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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114787] [13/14 Regression] wrong code at -O1
 on x86_64-linux-gnu (the generated code hangs)
Date: Mon, 22 Apr 2024 09:09:57 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114787

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Seems it is {,likely_}max_loop_iterations_int on the for (; i < 1; i++) loop
which matters (aka loop 3).  Given the i =3D 0 right before it (guess csmit=
h-ism,
don't see why it couldn't be in the for init expression) it estimates that =
it
loops once.
Then the copyprop2 pass removes the i++ latch and i <=3D 0 comparison in th=
at
loop header, so from all I can see that loop disappears.
At profile_estimate time, we have loop 1 the b<=3D0 loop which iterates jus=
t once
and then loop 4 f<=3D0 nested in loop 3 i<=3D0 nested in loop 2 a>=3D0, the=
 m loop
doesn't seem to be in loop structure maybe because of the goto into the loo=
p.
After copyprop, the loop 1 b<=3D0 is gone and the i<=3D0 loop is as well, b=
ut not
in the loop structure, loop 3 in the loop structure (presumably with the ca=
ched
number of loop estimates) has the f<=3D0 header and loop 4 nested in it has=
 a
header testing f<=3D0 too.=