[Bug tree-optimization/60206] IVOPT has no idea of inline asm

[olegendo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60206

Oleg Endo <olegendo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |olegendo at gcc dot gnu.org

--- Comment #8 from Oleg Endo <olegendo at gcc dot gnu.org> ---
(In reply to joseph@codesourcery.com from comment #3)
> On Fri, 14 Feb 2014, pinskia at gcc dot gnu.org wrote:
> 
> > I think the real issue __FP_FRAC_SUB_4 needs to be fixed not to use inline-asm
> > but normal C code.  The normal C code should be able to produce as good as the
> > inline-asm code now too.
> 
> Does GCC do a good job of detecting add-with-carry and 
> subtract-with-borrow patterns (i.e. detecting the comparison that 
> corresponds to the carry flag and its use in a subsequent operation)?

This can be done with combine patterns, although there are some limitations and
it has to be done for each target individually.  See also PR 54236, in
particular comment 6.