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[ELF][MIPS] Calculate default _gp value relative to the GPREL section with the lowest address

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llvm-svn: 289471
This commit is contained in:
Simon Atanasyan
2016-12-12 21:34:11 +00:00
parent 92ce0230b5
commit 2903a8a11f
2 changed files with 54 additions and 2 deletions
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12
lld/ELF/Writer.cpp
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@@ -1490,8 +1490,16 @@ template <class ELFT> void Writer<ELFT>::fixAbsoluteSymbols() {
// Setup MIPS _gp_disp/__gnu_local_gp symbols which should
// be equal to the _gp symbol's value.
if (Config->EMachine == EM_MIPS) {
if (!ElfSym<ELFT>::MipsGp->Value)
ElfSym<ELFT>::MipsGp->Value = In<ELFT>::MipsGot->getVA() + 0x7ff0;
if (!ElfSym<ELFT>::MipsGp->Value) {
// Find GP-relative section with the lowest address
// and use this address to calculate default _gp value.
uintX_t Gp = -1;
for (const OutputSectionBase * OS : OutputSections)
if ((OS->Flags & SHF_MIPS_GPREL) && OS->Addr < Gp)
Gp = OS->Addr;
if (Gp != (uintX_t)-1)
ElfSym<ELFT>::MipsGp->Value = Gp + 0x7ff0;
}
if (ElfSym<ELFT>::MipsGpDisp)
ElfSym<ELFT>::MipsGpDisp->Value = ElfSym<ELFT>::MipsGp->Value;
if (ElfSym<ELFT>::MipsLocalGp)

44
lld/test/ELF/mips-gp-lowest.s Normal file
View File

@@ -0,0 +1,44 @@
# Check that default _gp value is calculated relative
# to the GP-relative section with the lowest address.
# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
# RUN: echo "SECTIONS { \
# RUN: .sdata : { *(.sdata) } \
# RUN: .got : { *(.got) } }" > %t.rel.script
# RUN: ld.lld %t.o --script %t.rel.script -shared -o %t.so
# RUN: llvm-readobj -s -t %t.so | FileCheck %s
# REQUIRES: mips
.text
.global foo
foo:
lui $gp, %call16(foo)
.sdata
.word 0
# CHECK: Section {
# CHECK: Name: .sdata
# CHECK-NEXT: Type: SHT_PROGBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_MIPS_GPREL
# CHECK-NEXT: SHF_WRITE
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0xDD
# CHECK: }
# CHECK: Section {
# CHECK: Name: .got
# CHECK-NEXT: Type: SHT_PROGBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_MIPS_GPREL
# CHECK-NEXT: SHF_WRITE
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0xE4
# CHECK: }
# CHECK: Name: _gp (5)
# CHECK-NEXT: Value: 0x80CD
# ^-- 0xDD + 0x7ff0