From: Richard Biener <richard.guenther@gmail.com>
To: Andrew Stubbs <ams@codesourcery.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [OG12 commit] vect: WORKAROUND vectorizer bug
Date: Mon, 24 Oct 2022 20:06:13 +0200 [thread overview]
Message-ID: <C7C330FC-AB46-4EDB-B187-E42EFBD6737B@gmail.com> (raw)
In-Reply-To: <264e9c27-cef4-b2a5-8758-a8b621428e01@codesourcery.com>
> Am 24.10.2022 um 18:51 schrieb Andrew Stubbs <ams@codesourcery.com>:
>
> I've committed this to the OG12 branch to remove some test failures. We probably ought to have something on mainline also, but a proper fix would be better.
>
> Without this. the libgomp.oacc-c-c++-common/private-variables.c testcase fails to compile due to an ICE. The OpenACC worker broadcasting code is creating SLP optimizable loads and stores in amdgcn address-space-4. Previously this was "ok" as SLP didn't work with less that 64-lane vectors, but the newly implemented smaller vectors are working as intended and optimizing this.
>
> Unfortunately the vectorizer is losing the address-space data from the intermediate types, and it all falls apart during expand when it tries the convert a 32-bit address into a 64-bit address and that's not something that works. At first sight it looks like we could possibly make that work with POINTERS_EXTEND_UNSIGNED, but that only changes the error message. Fundamentally we need to make sure that various instances of "vectype" have the correct address space, but my attempts to do so showed that that's a larger task than I have time for right now.
Istr there were issues like this in the past that I fixed, so any testcase that exposes this with just a gcn cc1 would be nice to have.
Richard
>
> This patch simply prevents the vectorizer working in the case where it would break. This should not be a regression because this code didn't vectorize at all, previously.
>
> Andrew
> <221024-workarround-vec-addrspace-bug.patch>
next prev parent reply other threads:[~2022-10-24 18:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-24 16:50 Andrew Stubbs
2022-10-24 18:06 ` Richard Biener [this message]
2022-10-27 13:12 ` Andrew Stubbs
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