[Webkit-unassigned] [Bug 38814] Improve string indexing performance

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=38814


Chao-ying Fu <fu at mips.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fu at mips.com




--- Comment #5 from Chao-ying Fu <fu at mips.com>  2010-05-12 16:40:10 PST ---
Hi,

  I think the code in JIT::stringGetByValStubGenerator() may contain redundant code.
Ex:
...
#if USE(JSVALUE64)
    jit.zeroExtend32ToPtr(regT1, regT1);
#else
    jit.emitFastArithImmToInt(regT1);
#endif
...

  The same code appears in "JIT::emit_op_get_by_val()".  So, we may execute one more time in stringGetByValStubGenerator().

  I need to comment out jit.emitFastArithImmToInt(regT1) for MIPS to fix two new regressions.  Otherwise, regT1 is shifted right by 1 bit (twice) and the index to a string is wrong.  Thanks a lot!

Ex:
# svn diff JITPropertyAccess.cpp
...
-#if USE(JSVALUE64)
-    jit.zeroExtend32ToPtr(regT1, regT1);
-#else
-    jit.emitFastArithImmToInt(regT1);
-#endif


Regards,
Chao-ying

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