[Bug target/33989] Extra load/store for float with union

[seurer at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33989

seurer at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |seurer at gcc dot gnu.org
         Resolution|---                         |WORKSFORME

--- Comment #17 from seurer at gcc dot gnu.org ---
The reported problem was that with -O3 you get an extra load/store:

.L.f:
lfs 0,0(3)
fadds 0,1,0
stfs 0,-16(1)
lwz 0,-16(1)
stw 0,0(4)
blr

I tried the test code using both gcc 9 and 10 (on both powerpc64 BE and LE just
in case) and I see this:

f:
.LFB0:
.cfi_startproc
lfs 0,0(3)
fadds 1,1,0
stfs 1,0(4)
blr

No extra load/store.

FYI: I looked at gcc 5 (the distro version on one of older servers) and it
generated way different and probably equally not so good code. I tried on
another older system that has gcc 4.8.5 and it did indeed generate the extra
load/store as reported.