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Documentation issue: gccint: define_split "not" allowed to create pseudos


(This is a copy of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70078)

I'd like to clean up this documentation issue, but need some help:

Dominik Vogt 2016-03-04 11:05:16 UTC
> The section "Defining How to Split Instructions" in the gccint
> manual claims
>
>   The preparation-statements are similar to those statements that are
>   specified for define_expand.
>   ...
>   Unlike those in define_expand, however, these statements must not
>   generate any new pseudo-registers.  Once reload has completed, they
>   also must not allocate any space in the stack frame.
>
> Splitters seem to be allowed to generate new pseudos under
> certain circumstances (some splitters call can_create_psudo_p()).
> So, is this correct instead?
>   ...
>   Unlike those in define_expand, however, once reload has completed
>   these statements must neither generate any new pseudo-registers nor
>   allocate any space in the stack frame.  This can be checked by calling
>   can_create_pseudo_p.

Comment 1 Dominik Vogt 2016-03-04 11:45:00 UTC
> Hijacking this bug report for more unclear documentation in that
> section; proposed changes in marked with <...>.
> 
> Apart from the bad grammar, the meaning of this sentence is a
> mystery:
> 
>   Splitting of jump instruction into sequence that over by another jump 
>   instruction is always valid, as compiler expect identical behavior of
>   new jump.
> 
> =>
> 
>   Splitting of jump instruction<s> into <a> sequence that <??????>
>   another jump instruction is always valid, as <the> compiler
>   expect<s> <???what???>.
> 
> Anybody able to fill in the gaps?

Comment 2 Dominik Vogt 2016-03-04 11:50:36 UTC
> (I'll make a patch with these and some more corrections once it's
> lear how the wording should be.)

Ciao

Dominik ^_^  ^_^

-- 

Dominik Vogt
IBM Germany


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