[patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit targets

[Nigel Stephens]

Richard Sandiford wrote:

>Nigel Stephens <nigel@mips.com> writes:
>  
>
>>I have a patch against gcc-3.4 
>><snip>
>>If people really don't like the inline expansion, then maybe it could be
>>enabled or disabled by a new -m option.
>>    
>>
>
>IMO, controlling with optimize_size would be enough.  
>

Yes, that sounds right.

>But it sounds from
>your description like the patch just adds a new hard-coded multi-insn
>asm string.  Is that right?  If so, I'd really like to avoid that.
>
>  
>

Yes, and I totally agree with you.

>It would much better IMO if we handle this in the target-independent
>parts of the compiler.  We can already open-code certain non-native
>operations, it's "just" that wide shifts are a missing case.
>
>  
>

>If we handle it in a target-independent way, with each insn exposed
>separately, we will be able to optimize special cases better.
>We'll also get the usual scheduling benefits.
>  
>

I agree that we should open-code it for the obvious reasons, but does it 
have to be target independent, or could/should we prototype it with 
define_expand?

Nigel