Bolt currently links and initializes all LLVM targets. This
substantially increases the binary size, and link time if LTO is used.
Instead, only link the targets specified by BOLT_TARGETS_TO_BUILD. We
also have to only initialize those targets, so generate a
TargetConfig.def file with the necessary information. The way the
initialization is done mirrors what llvm-exegesis does.
This reduces llvm-bolt size from 137MB to 78MB for me.
Use LLVM's getMainExecutable() helper instead of rolling our own. This
will result in standard behavior across platforms, such as making sure
that symlinks are always resolved.
merge-fdata used to consider misprediction count as part of "signature",
or the aggregation key. This prevented it from collapsing profile lines
with different misprediction counts, which resulted in duplicate
`(from, to)` pairs with different misprediction and execution counts.
Fix that by splitting out misprediction count and accumulating it
separately.
Test Plan: updated bolt/test/merge-fdata-lbr-mode.test
Eliminate splitting the buffer into lines, and use `std::getline`
directly. Simplify no_lbr and boltedcollection handling as well.
Test Plan: For a large fdata file (200MB), fstream version is ~10%
faster.
When a basic sample profile is gathered without LBR info, the generated
profile contains a "no-lbr" tag in the first line of the fdata file.
This PR fixes merge-fdata to recognize and save this tag to the output
file.
Reuse the definition of profile density from llvm-profgen (#92144):
- the density is computed in perf2bolt using raw samples (perf.data or
pre-aggregated data),
- function density is the ratio of dynamically executed function bytes
to the static function size in bytes,
- profile density:
- functions are sorted by density in decreasing order, accumulating
their respective sample counts,
- profile density is the smallest density covering 99% of total sample
count.
In other words, BOLT binary profile density is the minimum amount of
profile information per function (excluding functions in tail 1% sample
count) which is sufficient to optimize the binary well.
The density threshold of 60 was determined through experiments with
large binaries by reducing the sample count and checking resulting
profile density and performance. The threshold is conservative.
perf2bolt would print the warning if the density is below the threshold
and suggest to increase the sampling duration and/or frequency to reach
a given density, e.g.:
```
BOLT-WARNING: BOLT is estimated to optimize better with 2.8x more samples.
```
Test Plan: updated pre-aggregated-perf.test
Reviewers: maksfb, wlei-llvm, rafaelauler, ayermolo, dcci, WenleiHe
Reviewed By: WenleiHe, wlei-llvm
Pull Request: https://github.com/llvm/llvm-project/pull/101094
Check invoked tool with `starts_with`.
Addresses the issue where `perf2bolt` invoked using a distro symlink
`perf2bolt-16` fails to run in perf2bolt mode and runs in llvm-bolt mode
instead.
The issue is mentioned in https://vondra.me/posts/playing-with-bolt-and-postgres/
Test Plan:
```
ln -sf perf2bolt perf2bolt-20
perf2bolt-20 clang -p perf.data -o fdata.clang -w yaml.clang
...
PERF2BOLT: wrote 188593 objects and 0 memory objects to fdata.clang
```
Reviewers: ayermolo, rafaelauler, dcci, maksfb
Reviewed By: maksfb
Pull Request: https://github.com/llvm/llvm-project/pull/111072
While merging profiles, some fields in the input header, e.g.
HashFunction, could be uninitialized leading to a UMR. Initialize merged
header with the first input header.
Fixes#109592
This ensures forward compatibility, where old BOLT versions can consume
the profile created by newer versions with extra keys.
Test Plan: added yaml-unknown-keys.test
The base class llvm::ThreadPoolInterface will be renamed
llvm::ThreadPool in a subsequent commit.
This is a breaking change: clients who use to create a ThreadPool must
now create a DefaultThreadPool instead.
Make core BOLT functionality more friendly to being used as a
library instead of in our standalone driver llvm-bolt. To
accomplish this, we augment BinaryContext with journaling streams
that are to be used by most BOLT code whenever something needs to
be logged to the screen. Users of the library can decide if logs
should be printed to a file, no file or to the screen, as
before. To illustrate this, this patch adds a new option
`--log-file` that allows the user to redirect BOLT logging to a
file on disk or completely hide it by using
`--log-file=/dev/null`. Future BOLT code should now use
`BinaryContext::outs()` for printing important messages instead of
`llvm::outs()`. A new test log.test enforces this by verifying that
no strings are print to screen once the `--log-file` option is
used.
In previous patches we also added a new BOLTError class to report
common and fatal errors, so code shouldn't call exit(1) now. To
easily handle problems as before (by quitting with exit(1)),
callers can now use
`BinaryContext::logBOLTErrorsAndQuitOnFatal(Error)` whenever code
needs to deal with BOLT errors. To test this, we have fatal.s
that checks we are correctly quitting and printing a fatal error
to the screen.
Because this is a significant change by itself, not all code was
yet ported. Code from Profiler libs (DataAggregator and friends)
still print errors directly to screen.
Co-authored-by: Rafael Auler <rafaelauler@fb.com>
Test Plan: NFC
Fix the bug where merge-fdata unconditionally outputs boltedcollection
line, regardless of whether input files have it set.
Test Plan:
Added bolt/test/X86/merge-fdata-nobat-mode.test which fails without this
fix.
Fix the bug where merge-fdata unconditionally outputs boltedcollection
line, regardless of whether input files have it set.
Test Plan:
Added bolt/test/X86/merge-fdata-nobat-mode.test which fails without this
fix.
This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.
I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
The existing BOLT install targets are broken on Windows becase they
don't properly handle the output extension. We cannot use the existing
LLVM macros since those make assumptions that don't hold for BOLT. This
change instead implements custom macros following the approach used by
Clang and LLD.
Differential Revision: https://reviews.llvm.org/D151595
The existing BOLT install targets are broken on Windows becase they
don't properly handle the output extension. We cannot use the existing
LLVM macros since those make assumptions that don't hold for BOLT. This
change instead implements custom macros following the approach used by
Clang and LLD.
Differential Revision: https://reviews.llvm.org/D151595
The existing BOLT install targets are broken on Windows becase they
don't properly handle output extension. Rather than reimplementing
this logic in BOLT, reuse the existing LLVM macros which already
handle this aspect correctly.
Differential Revision: https://reviews.llvm.org/D151595
Resovled the issue that when number of tasks is fewer than cores, we end
up creating as many threads as the number of cores, making the
performance worse than the single thread version.
This does *not* link with libLLVM, but with static archives instead. Not
super-great, but at least the build works, which is probably better than
failing.
Related to #57551
Differential Revision: https://reviews.llvm.org/D134434
Prefer using these accessors to access the special sub-commands
corresponding to the top-level (no subcommand) and all sub-commands.
This is a preparatory step towards removing the use of ManagedStatic:
with a subsequent change, these global instances will be moved to
be regular function-scope statics.
It is split up to give downstream projects a (albeit short) window in
which they can switch to using the accessors in a forward-compatible
way.
Differential Revision: https://reviews.llvm.org/D129118
This patch refactors BAT to be testable as a library, so we
can have open-source tests on it. This further fixes an issue with
basic blocks that lack a valid input offset, making BAT omit those
when writing translation tables.
Test Plan: new testcases added, new testing tool added (llvm-bat-dump)
Differential Revision: https://reviews.llvm.org/D129382
First of all, `LLVM_TOOLS_INSTALL_DIR` put there breaks our NixOS
builds, because `LLVM_TOOLS_INSTALL_DIR` defined the same as
`CMAKE_INSTALL_BINDIR` becomes an *absolute* path, and then when
downstream projects try to install there too this breaks because our
builds always install to fresh directories for isolation's sake.
Second of all, note that `LLVM_TOOLS_INSTALL_DIR` stands out against the
other specially crafted `LLVM_CONFIG_*` variables substituted in
`llvm/cmake/modules/LLVMConfig.cmake.in`.
@beanz added it in d0e1c2a550ef348aae036d0fe78cab6f038c420c to fix a
dangling reference in `AddLLVM`, but I am suspicious of how this
variable doesn't follow the pattern.
Those other ones are carefully made to be build-time vs install-time
variables depending on which `LLVMConfig.cmake` is being generated, are
carefully made relative as appropriate, etc. etc. For my NixOS use-case
they are also fine because they are never used as downstream install
variables, only for reading not writing.
To avoid the problems I face, and restore symmetry, I deleted the
exported and arranged to have many `${project}_TOOLS_INSTALL_DIR`s.
`AddLLVM` now instead expects each project to define its own, and they
do so based on `CMAKE_INSTALL_BINDIR`. `LLVMConfig` still exports
`LLVM_TOOLS_BINARY_DIR` which is the location for the tools defined in
the usual way, matching the other remaining exported variables.
For the `AddLLVM` changes, I tried to copy the existing pattern of
internal vs non-internal or for LLVM vs for downstream function/macro
names, but it would good to confirm I did that correctly.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D117977
First of all, `LLVM_TOOLS_INSTALL_DIR` put there breaks our NixOS
builds, because `LLVM_TOOLS_INSTALL_DIR` defined the same as
`CMAKE_INSTALL_BINDIR` becomes an *absolute* path, and then when
downstream projects try to install there too this breaks because our
builds always install to fresh directories for isolation's sake.
Second of all, note that `LLVM_TOOLS_INSTALL_DIR` stands out against the
other specially crafted `LLVM_CONFIG_*` variables substituted in
`llvm/cmake/modules/LLVMConfig.cmake.in`.
@beanz added it in d0e1c2a550ef348aae036d0fe78cab6f038c420c to fix a
dangling reference in `AddLLVM`, but I am suspicious of how this
variable doesn't follow the pattern.
Those other ones are carefully made to be build-time vs install-time
variables depending on which `LLVMConfig.cmake` is being generated, are
carefully made relative as appropriate, etc. etc. For my NixOS use-case
they are also fine because they are never used as downstream install
variables, only for reading not writing.
To avoid the problems I face, and restore symmetry, I deleted the
exported and arranged to have many `${project}_TOOLS_INSTALL_DIR`s.
`AddLLVM` now instead expects each project to define its own, and they
do so based on `CMAKE_INSTALL_BINDIR`. `LLVMConfig` still exports
`LLVM_TOOLS_BINARY_DIR` which is the location for the tools defined in
the usual way, matching the other remaining exported variables.
For the `AddLLVM` changes, I tried to copy the existing pattern of
internal vs non-internal or for LLVM vs for downstream function/macro
names, but it would good to confirm I did that correctly.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D117977
and recursively merge all files under said directory. This is similar
to `llvm-profdata merge`.
Differential Revision: https://reviews.llvm.org/D126695
When a profile is collected in a BOLTed binary, the generated
profile is tagged with a header string "boltedcollection" in the first
line of the fdata file. Fix merge-fdata to recognize this header
string and preserve it into the output.
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D125591
