Commit Graph

22 Commits

Author SHA1 Message Date
Rafael Espindola f931c179ca Don't depend on "call foo" producing a X86_64_PC32.
Newer versions of the gnu assembler produce a X86_64_PLT32 for
calls. There is a change under review in llvm to do the same, so update
the tests to not depend on it.

We can still produce a R_X86_64_PC32 with ".long foo - .".

llvm-svn: 325379
2018-02-16 20:05:58 +00:00
Rui Ueyama 1cf7f9cc80 Make .gnu.hash section smaller.
Our on-disk hash table was unnecessarily large. The cost of collision is
not high in the .gnu.hash table because each symbol in the .gnu.hash
table has a hash value with it. So, for each collided symbol, the
dynamic linker just compares an integer, which is pretty cheap.

This patch increases the load factor by about 8. Here's a comparison.

  $ readelf --histogram libclangSema.so.6.0.0svn-new-lld
  Histogram for `.gnu.hash' bucket list length (total of 582 buckets):
   Length  Number     % of total  Coverage
        0  11         (  1.9%)
        1  35         (  6.0%)      1.5%
        2  93         ( 16.0%)      9.5%
        3  108        ( 18.6%)     23.4%
        4  121        ( 20.8%)     44.1%
        5  86         ( 14.8%)     62.6%
        6  63         ( 10.8%)     78.8%
        7  38         (  6.5%)     90.2%
        8  18         (  3.1%)     96.4%
        9  6          (  1.0%)     98.7%
       10  3          (  0.5%)    100.0%

  $ readelf --histogram libclangSema.so.6.0.0svn-old-lld
  Histogram for `.gnu.hash' bucket list length (total of 4093 buckets):
   Length  Number     % of total  Coverage
        0  1498       ( 36.6%)
        1  1545       ( 37.7%)     37.7%
        2  712        ( 17.4%)     72.5%
        3  251        (  6.1%)     90.9%
        4  66         (  1.6%)     97.3%
        5  16         (  0.4%)     99.3%
        6  5          (  0.1%)    100.0%

  $ readelf --histogram libclangSema.so.6.0.0svn-bfd
  Histogram for `.gnu.hash' bucket list length (total of 1004 buckets):
   Length  Number     % of total  Coverage
      0  92         (  9.2%)
        1  227        ( 22.6%)      9.8%
        2  266        ( 26.5%)     32.6%
        3  222        ( 22.1%)     61.2%
        4  115        ( 11.5%)     81.0%
        5  55         (  5.5%)     92.8%
        6  21         (  2.1%)     98.2%
        7  6          (  0.6%)    100.0%

  $ readelf --histogram libclangSema.so.6.0.0svn-gold
  Histogram for `.gnu.hash' bucket list length (total of 2053 buckets):
   Length  Number     % of total  Coverage
        0  671        ( 32.7%)
        1  709        ( 34.5%)     30.4%
        2  470        ( 22.9%)     70.7%
        3  141        (  6.9%)     88.9%
        4  54         (  2.6%)     98.2%
        5  5          (  0.2%)     99.2%
        6  3          (  0.1%)    100.0%

Differential Revision: https://reviews.llvm.org/D40683

llvm-svn: 319503
2017-11-30 23:59:40 +00:00
Rafael Espindola f70502d3a6 Bring r319051 back.
It had been reverted because it depended on r319008 which has been
recommitted.

Original message:

Add a missing test.

We were not testing that we correctly handled a .o with a weak symbol
after a .so.

llvm-svn: 319217
2017-11-28 20:21:44 +00:00
Rafael Espindola 1d4b3023dc Bring back r319008.
This includes a fix to mark copy reloc aliases as used.

Original message:

[ELF] Do not keep symbols if they referenced only from discarded sections.

This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.

llvm-svn: 319215
2017-11-28 20:17:58 +00:00
Igor Kudrin a46522f369 Revert r319008, "[ELF] Do not keep symbols if they referenced only from discarded sections."
and r319051, "Add a missing test."

r319008 broke the LTO bots;
r319051 depends on changes in r319008.

llvm-svn: 319154
2017-11-28 08:39:40 +00:00
Rafael Espindola 1fea1e326e Add a missing test.
We were not testing that we correctly handled a .o with a weak symbol
after a .so.

llvm-svn: 319051
2017-11-27 17:18:09 +00:00
Igor Kudrin 40007586fc [ELF] Do not keep symbols if they referenced only from discarded sections.
This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.

Differential Revision: https://reviews.llvm.org/D38790

llvm-svn: 319008
2017-11-27 05:51:10 +00:00
Rafael Espindola 83f73f7908 Make a test stricter.
It now has a DT_NEEDED that could be removed by --gc-sections and one
that cannot. Without this all tests would pass if --gc-sections just
removed all DT_NEEDED.

llvm-svn: 318937
2017-11-23 23:40:33 +00:00
Rafael Espindola 06ea0ce1c9 Handle shared symbols in the gnu hash construction.
They are special in that they they need to be in the hash table iff we
are linking an executable that preempts them.

llvm-svn: 316065
2017-10-18 06:49:59 +00:00
Rafael Espindola 3038c6beb5 Revert "Bring back the rest of r315721."
This reverts commit r316051.

It fails on a bot.

llvm-svn: 316058
2017-10-18 03:06:45 +00:00
Rafael Espindola 07412df152 Bring back the rest of r315721.
The original patch was reported to break a libcxx bot. Unfortunately I
could not reproduce the issue and the bot log is not available anymore.

This patch changes the handling of shared symbols. I will watch the
bot and see it breaks.

Original message:
--------------------------------------------------------------
Handle shared and lazy symbol in the gnu hash construction.

We were not considering those symbols undefined and they could end up
in the end of the dynamic symbol table.
--------------------------------------------------------------

llvm-svn: 316051
2017-10-18 01:10:05 +00:00
NAKAMURA Takumi 09c234f857 Revert rL315721, "Handle shared and lazy symbol in the gnu hash construction."
It broke check-libcxx with stage1-clang and stage1-lld.

llvm-svn: 315803
2017-10-14 12:21:49 +00:00
Rafael Espindola 8bf95e4678 Handle shared and lazy symbol in the gnu hash construction.
We were not considering those symbols undefined and they could end up
in the end of the dynamic symbol table.

llvm-svn: 315721
2017-10-13 18:07:11 +00:00
Peter Collingbourne d6924d7474 Reland r315114, "ELF: Export preempted symbols even if there is a dynamic list." which was reverted in r315116.
I hadn't synced past the change that changed the default hash style
to --hash-style=both, so my test had the symbols in the wrong order.

llvm-svn: 315119
2017-10-06 22:09:03 +00:00
Peter Collingbourne accab5908d Revert r315114, "ELF: Export preempted symbols even if there is a dynamic list."
For some reason the symbols get emitted in the wrong order on one of the
buildbots: http://bb9.pgr.jp/#builders/15/builds/180

llvm-svn: 315116
2017-10-06 21:48:39 +00:00
Peter Collingbourne 5a8928c605 ELF: Export preempted symbols even if there is a dynamic list.
Dynamic lists in an executable are additive, not restrictive, so we
must continue to export preempted symbols even with a dynamic list.

This fixes sanitizer interception of libc symbols (and should also fix
symbol preemption by users of sanitizers).

Differential Revision: https://reviews.llvm.org/D38647

llvm-svn: 315114
2017-10-06 21:33:59 +00:00
George Rimar b444efb939 [ELF] - Update testcases after LLVM update. (D35351)
llvm-svn: 308034
2017-07-14 16:00:34 +00:00
Rafael Espindola 41a93a3edf Give priority to linker scripts over preemption.
LLD exports symbols that are also present in used shared libraries to
make sure they are preempted at runtime. That is a reasonable default,
but we must allow for it to be overwritten with linker script. If we
don't, libraries that expect to be able to hide a c++ delete operator
will fail.

This should fix the firebird build.

llvm-svn: 292146
2017-01-16 17:35:23 +00:00
Rafael Espindola 6239ce6889 Give preempting symbols precedence over linker script.
llvm-svn: 289212
2016-12-09 14:12:02 +00:00
Rafael Espindola d0ebd84c42 Change the implementation of --dynamic-list to use linker script parsing.
The feature is documented as
-----------------------------
The format of the dynamic list is the same as the version node
without scope and node name.  See *note VERSION:: for more
information.
--------------------------------

And indeed qt uses a dynamic list with an 'extern "C++"' in it. With
this patch we support that

The change to gc-sections-shared makes us match bfd. Just because we
kept bar doesn't mean it has to be in the dynamic symbol table.

The changes to invalid-dynamic-list.test and reproduce.s are because
of the new parser.

The changes to version-script.s are the only case where we change
behavior with regards to bfd, but I would like to see a mix of
--version-script and --dynamic-list used in the wild before
complicating the code.

llvm-svn: 289082
2016-12-08 17:54:26 +00:00
Rafael Espindola 4737f94132 Make this test more strict. NFC.
llvm-svn: 289069
2016-12-08 16:51:56 +00:00
Rafael Espindola 1b65ad1725 Don't gc symbols that have to go in the dynamic symbol table.
We were only doing it for .so and --export-dynamic, but those are not
the only ways a symbol ends up in the dynamic symbol table.

Problem diagnostic and earlier patch version by Peter Collingbourne.

llvm-svn: 267568
2016-04-26 16:26:45 +00:00