Re: [PATCH GCC]Fix PR57540, try to choose scaled_offset address mode when expanding array reference

[Eric Botcazou <ebotcazou at adacore dot com>]

> The problem occurs when accessing local array element. For example,
> # VUSE <.MEM_27>
> k_8 = parent[k_29];
> 
> GCC calculates the address in three steps:
> 1) addr is calculated as "r105 + (-2064)".
> 2) offset is calculated as "r165*4".
> 3) calls offset_address to combine the address into "r105+ r165*4 +
> (-2064)".
> 
> Since ADDR is valid and there is no call to memory_address_addr_space in
> offset_address, the invalid address expression has no chance to go through
> target dependent legitimization function.

But offset_address calls change_address_1 with validate set to 1 so during RTL 
expansion memory_address_addr_space should be invoked on the invalid address.

> Even there is a chance, the
> current implementation of memory_address_addr_space prevents the scaled
> address expression from being generated because of below code:
>       if (! cse_not_expected && !REG_P (x))
> 	  x = break_out_memory_refs (x);

Where are the memory references in the above address?

-- 
Eric Botcazou