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From: "olegendo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/49263] SH Target: underutilized "TST #imm, R0"
 instruction
Date: Wed, 24 May 2023 11:57:20 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D49263

--- Comment #36 from Oleg Endo <olegendo at gcc dot gnu.org> ---
(In reply to Alexander Klepikov from comment #35)
>=20
> As I understand, you meant the following (I added new functions at the end
> of file):
>=20
> $ cat f.c
> #define ADDR 0xFFFF0000
> #define P ((unsigned char *)ADDR)
> #define FLAG 0x40
> #define S 7
> ....

Yes, that's what I meant, thanks.

Can you also compile for little endian, and most of all, use -O2 optimizati=
on
level.  Some optimizations are not done below -O2.

>=20
> I choose that name because I wanted to disable dynamic shift instructions
> for all CPUs. I did not hope that it will affect SH-2E code in such way.
>=20
> I can rewrite the patch so that it only affects CPUs that do not support
> dynamic shifts and disables library call for dynamic shifts. I'll do it
> anyway because I need it badly. How do you think, what name of option wou=
ld
> be better: '-mdisable-dynshift-libcall' or '-mhw-shift'? Or if you want,
> please suggest another one. Thank you!

'-mdisable-dynshift-libcall' would be more appropriate for what it tries to=
 do,
I think.  Although that is a whole different issue ... but what is it going=
 to
do for real dynamic shifts on SH2?

What kind of code is it supposed to emit for things like

unsigned int dyn_shift (unsigned int x, unsigned int y)
{
  return x << (y & 31);
}=