Summary:
r336838 allowed these to be toggleable.
r336858 reverted r336838.
r336943 made the generation of these sections conditional on LDPO_REL.
This commit brings back the toggle-ability. You can specify:
-plugin-opt=-function-sections
-plugin-opt=-data-sections
For your linker flags to disable the changes made in r336943.
Without toggling r336943 off, arm64 linux kernels linked with gold-plugin
see significant boot time regressions, but with r336943 outright reverted
x86_64 linux kernels linked with gold-plugin fail to boot.
Reviewers: pcc, void
Reviewed By: pcc
Subscribers: javed.absar, kristof.beyls, llvm-commits, srhines
Differential Revision: https://reviews.llvm.org/D55291
llvm-svn: 348389
Summary: This is to be consistent with lld behavior since rLLD340364.
Reviewers: tejohnson
Reviewed By: tejohnson
Subscribers: steven_wu, eraman, mehdi_amini, inglorion, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51060
llvm-svn: 340380
Not all programs want section ordering when compiled with LTO.
In particular, the Linux kernel is very sensitive when it comes to linking, and
doesn't boot when each function is placed in its own sections.
Reviewed By: pcc
Differential Revision: https://reviews.llvm.org/D48756
llvm-svn: 336943
Some programs (e.g. Linux) aren't able to handle function/data sections when
LTO is used. Thus they need a way to disable it. That can be done with these
plugin options:
-plugin-opt=-function-sections=0
-plugin-opt=-data-sections=0
llvm-svn: 336838
I don't know how to build this code, but based on the failing
buildbot error message it looks like this change should get
the buildbot up and running again.
llvm-svn: 334231
With the upcoming patch to add summary parsing support, IsAnalysis would
be true in contexts where we are not performing module summary analysis.
Rename to the more specific and approprate HaveGVs, which is essentially
what this flag is indicating.
llvm-svn: 334140
This patch adds a StatsFile option to LTO/Config.h and updates both
LLVMGold and llvm-lto2 to set it.
Reviewers: MatzeB, tejohnson, espindola
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D45531
llvm-svn: 330411
Summary:
Instead of manually invoking PrintStatistics, simply invoke
llvm_shutdown which will take care of destroying managed statics, and as
a side effect will destroy the StatisticInfo ManagedStatic, invoking
PrintStatistics when needed.
Reviewers: fhahn
Subscribers: inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D45820
llvm-svn: 330341
Summary: This enables debug fission on implicit ThinLTO when linked with gold. It will put the .dwo files in a directory specified by user.
Reviewers: tejohnson, pcc, dblaikie
Reviewed By: pcc
Subscribers: JDevlieghere, mehdi_amini, inglorion
Differential Revision: https://reviews.llvm.org/D44792
llvm-svn: 329988
These aren't the .def style files used in LLVM that require a macro
defined before their inclusion - they're just basic non-modular includes
to stamp out command line flag variables.
llvm-svn: 329840
It was reported that this change measurably regressed -plugin-opt=O3
performance.
There is an ongoing discussion on llvm-dev about the correct way to
set the CG opt level, see thread "[llvm-dev] [RFC] Adding function
attributes to represent codegen optimization level".
llvm-svn: 329458
Summary:
(Restores r327459 with handling for old plugin-api.h)
Utilize new gold plugin api interface for obtaining --wrap option
arguments, and LTO API handling (added for --wrap support in lld LTO),
to mark symbols so that LTO does not optimize them inappropriately.
Note the test cases will be in a new gold test subdirectory that
is dependent on the next release of gold which will contain the new
interfaces.
Reviewers: pcc, tmsriram
Subscribers: mehdi_amini, llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D44235
llvm-svn: 327506
Summary:
Utilize new gold plugin api interface for obtaining --wrap option
arguments, and LTO API handling (added for --wrap support in lld LTO),
to mark symbols so that LTO does not optimize them inappropriately.
Note the test cases will be in a new gold test subdirectory that
is dependent on the next release of gold which will contain the new
interfaces.
Reviewers: pcc, tmsriram
Subscribers: mehdi_amini, llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D44235
llvm-svn: 327459
Summary:
As pointed out in the review for D37993, for consistency with other
linkers, gold plugin should perform cache pruning whenever there is a
cache directory specified, which will use the default cache policy.
Reviewers: pcc
Subscribers: llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D43389
llvm-svn: 325830
Summary:
ThinLTO indexing may decide to skip all objects. If we don't write something to
the list build system may consider this as failure or linker can reuse a file
from the previews build.
Reviewers: pcc, tejohnson
Subscribers: mehdi_amini, inglorion, eraman, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D43415
llvm-svn: 325819
Summary:
With D43396, no clients use the Path parameter anymore.
Depends on D43396.
Reviewers: pcc
Subscribers: mehdi_amini, inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D43400
llvm-svn: 325619
Summary:
This will avoid the race condition described in the review for D37993.
I believe that the Path parameter to AddBufferFn is no longer utilized.
I would prefer to remove that as a follow up clean up patch to reduce
the diffs in this patch.
Reviewers: pcc
Reviewed By: pcc
Subscribers: inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D43396
llvm-svn: 325618
Summary:
Gold plugin does not add pass to ThinLTO modules without useful symbols.
In this case ThinLTO can't create corresponding index file and some features, like CFI,
cannot be processes by backed correctly without index.
Given that we don't need the backed output we can request it to avoid
processing the module. This is implemented by this patch using new
"SkipModuleByDistributedBackend" flag.
Reviewers: pcc, tejohnson
Subscribers: mehdi_amini, inglorion, eraman, cfe-commits
Differential Revision: https://reviews.llvm.org/D42995
llvm-svn: 325411
The LTO opt level should not affect the codegen opt level, and indeed
it does not affect it in lld. Ideally the codegen opt level should
be controlled by an IR-level attribute based on the compile-time opt
level, but that hasn't been implemented yet.
Differential Revision: https://reviews.llvm.org/D43040
llvm-svn: 324557
Summary: ThinLTO may skip object for other reasons, e.g. if there is no summary.
Reviewers: pcc, eugenis
Subscribers: mehdi_amini, inglorion, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D42514
llvm-svn: 323818
Since this isn't a real header - it includes static functions and had
external linkage variables (though this change makes them static, since
that's what they should be) so can't be included more than once in a
program.
llvm-svn: 319082
Adds the option 'new-pass-manager' to the gold pluggin to enable using the
new pass manager during the lto/thinlto link step.
Patch by Graham Yiu.
Differential Revision: https://reviews.llvm.org/D38517
llvm-svn: 314963
This is both a potential security issue and a potential functionality
issue because we create temporary files from multiple threads. Use
the safe version of createTemporaryFile instead.
llvm-svn: 310636
This is needed, among others, to respect --section-ordering-file
with LTO. I'll follow up with a similar change for data sections.
I hope every version of gold available on the bots has support for
--section-ordering file.
llvm-svn: 309056
Summary:
ELF linkers generate __start_<secname> and __stop_<secname> symbols
when there is a value in a section <secname> where the name is a valid
C identifier. If dead stripping determines that the values declared
in section <secname> are dead, and we then internalize (and delete)
such a symbol, programs that reference the corresponding start and end
section symbols will get undefined reference linking errors.
To fix this, add the section name to the IRSymtab entry when a symbol is
defined in a specific section. Then use this in the gold-plugin to mark
the symbol as external and visible from outside the summary when the
section name is a valid C identifier.
Reviewers: pcc
Subscribers: mehdi_amini, inglorion, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D35639
llvm-svn: 309009
Introduce symbol table data structures that can be potentially written to
disk, have the LTO library build those data structures using temporarily
constructed modules and redirect the LTO library implementation to go through
those data structures. This allows us to remove the LLVMContext and Modules
owned by InputFile.
With this change I measured a peak memory consumption decrease from 5.4GB to
2.8GB in a no-op incremental ThinLTO link of Chromium on Linux. The impact on
memory consumption is larger in COFF linkers where we are currently forced
to materialize all metadata in order to read linker options. Peak memory
consumption linking a large piece of Chromium for Windows with full LTO and
debug info decreases from >64GB (OOM) to 15GB.
Part of PR27551.
Differential Revision: https://reviews.llvm.org/D31364
llvm-svn: 299168
Summary:
The cumulative size of the bitcode files for a very large application
can be huge, particularly with -g. In a distributed build environment,
all of these files must be sent to the remote build node that performs
the thin link step, and this can exceed size limits.
The thin link actually only needs the summary along with a bitcode
symbol table. Until we have a proper bitcode symbol table, simply
stripping the debug metadata results in significant size reduction.
Add support for an option to additionally emit minimized bitcode
modules, just for use in the thin link step, which for now just strips
all debug metadata. I plan to add a cc1 option so this can be invoked
easily during the compile step.
However, care must be taken to ensure that these minimized thin link
bitcode files produce the same index as with the original bitcode files,
as these original bitcode files will be used in the backends.
Specifically:
1) The module hash used for caching is typically produced by hashing the
written bitcode, and we want to include the hash that would correspond
to the original bitcode file. This is because we want to ensure that
changes in the stripped portions affect caching. Added plumbing to emit
the same module hash in the minimized thin link bitcode file.
2) The module paths in the index are constructed from the module ID of
each thin linked bitcode, and typically is automatically generated from
the input file path. This is the path used for finding the modules to
import from, and obviously we need this to point to the original bitcode
files. Added gold-plugin support to take a suffix replacement during the
thin link that is used to override the identifier on the MemoryBufferRef
constructed from the loaded thin link bitcode file. The assumption is
that the build system can specify that the minimized bitcode file has a
name that is similar but uses a different suffix (e.g. out.thinlink.bc
instead of out.o).
Added various tests to ensure that we get identical index files out of
the thin link step.
Reviewers: mehdi_amini, pcc
Subscribers: Prazek, llvm-commits
Differential Revision: https://reviews.llvm.org/D31027
llvm-svn: 298638
Nick Desaulniers