On Tue, 25 Mar 2014, Richard Biener wrote: > On Tue, 25 Mar 2014, Jakub Jelinek wrote: > > > Hi! > > > > While working on previous patch, I've noticed a severe omission in the > > -fsanitize=signed-integer-overflow support. Nothing ever > > folds addition/subtraction of 0 and multiplication by [0,1], none of these > > may ever overflow and thus we can fold them to normal operations and let > > those be folded as normal operations. > > > > Bootstrapped/regtested on x86_64-linux and i686-linux, tested with > > --with-build-config=bootstrap-ubsan bootstrap on i686-linux, ok for trunk? > > I think you only need to adjust gimple_fold_stmt_to_constant_1.
Actually there only for a * 0 and a - a, as others don't result in constants. Still the other cases should be handled in fold_stmt, not only in VRP. Richard. > Richard. > > > 2014-03-25 Jakub Jelinek <ja...@redhat.com> > > > > * tree-vrp.c (simplify_internal_call_using_ranges): If only > > one range is range_int_cst_p, but not both, at least optimize > > addition/subtraction of 0 and multiplication by 0 or 1. > > > > --- gcc/tree-vrp.c.jj 2014-03-12 10:14:18.000000000 +0100 > > +++ gcc/tree-vrp.c 2014-03-24 16:14:50.822674164 +0100 > > @@ -9336,31 +9336,58 @@ simplify_internal_call_using_ranges (gim > > else if (TREE_CODE (op0) == INTEGER_CST) > > set_value_range_to_value (&vr0, op0, NULL); > > else > > - return false; > > + set_value_range_to_varying (&vr0); > > > > if (TREE_CODE (op1) == SSA_NAME) > > vr1 = *get_value_range (op1); > > else if (TREE_CODE (op1) == INTEGER_CST) > > set_value_range_to_value (&vr1, op1, NULL); > > else > > - return false; > > + set_value_range_to_varying (&vr1); > > > > - if (!range_int_cst_p (&vr0) || !range_int_cst_p (&vr1)) > > - return false; > > - > > - tree r1 = int_const_binop (subcode, vr0.min, vr1.min); > > - tree r2 = int_const_binop (subcode, vr0.max, vr1.max); > > - if (r1 == NULL_TREE || TREE_OVERFLOW (r1) > > - || r2 == NULL_TREE || TREE_OVERFLOW (r2)) > > - return false; > > - if (subcode == MULT_EXPR) > > + if (!range_int_cst_p (&vr0)) > > + { > > + /* If one range is VR_ANTI_RANGE, VR_VARYING etc., > > + optimize at least x = y + 0; x = y - 0; x = y * 0; > > + and x = y * 1; which never overflow. */ > > + if (!range_int_cst_p (&vr1)) > > + return false; > > + if (tree_int_cst_sgn (vr1.min) == -1) > > + return false; > > + if (compare_tree_int (vr1.max, subcode == MULT_EXPR) == 1) > > + return false; > > + } > > + else if (!range_int_cst_p (&vr1)) > > + { > > + /* If one range is VR_ANTI_RANGE, VR_VARYING etc., > > + optimize at least x = 0 + y; x = 0 * y; and x = 1 * y; > > + which never overflow. */ > > + if (subcode == MINUS_EXPR) > > + return false; > > + if (!range_int_cst_p (&vr0)) > > + return false; > > + if (tree_int_cst_sgn (vr0.min) == -1) > > + return false; > > + if (compare_tree_int (vr0.max, subcode == MULT_EXPR) == 1) > > + return false; > > + } > > + else > > { > > - tree r3 = int_const_binop (subcode, vr0.min, vr1.max); > > - tree r4 = int_const_binop (subcode, vr0.max, vr1.min); > > - if (r3 == NULL_TREE || TREE_OVERFLOW (r3) > > - || r4 == NULL_TREE || TREE_OVERFLOW (r4)) > > + tree r1 = int_const_binop (subcode, vr0.min, vr1.min); > > + tree r2 = int_const_binop (subcode, vr0.max, vr1.max); > > + if (r1 == NULL_TREE || TREE_OVERFLOW (r1) > > + || r2 == NULL_TREE || TREE_OVERFLOW (r2)) > > return false; > > + if (subcode == MULT_EXPR) > > + { > > + tree r3 = int_const_binop (subcode, vr0.min, vr1.max); > > + tree r4 = int_const_binop (subcode, vr0.max, vr1.min); > > + if (r3 == NULL_TREE || TREE_OVERFLOW (r3) > > + || r4 == NULL_TREE || TREE_OVERFLOW (r4)) > > + return false; > > + } > > } > > + > > gimple g = gimple_build_assign_with_ops (subcode, gimple_call_lhs (stmt), > > op0, op1); > > gsi_replace (gsi, g, false); > > > > Jakub > > > > > > -- Richard Biener <rguent...@suse.de> SUSE / SUSE Labs SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746 GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer