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[PPC64] Add TLS local dynamic to local exec relaxation
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This patch adds the target call back relaxTlsLdToLe to support TLS relaxation
from local dynamic to local exec model.

Differential Revision: https://reviews.llvm.org/D48293

llvm-svn: 336559
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@syzaara
syzaara committed Jul 9, 2018
1 parent a627253 commit 75c348a
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Showing 5 changed files with 152 additions and 8 deletions.
50 changes: 50 additions & 0 deletions lld/ELF/Arch/PPC64.cpp
View file
Expand Up @@ -55,6 +55,7 @@ class PPC64 final : public TargetInfo {
RelExpr Expr) const override;
void relaxTlsGdToIe(uint8_t *Loc, RelType Type, uint64_t Val) const override;
void relaxTlsGdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const override;
void relaxTlsLdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const override;
};
} // namespace

Expand Down Expand Up @@ -165,6 +166,52 @@ void PPC64::relaxTlsGdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const {
}
}


void PPC64::relaxTlsLdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const {
// Reference: 3.7.4.3 of the 64-bit ELF V2 abi supplement.
// The local dynamic code sequence for a global `x` will look like:
// Instruction Relocation Symbol
// addis r3, r2, x@got@tlsld@ha R_PPC64_GOT_TLSLD16_HA x
// addi r3, r3, x@got@tlsld@l R_PPC64_GOT_TLSLD16_LO x
// bl __tls_get_addr(x@tlsgd) R_PPC64_TLSLD x
// R_PPC64_REL24 __tls_get_addr
// nop None None

// Relaxing to local exec entails converting:
// addis r3, r2, x@got@tlsld@ha into nop
// addi r3, r3, x@got@tlsld@l into addis r3, r13, 0
// bl __tls_get_addr(x@tlsgd) into nop
// nop into addi r3, r3, 4096

uint32_t EndianOffset = Config->EKind == ELF64BEKind ? 2U : 0U;
switch (Type) {
case R_PPC64_GOT_TLSLD16_HA:
write32(Loc - EndianOffset, 0x60000000); // nop
break;
case R_PPC64_GOT_TLSLD16_LO:
write32(Loc - EndianOffset, 0x3c6d0000); // addis r3, r13, 0
break;
case R_PPC64_TLSLD:
write32(Loc, 0x60000000); // nop
write32(Loc + 4, 0x38631000); // addi r3, r3, 4096
break;
case R_PPC64_DTPREL16:
case R_PPC64_DTPREL16_HA:
case R_PPC64_DTPREL16_HI:
case R_PPC64_DTPREL16_DS:
case R_PPC64_DTPREL16_LO:
case R_PPC64_DTPREL16_LO_DS:
case R_PPC64_GOT_DTPREL16_HA:
case R_PPC64_GOT_DTPREL16_LO_DS:
case R_PPC64_GOT_DTPREL16_DS:
case R_PPC64_GOT_DTPREL16_HI:
relocateOne(Loc, Type, Val);
break;
default:
llvm_unreachable("unsupported relocation for TLS LD to LE relaxation");
}
}

RelExpr PPC64::getRelExpr(RelType Type, const Symbol &S,
const uint8_t *Loc) const {
switch (Type) {
Expand Down Expand Up @@ -230,6 +277,7 @@ RelExpr PPC64::getRelExpr(RelType Type, const Symbol &S,
case R_PPC64_TLSGD:
return R_TLSDESC_CALL;
case R_PPC64_TLSLD:
return R_TLSLD_HINT;
case R_PPC64_TLS:
return R_HINT;
default:
Expand Down Expand Up @@ -431,6 +479,8 @@ RelExpr PPC64::adjustRelaxExpr(RelType Type, const uint8_t *Data,
RelExpr Expr) const {
if (Expr == R_RELAX_TLS_GD_TO_IE)
return R_RELAX_TLS_GD_TO_IE_GOT_OFF;
if (Expr == R_RELAX_TLS_LD_TO_LE)
return R_RELAX_TLS_LD_TO_LE_ABS;
return Expr;
}

Expand Down
3 changes: 3 additions & 0 deletions lld/ELF/InputSection.cpp
View file
Expand Up @@ -483,6 +483,7 @@ static uint64_t getRelocTargetVA(const InputFile *File, RelType Type, int64_t A,
case R_INVALID:
return 0;
case R_ABS:
case R_RELAX_TLS_LD_TO_LE_ABS:
case R_RELAX_GOT_PC_NOPIC:
return Sym.getVA(A);
case R_ADDEND:
Expand Down Expand Up @@ -516,6 +517,7 @@ static uint64_t getRelocTargetVA(const InputFile *File, RelType Type, int64_t A,
case R_HINT:
case R_NONE:
case R_TLSDESC_CALL:
case R_TLSLD_HINT:
llvm_unreachable("cannot relocate hint relocs");
case R_MIPS_GOTREL:
return Sym.getVA(A) - InX::MipsGot->getGp(File);
Expand Down Expand Up @@ -767,6 +769,7 @@ void InputSectionBase::relocateAlloc(uint8_t *Buf, uint8_t *BufEnd) {
Target->relaxTlsIeToLe(BufLoc, Type, TargetVA);
break;
case R_RELAX_TLS_LD_TO_LE:
case R_RELAX_TLS_LD_TO_LE_ABS:
Target->relaxTlsLdToLe(BufLoc, Type, TargetVA);
break;
case R_RELAX_TLS_GD_TO_LE:
Expand Down
21 changes: 13 additions & 8 deletions lld/ELF/Relocations.cpp
View file
Expand Up @@ -188,13 +188,17 @@ handleTlsRelocation(RelType Type, Symbol &Sym, InputSectionBase &C,
return 1;
}

if (isRelExprOneOf<R_TLSLD_GOT, R_TLSLD_GOT_FROM_END, R_TLSLD_PC>(Expr)) {
if (isRelExprOneOf<R_TLSLD_GOT, R_TLSLD_GOT_FROM_END, R_TLSLD_PC,
R_TLSLD_HINT>(Expr)) {
// Local-Dynamic relocs can be relaxed to Local-Exec.
if (!Config->Shared) {
C.Relocations.push_back(
{R_RELAX_TLS_LD_TO_LE, Type, Offset, Addend, &Sym});
return 2;
{Target->adjustRelaxExpr(Type, nullptr, R_RELAX_TLS_LD_TO_LE), Type,
Offset, Addend, &Sym});
return Target->TlsGdRelaxSkip;
}
if (Expr == R_TLSLD_HINT)
return 1;
if (InX::Got->addTlsIndex())
InX::RelaDyn->addReloc(Target->TlsModuleIndexRel, InX::Got,
InX::Got->getTlsIndexOff(), nullptr);
Expand All @@ -203,9 +207,10 @@ handleTlsRelocation(RelType Type, Symbol &Sym, InputSectionBase &C,
}

// Local-Dynamic relocs can be relaxed to Local-Exec.
if (isRelExprOneOf<R_ABS, R_TLSLD_GOT_FROM_END, R_TLSLD_PC>(Expr) &&
!Config->Shared) {
C.Relocations.push_back({R_RELAX_TLS_LD_TO_LE, Type, Offset, Addend, &Sym});
if (Expr == R_ABS && !Config->Shared) {
C.Relocations.push_back(
{Target->adjustRelaxExpr(Type, nullptr, R_RELAX_TLS_LD_TO_LE), Type,
Offset, Addend, &Sym});
return 1;
}

Expand Down Expand Up @@ -357,8 +362,8 @@ static bool isStaticLinkTimeConstant(RelExpr E, RelType Type, const Symbol &Sym,
R_MIPS_GOTREL, R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32, R_MIPS_GOT_GP_PC,
R_MIPS_TLSGD, R_GOT_PAGE_PC, R_GOT_PC, R_GOTONLY_PC,
R_GOTONLY_PC_FROM_END, R_PLT_PC, R_TLSGD_GOT, R_TLSGD_GOT_FROM_END,
R_TLSGD_PC, R_PPC_CALL_PLT, R_TLSDESC_CALL, R_TLSDESC_PAGE, R_HINT>(
E))
R_TLSGD_PC, R_PPC_CALL_PLT, R_TLSDESC_CALL, R_TLSDESC_PAGE, R_HINT,
R_TLSLD_HINT>(E))
return true;

// These never do, except if the entire file is position dependent or if
Expand Down
2 changes: 2 additions & 0 deletions lld/ELF/Relocations.h
View file
Expand Up @@ -73,6 +73,7 @@ enum RelExpr {
R_RELAX_TLS_GD_TO_LE_NEG,
R_RELAX_TLS_IE_TO_LE,
R_RELAX_TLS_LD_TO_LE,
R_RELAX_TLS_LD_TO_LE_ABS,
R_SIZE,
R_TLS,
R_TLSDESC,
Expand All @@ -84,6 +85,7 @@ enum RelExpr {
R_TLSLD_GOT,
R_TLSLD_GOT_FROM_END,
R_TLSLD_GOT_OFF,
R_TLSLD_HINT,
R_TLSLD_PC,
};

Expand Down
84 changes: 84 additions & 0 deletions lld/test/ELF/ppc64-tls-ld-le.s
View file
@@ -0,0 +1,84 @@
// REQUIRES: ppc

// RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t.o
// RUN: llvm-readelf -relocations --wide %t.o | FileCheck --check-prefix=InputRelocs %s
// RUN: ld.lld %t.o -o %t
// RUN: llvm-objdump -D %t | FileCheck --check-prefix=Dis %s
// RUN: llvm-readelf -relocations --wide %t | FileCheck --check-prefix=OutputRelocs %s

// RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %t.o
// RUN: llvm-readelf -relocations --wide %t.o | FileCheck --check-prefix=InputRelocs %s
// RUN: ld.lld %t.o -o %t
// RUN: llvm-objdump -D %t | FileCheck --check-prefix=Dis %s
// RUN: llvm-readelf -relocations --wide %t | FileCheck --check-prefix=OutputRelocs %s

.text
.abiversion 2
.globl _start # -- Begin function _start
.p2align 4
.type _start,@function
_start: # @_start
.Lfunc_begin0:
.Lfunc_gep0:
addis 2, 12, .TOC.-.Lfunc_gep0@ha
addi 2, 2, .TOC.-.Lfunc_gep0@l
.Lfunc_lep0:
.localentry _start, .Lfunc_lep0-.Lfunc_gep0
# %bb.0: # %entry
mflr 0
std 31, -8(1)
std 0, 16(1)
stdu 1, -64(1)
mr 31, 1
std 30, 48(31) # 8-byte Folded Spill
li 3, 0
stw 3, 44(31)
addis 3, 2, a@got@tlsld@ha
addi 3, 3, a@got@tlsld@l
bl __tls_get_addr(a@tlsld)
nop
addis 3, 3, a@dtprel@ha
addi 3, 3, a@dtprel@l
lwz 30, 0(3)
extsw 3, 30
ld 30, 48(31) # 8-byte Folded Reload
addi 1, 1, 64
ld 0, 16(1)
ld 31, -8(1)
mtlr 0
blr
.long 0
.quad 0
.Lfunc_end0:
.size _start, .Lfunc_end0-.Lfunc_begin0
# -- End function
.globl __tls_get_addr
.type __tls_get_addr,@function
__tls_get_addr:
.type a,@object # @a
.section .tdata,"awT",@progbits
.p2align 2
a:
.long 2 # 0x2
.size a, 4

// Verify that the input has local-dynamic tls relocation types
// InputRelocs: Relocation section '.rela.text'
// InputRelocs: R_PPC64_GOT_TLSLD16_HA {{0+}} a + 0
// InputRelocs: R_PPC64_GOT_TLSLD16_LO {{0+}} a + 0
// InputRelocs: R_PPC64_TLSLD {{0+}} a + 0

// Verify that the local-dynamic sequence is relaxed to local exec.
// Dis: _start:
// Dis: nop
// Dis: addis 3, 13, 0
// Dis: nop
// Dis: addi 3, 3, 4096

// #ha(a@dtprel) --> (0x0 -0x8000 + 0x8000) >> 16 = 0
// #lo(a@dtprel) --> (0x0 -0x8000) = -0x8000 = -32768
// Dis: addis 3, 3, 0
// Dis: addi 3, 3, -32768

// Verify that no local-dynamic relocations exist for the dynamic linker.
// OutputRelocs-NOT: R_PPC64_DTPMOD64

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