https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68234
Jiong Wang <jiwang at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|tree-vrp pass need to be |tree-vrp pass need to be |improved when handling |improved when handling |ASSERT/PLUS/MINUS/_EXPR and |ASSERT_EXPR |Phi node | --- Comment #2 from Jiong Wang <jiwang at gcc dot gnu.org> --- (In reply to Richard Biener from comment #1) > I think the issue is that we insert the assert in the first place or > that we intersect to a symbolic range this causes us to not use SCEV / loop > analysis to get at the range for c_1. That is, in vrp_visit_phi_node > the early outs to varying: shouldn't skip > > /* If we dropped either bound to +-INF then if this is a loop > PHI node SCEV may known more about its value-range. */ > if ((cmp_min > 0 || cmp_min < 0 > || cmp_max < 0 || cmp_max > 0) > && (l = loop_containing_stmt (phi)) > && l->header == gimple_bb (phi)) > adjust_range_with_scev (&vr_result, l, phi, lhs); > > sth like > > Index: gcc/tree-vrp.c > =================================================================== > --- gcc/tree-vrp.c (revision 229804) > +++ gcc/tree-vrp.c (working copy) > @@ -8827,6 +8805,24 @@ update_range: > > /* No match found. Set the LHS to VARYING. */ > varying: > + > + /* If we dropped either bound to +-INF then if this is a loop > + PHI node SCEV may known more about its value-range. */ > + if ((l = loop_containing_stmt (phi)) > + && l->header == gimple_bb (phi)) > + { > + adjust_range_with_scev (&vr_result, l, phi, lhs); > + > + /* If we will end up with a (-INF, +INF) range, set it to > + VARYING. Same if the previous max value was invalid for > + the type and we end up with vr_result.min > vr_result.max. */ > + if (!((vrp_val_is_max (vr_result.max) > + && vrp_val_is_min (vr_result.min)) > + || compare_values (vr_result.min, > + vr_result.max) > 0)) > + goto update_range; > + } > + > set_value_range_to_varying (lhs_vr); > return SSA_PROP_VARYING; > } > > which ends up with > > Value ranges after VRP: > > c_1: [0, +INF] > > as desired. Maybe you can take the above and put it to testing. Thanks for the explanation on those issues. The "if" check needs to be guarded by vr_result.type == VR_RANGE, otherwise above draft patch passed my testing. bootstrapping on x86-64 and AArch64 OK. no regresson on both.