Commit Graph

9 Commits

Author SHA1 Message Date
Benjamin Kramer 61085ca999 Update lld tests after r321526.
llvm-svn: 321529
2017-12-28 17:20:41 +00:00
Rafael Espindola 49419bb303 Use 0 as sh_link when we don't have a dynamic symbol table.
It doesn't make sense to link from an alloc section to a non alloc
one as we were doing.

This matches the behavior of both gold and bfd.

llvm-svn: 315584
2017-10-12 15:05:04 +00:00
Peter Smith baffdb8bc2 [ELF] ifunc implementation using synthetic sections
This change introduces new synthetic sections IpltSection, IgotPltSection
that represent the ifunc entries that would previously have been put in
the PltSection and the GotPltSection. The separation makes sure that
the R_*_IRELATIVE relocations are placed after the non R_*_IRELATIVE
relocations, which permits ifunc resolvers to know that the .got.plt
slots will be initialized prior to the resolver being called.

A secondary benefit is that for ARM we can move the IgotPltSection and its
dynamic relocations to the .got and .rel.dyn as the ARM glibc expects all
the R_*_IRELATIVE relocations to be in the .rel.dyn

Differential revision: https://reviews.llvm.org/D27406

llvm-svn: 289045
2016-12-08 12:58:55 +00:00
Rui Ueyama 3da3f06dd3 Include version string into ".comment" section.
Summary:
This patch adds a ".comment" section to an output. The comment
section contains the linker's version string. You can now
find out whether a binary is created by LLD or not using objdump
command like this.

  $ objdump -s -j .comment foo

  foo:     file format elf64-x86-64

  Contents of section .comment:
   0000 00474343 3a202855 62756e74 7520342e  .GCC: (Ubuntu 4.
   0010 382e342d 32756275 6e747531 7e31342e  8.4-2ubuntu1~14.
   ...
   00c0 766d2f74 72756e6b 20323835 38343629  vm/trunk 285846)
   00d0 004c696e 6b65723a 204c4c44 20342e30  .Linker: LLD 4.0
   00e0 2e302028 7472756e 6b203238 36343036  .0 (trunk 286406
   00f0 2900                                 ).

Compilers emits .comment section as well, so the output contains
both compiler and linker information.

Alternative considered:

I first tried to add a SHT_NOTE section because GNU gold does that.
A NOTE section starts with a header which contains content type.
It turned out that ld.gold sets type NT_GNU_GOLD_VERSION to their
NOTE section. So the NOTE type is only for GNU gold (surprise!)

Next, I tried to create ".linker-version" section. However, it seems
that reusing the existing ".comment" section is better because 1)
other tools already know about .comment section and is able to strip
it and 2) the result contans not only linker info but also compiler
info.

Differential Revision: https://reviews.llvm.org/D26487

llvm-svn: 286496
2016-11-10 20:20:37 +00:00
Peter Collingbourne dbcf5b99d0 Remove unnecessary function type directives for ifuncs.
llvm-svn: 267569
2016-04-26 16:50:02 +00:00
Mandeep Singh Grang 01ae1daafe [LLD] Remove unwanted --check-prefix=CHECK from unit tests. NFC.
Summary:
Removed unwanted --check-prefix=CHECK from the following unit tests:
      ELF/aarch64-gnu-ifunc.s
      ELF/gnu-ifunc-i386.s
      ELF/gnu-ifunc.s
      ELF/plt-i686.s

Patch by: Mandeep Singh Grang (mgrang)

Reviewers: rafael

Subscribers: aemerson

Projects: #lld

Differential Revision: http://reviews.llvm.org/D19149

llvm-svn: 266453
2016-04-15 17:21:29 +00:00
Rafael Espindola 03ef404e97 Simplify the creation of __rel[a]_iplt_{start,end}.
They can be regular DefinedSynthetic.

llvm-svn: 265981
2016-04-11 19:14:59 +00:00
Rafael Espindola ccfe3cb3d6 Don't store an Elf_Sym for most symbols.
Our symbol representation was redundant, and some times would get out of
sync. It had an Elf_Sym, but some fields were copied to SymbolBody.

Different parts of the code were checking the bits in SymbolBody and
others were checking Elf_Sym.

There are two general approaches to fix this:
* Copy the required information and don't store and Elf_Sym.
* Don't copy the information and always use the Elf_Smy.

The second way sounds tempting, but has a big problem: we would have to
template SymbolBody. I started doing it, but it requires templeting
*everything* and creates a bit chicken and egg problem at the driver
where we have to find ELFT before we can create an ArchiveFile for
example.

As much as possible I compared the test differences with what gold and
bfd produce to make sure they are still valid. In most cases we are just
adding hidden visibility to a local symbol, which is harmless.

In most tests this is a small speedup. The only slowdown was scylla
(1.006X). The largest speedup was clang with no --build-id, -O3 or
--gc-sections (i.e.: focus on the relocations): 1.019X.

llvm-svn: 265293
2016-04-04 14:04:16 +00:00
George Rimar a07ff66112 [ELF] - Implemented R_*_IRELATIVE relocations for x86, x64 targets.
This relocation is similar to R_*_RELATIVE except that the value used in this relocation is the program address returned by the function, which takes no arguments, at the address of
the result of the corresponding R_*_RELATIVE relocation as specified in the processor-specific ABI. The purpose of this relocation to avoid name lookup for locally defined STT_GNU_IFUNC symbols at load-time.

More info can be found in ifunc.txt from https://sites.google.com/site/x32abi/documents.

Differential revision: http://reviews.llvm.org/D15235

llvm-svn: 256144
2015-12-21 10:12:06 +00:00