Add support for continuously syncing profile counter updates to a file.
The motivation for this is that programs do not always exit cleanly. On
iOS, for example, programs are usually killed via a signal from the OS.
Running atexit() handlers after catching a signal is unreliable, so some
method for progressively writing out profile data is necessary.
The approach taken here is to mmap() the `__llvm_prf_cnts` section onto
a raw profile. To do this, the linker must page-align the counter and
data sections, and the runtime must ensure that counters are mapped to a
page-aligned offset within a raw profile.
Continuous mode is (for the moment) incompatible with the online merging
mode. This limitation is lifted in https://reviews.llvm.org/D69586.
Continuous mode is also (for the moment) incompatible with value
profiling, as I'm not sure whether there is interest in this and the
implementation may be tricky.
As I have not been able to test extensively on non-Darwin platforms,
only Darwin support is included for the moment. However, continuous mode
may "just work" without modification on Linux and some UNIX-likes. AIUI
the default value for the GNU linker's `--section-alignment` flag is set
to the page size on many systems. This appears to be true for LLD as
well, as its `no_nmagic` option is on by default. Continuous mode will
not "just work" on Fuchsia or Windows, as it's not possible to mmap() a
section on these platforms. There is a proposal to add a layer of
indirection to the profile instrumentation to support these platforms.
rdar://54210980
Differential Revision: https://reviews.llvm.org/D68351
Function names in ObjC can have spaces in them. This interacts poorly
with name compression, which uses spaces to separate PGO names. Fix the
issue by using a different separator and update a test.
I chose "\01" as the separator because 1) it's non-printable, 2) we
strip it from PGO names, and 3) it's the next natural choice once "\00"
is discarded (that one's overloaded).
What's changed since the original commit?
- I fixed up the covmap-V2 binary format tests using a linux VM.
- I weakened the CHECK lines in instrprof-comdat.h to account for the
fact that there have been bugfixes to clang coverage. These will be
fixed up in a follow-up.
- I added an assert to make sure we don't get bitten by this again.
- I constructed the c-general.profraw file without name compression
enabled to appease some bots.
Differential Revision: http://reviews.llvm.org/D18516
llvm-svn: 264658
Function names in ObjC can have spaces in them. This interacts poorly
with name compression, which uses spaces to separate PGO names. Fix the
issue by using a different separator and update a test.
I chose "\01" as the separator because 1) it's non-printable, 2) we
strip it from PGO names, and 3) it's the next natural choice once "\00"
is discarded (that one's overloaded).
This reverts the revert commit beaf3d18. What's changed?
- I fixed up the covmap-V2 binary format tests using a linux VM.
- I updated the expected counts in instrprof-comdat.h to account for
the fact that there have been bugfixes to clang coverage.
- I added an assert to make sure we don't get bitten by this again.
Differential Revision: http://reviews.llvm.org/D18516
llvm-svn: 264641
This reduces sizes of instrumented object files, final binaries,
process images, and raw profile data.
The format of the indexed profile data remain the same.
Differential Revision: http://reviews.llvm.org/D16388
llvm-svn: 260117
This change introduces an instrumentation intrinsic instruction for
value profiling purposes, the lowering of the instrumentation intrinsic
and raw reader updates. The raw profile data files for llvm-profdata
testing are updated.
llvm-svn: 253484
Since the profile can come from 32-bit machines, we need to check the
pointer size. Change the magic number to facilitate this.
Adds tests for reading 32-bit and 64-bit binaries (both big- and
little-endian). The tests write a binary using printf in RUN lines
(like raw-magic-but-no-header.test). Assuming the bots don't complain,
this seems like a better way forward for testing RawInstrProfReader than
committing binary files.
<rdar://problem/16400648>
llvm-svn: 204557
Vedant Kumar