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From: "sebastien.michelland@ens-lyon.fr" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/106609] [SH] miscompilation of loop involving
 noreturn call
Date: Mon, 15 Aug 2022 09:47:06 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106609

--- Comment #2 from S=C3=A9bastien Michelland <sebastien.michelland@ens-lyo=
n.fr> ---
Yes there are delay slots for all branches except bt and bf, so here bt.s, =
jsr
and rts all have one. (-fno-delayed-branches avoids them but that doesn't
affect the bad optimization in this case.)

Adding -fno-schedule-insns -fno-schedule-insns2 doesn't help; the test and =
load
are still eliminated. In fact, I negated the entirety of -Q --help=3Doptimi=
zers
and still got an incorrect output.

It seems that the problem lies further downstream. I dumped various RTL sta=
ges
and -fdump-rtl-mach is the first stage where the comparison to 0 is gone, if
the order in the manual is anything to go by. Since I have both functional =
and
non-functional outputs from different RTL stages, I'm switching the compone=
nt
to rtl-optimization.=