Re: [PATCH] tcg: refactor pool data for simplicity and comprehension

[Richard Henderson <richard.henderson@linaro.org>]

On 2/15/25 14:40, Michael Clark wrote:
> On 2/16/25 10:50, Richard Henderson wrote:
>> On 2/15/25 12:24, Michael Clark wrote:
>>>> Why?  varargs generally produces horrible code.
>>>> The split between alloc and insert was intentional to avoid this.
>>>
>>> it's pretty good code on SysV because it goes via registers except for perhaps 
>>> new_pool_l8 which will spill to stack and get copied unless the inliner can eliminate 
>>> the copies. maybe windows has bad varargs. but I like the style better than deeper 
>>> layers of wrapper functions. they should fix the compiler so that it produces better code.
>>
>> varargs will generally prevent inlining.
>>
>> Indeed, just a quick look at aarch64 tcg_out_movi shows that without your change, 
>> new_pool_label, new_pool_data and new_pool_insert are all inlined.  With your change, 
>> new_pool_data is not inlined, all the argument regs are dumped to the stack, etc.
>>
>> I don't think this is a good change to make.
> 
> fixing varargs codegen in GCC/Clang would be a good change. count based varargs can be 
> reasoned about statically relatively easily. what is it like with an explicit inline as 
> opposed to just static?

Inline will still be rejected.


r~