Re: [RFC PATCH v3 26/34] Hexagon (target/hexagon) macros referenced in instruction semantics

[Richard Henderson]

On 8/30/20 1:23 PM, Taylor Simpson wrote:
>> I think the merge stuff is a mistake.  I think you can get the semantics that
>> you want with
>>
>> probe_read(ld_addr, ld_len)
>> qemu_st(st_value, st_addr)
>> qemu_ld(ld_value, ld_addr)
>>
>> In this way, all exceptions are recognized before the store is complete, the
>> normal memory operations handle any possible overlap.
> 
> So, do this inside the helper?  Or is there a way to generate TCG code?

I was thinking TCG code, where you can look at the packet before any code gen,
and decide whether or not this situation actually applies.

The probe is a simple helper call, for which the generic machinery exists
(probe_access, probe_write, probe_read).  All you have to do is write the 
wrapper.

The loads and stores are, well, normal loads and stores.


r~