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Documentation issue: gccint: define_split "not" allowed to create pseudos
- From: Dominik Vogt <vogt at linux dot vnet dot ibm dot com>
- To: gcc at gcc dot gnu dot org
- Date: Tue, 15 Mar 2016 07:18:02 +0100
- Subject: Documentation issue: gccint: define_split "not" allowed to create pseudos
- Authentication-results: sourceware.org; auth=none
- Reply-to: vogt at linux dot vnet dot ibm dot com
(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
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
> 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.)
Dominik ^_^ ^_^