Re: [PATCH] Support multi-versioning on self-recursive function (ipa/92133)

[Feng Xue OS <fxue@os.amperecomputing.com>]

> I noticed similar issue when analyzing the SPEC, self-recursive function is
> not versioned and posted my observations in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92074.

> Generally, this could be implemented well by your patch, while I am
> wondering whether it is OK to convert the recursive function to
> non-recursive function in a independent pass after ipa-cp and ipa-sra instead
> of reuse the ipa-cp framework?
> The reason is sometimes the argument is passed-by-reference, and
> ipa-sra runs after ipa-cp, so this kind of optimization may not be done in
> WPA.  What's your idea about this, please?   Thanks.

Function versioning is done in ipa-cp, there is nothing special for recursive function.
So adding a dedicated pass for recursive seems to be redundant.

We might not need to resort to ipa-sra to resolve concern you mentioned. Original
ipa-cp already supports a simple kind of propagation on by-ref argument, who must
be defined by constant. And for an extended form as:  *arg = *param OP constant,  I've
created a tracker PR91682,  also composed a patch:
https://gcc.gnu.org/ml/gcc-patches/2019-09/msg01189.html.

Feng