On Thu, May 12, 2011 at 7:36 AM, Jakub Jelinek <ja...@redhat.com> wrote: > Hi! > > 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 H.J.
