зеркало из https://github.com/mozilla/gecko-dev.git
7eda9d1a96
This removes LUL's ability to recover frames by the heuristic mechanism of
stack scanning. Stack scanning is a last-ditch way to try to recover the
unwind when all other methods (metadata-based, frame-pointer chasing) have
failed, by scanning back up the stack and looking for the first word that
could plausibly be a return address. It often mis-identifies return addresses
because it has no way to distinguish live ones from dead ones that have not
been overwritten, and very often causes the unwind to fail as a result.
In any case LUL's stack scanning ability has actually been switched off (by
the parameters passed to LUL::Unwind) for some considerable time now, so this
change should make no observable difference to behaviour. Specific changes:
In LUL::Unwind():
* Removes formal parameters |scannedFramesAcquired| and |scannedFramesAllowed|
* Removes code that does stack scanning
* Simplifies control flow in the main unwind loop, so that loop now
has the easier-to-follow structure
while (true) {
// preliminary stuff
if (CFI data available for current PC) {
do CFI step;
continue;
}
if (FP chasing possible for current PC) {
do FP step;
continue;
}
// give up
break;
}
* Moves two #ifdefs upwards to enclose the comments pertaining to them, as
well as the code. This makes the top level structure easier to follow. The
corresponding #endifs are likewise commented with the condition.
From class LULStats, removes |mScanned|.
Removes PriMap::MaybeIsReturnPoint() entirely. This is a heuristic helper
only used by stack scanning.
In all, 395 lines of code are removed, according to hg diff --stat.
--HG--
extra : rebase_source : 5ffa73c64923149a58df3228cf940cb539f8f707
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| .. | ||
| bloatview | ||
| compare-locales | ||
| coverity | ||
| docs | ||
| fuzzing | ||
| git | ||
| jprof | ||
| leak-gauge | ||
| lint | ||
| memory-profiler | ||
| mercurial | ||
| power | ||
| profiler | ||
| quitter | ||
| rb | ||
| rewriting | ||
| update-packaging | ||
| mach_commands.py | ||
| moz.build | ||