wangtao
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Simplify createPhdrs. NFC. 

Instead of creating multiple PHDRs in a single loop, this patch
runs one for loop for each PHDR type. I think this improves code
readability.

llvm-svn: 293832
This commit is contained in:
Rui Ueyama 2017-02-01 22:42:17 +00:00
parent 35c5b86737
commit db00b61860
1 changed files with 22 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
lld/ELF/Writer.cpp
View File

@ -1193,31 +1193,18 @@ template <class ELFT> std::vector<PhdrEntry> Writer<ELFT>::createPhdrs() {
};
// The first phdr entry is PT_PHDR which describes the program header itself.
PhdrEntry &Hdr = *AddHdr(PT_PHDR, PF_R);
Hdr.add(Out<ELFT>::ProgramHeaders);
AddHdr(PT_PHDR, PF_R)->add(Out<ELFT>::ProgramHeaders);
// PT_INTERP must be the second entry if exists.
if (OutputSectionBase *Sec = findSection(".interp")) {
PhdrEntry &Hdr = *AddHdr(PT_INTERP, Sec->getPhdrFlags());
Hdr.add(Sec);
}
if (OutputSectionBase *Sec = findSection(".interp"))
AddHdr(PT_INTERP, Sec->getPhdrFlags())->add(Sec);
// Add the first PT_LOAD segment for regular output sections.
uintX_t Flags = computeFlags<ELFT>(PF_R);
PhdrEntry *Load = AddHdr(PT_LOAD, Flags);
PhdrEntry TlsHdr(PT_TLS, PF_R);
PhdrEntry RelRo(PT_GNU_RELRO, PF_R);
for (OutputSectionBase *Sec : OutputSections) {
if (!(Sec->Flags & SHF_ALLOC))
break;
// If we meet TLS section then we create TLS header
// and put all TLS sections inside for further use when
// assign addresses.
if (Sec->Flags & SHF_TLS)
TlsHdr.add(Sec);
if (!needsPtLoad<ELFT>(Sec))
continue;
@ -1233,48 +1220,47 @@ template <class ELFT> std::vector<PhdrEntry> Writer<ELFT>::createPhdrs() {
}
Load->add(Sec);
if (isRelroSection<ELFT>(Sec))
RelRo.add(Sec);
}
// Add the TLS segment unless it's empty.
// Add a TLS segment if any.
PhdrEntry TlsHdr(PT_TLS, PF_R);
for (OutputSectionBase *Sec : OutputSections)
if (Sec->Flags & SHF_TLS)
TlsHdr.add(Sec);
if (TlsHdr.First)
Ret.push_back(std::move(TlsHdr));
// Add an entry for .dynamic.
if (In<ELFT>::DynSymTab) {
PhdrEntry &H =
*AddHdr(PT_DYNAMIC, In<ELFT>::Dynamic->OutSec->getPhdrFlags());
H.add(In<ELFT>::Dynamic->OutSec);
}
if (In<ELFT>::DynSymTab)
AddHdr(PT_DYNAMIC, In<ELFT>::Dynamic->OutSec->getPhdrFlags())
->add(In<ELFT>::Dynamic->OutSec);
// PT_GNU_RELRO includes all sections that should be marked as
// read-only by dynamic linker after proccessing relocations.
PhdrEntry RelRo(PT_GNU_RELRO, PF_R);
for (OutputSectionBase *Sec : OutputSections)
if (needsPtLoad<ELFT>(Sec) && isRelroSection<ELFT>(Sec))
RelRo.add(Sec);
if (RelRo.First)
Ret.push_back(std::move(RelRo));
// PT_GNU_EH_FRAME is a special section pointing on .eh_frame_hdr.
if (!Out<ELFT>::EhFrame->empty() && In<ELFT>::EhFrameHdr) {
PhdrEntry &Hdr =
*AddHdr(PT_GNU_EH_FRAME, In<ELFT>::EhFrameHdr->OutSec->getPhdrFlags());
Hdr.add(In<ELFT>::EhFrameHdr->OutSec);
}
if (!Out<ELFT>::EhFrame->empty() && In<ELFT>::EhFrameHdr)
AddHdr(PT_GNU_EH_FRAME, In<ELFT>::EhFrameHdr->OutSec->getPhdrFlags())
->add(In<ELFT>::EhFrameHdr->OutSec);
// PT_OPENBSD_RANDOMIZE specifies the location and size of a part of the
// memory image of the program that must be filled with random data before any
// code in the object is executed.
if (OutputSectionBase *Sec = findSection(".openbsd.randomdata")) {
PhdrEntry &Hdr = *AddHdr(PT_OPENBSD_RANDOMIZE, Sec->getPhdrFlags());
Hdr.add(Sec);
}
if (OutputSectionBase *Sec = findSection(".openbsd.randomdata"))
AddHdr(PT_OPENBSD_RANDOMIZE, Sec->getPhdrFlags())->add(Sec);
// PT_GNU_STACK is a special section to tell the loader to make the
// pages for the stack non-executable.
if (!Config->ZExecstack) {
PhdrEntry &Hdr = *AddHdr(PT_GNU_STACK, PF_R | PF_W);
PhdrEntry *Hdr = AddHdr(PT_GNU_STACK, PF_R | PF_W);
if (Config->ZStackSize != uint64_t(-1))
Hdr.p_memsz = Config->ZStackSize;
Hdr->p_memsz = Config->ZStackSize;
}
// PT_OPENBSD_WXNEEDED is a OpenBSD-specific header to mark the executable