2008-10-08 Maciej Stachowiak <mjs@apple.com>

2008-10-08  Maciej Stachowiak  <mjs@apple.com>

        Reviewed by Oliver Hunt.

        Re-landing the following fix with the crashing bug in it fixed (r37405):

        - optimize away multiplication by constant 1.0

        2.3% speedup on v8 RayTrace benchmark

        Apparently it's not uncommon for JavaScript code to multiply by
        constant 1.0 in the mistaken belief that this converts integer to
        floating point and that there is any operational difference.

        * VM/CTI.cpp:
        (JSC::CTI::privateCompileMainPass): Optimize to_jsnumber for
        case where parameter is already number.
        (JSC::CTI::privateCompileSlowCases): ditto
        * VM/Machine.cpp:
        (JSC::Machine::privateExecute): ditto
        * kjs/grammar.y:
        (makeMultNode): Transform as follows:
        +FOO * BAR ==> FOO * BAR
        FOO * +BAR ==> FOO * BAR
        FOO * 1 ==> +FOO
        1 * FOO ==> +FOO
        (makeDivNode): Transform as follows:
        +FOO / BAR ==> FOO / BAR
        FOO / +BAR ==> FOO / BAR
        (makeSubNode): Transform as follows:
        +FOO - BAR ==> FOO - BAR
        FOO - +BAR ==> FOO - BAR
        * kjs/nodes.h:
        (JSC::ExpressionNode::stripUnaryPlus): Helper for above
        grammar.y changes
        (JSC::UnaryPlusNode::stripUnaryPlus): ditto

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@37417 268f45cc-cd09-0410-ab3c-d52691b4dbfc