Re: [PATCH] frv: fix build failure

From: Vineet Gupta
Date: Wed Dec 06 2017 - 17:00:42 EST


On 12/03/2017 02:32 PM, Sudip Mukherjee wrote:
On Mon, Nov 27, 2017 at 10:25:16AM -0800, Vineet Gupta wrote:
+CC linux-arch, Arnd

On 11/23/2017 09:17 AM, Alexey Brodkin wrote:
Hi Sudip,

On Tue, 2017-11-21 at 22:10 +0000, Sudip Mukherjee wrote:

<snip>

I understand the case/need for adding a weak/common abort() as a
quick fix for handling such cases, but perhaps we should not and
instead fix the rootcause. In this specific case, Claudiu mentioned
that gcc was generating abort due to something like this (flagging a
possible divide by zero due to
-fno-isolate-erroneous-paths-dereference.

a;

fn1() {
switch (a)
case 0:
return 1 / a;
}

Sudeep can you confirm that removing this hacking FRV build to not
have this toggle fixes the abort issue.

So the offending code needs to be fixed as in the end when that code
path is taken system is hosed.

The above case that you mentioned is indeed the case here.
mpihelp_divrem() in lib/mpi/mpih-div.c has this same divide by zero case.

So, what should be the actual fix here?

To remove the divide by zero.

Or atleast have a __weak abort() defined in common code so all arches benefit from it !

-Vineet