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Re: Errors building libgcc for powerpc64le-linux-gnu
- From: "Ian Lance Taylor via gcc" <gcc at gcc dot gnu dot org>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: GCC Development <gcc at gcc dot gnu dot org>
- Date: Sun, 15 Dec 2019 09:43:20 -0800
- Subject: Re: Errors building libgcc for powerpc64le-linux-gnu
- References: <CAKOQZ8yXML2xPmKPrE7JipB=o7uGi6e9_EASavLTHy0Qkk1oEw@mail.gmail.com> <20191215072457.GY3152@gate.crashing.org>
- Reply-to: Ian Lance Taylor <iant at google dot com>
On Sat, Dec 14, 2019 at 11:25 PM Segher Boessenkool
> On Sat, Dec 14, 2019 at 10:51:50AM -0800, Ian Lance Taylor via gcc wrote:
> > I'm seeing compiler crashes building libgcc for powerpc64le-linux-gnu,
> > cross-compiling from x86_64-pc-linux-gnu. I'm at SVN revision 279830.
> > I'm seeing the following. Is anybody else seeing this crash? Thanks.
> No, and that makes me wonder what is going on. The error is simple enough
> of course, as you note in a later message; but why do we not see it on
> every other build?
I think it's because clang treats a left shift by a negative number as
undefined behavior but GCC does not. So GCC is consistently producing
some number, and clang is producing different numbers.
I should note that I don't really understand what purpose that
constant is serving anyhow.