Request for reviews (S): 7063674: Wrong results from basic comparisons after calls to Long.bitCount(long)

[Christian Thalinger]

On Jun 11, 2012, at 4:14 PM, Vladimir Kozlov wrote:

> I looked around and ReverseBytes instructions (which use shifts in addition to bswap) also missing KILL cr.

Good catch.  I fixed them too and updated the webrev.

-- Chris

> 
> Thanks,
> Vladimir
> 
> Christian Thalinger wrote:
>> http://cr.openjdk.java.net/~twisti/7063674
>> 7063674: Wrong results from basic comparisons after calls to Long.bitCount(long)
>> Reviewed-by:
>> We are scheduling popcnt instructions between compare and branch/conditional
>> move instructions because AD instructs are not defined to kill flags.
>> But the Intel Instruction Set Reference says for POPCNT:
>> Flags Affected
>> OF, SF, ZF, AF, CF, PF are all cleared. ZF is set if SRC = 0, otherwise ZF is cleared
>> The fix is to kill the flags in instructs that are using popcnt instructions.
>> Tested with test case of CR. src/cpu/x86/vm/x86_32.ad
>> src/cpu/x86/vm/x86_64.ad