Fix wrong TLS symbol values.

[ruiu]

Summary

I do not fully understand why we had these values in the tests, but
the new value matches what ld.bfd and ld.gold set, so I guess that
was just a mistake.

[grimar]

LGTM

lld/ELF/SyntheticSections.cpp

1399

At least for non-mips part (gc-debuginfo-tls.s), this code does not look correct.

ELF spec says:
"In dynamic executables and shared objects, the st_value field of a STT_TLS symbol contains the assigned TLS offset for defined symbols. "
That is not what we see in gc-debuginfo-tls.s before this patch. Mips part seems have similar issue.

getSymVA, called inside Body->getVA() handled TLS specially:

if (D.isTls() && !Config->Relocatable) {
  if (!Out::TlsPhdr)
    fatal(toString(D.File) +
          " has a STT_TLS symbol but doesn't have a PT_TLS section");
  return VA - Out::TlsPhdr->p_vaddr;
}

The rest of logic looks almost similar to what happens for DefinedRegular inside getVA() called at line 1388. So I also feel that code doesn't make sense.

lld/ELF/SyntheticSections.cpp

for (SymbolTableEntry &Ent : Symbols) {
     }
 
     ESym->st_name = Ent.StrTabOffset;
     ESym->st_size = Body->getSize<ELFT>();
     ESym->st_value = Body->getVA<ELFT>();
 
     if (const OutputSection *OutSec = getOutputSection(Body)) {
       ESym->st_shndx = OutSec->SectionIndex;
-
-      // This piece of code should go away as it doesn't make sense,
-      // but we want to keep it tentatively because some tests for TLS
-      // variable depends on this. We should fix the test and remove
-      // this code.
-      if (Body->isLocal())
-        if (auto *DS = dyn_cast<DefinedRegular<ELFT>>(Body))
-          ESym->st_value = OutSec->Addr + DS->Section->getOffset(*DS);
     } else if (isa<DefinedRegular<ELFT>>(Body)) {
       ESym->st_shndx = SHN_ABS;
     } else if (isa<DefinedCommon>(Body)) {
       ESym->st_shndx = SHN_COMMON;
       ESym->st_value = cast<DefinedCommon>(Body)->Alignment;
     }
     ++ESym;
   }

lld/test/ELF/gc-debuginfo-tls.s

 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 # RUN: ld.lld %t.o --gc-sections -shared -o %t1
 # RUN: ld.lld %t.o -shared -o %t2
 # RUN: llvm-readobj -symbols %t1 | FileCheck %s --check-prefix=GC
 # RUN: llvm-readobj -symbols %t2 | FileCheck %s --check-prefix=NOGC
 
 # NOGC: Symbol {
 # NOGC:   Name: (0)
-# NOGC:   Value: 0x1000
+# NOGC:   Value: 0x0
 # NOGC:   Size: 0
 # NOGC:   Binding: Local
 # NOGC:   Type: TLS
 # NOGC:   Other: 0
 # NOGC:   Section: .tbss
 # NOGC: }
 
 # GC-NOT: tbss
 
 .section .tbss,"awT",@nobits
 patatino:
   .long 0
   .section .noalloc,""
   .quad patatino

lld/test/ELF/mips-tls-64.s

 
 # DIS:      Contents of section .got:
 # DIS-NEXT:  30010 00000000 00000000 80000000 00000000
 # DIS-NEXT:  30020 00000000 00000000 00000000 00000000
 # DIS-NEXT:  30030 00000000 00000000 00000000 00000001
 # DIS-NEXT:  30040 00000000 00000000 00000000 00000001
 # DIS-NEXT:  30050 ffffffff ffff8004 ffffffff ffff9004
 
-# DIS: 0000000000040000 l       .tdata          00000000 loc
+# DIS: 0000000000000000 l       .tdata          00000000 loc
 # DIS: 0000000000000004 g       .tdata          00000000 bar
 # DIS: 0000000000000000 g       *UND*           00000000 foo
 
 # CHECK:      Relocations [
 # CHECK-NEXT:   Section (7) .rela.dyn {
 # CHECK-NEXT:     0x30020 R_MIPS_TLS_DTPMOD64/R_MIPS_NONE/R_MIPS_NONE foo 0x0
 # CHECK-NEXT:     0x30028 R_MIPS_TLS_DTPREL64/R_MIPS_NONE/R_MIPS_NONE foo 0x0
 # CHECK-NEXT:     0x30030 R_MIPS_TLS_TPREL64/R_MIPS_NONE/R_MIPS_NONE foo 0x0

lld/test/ELF/mips-tls-hilo.s

 #                       %hi(loc0 - .tdata - 0x8000) --^
 # DIS-NEXT:    20004:   24 62 80 00   addiu   $2, $3, -32768
 #                       %lo(loc0 - .tdata - 0x8000) --^
 # DIS-NEXT:    20008:   24 62 00 00   addiu   $2, $3, 0
 #                       %hi(loc0 - .tdata - 0x7000) --^
 # DIS-NEXT:    2000c:   24 62 90 00   addiu   $2, $3, -28672
 #                       %lo(loc0 - .tdata - 0x7000) --^
 
-# DIS: 00040000 l       .tdata          00000000 loc0
+# DIS: 00000000 l       .tdata          00000000 loc0
 
 # CHECK:      Relocations [
 # CHECK-NEXT: ]
 # CHECK-NOT:  Primary GOT
 
 # SO:      Relocations [
 # SO-NEXT: ]
 # SO:      Primary GOT {

lld/test/ELF/mips-tls.s

 # DIS-NEXT:    2000c:   24 62 80 2c   addiu   $2, $3, -32724
 # DIS-NEXT:    20010:   24 62 80 34   addiu   $2, $3, -32716
 
 # DIS:      Contents of section .got:
 # DIS-NEXT:  30010 00000000 80000000 00000000 00000000
 # DIS-NEXT:  30020 00000000 00000001 00000000 00000001
 # DIS-NEXT:  30030 ffff8004 ffff9004
 
-# DIS: 00040000 l       .tdata          00000000 loc
+# DIS: 00000001 l       .tdata          00000000 loc
 # DIS: 00000004 g       .tdata          00000000 bar
 # DIS: 00000000 g       *UND*           00000000 foo
 
 # CHECK:      Relocations [
 # CHECK-NEXT:   Section (7) .rel.dyn {
 # CHECK-NEXT:     0x30018 R_MIPS_TLS_DTPMOD32 foo 0x0
 # CHECK-NEXT:     0x3001C R_MIPS_TLS_DTPREL32 foo 0x0
 # CHECK-NEXT:     0x30020 R_MIPS_TLS_TPREL32 foo 0x0