Bug 20796 – Combine op_eq and op_lesseq with op_jfalse

• Status: RESOLVED
• Resolution: INVALID
• Component: JavaScriptCore

[Gabor Loki]

I have found that op_eq and op_jfalse instructions appear 441683 times (0.72%) and op_lesseq and op_jfalse are 340196 times (0.55%) in SunSpider.

These two instruction pair mostly come up in condition fields, where the results of the binary operator never used after the jump.

So it is possible to introduce two super-instructions for those cases (like op_jnless).
I have implemented these op_jneq and op_jnlesseq instructions, and the result is 0.8% progression in SunSpider.

[Gabor Loki]

Created attachment 23369 [details]
op_jneq and op_jnlesseq instructions

[Gabor Loki]

Created attachment 23370 [details]
SunSpider result for op_jneq and op_jnlesseq instructions

[Maciej Stachowiak]

Looks like some good results, though we will also need CTI / native code implementations of these.

[Darin Adler]

Maciej, this seems to be related to the work you're doing right now. Maybe you could review and land this?

[Darin Adler]

Comment on attachment 23369 [details]
op_jneq and op_jnlesseq instructions

Looks great.

Now that CTI is landed, we need the CTI versions -- we can't add an opcode without that. So review- because of that issue.

[Gabor Loki]

Created attachment 25263 [details]
op_jneq and op_jnlesseq instructions (v2)

I have added the CTI part of these instructions.
The SunSpider results are the follwing on Qt-linux:
 - NON-JIT: 1.007% progression
 - JIT: 1.001% propression

I am going to attach the full SunSpider, V8, WindScorpion results.

[Gabor Loki]

Err. Wrong number. Those numbers are from sunspider-compare-results, but they are not percentages.

The valid numbers:
 - NON-JIT: 0.7% progression
 - JIT: 0.1% propression

[Gabor Loki]

Created attachment 25269 [details]
SunSpider, V8, WindScorpion results (non-jit)

Here are the non-JIT results of the last patch on Qt-linux.

[Gabor Loki]

Created attachment 25270 [details]
SunSpider, V8, WindScorpion results (JIT)

JIT results of the last patch on Qt-linux.

[Gabor Loki]

Created attachment 26094 [details]
op_jneq and op_jnlesseq instructions (v3)

I have updated the previous patch on ToT.
The results are almost the same. I will attach them later.

[Gabor Loki]

Created attachment 26095 [details]
SunSpider, V8, WindScorpion results (non-jit)

[Gabor Loki]

Created attachment 26096 [details]
SunSpider, V8, WindScorpion results (JIT)

[Eric Seidel (no email)]

Is this bug even still relevant?  It's been sitting in the queue for 5 months...

[Gabor Loki]

This is still valid. There is about 1-2% progression on x86 without JIT. I am going to send the patch and the results tomorrow.

[Gabor Loki]

It looks like op_jnlesseq instruction have been added in r43401. The op_jneq does not give more speedup on x86 without JIT. So, this bug should be closed.

[Eric Seidel (no email)]

Closing per loki's comment.

[Eric Seidel (no email)]

Comment on attachment 26094 [details]
op_jneq and op_jnlesseq instructions (v3)

obsoleting patch.