[Webkit-unassigned] [Bug 33860] potential speed up of parser by recoding expression rules

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=33860





--- Comment #3 from Patrick Mueller <pmuellr at yahoo.com>  2010-01-21 13:19:55 PST ---
Some stats from using YYDEBUG and then running jsc on the file
SunSpider/tests/parse-only/jquery-1.3.2.js, looking at output lines of the
form:

   -> $$ = nterm [whatever}

which appear to be giving interim parse states.

 240,083 total states 
 224,882 states containing "NoNode"
  16,074 states containing "NoBF"
 174,595 states containing "Expr_NoNode"
  10,008 states containing "PostfixExpr_NoNode"
   7,821 states containing "ConditionalExpr_NoNode"

so it looks like concentrating on just the "expressions", and the NoNode
variety in particular, will hit a large swath of the reductions.   The
PostFixExpr and ConditionalExpr counts are interesting, because of the number
of reductions from the first to the last.  There are 13 states between them, so
if you ball-park that 7.8K of them went through all 13 states, that's about
100K states.  40% of the states hit in total.

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