Re: [PATCH v2 16/21] accel/tcg: actually cache our partial icount TB

[Alex Bennée]

Philippe Mathieu-Daudé <f4bug@amsat.org> writes:

> On 2/11/21 7:48 PM, Richard Henderson wrote:
>> On 2/11/21 2:21 AM, Philippe Mathieu-Daudé wrote:
>>>> -    insns_left = MIN(0xffff, cpu->icount_budget);
>>>> +    insns_left = MIN(CF_COUNT_MASK, cpu->icount_budget);
>>>
>>> Can you describe this change a bit please?
>> 
>> Replacing a magic number with its proper symbol.
>
> I am confuse because I see:
>
> #define CF_COUNT_MASK  0x00007fff

This is the largest partial count you can store in the CF flags (0x8000
is used for LAST_IO). The decrement field can handle the full u16
although in practice I would never expect a final block to be more than
a few instructions. We could probably shorten the mask without any
deleterious effect if we needed to scrape together any more CFLAGS.

-- 
Alex Bennée