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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/103979] asm goto is not considered volatile
 with output operands
Date: Mon, 30 Jan 2023 18:06:59 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103979

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
struct S { char a[64]; };

int
foo (void)
{
  struct S s, t;
  asm goto ("" : "=3Dg" (s) : : : l);
  t =3D s;
  asm goto ("" : "=3Dg" (s) : : : l);
  return s.a[0] + t.a[63];
l:
  return -1;
}

also ICEs at -O2, not during fwprop (note, I can't reproduce the #c0 testca=
se,
neither with trunk nor 11 branch on x86_64-linux), but during sra.

I think we shouldn't just follow blindly the docs, but see what e.g. Linux
kernel as heavy user of asm goto with outputs (and I think mostly without
volatile) wants.=