https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92999
Bug ID: 92999
Summary: [armhf] struct with adjacent __fp16's copies wrongly
Product: gcc
Version: 8.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: jimreesma at gmail dot com
Target Milestone: ---
Created attachment 47523
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47523&action=edit
Reproducer source
Discovered on "cc (Raspbian 8.3.0-6+rpi1) 8.3.0"
-dumpmachine ==> arm-linux-gnueabihf
Copying a struct with two adjacent __fp16's effectively copies the second
__fp16 onto the first.
See attached reproducer code.
Upon examining the assembly, it seems to be expecting to return the structure
in a single-precision floating point register -- the copy function converts the
2nd field to the single-precision register, then the caller treats that result
as the value from both fields.
The bug is consistent with -O0 through -O3. The copy function must not be
inlined, else the compiler bypasses the copy entirely, so this is an issue with
structure copy semantics.
