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

[joseph at codesourcery dot com]

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

--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
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)?

(The Clang __builtin_addc* / __builtin_subc* functions might also be a 
useful addition for this sort of purpose.)