https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78188
--- Comment #2 from David Edelsohn <dje at gcc dot gnu.org> --- I built the GCC stage1 with and without the tree-vrp.c patch. Same sources, same revision, same directory. cc1plus.good and cc1plus.bad. Then I used both versions of cc1plus to compile tree-ssa-sccvn.c with -fdump-tree-all-all -frandom-seed=0. The differences start in 027t.fixup_cfg3, all like: tree-ssa-sccvn.c.027t.fixup_cfg3 < _4 = _ZN2wi10int_traitsI16generic_wide_intI22fixed_wide_int_storageILi128EEE E13get_precisionERKS4_.isra.113D.101391 (); --- > _4 = _ZN2wi10int_traitsI16generic_wide_intI22fixed_wide_int_storageILi128EEE E13get_precisionERKS4_.isra.114D.101527 (); tree-ssa-sccvn.c.028t.inline_param1 25946c25946 < loop depth: 0 freq:1000 size: 3 time: 12 callee size: 5 stack: 0 predica te: (op0[ref offset: 160] == 0B) && (op0[ref offset: 0] == 1) --- > loop depth: 0 freq:1000 size: 3 time: 12 callee size: 4 stack: 0 predica te: (op0[ref offset: 160] == 0B) && (op0[ref offset: 0] == 1) 26863c26863 < loop depth: 0 freq:1000 size: 3 time: 12 callee size: 5 stack: 0 predica te: (op0[ref offset: 0] == 3) --- > loop depth: 0 freq:1000 size: 3 time: 12 callee size: 4 stack: 0 predica te: (op0[ref offset: 0] == 3) 27608c27608 < loop depth: 0 freq:1000 size: 6 time: 15 callee size: 7 stack: 0 --- > loop depth: 0 freq:1000 size: 6 time: 15 callee size: 6 stack: 0 tree-ssa-sccvn.c.029t.einline 26729c26729 < size:7 time:6 --- > size:5 time:5 26732c26732 < size:7 time:6 --- > size:5 time:5 26736c26736 < size:7 time:6 --- > size:5 time:5 26739,26740c26739 < Accounting size:2.00, time:1.66 on predicate:(op0[ref offset: 16 0] == 0B) && (op0[ref offset: 0] == 1) < Accounting size:0.50, time:0.40 on predicate:(op0[ref offset: 16 0] == 0B) && (op0[ref offset: 0] == 1) --- > Accounting size:0.50, time:0.41 on predicate:(op0[ref offset: 16 0] == 0B) && (op0[ref offset: 0] == 1) 26767,26769c26766,26768 < Merging blocks 13 and 33 < Merging blocks 31 and 26 < Merging blocks 35 and 32 --- > Merging blocks 13 and 32 > Merging blocks 30 and 26 > Merging blocks 34 and 31 26795d26793 < Registering new PHI nodes in block #10 26797c26795 < Registering new PHI nodes in block #11 And more extensive differences in 038t.evrp The full tree dumps are about 470MB each.