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

Christian Thalinger christian.thalinger at oracle.com
Mon Jun 11 16:22:10 PDT 2012

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/x8632.ad src/cpu/x86/vm/x8664.ad

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