* [musl] -frounding-math breaking src/math/acosf.c
@ 2020-10-09 22:16 joao
2020-10-09 23:10 ` Rich Felker
0 siblings, 1 reply; 5+ messages in thread
From: joao @ 2020-10-09 22:16 UTC (permalink / raw)
To: musl
Hi,
I just noticed that the upstream LLVM is no longer capable of compiling musl 1.2.0 (and possibly more recent versions too) when -frounding-math is in use. I bisected the LLVM commit to https://reviews.llvm.org/D87822, and pointed the problem there.
Just reporting in case someone else also has issues with this.
Best,
Joao.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] -frounding-math breaking src/math/acosf.c
2020-10-09 22:16 [musl] -frounding-math breaking src/math/acosf.c joao
@ 2020-10-09 23:10 ` Rich Felker
2020-10-09 23:15 ` joao
2020-10-12 9:39 ` Szabolcs Nagy
0 siblings, 2 replies; 5+ messages in thread
From: Rich Felker @ 2020-10-09 23:10 UTC (permalink / raw)
To: joao; +Cc: musl
On Sat, Oct 10, 2020 at 12:16:13AM +0200, joao@overdrivepizza.com wrote:
> Hi,
>
> I just noticed that the upstream LLVM is no longer capable of
> compiling musl 1.2.0 (and possibly more recent versions too) when
> -frounding-math is in use. I bisected the LLVM commit to
> https://reviews.llvm.org/D87822, and pointed the problem there.
>
> Just reporting in case someone else also has issues with this.
>
> Best,
> Joao.
Thanks. This probably needs to be reported as aa bug against LLVM (or
clang?) rather than just a comment on the review so that it's tracked
as such. It seems they've erroneously made it treat static
initializers as non-constant-expressions rather than evaluating them
statically in the default rounding mode per the spec.
Rich
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] -frounding-math breaking src/math/acosf.c
2020-10-09 23:10 ` Rich Felker
@ 2020-10-09 23:15 ` joao
2020-10-12 9:39 ` Szabolcs Nagy
1 sibling, 0 replies; 5+ messages in thread
From: joao @ 2020-10-09 23:15 UTC (permalink / raw)
To: Rich Felker; +Cc: musl
> Thanks. This probably needs to be reported as aa bug against LLVM (or
> clang?) rather than just a comment on the review so that it's tracked
> as such.
Makes sense, I'll submit/report it.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] -frounding-math breaking src/math/acosf.c
2020-10-09 23:10 ` Rich Felker
2020-10-09 23:15 ` joao
@ 2020-10-12 9:39 ` Szabolcs Nagy
2020-12-18 17:13 ` Fangrui Song
1 sibling, 1 reply; 5+ messages in thread
From: Szabolcs Nagy @ 2020-10-12 9:39 UTC (permalink / raw)
To: Rich Felker; +Cc: joao, musl
* Rich Felker <dalias@libc.org> [2020-10-09 19:10:00 -0400]:
> On Sat, Oct 10, 2020 at 12:16:13AM +0200, joao@overdrivepizza.com wrote:
> > Hi,
> >
> > I just noticed that the upstream LLVM is no longer capable of
> > compiling musl 1.2.0 (and possibly more recent versions too) when
> > -frounding-math is in use. I bisected the LLVM commit to
> > https://reviews.llvm.org/D87822, and pointed the problem there.
> >
> > Just reporting in case someone else also has issues with this.
> >
> > Best,
> > Joao.
>
> Thanks. This probably needs to be reported as aa bug against LLVM (or
> clang?) rather than just a comment on the review so that it's tracked
> as such. It seems they've erroneously made it treat static
> initializers as non-constant-expressions rather than evaluating them
> statically in the default rounding mode per the spec.
const expressions should work as described in
http://port70.net/~nsz/c/c11/n1570.html#F.8.4
but it seems clang handles literals that don't
need conversion:
float x = 0.1f; // works
float y = 0.1; // fails
we may want to fix this anyway in musl to always
use the right type of literal (then it's clear
that there is no double rounding).
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] -frounding-math breaking src/math/acosf.c
2020-10-12 9:39 ` Szabolcs Nagy
@ 2020-12-18 17:13 ` Fangrui Song
0 siblings, 0 replies; 5+ messages in thread
From: Fangrui Song @ 2020-12-18 17:13 UTC (permalink / raw)
To: musl, Rich Felker, joao
On Mon, Oct 12, 2020 at 2:40 AM Szabolcs Nagy <nsz@port70.net> wrote:
>
> * Rich Felker <dalias@libc.org> [2020-10-09 19:10:00 -0400]:
>
> > On Sat, Oct 10, 2020 at 12:16:13AM +0200, joao@overdrivepizza.com wrote:
> > > Hi,
> > >
> > > I just noticed that the upstream LLVM is no longer capable of
> > > compiling musl 1.2.0 (and possibly more recent versions too) when
> > > -frounding-math is in use. I bisected the LLVM commit to
> > > https://reviews.llvm.org/D87822, and pointed the problem there.
> > >
> > > Just reporting in case someone else also has issues with this.
> > >
> > > Best,
> > > Joao.
> >
> > Thanks. This probably needs to be reported as aa bug against LLVM (or
> > clang?) rather than just a comment on the review so that it's tracked
> > as such. It seems they've erroneously made it treat static
> > initializers as non-constant-expressions rather than evaluating them
> > statically in the default rounding mode per the spec.
>
> const expressions should work as described in
>
> http://port70.net/~nsz/c/c11/n1570.html#F.8.4
clang main has fixed (https://reviews.llvm.org/D89360) the regression
of https://reviews.llvm.org/D87822
> but it seems clang handles literals that don't
> need conversion:
>
> float x = 0.1f; // works
> float y = 0.1; // fails
>
> we may want to fix this anyway in musl to always
> use the right type of literal (then it's clear
> that there is no double rounding).
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-12-18 17:20 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2020-10-09 22:16 [musl] -frounding-math breaking src/math/acosf.c joao
2020-10-09 23:10 ` Rich Felker
2020-10-09 23:15 ` joao
2020-10-12 9:39 ` Szabolcs Nagy
2020-12-18 17:13 ` Fangrui Song
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