A strange bit of code in MacroAssembler::multiply_128_x_128_loop
vladimir.kozlov at oracle.com
Fri Apr 10 16:30:45 UTC 2015
It restores counter after:
The value could be 1,2,3 before this point (idx & 3 before).
After 'sub 2': -1, 0, 1.
So we have to restore to positive values before subtracting 1.
On 4/10/15 8:12 AM, Daniel D. Daugherty wrote:
> Adding in the Compiler team since this is the MacroAssembler...
> On 4/10/15 9:06 AM, Andrew Haley wrote:
>> This is for x86:
>> addl (idx, 0x2);
>> andl (idx, 0x1);
>> subl(idx, 1);
>> jcc(Assembler::negative, L_post_third_loop_done);
>> I'm trying to guess what the "addl (idx, 0x2)" instruction was supposed to do.
>> I don't think it has any effect now.
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