https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112573
Wilco <wilco at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-11-20
Ever confirmed|0 |1
CC| |wilco at gcc dot gnu.org
Status|UNCONFIRMED |NEW
--- Comment #3 from Wilco <wilco at gcc dot gnu.org> ---
We should reassociate the immediate last for more optimal addressing like LLVM:
adrp x8, a
add x8, x8, :lo12:a
lsr w9, w0, #8
add x8, x8, w1, sxtw
strb w9, [x8, #1]
lsr w9, w0, #16
strb w0, [x8, #3]
strb w9, [x8, #2]
lsr w9, w0, #24
strb w9, [x8]
ret
However GCC's reassociation is incorrect - it has been for many years and
things got much worse in GCC12...
As a result we may merge the immediate offset into the base address like in
'h'. Using -fdata-sections behaves like -fno-section-anchors, so it works as
expected (and 'extern' is the same as well). We could block merging offsets to
get more address CSEs if that ends up better overall.
