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Refactor R_RELAX_TLS_* value computation.

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This makes it explicit that each R_RELAX_TLS_* is equivalent to some
other expression.

With this I think we are at a sweet spot for how much is done in
Target.cpp. I did experiment with moving *all* the value math out of it.
It has the advantage that we know the final value in target independent
code, but it gets quite verbose.

llvm-svn: 270277
This commit is contained in:
Rafael Espindola 2016-05-20 21:23:52 +00:00
parent 14d965166c
commit ebed1fe0de
4 changed files with 32 additions and 11 deletions
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35
lld/ELF/InputSection.cpp
View File

@ -135,15 +135,44 @@ static uint64_t getAArch64Page(uint64_t Expr) {
return Expr & (~static_cast<uint64_t>(0xFFF));
}
// For computing values, each R_RELAX_TLS_* corresponds to whatever expression
// the target uses in the mode this is being relaxed into. For example, anything
// that relaxes to LE just needs an R_TLS since that is what is used if we
// had a local exec expression to begin with.
static RelExpr getRelaxedExpr(RelExpr Expr) {
switch (Expr) {
default:
return Expr;
case R_RELAX_TLS_GD_TO_LE:
if (Config->EMachine == EM_386)
return R_NEG_TLS;
return R_TLS;
case R_RELAX_TLS_GD_TO_IE:
if (Config->EMachine == EM_386)
return R_GOT_FROM_END;
return R_GOT_PC;
case R_RELAX_TLS_IE_TO_LE:
case R_RELAX_TLS_LD_TO_LE:
return R_TLS;
}
}
template <class ELFT>
static typename ELFT::uint
getSymVA(uint32_t Type, typename ELFT::uint A, typename ELFT::uint P,
const SymbolBody &Body, uint8_t *BufLoc,
const elf::ObjectFile<ELFT> &File, RelExpr Expr) {
typedef typename ELFT::uint uintX_t;
Expr = getRelaxedExpr(Expr);
switch (Expr) {
case R_HINT:
llvm_unreachable("cannot relocate hint relocs");
case R_RELAX_TLS_GD_TO_LE:
case R_RELAX_TLS_GD_TO_IE:
case R_RELAX_TLS_IE_TO_LE:
case R_RELAX_TLS_LD_TO_LE:
llvm_unreachable("Should have been mapped");
case R_TLSLD:
return Out<ELFT>::Got->getTlsIndexOff() + A -
Out<ELFT>::Got->getNumEntries() * sizeof(uintX_t);
@ -168,7 +197,6 @@ getSymVA(uint32_t Type, typename ELFT::uint A, typename ELFT::uint P,
case R_GOTREL:
return Body.getVA<ELFT>(A) - Out<ELFT>::Got->getVA();
case R_GOT_FROM_END:
case R_RELAX_TLS_GD_TO_IE:
return Body.getGotOffset<ELFT>() + A -
Out<ELFT>::Got->getNumEntries() * sizeof(uintX_t);
case R_GOT:
@ -176,13 +204,9 @@ getSymVA(uint32_t Type, typename ELFT::uint A, typename ELFT::uint P,
case R_GOT_PAGE_PC:
return getAArch64Page(Body.getGotVA<ELFT>() + A) - getAArch64Page(P);
case R_GOT_PC:
case R_RELAX_TLS_GD_TO_IE_PC:
return Body.getGotVA<ELFT>() + A - P;
case R_GOTONLY_PC:
return Out<ELFT>::Got->getVA() + A - P;
case R_RELAX_TLS_GD_TO_LE:
case R_RELAX_TLS_IE_TO_LE:
case R_RELAX_TLS_LD_TO_LE:
case R_TLS:
if (Target->TcbSize)
return Body.getVA<ELFT>(A) +
@ -308,7 +332,6 @@ void InputSectionBase<ELFT>::relocate(uint8_t *Buf, uint8_t *BufEnd) {
case R_RELAX_TLS_GD_TO_LE:
Target->relaxTlsGdToLe(BufLoc, Type, SymVA);
break;
case R_RELAX_TLS_GD_TO_IE_PC:
case R_RELAX_TLS_GD_TO_IE:
Target->relaxTlsGdToIe(BufLoc, Type, SymVA);
break;

1
lld/ELF/InputSection.h
View File

@ -47,7 +47,6 @@ enum RelExpr {
R_PPC_PLT_OPD,
R_PPC_TOC,
R_RELAX_TLS_GD_TO_IE,
R_RELAX_TLS_GD_TO_IE_PC,
R_RELAX_TLS_GD_TO_LE,
R_RELAX_TLS_IE_TO_LE,
R_RELAX_TLS_LD_TO_LE,

2
lld/ELF/Target.cpp
View File

@ -400,7 +400,7 @@ void X86TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
0x81, 0xe8, 0x00, 0x00, 0x00, 0x00 // subl 0(%ebx), %eax
};
memcpy(Loc - 3, Inst, sizeof(Inst));
relocateOne(Loc + 5, R_386_32, -Val);
relocateOne(Loc + 5, R_386_32, Val);
}
void X86TargetInfo::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,

5
lld/ELF/Writer.cpp
View File

@ -336,9 +336,8 @@ static unsigned handleTlsRelocation(uint32_t Type, SymbolBody &Body,
// Global-Dynamic relocs can be relaxed to Initial-Exec or Local-Exec
// depending on the symbol being locally defined or not.
if (Body.isPreemptible()) {
Expr =
Expr == R_TLSGD_PC ? R_RELAX_TLS_GD_TO_IE_PC : R_RELAX_TLS_GD_TO_IE;
C.Relocations.push_back({Expr, Type, Offset, Addend, &Body});
C.Relocations.push_back(
{R_RELAX_TLS_GD_TO_IE, Type, Offset, Addend, &Body});
if (!Body.isInGot()) {
Out<ELFT>::Got->addEntry(Body);
Out<ELFT>::RelaDyn->addReloc({Target->TlsGotRel, Out<ELFT>::Got,