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    Revert of Extend CPU profiler with mapping ticks to source lines (patchset #3... · 08c40baa
    yurys@chromium.org authored
    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, error column reported by window.onerror is now wrong (I believe it is because of the change in full-codegen):
    
    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.pravdin@intel.com>
    > BUG=None
    > LOG=Y
    > R=svenpanne@chromium.org
    >
    > Committed: https://code.google.com/p/v8/source/detail?r=24389
    
    TBR=svenpanne@chromium.org,danno@chromium.org,alph@chromium.org,denis.pravdin@intel.com,weiliang.lin@intel.com
    BUG=None
    LOG=N
    
    Review URL: https://codereview.chromium.org/624443005
    
    git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24394 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
    08c40baa
cpu-profiler.cc 15.1 KB