Request for reviews (S): 7097546: Optimize use of CMOVE instructions
tom.rodriguez at oracle.com
Tue Oct 25 16:36:54 PDT 2011
On Oct 21, 2011, at 4:23 PM, Vladimir Kozlov wrote:
> 7097546: Optimize use of CMOVE instructions
> Avoid CMove in a loop if possible. May generate CMove if it could be moved outside a loop. Don't generated CMoveD/CmoveF: it is expensive to compute both float/double values + cmove. Note, on x86 when SSE>=2 (all modern cpus) CMoveD/CMoveF mach instructions are implemented as jmp+move. Don't generated CMove when BlockLayoutByFrequency optimization moves infrequent branch from hot path. Added Cmove mach instructions with jmp+move to x86 when there is no HW cmove instruction.
> Main part of changes in loopopts.cpp is coding style correction.
> Print size of compiled method and compilation time when PrintCompilation and PrintInlining are specified on command line. I thought first to print it with just PrintCompilation but it will double output.
> No effect on refworkload but it will help later for 6890673 fix. Verified with microbenchmark I wrote (attached to the bug report).
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