Re: Softfloat miscompiled by gcc 4.5.x

[Masanobu SAITOH <msaitoh%execsw.org@localhost>]

(2012/11/13 19:24), Masanobu SAITOH wrote:
> (2012/10/01 17:08), Martin Husemann wrote:
> > On Mon, Oct 01, 2012 at 07:45:01AM +0100, David Laight wrote:
> > > I don't call that a fix.
> >
> > Neither do I.
> >
> > > There is either a bug in gcc (which will affect other code), or bugs
> > > in the softfloat code itself - which will appear again later.
> >
> > Yes - my bet is on the former for now.
>
>   I debugged this.
>
>      The problem occurs with -O1 -ftree-vrp.
>
>      The problem doesn't occur with -O2 -fno-tree-vrp.
>
>      The problem doesn't occur when SOFTFLOAT_BITS=64
>      (Note that only arm and emips set it with 64)
>
>   How about COPTS.softfloat.c+=-fno-tree-vrp?
>
> The ATF test result in /usr/tests/lib/libm was as follows (netbsd-6):
>
> Summary for 20 test programs:
>      311 passed test cases.
>      0 failed test cases.      <======== Changed from 16 to 0
>      4 expected failed test cases.
>      5 skipped test cases.


 I tried to fix tree-vrp.c but I knew it's little hard for me to fix :-(





> > > Shouldn't be too hard to isolate 1 buggy file and work out exactly
> > > where it goes wrong.
> > > I'd guess a 'strict aliasing' issue....
> >
> > For someone with enough arm asm fu - probably. The differences in the
> > generated asm are "not small" though, and unfortunately I don't have time
> > to look at details right now. Volunteers welcome...
> >
> > Martin


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-----------------------------------------------
                SAITOH Masanobu (msaitoh%execsw.org@localhost
                                 msaitoh%netbsd.org@localhost)