Last Comment Bug 1329016 - CacheIR: Allow -0 (negative zero) index
: CacheIR: Allow -0 (negative zero) index
: perf
Product: Core
Classification: Components
Component: JavaScript Engine: JIT (show other bugs)
: unspecified
: Unspecified Unspecified
P3 normal with 1 vote (vote)
: mozilla53
Assigned To: Tom Schuster [:evilpie]
: Hannes Verschore [:h4writer]
Depends on:
Blocks: CacheIR jsperf
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Reported: 2017-01-05 13:58 PST by Tom Schuster [:evilpie]
Modified: 2017-01-20 19:05 PST (History)
2 users (show)
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Allow negative zero in CacheIR index check (2.14 KB, patch)
2017-01-19 08:43 PST, Tom Schuster [:evilpie]
jdemooij: review+
Details | Diff | Splinter Review

Description User image Tom Schuster [:evilpie] 2017-01-05 13:58:10 PST
Google Docs has IC misses caused by -0. We can truncate those to 0, because ToString(-0) is "0". (Btw we can't do this for strings like "-0", integer exotic objects should even return undefined for this)

We have to communicate this clearly, because if we try to use guardIsInt32 outside of array accesses this is not a valid transformation!
Comment 1 User image Tom Schuster [:evilpie] 2017-01-19 08:43:19 PST
Created attachment 8828387 [details] [diff] [review]
Allow negative zero in CacheIR index check

As you said, fixing bug 1330793 made this trivial.
Comment 2 User image Jan de Mooij [:jandem] 2017-01-19 09:31:40 PST
Comment on attachment 8828387 [details] [diff] [review]
Allow negative zero in CacheIR index check

Review of attachment 8828387 [details] [diff] [review]:

Comment 3 User image Pulsebot 2017-01-20 03:44:13 PST
Pushed by
Allow negative zero in CacheIR index check. r=jandem
Comment 4 User image Phil Ringnalda (:philor) 2017-01-20 19:05:12 PST

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