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From: "jiawei at iscas dot ac.cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/102892] [12 Regression] Dead Code Elimination
 Regression at -O3 (trunk vs 11.2.0)
Date: Fri, 22 Apr 2022 03:04:03 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102892

jiawei <jiawei at iscas dot ac.cn> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jiawei at iscas dot ac.cn

--- Comment #11 from jiawei <jiawei at iscas dot ac.cn> ---
(In reply to Eric Botcazou from comment #8)
I use the RISC-V target test and get the same result, and link fail with
'undefined reference to `foo`'.

> The test fails (to link) on SPARC though, here's the .optimized dump at -=
O3:
>=20
> ;; Function main (main, funcdef_no=3D0, decl_uid=3D1488, cgraph_uid=3D1,
> symbol_order=3D1) (executed once)
>=20
> Removing basic block 8
> Removing basic block 9
> Removing basic block 10
> Removing basic block 11
> int main ()
> {
>   unsigned int ivtmp.8;
>   long int a;
>   long int _1;
>   void * _2;
>   unsigned int _17;
>=20
>   <bb 2> [local count: 44232128]:
>   if (a_9(D) !=3D 1)
>     goto <bb 6>; [89.00%]
>   else
>     goto <bb 7>; [11.00%]
>=20
>   <bb 3> [local count: 715863673]:
>   # ivtmp.8_23 =3D PHI <ivtmp.8_24(5), ivtmp.8_7(6)>
>   bar ();
>   _2 =3D (void *) ivtmp.8_23;
>   _1 =3D MEM[(long int *)_2];
>   if (_1 =3D=3D 1)
>     goto <bb 4>; [20.24%]
>   else
>     goto <bb 5>; [79.76%]
>=20
>   <bb 4> [local count: 144890806]:
>   foo ();
>=20
>   <bb 5> [local count: 715863674]:
>   ivtmp.8_24 =3D ivtmp.8_23 + 4;
>   if (_17 !=3D ivtmp.8_24)
>     goto <bb 3>; [66.67%]
>   else
>     goto <bb 7>; [33.33%]
>=20
>   <bb 6> [local count: 238597362]:
>   ivtmp.8_7 =3D (unsigned int) &b;
>   _17 =3D ivtmp.8_7 + 8;
>   goto <bb 3>; [100.00%]
>=20
>   <bb 7> [local count: 44232131]:
>   return 0;
> }=