got@tprel at l([[REG1]])
+;OPT0-PPC32:       lwz [[REG2:[0-9]+]], a2 at got@tprel([[REG1]])
 ;OPT0-PPC32:       add 3, [[REG2]], a2 at tls
 
 ;OPT0-PPC32-PIC-LABEL:  main2:
@@ -51,4 +51,4 @@ entry:
 ;OPT0-PPC32-PIC-NOT:    li {{[0-9]+}}, _GLOBAL_OFFSET_TABLE_ at l
 ;OPT0-PPC32-PIC-NOT:    addis {{[0-9]+}}, {{[0-9+]}}, _GLOBAL_OFFSET_TABLE_ at ha
 ;OPT0-PPC32-PIC-NOT:    bl __tls_get_addr(a2 at tlsgd)@PLT
-;OPT0-PPC32-PIC:        lwz {{[0-9]+}}, a2 at got@tprel at l({{[0-9]+}})
+;OPT0-PPC32-PIC:        lwz {{[0-9]+}}, a2 at got@tprel({{[0-9]+}})