[llvm-dev] [Release-testers] [7.0.0 Release] rc1 has been tagged

[Wei Mi via llvm-dev]

On Fri, Aug 17, 2018 at 1:27 PM, Dimitry Andric <dimitry at andric.com> wrote:

> On 16 Aug 2018, at 00:51, Joerg Sonnenberger via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> > On Tue, Aug 07, 2018 at 09:49:16PM +0200, Dimitry Andric via llvm-dev
> wrote:
> >> This is a regression caused by https://reviews.llvm.org/rL323281:
> >>
> >> ------------------------------------------------------------
> ------------
> >> r323281 | wmi | 2018-01-23 23:27:57 +0000 (Tue, 23 Jan 2018) | 12 lines
> >>
> >> Adjust MaxAtomicInlineWidth for i386/i486 targets.
> >>
> >> This is to fix the bug reported in https://bugs.llvm.org/show_
> bug.cgi?id=34347#c6.
> >> Currently, all  MaxAtomicInlineWidth of x86-32 targets are set to 64.
> However,
> >> i386 doesn't support any cmpxchg related instructions. i486 only
> supports cmpxchg.
> >> So in this patch MaxAtomicInlineWidth is reset as follows:
> >> For i386, the MaxAtomicInlineWidth should be 0 because no cmpxchg is
> supported.
> >> For i486, the MaxAtomicInlineWidth should be 32 because it supports
> cmpxchg.
> >> For others 32 bits x86 cpu, the MaxAtomicInlineWidth should be 64
> because of cmpxchg8b.
> >
> > This seems to be somewhat undesirable. Does *anyone* care about real
> > i386 support at this point? NetBSD certainly doesn't and I think we are
> > already the odd man for a number of cases like this.
>
>
> Yes, and since this causes quite a number of regressions for us, I would
> really prefer this revision to be reverted, at least in the 7.0.0
> branch.  I have already reverted it locally in our FreeBSD project
> branch for importing llvm/clang 7.0.0.  Hans, what is your opinion about
> this?
>
> -Dimitry
>
>
Sorry I missed the thread for quite a while. Dimitry, I am very confused
because you reported the issue in
https://bugs.llvm.org/show_bug.cgi?id=34347#c6, so you want r323281 to be
reverted and let llvm to generate cmxchg8b instruction for i486?

Wei.
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