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From: "hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/109093] [13 regression] csmith: a February runtime bug ?
Date: Tue, 14 Mar 2023 01:08:31 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109093

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |crazylht at gmail dot com

--- Comment #10 from H.J. Lu <hjl.tools at gmail dot com> ---
We have

static bool
ix86_can_eliminate (const int from, const int to)
{
  if (stack_realign_fp)
    return ((from =3D=3D ARG_POINTER_REGNUM
             && to =3D=3D HARD_FRAME_POINTER_REGNUM)
            || (from =3D=3D FRAME_POINTER_REGNUM
                && to =3D=3D STACK_POINTER_REGNUM));
  else=20=20
    return to =3D=3D STACK_POINTER_REGNUM ? !frame_pointer_needed : true;=20
}

Before IRA, stack_realign_fp is set to true by AVX piecewise move and store.
LRA replaces frame pointer with stack pointer:

insn 259 261 297 4 (set (reg/f:DI 2 cx [144])
        (plus:DI (reg/f:DI 7 sp)
            (const_int -32 [0xffffffffffffffe0]))) 241 {*leadi}
     (expr_list:REG_EQUAL (plus:DI (reg/f:DI 19 frame)
            (const_int -32 [0xffffffffffffffe0]))
        (nil)))

In ix86_finalize_stack_frame_flags, stack_realign_fp is set to false. Since
the stack realignment skipped, local variable is no longer properly aligned=
.=