On 05/28/2018 05:23 AM, Jozef Lawrynowicz wrote:
> pr39240.c fails at execution at -O1 and above for msp430, due to an erroneous
>
> subreg expression in the zero_extendqisi2 msp430 insn pattern. This causes the
>
> zero extension operation to get optimized out.
>
> The attached patch fixes the insn pattern, and also removes the msp430x ISA
> restriction on zero_extendqisi2 and zero_extendhisi2. The assembly
> instructions
>
> in these patterns can be used in the base MSP430 ISA; they are not MSP430x
> specific.
>
> Successfully regtested the GCC testsuite for msp430-elf in the
> -mcpu=msp430x/-mlarge configuration.
>
> If the patch is acceptable, I would appreciate if someone would commit it for
>
> me, as I don't have write access.
>
>
> 0001-MSP430-Fix-PR39240-execution-failure-for-msp430-elf.patch
>
>
> From 4f96a05f4849e28064f5c202a55b753b59a106ef Mon Sep 17 00:00:00 2001
> From: Jozef Lawrynowicz <joze...@mittosystems.com>
> Date: Sun, 27 May 2018 21:09:49 +0100
> Subject: [PATCH] MSP430: Fix PR39240 execution failure for msp430-elf
>
> 2018-05-28 Jozef Lawrynowicz <joze...@mittosystems.com>
>
> * gcc/config/msp430/msp430.md: Remove erroneous subreg expression from
> zero_extendqisi2 insn pattern. Remove msp430x ISA restriction on
> zero_extend{q,h}isi2.
It's not clear why having that subreg is causing incorrect code to be
generated, but the subreg is clearly wrong since it's a qisi pattern not
a hisi pattern. Based on that I've approved and installed the change.
I'm a big believer that any subreg appearing in an md is fishy and
should be reviewed and justified. I've found they're generally a bad idea.
Jeff
