Time profiler emits relative timestamps for events (the number of
microseconds passed since the start of the current process).
This patch allows combining events from different processes while
preserving their relative timing by emitting a new attribute
"beginningOfTime". This attribute contains the system time that
corresponds to the zero timestamp of the time profiler.
This has at least two use cases:
- Build systems can use this to merge time traces from multiple compiler
invocations and generate statistics for the whole build. Tools like
ClangBuildAnalyzer could also leverage this feature.
- Compilers that use LLVM as their backend by invoking llc/opt in
a child process. If such a compiler supports generating time traces
of its own events, it could merge those events with LLVM-specific
events received from llc/opt, and produce a more complete time trace.
A proof-of-concept script that merges multiple logs that
contain a synchronization point into one log:
https://github.com/broadwaylamb/merge_trace_events
Differential Revision: https://reviews.llvm.org/D78030
Added a write method for TimeTrace that takes two strings representing
file names. The first is any file name that may have been provided by the
user via `time-trace-file` flag, and the second is a fallback that should
be configured by the caller. This method makes it cleaner to write the
trace output because there is no longer a need to check file names at the
caller and simplifies future TimeTrace usages.
Reviewed By: modocache
Differential Revision: https://reviews.llvm.org/D74514
This patch wraps an external thread local storage variable inside of a
getter function and makes it have internal linkage. This allows LLVM to
be built with BUILD_SHARED_LIBS on windows with MinGW. Additionally it
allows Clang versions prior to 10 to compile current trunk for MinGW.
Differential Revision: https://reviews.llvm.org/D73639
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.
This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.
This doesn't actually modify StringRef yet, I'll do that in a follow-up.
This makes TimeTraceProfilerInstance thread local. Added
timeTraceProfilerFinishThread() which moves the thread local instance to
a global vector of instances. timeTraceProfilerWrite() then writes
recorded data from all instances.
Threads are identified based on their thread ids. Totals are reported
with artificial thread ids higher than the real ones.
This fixes the previous version to work with __thread as well as
thread_local.
Differential Revision: https://reviews.llvm.org/D71059
and "[Support] Try to fix bot failure after 8ddcd1dc26"
This reverts commits f70f180148 and 8ddcd1dc26 as this was breaking the
MacOS build, which doesn't support thread_local.
Following on from 8ddcd1dc26, which added the support. As pointed out
on D71059 this does not build on some systems with LLVM_ENABLE_THREADS=OFF.
Differential Revision: https://reviews.llvm.org/D71548
This makes TimeTraceProfilerInstance thread local. Added
timeTraceProfilerFinishThread() which moves the thread local instance to
a global vector of instances. timeTraceProfilerWrite() then writes
recorded data from all instances.
Threads are identified based on their thread ids. Totals are reported
with artificial thread ids higher than the real ones.
Replaced raw pointer for TimeTraceProfilerInstance with unique_ptr.
Differential Revision: https://reviews.llvm.org/D71059
This simplifies code where no extra details are required
Also don't write out detail when it is empty.
Differential Revision: https://reviews.llvm.org/D71347
This was hard-coded to "clang". This change allows it to to be used on
processes other than clang (such as lld).
This gets reported as clang-10 on Linux and clang.exe on Windows so
adapted test to accommodate this.
Differential Revision: https://reviews.llvm.org/D70950
-ftime-trace could break flame-graph assumptions on Windows, with an
inner scope overrunning outer scopes. This was due to the way that times
were truncated. Changed this so time_points for the flame-graph are
truncated instead of durations, preserving the relative order of event
starts and ends.
I have tried to retain the extra precision for the totals, which count
thousands or millions of events.
Added assert to check this property holds in future.
Fixes PR43043
Differential Revision: https://reviews.llvm.org/D66411
llvm-svn: 371039
Summary:
Add `Frontend` time trace entry to `HandleTranslationUnit()` function.
Add test to check all codegen blocks are inside frontend blocks.
Also, change `--time-trace-granularity` option a bit to make sure very small
time blocks are outputed to json-file when using `--time-trace-granularity=0`.
This fixes http://llvm.org/pr41969
Reviewers: russell.gallop, lebedev.ri, thakis
Reviewed By: russell.gallop
Subscribers: vsapsai, aras-p, lebedev.ri, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D63325
llvm-svn: 369308
Summary:
Move `-ftime-trace-granularity` option to frontend options. Without patch
this option is showed up in the help for any tool that links libSupport.
Reviewers: sammccall
Subscribers: hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D65202
llvm-svn: 366911
Summary:
There's still a little bit of constant factor that could be trimmed (e.g.
more overloads to avoid round-tripping primitives through json::Value).
But this solves the memory scaling problem, and greatly improves the performance
constant factor, and the API should leave room for optimization if needed.
Adapt TimeProfiler to use it, eliminating almost all the performance regression
from r358476.
Performance test on my machine:
perf stat -r 5 ~/llvmbuild-opt/bin/clang++ -w -S -ftime-trace -mllvm -time-trace-granularity=0 spirit.cpp
Handcrafted JSON (HEAD=r358532 with r358476 reverted): 2480ms
json::Value (HEAD): 2757ms (+11%)
After this patch: 2520 ms (+1.6%)
Reviewers: anton-afanasyev, lebedev.ri
Subscribers: kristina, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60804
llvm-svn: 359186
Summary:
Use llvm::json::Array.reserve() to optimize json output time. Here is motivation:
https://reviews.llvm.org/D60609#1468941. In short: for the json array
with ~32K entries, pushing back each entry takes ~4% of whole time compared
to the method of preliminary memory reservation: (3995-3845)/3995 = 3.75%.
Reviewers: lebedev.ri
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60792
llvm-svn: 358522
Summary:
Use optimized hashing while writing time trace by join two hashes to one.
Used for -ftime-trace option.
Reviewers: rnk, takuto.ikuta
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60404
llvm-svn: 357998
This change adds hierarchical "time trace" profiling blocks that can be visualized in Chrome, in a "flame chart" style. Each profiling block can have a "detail" string that for example indicates the file being processed, template name being instantiated, function being optimized etc.
This is taken from GitHub PR: https://github.com/aras-p/llvm-project-20170507/pull/2
Patch by Aras Pranckevičius.
Differential Revision: https://reviews.llvm.org/D58675
llvm-svn: 357340
Sergej Jaskiewicz