On Thu, Jul 30, 2020 at 09:02:43AM -0500, Steven Munroe wrote:
Sergio writes:
> Hello opencv [1] build also failed around LTO
Looking at the build logs:
https://koji.fedoraproject.org/koji/taskinfo?taskID=48055082
For the build.log that ends with:
lto1: error: '__builtin_altivec_vadub' requires the '-mcpu=power9'
option
lto1: fatal error: target specific builtin not available
compilation terminated.
The build uses a mix of compiler options.
-mcpu=power8 -mtune=power8
and
-mcpu=power9 -mtune=power9
and sometimes
-mcpu=power8 ... -mcpu=power9 -mtune=power9
I suspect this works at the level of individual object (*.o)
generation but this might cause problems when a mix of -mcpu=power8
and -mcpu=power9 objects are combined in LTO optimization.
The compiler might get confused.
For targets which do support the target attribute, each function should be
marked with the right set of options before streaming it, there can be bugs
of course, especially on the rs6000 side which uses target attribute far
less often then e.g. x86_64.
Jakub