Re: input address reload issue

[Aurelien Buhrig <aurelien dot buhrig dot gcc at gmail dot com>]

>> So the insn:
>> (set (reg:QI 0 r0) (mem:QI (plus:SI (reg:SI 2 r2)(const_int 1))
>>
>> is transformed into:
>> (set (reg:SI 8 a0) (reg:SI 2 r2))
>> (set (reg:SI 8 a0) (const_int 1))
>> (set (reg:SI 8 a0) (plus:SI (reg:SI 8 a0) (reg:SI 8 a0)))
>> (set (reg:QI 0 r0) (mem:QI (reg:SI 8 a0))
>>
>> This "basic" transformation requires two reload regs, but only one is
>> given/used/possible from the rl structure (in emit_reload_insns).
>>
>> So where does the issue comes from? The need for 2 reload regs, the
>> transformation which is too "basic" and could be optimized to use only
>> one reload reg, or any wrong/missing reload target hook?
> Sounds like you need secondary or intermediate reloads.
Thank you Jeff for your help.
Currently, the TARGET_SECONDARY_RELOAD does not check if the address of
a mem rtx is legitimate address and it returns NO_REG with (mem:QI r2).
Do you suggest the secondary reload must implement a scratch reg & md
pattern to implement this reload?