579466 - JM: fast path for JSOP_MOD on int operands

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[David Mandelin [:dmandelin]]

We do 223331 of these in SunSpider. 

JM wanted SS win: 9 ms

Comment 1

[Sean Stangl [:sstangl]]

Integer mod should be done using idiv. Since this requires clobbering %eax and %edx, mod should not be implemented within jsop_binary(), even though its constant-folding function can be used.

This is highly non-trivial to implement in the current state if you want fast-paths for (int, double) and (double, int), like jsop_binary() has.

Comment 2

[David Mandelin [:dmandelin]]

(In reply to comment #1)
> This is highly non-trivial to implement in the current state if you want
> fast-paths for (int, double) and (double, int), like jsop_binary() has.

We only need mod for ints for now.

Comment 3

[David Anderson [:dvander] - inactive, e-mail if emergency]

this path ends up being pretty gross, lots of guards. down to ~11,000 calls to slow::Mod now.

looks like a 5.5ms win, though it's not totally clear where this went. the biggest deltas are in users of MOD, though.

http://hg.mozilla.org/users/danderson_mozilla.com/moo/rev/4997d6d1141d