[Bug tree-optimization/59660] We fail to optimize common boolean checks pre-inlining

[rguenther at suse dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59660

--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 7 Jan 2014, hubicka at ucw dot cz wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59660
> 
> --- Comment #4 from Jan Hubicka <hubicka at ucw dot cz> ---
> > Not all testcases can be handled at gimplification time IIRC.  Which
> > means "testcases welcome" first, so we can look at them individually.
> 
> The GCC one I saw was equivalent of:
> #include <stdbool.h>
> bool
> m_is_less_than_n (int n, int m)
> {
>    return (n==m || m_is_less_than_n (n-1,m));
> }

That's only optimizable after the 'mergephi' pass.  Before the
temporary setting is shared by the n==m code.  Thus maybe
'mergephi' itself can handle this ...