https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79261
Bug ID: 79261
Summary: vec_xxpermdi appears to have endian issues
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: wschmidt at gcc dot gnu.org
Target Milestone: ---
Use of the vec_xxpermdi built-in appears to work incorrectly on little endian;
it seems to be using big-endian semantics. This may be working as designed
(direct access to the instruction), but if so it is a confusing implementation.
Note that this is not an official API function as defined in the ELFv2 ABI
appendices, so the semantics are not well-defined.
This should either be fixed to use little-endian semantics, or documented
carefully in the GCC user manual. Since it has not been previously
well-documented, we probably have the flexibility to change the implementation.
