Reviewers: Sven Panne, danno, alph, Denis Pravdin, Weiliang,
Message:
Created Revert of Extend CPU profiler with mapping ticks to source lines
Description:
Revert of Extend CPU profiler with mapping ticks to source lines (patchset
#3
id:40001 of https://codereview.chromium.org/616963005/)
Reason for revert:
It broke layout test fast/events/window-onerror-02.html:
http://build.chromium.org/p/client.v8/builders/V8-Blink%20Linux%2064%20%28dbg%29/builds/652
Original issue's description:
Extend CPU profiler with mapping ticks to source lines
The idea behind of this solution is to use the existing "relocation info"
instead of consumption the CodeLinePosition events emitted by the V8
compilers.
During generation code and relocation info are generated simultaneously.
When code generation is done you each code object has
associated "relocation
info".
Relocation information lets V8 to mark interesting places in the generated
code: the pointers that might need to be relocated (after garbage
collection),
correspondences between the machine program counter and source locations
for
stack walking.
This patch:
1. Add more source positions info in reloc info to make it suitable for
source
level mapping.
The amount of data should not be increased dramatically because (1) V8
already
marks interesting places in the generated code and
(2) V8 does not write redundant information (it writes a pair (pc_offset,
pos)
only if pos is changed and skips other).
I measured it on Octane benchmark - for unoptimized code the number of
source
positions may achieve 2x ('lin_solve' from NavierStokes benchmark).
2. When a sample happens, CPU profiler finds a code object by pc, then
use its
reloc info to match the sample to a source line.
If a source line is found that hit counter is increased by one for this
line.
3. Add a new public V8 API to get the hit source lines by CDT CPU
profiler.
Note that it's expected a minor patch in Blink to pack the source level
info
in JSON to be shown.
4.Add a test that checks how the samples are distributed through source
lines.
It tests two cases: (1) relocation info created during code generation
and (2)
relocation info associated with precompiled function's version.
Patch from Denis Pravdin <denis.prav...@intel.com>
BUG=None
LOG=Y
R=svenpa...@chromium.org
Committed: https://code.google.com/p/v8/source/detail?r=24389
TBR=svenpa...@chromium.org,da...@chromium.org,a...@chromium.org,denis.prav...@intel.com,weiliang....@intel.com
NOTREECHECKS=true
NOTRY=true
BUG=None
Please review this at https://codereview.chromium.org/624443005/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+55, -346 lines):
M include/v8-profiler.h
M src/api.cc
M src/cpu-profiler.cc
M src/full-codegen.cc
M src/profile-generator.h
M src/profile-generator.cc
M src/profile-generator-inl.h
M test/cctest/test-cpu-profiler.cc
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