This reverts commit e35afbe535f96086141f57a5ce7d679429b4405f, reapplying
022ccedde8877e877b45e49641544b5e4fff0b42 and
e7ed5c920db3f537a85d962c1c918a1bb6de99fd.
- The first attempt missed defining `SignpostEmitterImpl`.
- The second attempt missed defining `llvm::SignpostEmitterImpl`.
Not sure how I failed to test both versions locally before; I thought
I'd turned the feature off via rerunning `cmake` but it must have been
stuck in place. This time I confirmed via `clang -E` that I was testing
both build configurations.
Original commit message:
Replace some manual memory management with std::unique_ptr.
Differential Revision: https://reviews.llvm.org/D100151
This reverts commit 078072285d3fbdaa94f9a91140eb5c1223b548af, reapplying
022ccedde8877e877b45e49641544b5e4fff0b42.
I figured out why this was failing in other environments: it's not a
problem with std::unique_ptr, but that SignpostEmitterImpl only has a
forward declaration. Adding an empty definition should do the trick.
Original commit message:
Replace some manual memory management with std::unique_ptr.
Differential Revision: https://reviews.llvm.org/D100151
The destructor for SignPostEmitterImpl::SignpostLog is known statically. Avoid
the unnecessary vtable indirection through std::function in the std::unique_ptr
by turning LogDeleter into a struct. No real functionality change here.
Differential Revision: https://reviews.llvm.org/D100154
This is a DenseMap, which has its own initializer; we don't need to explicitly
call the default constructor here.
Differential Revision: https://reviews.llvm.org/D100152
Add availability checks to the os_signpost code so this can be used with
an older deployment target.
Differential revision: https://reviews.llvm.org/D97410
Use a mutex to protect concurrent access to the signpost map. This fixes
nondeterministic crashes in LLDB that appeared after using signposts in
the timer implementation.
Differential revision: https://reviews.llvm.org/D94285
Make llvm::Signpost more generic by untying from llvm::Timer. This
allows signposts to be used in a different context.
My motivation for doing this is being able to use signposts in LLDB.
Differential revision: https://reviews.llvm.org/D93655
Summary:
Instruments is a useful tool for finding performance issues in LLVM but it can
be difficult to identify regions of interest on the timeline that we can use
to filter the profiler or allocations instrument. Xcode 10 and the latest
macOS/iOS/etc. added support for the os_signpost() API which allows us to
annotate the timeline with information that's meaningful to LLVM.
This patch causes timer start and end events to emit signposts. When used with
-time-passes, this causes the passes to be annotated on the Instruments timeline.
In addition to visually showing the duration of passes on the timeline, it also
allows us to filter the profile and allocations instrument down to an individual
pass allowing us to find the issues within that pass without being drowned out
by the noise from other parts of the compiler.
Using this in conjunction with the Time Profiler (in high frequency mode) and
the Allocations instrument is how I found the SparseBitVector that should have
been a BitVector and the DenseMap that could be replaced by a sorted vector a
couple months ago. I added NamedRegionTimers to TableGen and used the resulting
annotations to identify the slow portions of the Register Info Emitter. Some of
these were placed according to educated guesses while others were placed
according to hot functions from a previous profile. From there I filtered the
profile to a slow portion and the aforementioned issues stood out in the
profile.
To use this feature enable LLVM_SUPPORT_XCODE_SIGNPOSTS in CMake and run the
compiler under Instruments with -time-passes like so:
instruments -t 'Time Profiler' bin/llc -time-passes -o - input.ll'
Then open the resulting trace in Instruments.
There was a talk at WWDC 2018 that explained the feature which can be found at
https://developer.apple.com/videos/play/wwdc2018/405/ if you'd like to know
more about it.
Reviewers: bogner
Reviewed By: bogner
Subscribers: jdoerfert, mgorny, kristina, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D52954
llvm-svn: 354365
