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From: "vmakarov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/113354] Regression/14: unable to find a register to
 spill on mips
Date: Fri, 12 Jan 2024 18:34:32 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113354

Vladimir Makarov <vmakarov at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vmakarov at gcc dot gnu.org

--- Comment #2 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
Thank you for reporting this.  The issue is not in the patch itself.  The p=
atch
simply triggered a hidden bug.

The insn in the question looks like

1657: {r3001:SI=3Dr291:SI*r294:SI+r3002:SI;clobber r2788:SI;clobber r2390:S=
I;}

On the 1st subpass we choose alternative with the following constraints

(0) l  (1) d  (2) d  (3) l  (4) X  (5) X {*mul_acc_si}

On the second subpass we choose alternative

(0) l  (1) d  (2) d  (3) l  (4) X  (5) X {*mul_acc_si}

p2788 happened to get MD0 and it prevents p3001 to get MD0 too.   p2788 can=
 be
in any location for this alternative but LRA assignment subpass does not ta=
ke
this into account.

I'll try to fix this hidden bug on the beginning of the next week.=