On Mon, May 23, 2011 at 06:06:55AM -0700, H.J. Lu wrote:
> On Thu, May 12, 2011 at 7:36 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> > The read from a 1-bit signed bitfield initialized by a comparison
> > is optimized into the comparison, which has that 1-bit signed bitfield
> > comparison. Unfortunately that is still expanded as setting the result
> > to 0 resp. 1 instead of this case 0 resp. -1 QImode pseudo, which is then
> > sign extended into SImode for the comparison.
> >
> > Fixed by special casing expansion in that case. I think it is rare enough
> > we can just ignore the fold_single_bit_test optimization in that case,
> > rather than having two versions thereof.
> >
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk/4.6?
> >
> > 2011-05-12 Jakub Jelinek <ja...@redhat.com>
> >
> > PR middle-end/48973
> > * expr.c (expand_expr_real_2) <case LT_EXPR>: If do_store_flag
> > failed and the comparison has a single bit signed type, use
> > constm1_rtx instead of const1_rtx for true value.
> > (do_store_flag): If ops->type is single bit signed type, disable
> > signel bit test optimization and pass -1 instead of 1 as last
> > parameter to emit_store_flag_force.
> >
> > * gcc.c-torture/execute/pr48973-1.c: New test.
> > * gcc.c-torture/execute/pr48973-2.c: New test.
> >
>
> This caused:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49123
Can't reproduce, all tests succeed just fine, both on the trunk and in 4.6,
both x86_64-linux {-m32,-m64} and 32-bit HWI i686-linux, including -flto.
Jakub
