On 2/15/23 08:34, Hans-Peter Nilsson via Gcc-patches wrote:
Regtested cris-elf with its LEGITIMIZE_RELOAD_ADDRESS
disabled, where it regresses gcc.target/cris/rld-legit1.c;
as expected, because that test guards proper function of its
LEGITIMIZE_RELOAD_ADDRESS i.e., that there's no sign of
decomposed address elements.
LRA also causes a similar decomposition (and worse, in even
smaller bits), but it can create valid insns as-is.
Unfortunately, it doesn't have something equivalent to
LEGITIMIZE_RELOAD_ADDRESS so it generates worse code for
cases where that hook helped reload.
I fear reload-related patches these days are treated like a
redheaded stepchild and even worse as this one is intended
for stage 1. Either way, I need to create a reference to
it, and it's properly tested and has been a help when
working towards LRA, thus might help other targets: ok to
install for the next stage 1?
-- >8 --
When LEGITIMIZE_RELOAD_ADDRESS for cris-elf is disabled,
this code is now required for reload to generate valid insns
from some reload-decomposed addresses, for example the
(plus:SI
(sign_extend:SI (mem:HI (reg/v/f:SI 32 [ a ]) [1 *a_6(D)+0 S2 A8]))
(reg/v/f:SI 33 [ y ]))
generated in gcc.target/cris/rld-legit1.c (a valid address
but with two registers needing reload). Now after decc0:ing,
most SET insns for former cc0 targets need to be a parallel
with a clobber of the flags register. Such targets
typically have TARGET_FLAGS_REGNUM set to a valid register.
* reload1.cc (emit_insn_if_valid_for_reload_1): Rename from
emit_insn_if_valid_for_reload.
(emit_insn_if_valid_for_reload): Call new helper, and if a SET fails
to be recognized, also try emitting a parallel that clobbers
TARGET_FLAGS_REGNUM, as applicable.
BUt isn't it the case that we're not supposed to be exposing the flags
register until after reload? And if that's the case, then why would
this be necessary? Clearly I must be missing something.
jeff
