Commit Graph

3 Commits

Author SHA1 Message Date
jarin
0d4c526a1d [crankshaft] Reland "Only exclude explicit 'arguments' (and 'this') from liveness analysis."
Reland of https://codereview.chromium.org/2026173003 (reverted by
https://codereview.chromium.org/2029563002).

Additionally, we need to record environment markers even for the
case of a.length, where a is aliased arguments (which crankshaft
optimizes to constant for the inlined case or to HArgumentsLength
when not inlined).

BUG=chromium:612146

Review-Url: https://codereview.chromium.org/2028243002
Cr-Commit-Position: refs/heads/master@{#36662}
2016-06-02 04:30:17 +00:00
machenbach
8b0a6dd652 Revert of [crankshaft] Only exclude explicit 'arguments' (and 'this') from liveness analysis. (patchset #2 id:20001 of https://codereview.chromium.org/2026173003/ )
Reason for revert:
Triggers crashes on the deopt fuzzer:
https://build.chromium.org/p/client.v8/builders/V8%20Deopt%20Fuzzer/builds/10608

Repro:
out/Release/d8 --test --random-seed=849179141 --deopt-every-n-times 149 --nohard-abort --nodead-code-elimination --nofold-constants --noconcurrent-recompilation test/webkit/resources/standalone-pre.js test/webkit/dfg-arguments-mixed-alias.js test/webkit/resources/standalone-post.js

Original issue's description:
> [crankshaft] Only exclude explicit 'arguments' (and 'this') from liveness analysis.
>
> Currently, we do not emit EnvironmentMarkers if the hydrogen value
> in the environment is arguments object. As the hydrogen value can change
> for local variables, we emit only some environment markers. That can
> cause environment liveness analysis to mark part of live range as live
> and part as dead. The zapping phase then only inserts zaps in
> live->dead transitions, potentially zapping a live value.
>
> With this CL, we only emit EnvironmentMarkers for 'this' and
> 'arguments' local variables, disregarding the hydrogen value.
>
> BUG=chromium:612146
> LOG=n
>
> Committed: https://crrev.com/1428fbe224dc2df0cb6f59e4959430f7aa614064
> Cr-Commit-Position: refs/heads/master@{#36641}

TBR=jkummerow@chromium.org,jarin@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:612146

Review-Url: https://codereview.chromium.org/2029563002
Cr-Commit-Position: refs/heads/master@{#36644}
2016-06-01 12:45:06 +00:00
jarin
1428fbe224 [crankshaft] Only exclude explicit 'arguments' (and 'this') from liveness analysis.
Currently, we do not emit EnvironmentMarkers if the hydrogen value
in the environment is arguments object. As the hydrogen value can change
for local variables, we emit only some environment markers. That can
cause environment liveness analysis to mark part of live range as live
and part as dead. The zapping phase then only inserts zaps in
live->dead transitions, potentially zapping a live value.

With this CL, we only emit EnvironmentMarkers for 'this' and
'arguments' local variables, disregarding the hydrogen value.

BUG=chromium:612146
LOG=n

Review-Url: https://codereview.chromium.org/2026173003
Cr-Commit-Position: refs/heads/master@{#36641}
2016-06-01 12:04:35 +00:00