Differential Revision: https://reviews.llvm.org/D47234

llvm-svn: 333040

The --keep-unique <symbol> option is taken from gold. The intention is that
<symbol> will be prevented from being folded by ICF. Although not
specifically mentioned in the documentation <symbol> only matches
global symbols, with a warning if the symbol is not found.

The implementation finds the Section defining <symbol> and removes it from
the set of sections considered for ICF.

Differential Revision: https://reviews.llvm.org/D46755

llvm-svn: 332332

Summary:
r328610 fixed a data race in the COFF linker. This change makes a
similar fix to the ELF linker.

Reviewers: ruiu, pcc, rnk

Reviewed By: ruiu

Subscribers: emaste, llvm-commits, arichardson

Differential Revision: https://reviews.llvm.org/D45192

llvm-svn: 329088

llvm-svn: 328739

The Data member of synthetic section's is not valid and empty. The Data
member is required to be valid by ICF as it is used by ICF to determine
the equality of section contents. Therefore, exclude synthetic sections
from ICF.

Fixes bug PR36910.

Differential Revision: https://reviews.llvm.org/D44923

llvm-svn: 328624

Latest patch version now.

Original commit message:

[ELF] - Do not crash with --emit-relocs and --icf=all together.

Previously we would crash because did not mark .rel[a] sections
as dead and they tried to access parent which was not live
after ICF and therefore was null.

Differential revision: https://reviews.llvm.org/D43241

llvm-svn: 325879

Differential Revision: https://reviews.llvm.org/D43251

llvm-svn: 325065

llvm-svn: 325038

llvm-svn: 324830

llvm-svn: 324756

GNU gold doesn't print out ICF sections for -verbose. It only shows
them for -print-icf-sections. We printed out them for -verbose because
we didn't have -print-icf-sections. Now that we have the option, there's
no reason to print out for -verbose.

Differential Revision: https://reviews.llvm.org/D43100

llvm-svn: 324755

llvm-svn: 324684

Previously, multiple chunks of --print-icf-sections messages were interleaved
and didn't make sense. This is because forEachClass is multi-threaded.

llvm-svn: 324683

Currently ICF information is output through stderr if the "--verbose"
flag is used. This differs to Gold for example, which uses an explicit
flag to output this to stdout. This commit adds the
"--print-icf-sections" and "--no-print-icf-sections" flags and changes
the output message format for clarity and consistency with
"--print-gc-sections". These messages are still output to stderr if
using the verbose flag. However to avoid intermingled message output to
console, this will not occur when the "--print-icf-sections" flag is
used.

Existing tests have been modified to expect the new message format from
stderr.

Patch by Owen Reynolds.

Differential Revision: https://reviews.llvm.org/D42375

Reviewers: ruiu, rafael

Reviewed by: 

llvm-svn: 323976

When we have --icf=safe we should be able to define --icf=all as a
shorthand for --icf=safe --ignore-function-address-equality.

For now --ignore-function-address-equality is used only to control
access to non preemptable symbols in shared libraries.

llvm-svn: 322152

An internal linker has support for merging identical data and in some
cases it can be a significant win.

This is behind an off by default flag so it has to be requested
explicitly.

llvm-svn: 320448

They were not used in InputFiles.h and it was getting too easy to add
circular includes.

llvm-svn: 320256

Now that DefinedRegular is the only remaining derived class of
Defined, we can merge the two classes.

Differential Revision: https://reviews.llvm.org/D39667

llvm-svn: 317448

Now that we have only SymbolBody as the symbol class. So, "SymbolBody"
is a bit strange name now. This is a mechanical change generated by

  perl -i -pe s/SymbolBody/Symbol/g $(git grep -l SymbolBody lld/ELF lld/COFF)

nd clang-format-diff.

Differential Revision: https://reviews.llvm.org/D39459

llvm-svn: 317370

Summary:
This will allow using the functionality from other linkers. It is also
a prerequisite for sharing the error logging code.

Reviewers: ruiu

Reviewed By: ruiu

Subscribers: emaste, mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D38822

llvm-svn: 315725

Computing section content hashes early seems like a win in terms of
performance. It increases a chance that two different sections will get
different class IDs from the beginning.

Without threads, this patch improves Chromium link time by about 0.3
seconds. With threads, by 0.1 seconds. That's less than 1% time saving
but not bad for a small patch.

llvm-svn: 314644

Looks like there's no need to use a higher order function. We can simply
use the regular for-loop.

llvm-svn: 311942

Relocations referring to merge sections are considered equal if they
resolve to the same offset in the same output section.

Differential Revision: https://reviews.llvm.org/D34094

llvm-svn: 305177

This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.

Differential Revision: https://reviews.llvm.org/D33843

llvm-svn: 304864

This is the only place we use threads for ICF. The intention of this code
was to split an input vector into 256 shards and process them in parallel.
What the code was actually doing was to split an input into 257 shards,
process the first 256 shards in parallel, and the remaining one in serial.

That means this code takes ceil(256/n)+1 instead of ceil(256/n) where n
is the number of available CPU cores. The former converges to 2 while
the latter converges to 1.

This patches fixes the above issue.

llvm-svn: 303797

So that it is clear that the function is a wrapper for for_each_n.

llvm-svn: 302718

    
ARM Exception Index Table sections .ARM.exidx have an implicit dependency
on code sections via SHF_LINK_ORDER. When code sections are folded by ICF
we must mark the unique .ARM.exidx table that describes it as not live
to prevent an illegal entry in the exception table.
    
Note that we do not try and follow the relocations from the .ARM.exidx
section to the .ARM.extab sections to mark these as not live. Leaving
these sections is not a correctness problem. In theory these could be
removed via an application of garbage collection.
    
Fixes https://bugs.llvm.org/show_bug.cgi?id=32614

Differential Revision: https://reviews.llvm.org/D31932

llvm-svn: 300182

"Parallel" is the most important aspect of the functions,
so we shouldn't omit that.

llvm-svn: 298557

We had a few Config member functions that returns configuration values.
For example, we had is64() which returns true if the target is 64-bit.
The return values of these functions are constant and never change.

This patch is to compute them only once to make it clear that they'll
never change.

llvm-svn: 298168

llvm-svn: 297287

llvm-svn: 297107

Previously, LLD merged all read-only sections. So the following
program prints out "true" if -icf=all is specified.

  static const int foo = 1;
  static const int bar = 1;
  int main() { printf("%s\n", &foo == &bar ? "true" : "false"); }

This is somewhat counter-intuitive, and it actually caused nasty issues.
One example is https://bugs.chromium.org/p/chromium/issues/detail?id=682773#c24.

This patch changes the way how it works. Now ICF merges only functions
(i.e. executable sections).

Differential Revision: https://reviews.llvm.org/D30365

llvm-svn: 296534

Differential Revision: https://reviews.llvm.org/D30348

llvm-svn: 296508

The list of all input sections was defined in SymbolTable class for a
historical reason. The list itself is not a template. However, because
SymbolTable class is a template, we needed to pass around ELFT to access
the list. This patch moves the list out of the class so that it doesn't
need ELFT.

llvm-svn: 296309

With the current design an InputSection is basically anything that
goes directly in a OutputSection. That includes plain input section
but also synthetic sections, so this should probably not be a
template.

llvm-svn: 295993

Removing this template is not a big win by itself, but opens the way
for removing more templates.

llvm-svn: 295923

If two sections contained relocations to absolute symbols with the same
value we would crash when trying to access their sections. Add a check that
both symbols point to sections before accessing their sections, and treat
absolute symbols as equal if their values are equal.

Differential Revision: https://reviews.llvm.org/D28935

llvm-svn: 292578

llvm-svn: 292044

Also add a citation to GNU gold safe ICF paper.

Differential Revision: https://reviews.llvm.org/D27398

llvm-svn: 288684

llvm-svn: 288630