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[ELF][MIPS] Enumerate absolute MIPS relocations in the isRelRelative 

This commit does two related thing. At first, it enumerates supported
absolute MIPS relocations in the `MipsTargetInfo<ELFT>::isRelRelative`
method. In that case the code is shorter and the case switch does not
tend to grow. At second, it prevents R_MIPS_COPY and PLT creation for
relative relocations. For almost all relative MIPS relocations like
R_MIPS_PC19_S2, R_MIPS_PCHI16 etc it does not have a sence. The only
exception is R_MIPS_PC32. GNU linker creates a copy relocation or PLT
entry for it. But I could not find any real test case uses R_MIPS_PC32
with DSO defined symbol as a target. So for now I prefer to skip this
case to simplify the LLD code.

llvm-svn: 261822
This commit is contained in:
Simon Atanasyan 2016-02-25 05:03:52 +00:00
parent 2b972dfebb
commit 49bc69b9bb
2 changed files with 12 additions and 15 deletions
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21
lld/ELF/Target.cpp
View File

@ -1700,7 +1700,7 @@ void MipsTargetInfo<ELFT>::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
template <class ELFT>
bool MipsTargetInfo<ELFT>::needsCopyRelImpl(uint32_t Type) const {
return Type == R_MIPS_HI16 || Type == R_MIPS_LO16 || isRelRelative(Type);
return !isRelRelative(Type);
}
template <class ELFT>
@ -1716,9 +1716,8 @@ bool MipsTargetInfo<ELFT>::needsPltImpl(uint32_t Type,
return false;
if (Type == R_MIPS_26 && canBePreempted(&S, false))
return true;
if (Type == R_MIPS_HI16 || Type == R_MIPS_LO16 || isRelRelative(Type))
if (S.isShared())
return true;
if (!isRelRelative(Type) && S.isShared())
return true;
return false;
}
@ -1826,15 +1825,13 @@ template <class ELFT>
bool MipsTargetInfo<ELFT>::isRelRelative(uint32_t Type) const {
switch (Type) {
default:
return false;
case R_MIPS_PC16:
case R_MIPS_PC19_S2:
case R_MIPS_PC21_S2:
case R_MIPS_PC26_S2:
case R_MIPS_PC32:
case R_MIPS_PCHI16:
case R_MIPS_PCLO16:
return true;
case R_MIPS_26:
case R_MIPS_32:
case R_MIPS_64:
case R_MIPS_HI16:
case R_MIPS_LO16:
return false;
}
}

6
lld/test/ELF/mips-plt-copy.s
View File

@ -80,6 +80,6 @@ loc:
gd:
.word 0
ld:
.word data1+8-. # R_MIPS_PC32 requires COPY rel for DSO defined data.
.word foo1+8-. # R_MIPS_PC32 requires JUMP_SLOT/PLT entry
# for DSO defined func.
.word data1+8 # R_MIPS_32 requires REL32 dnamic relocation
# for DSO defined data. For now we generate COPY one.
.word foo1+8 # R_MIPS_32 requires PLT entry for DSO defined func.