> That is because propagate_for_debug stops at the insn before last, doesn't > process last any longer. So, if there is a DEBUG_INSN right before the > jump being deleted, and it has been propagated into, after the jump is > deleted and retry is done at i2 earlier, following propagate_for_debug > won't see that DEBUG_INSN any longer.
Ah, yes, thanks. > We could certainly change propagate_for_debug, so that it would stop either > before end (NEXT_INSN (BB_END (this_basic_block)) added in this patch), or > after processing last (which doesn't change anything in the non-deleted > insn case, because i3 from any try_combine surely isn't a DEBUG_INSN and > propagate_for_debug only propagates into those), then on deletion set it to > PREV_INSN instead of NEXT_INSN. I wonder whether we couldn't be deleting > the first insn in a basic block, but probably there should be at least a > note before it. This looks fine to me. > Perhaps instead of the assert we could in that case just set > last_combined_insn to insn. Yes, this looks preferable to me, IMO we don't need to stop the compiler when something goes wrong with debug insns. > 2011-04-12 Jakub Jelinek <ja...@redhat.com> > > PR rtl-optimization/48549 > * combine.c (propagate_for_debug): Also stop after BB_END of > this_basic_block. Process LAST and just stop processing after it. > (combine_instructions): If last_combined_insn has been deleted, > set last_combined_insn to its PREV_INSN. > > * g++.dg/opt/pr48549.C: New test. So OK modulo the last point, thanks. -- Eric Botcazou
