RESOLVED FIXED 19821
Merge the instruction pair (less, jfalse) 
https://bugs.webkit.org/show_bug.cgi?id=19821
Summary Merge the instruction pair (less, jfalse)
Cameron Zwarich (cpst)
Reported 2008-06-29 19:56:49 PDT
The pair (less, jfalse) is 1.61% of SunSpider instruction pairs. Merging them into a new opcode jnless is generally a win, but is a large regression on the regexp-dna and nbody tests.
Attachments
Patch (3.92 KB, patch)
2008-06-29 19:58 PDT, Cameron Zwarich (cpst) 		no flags
DetailsFormatted DiffDiff
SunSpider results (3.55 KB, text/plain)
2008-06-29 20:01 PDT, Cameron Zwarich (cpst) 		no flags
Details
Proposed patch (4.94 KB, patch)
2008-06-29 23:03 PDT, Cameron Zwarich (cpst) 		oliver: review+
DetailsFormatted DiffDiff
New SunSpider results (3.58 KB, text/plain)
2008-06-29 23:04 PDT, Cameron Zwarich (cpst) 		no flags
Details
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.
Cameron Zwarich (cpst)
Comment 1 2008-06-29 19:58:07 PDT
Created attachment 21999 [details] Patch Here's a patch that implements jnless. It has no dump code for the new opcode and the opcode documentation is wrong.
Cameron Zwarich (cpst)
Comment 2 2008-06-29 20:01:39 PDT
Created attachment 22000 [details] SunSpider results Here are the SunSpider results. I'll do a before-and-after with Shark on the regexp-dna test.
Cameron Zwarich (cpst)
Comment 3 2008-06-29 22:11:25 PDT
The regression seems to be entirely caused by the CodeGenerator logic, even though the regexp-dna test doesn't hit it. I can substitute an empty opcode at the end of the opcodes in Machine.cpp and I still get the regression. If I remove the extra logic in CodeGenerator::emitJumpIfFalse, it's fine.
Cameron Zwarich (cpst)
Comment 4 2008-06-29 23:03:49 PDT
Created attachment 22002 [details] Proposed patch It turns out that the regression was entirely due to the changes in CodeGenerator. Adding ALWAYS_INLINE to CodeGenerator::rewindBinaryOp() fixed the regression. It is now a 2.4% progression on SunSpider.
Cameron Zwarich (cpst)
Comment 5 2008-06-29 23:04:36 PDT
Created attachment 22003 [details] New SunSpider results Here are new SunSpider results, for a reference.
Oliver Hunt
Comment 6 2008-06-29 23:10:26 PDT
Comment on attachment 22002 [details] Proposed patch r=me
Cameron Zwarich (cpst)
Comment 7 2008-06-29 23:26:04 PDT
Landed in r34883.
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