On Wed, Jul 30, 2008 at 3:06 PM, Michael McCandless <[EMAIL PROTECTED]> wrote: > > Neat! > > Do you know how to get the corresponding asm that the hostpot compiler > produces? This way we can see if this difference "survives" through java...
Thanks to the tool that Stephen pointed out, I can now see that the difference does survive. -Yonik > Yonik Seeley wrote: > >> disclaimer: this is just for fun.... differences should be in the >> noise in any complex system, and I'm not suggesting any code changes. >> >> Actually, with 32 bit registers, x<0 should be faster than x==-1 by >> one cycle. If it doesn't test faster, then it's because of some >> optimizations that could be pulled off via inlining and data flow >> analysis (set of -1 followed by a check for -1, etc). >> >> Here's the optimized code that gcc produces for a 64 bit long comparison: >> >> # if (foo() == -1) >> andl %edx, %eax >> incl %eax >> jne L2 >> >> # if (foo() < 0) >> testl %edx, %edx >> jns L9 >> >> -Yonik >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
