This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH] combine: Improve change_zero_ext (fixes PR71847)
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Georg-Johann Lay <avr at gjlay dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Wed, 23 Nov 2016 10:25:51 -0600
- Subject: Re: [PATCH] combine: Improve change_zero_ext (fixes PR71847)
- Authentication-results: sourceware.org; auth=none
- References: <38c2d1e084df72fff63c91606f31eb7b92a63845.1477390755.git.segher@kernel.crashing.org> <ca8e5b97-53bc-a4bb-ce59-05801b885e2d@gjlay.de>
On Wed, Nov 23, 2016 at 04:58:22PM +0100, Georg-Johann Lay wrote:
> Hi, this causes an illegal code issue on avr.
Sorry about that.
[ snip ]
> Trying 19 -> 7:
> Failed to match this instruction:
> (set (reg:HI 45 [ x+3 ])
> (zero_extend:HI (reg:QI 25 r25 [ x+3 ])))
> Successfully matched this instruction:
> (set (reg:HI 45 [ x+3 ])
> (and:HI (reg:HI 25 r25)
> (const_int 255 [0xff])))
> allowing combination of insns 19 and 7
> R25 is a 16-bit hard reg, but HImode (and larger) registers must start
> at an even register number.
So why does the define_insn allow it?
Please open a PR so I don't lose track.
Thanks,
Segher