1136993 - JSNES spends 8% of time in MulValues

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Sean Stangl [:sstangl]]

We're doing much better than d8, but a profile of the JSNES shell benchmark shows 8% of time spent in the VM multiplying values, which is suspicious.

Comment 1

[Jan de Mooij [:jandem]]

Is this for a JSOP_POS maybe? It could be the same issue as bug 1131537...

Comment 2

[Sean Stangl [:sstangl]]

Yeah, it appears to be for JSOP_POS. The value flowing into the MMul is, e.g. (not in analysis mode):

TypeBarrier(CallGetProperty(Object, "lengthCounter"))

where "lengthCounter" is initialized to null, reset to integer 0, and usually an integer. So although static analysis would tell us that it can be Object null, baseline caches should only see Int32.

Comment 3

[Sean Stangl [:sstangl]]

It appears that TI claims to know nothing about these accesses.

Comment 4

[Tom S]

I just saw a underscore benchmark that spends 37% of its runtime in MulValues: http://jsperf.com/underscore-indexof-binary/2#chart=bar

Comment 5

[Tom S]

Oh this is bug 1131537.

Comment 6

[André Bargull [:anba]]

Bug 1131537 has been closed as WFM.

This bug report has no link to a test case available, therefore closing as INCOMPLETE.