Bug 151607 – Snippefy op_div for the baseline JIT.

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Mark Lam]

Patch coming.

[Radar WebKit Bug Importer]

<rdar://problem/23664944>

[Mark Lam]

Created attachment 266168 [details]
proposed patch.

This patch has passed the JSC tests on x86, x86_64, armv7, and arm64.  It has also passed the layout test on x86_64.

[WebKit Commit Bot]

Attachment 266168 [details] did not pass style-queue:


ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:42:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:43:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:44:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:45:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:46:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:47:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:48:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:49:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:50:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:51:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:63:  The parameter name "op" adds no information, so it should be removed.  [readability/parameter_name] [5]
Total errors found: 11 in 12 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Csaba Osztrogonác]

I'll check the Linux build in a day.

[Csaba Osztrogonác]

Comment on attachment 266168 [details]
proposed patch.

View in context: https://bugs.webkit.org/attachment.cgi?id=266168&action=review

> Source/JavaScriptCore/jit/JITDivGenerator.cpp:29
> +#include "config.h"
> +
> +#if ENABLE(JIT)
> +#include "JITDivGenerator.h"

The primary header should be next to config.h, and including
JSCJSValueInlines.h fixes EFL build and I think GTK too.

#include "config.h"
#include "JITDivGenerator.h"

#if ENABLE(JIT)

#include "JSCJSValueInlines.h"

[Mark Lam]

Thanks.  Will fix.

(In reply to comment #5)
> Comment on attachment 266168 [details]
> proposed patch.
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=266168&action=review
> 
> > Source/JavaScriptCore/jit/JITDivGenerator.cpp:29
> > +#include "config.h"
> > +
> > +#if ENABLE(JIT)
> > +#include "JITDivGenerator.h"
> 
> The primary header should be next to config.h, and including
> JSCJSValueInlines.h fixes EFL build and I think GTK too.
> 
> #include "config.h"
> #include "JITDivGenerator.h"
> 
> #if ENABLE(JIT)
> 
> #include "JSCJSValueInlines.h"

[Mark Lam]

Created attachment 266187 [details]
patch 2: with build fixes for linux ports.

[WebKit Commit Bot]

Attachment 266187 [details] did not pass style-queue:


ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:42:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:43:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:44:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:45:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:46:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:47:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:48:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:49:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:50:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:51:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
Total errors found: 10 in 12 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Mark Lam]

Created attachment 266191 [details]
patch 3: some cosmetic changes to make later refactoring of other operators to use SnippetOperand cleaner.

[WebKit Commit Bot]

Attachment 266191 [details] did not pass style-queue:


ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:42:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:43:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:44:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:45:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:46:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:47:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:48:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:49:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:50:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
ERROR: Source/JavaScriptCore/jit/JITDivGenerator.h:51:  Wrong number of spaces before statement. (expected: 12)  [whitespace/indent] [4]
Total errors found: 10 in 12 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Mark Lam]

Created attachment 266274 [details]
x86_64 benchmark result.

[Mark Lam]

Created attachment 266275 [details]
x86 benchmark result.

[Mark Lam]

Created attachment 266276 [details]
x86_64 benchmark result without DFG.

[Mark Lam]

Created attachment 266277 [details]
x86 benchmark result without DFG.

[Mark Lam]

From the benchmark results, perf appears to be a wash when the DFG is enabled.

With the DFG disabled, perf on x86_64 is also a wash.  The only "definitely" result that was reproducible was Kraken's audio-fft which was 1.05x slower.  However, simply adding 2 xor instructions to the snippet (effectively no-ops) makes this regression disappear.  In summary, this regression is likely to be due to cache-line alignment effects i.e. not something we should worry about.

With the DFG disabled, perf on x86 is also mostly a wash with 3 differences that were reproducible:
    LongSpider's math-spectral-norm: definitely 1.0269x slower
    JSRegress' constant-test: definitely 1.1342x faster
    JSRegress' div-boolean-double: definitely 1.2549x faster

Inspecting the generated code for x86, the op_div snippet is slightly less efficient for x86.  This is what accounts for the 2.7x regression on math-spectral-norm.  However, this had no impact on the aggregate score for LongSpider.  So, we're going to let it slide.

[Geoffrey Garen]

> This is what accounts for the 2.7x regression on math-spectral-norm.

2.7%

[Mark Lam]

(In reply to comment #16)
> > This is what accounts for the 2.7x regression on math-spectral-norm.
> 
> 2.7%

Yes, it's a typo: should be 2.7%, not 2.7x.

[Geoffrey Garen]

Comment on attachment 266191 [details]
patch 3: some cosmetic changes to make later refactoring of other operators to use SnippetOperand cleaner.

r=me

[Mark Lam]

Thanks for the review.  Landed in r192836: <http://trac.webkit.org/r192836>.