[Bug tree-optimization/82128] [8 Regression] ICE on valid code

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82128

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, causes

Running /tmp/trunk/gcc/testsuite/g++.dg/dg.exp ...
FAIL: g++.dg/ipa/pr65263.C  -std=gnu++98 (internal compiler error)
FAIL: g++.dg/ipa/pr65263.C  -std=gnu++98 (test for excess errors)
FAIL: g++.dg/ipa/pr65263.C  -std=gnu++11 (internal compiler error)
FAIL: g++.dg/ipa/pr65263.C  -std=gnu++11 (test for excess errors)
FAIL: g++.dg/ipa/pr65263.C  -std=gnu++14 (internal compiler error)
FAIL: g++.dg/ipa/pr65263.C  -std=gnu++14 (test for excess errors)

                === g++ Summary ===

# of unexpected failures        6

/tmp/trunk/gcc/testsuite/g++.dg/ipa/pr65263.C: In member function 'int
D::F::operator()() const':^M
/tmp/trunk/gcc/testsuite/g++.dg/ipa/pr65263.C:42:5: internal compiler error:
Segmentation fault^M
0x11cea13 crash_signal^M
        /tmp/trunk/gcc/toplev.c:341^M
0xc6da67 compute_call_stmt_bb_frequency(tree_node*, basic_block_def*)^M
        /tmp/trunk/gcc/cgraphbuild.c:195^M
0xc677e4 cgraph_node::verify_node()^M
        /tmp/trunk/gcc/cgraph.c:3244^M
0xc564a9 symtab_node::verify()^M
        /tmp/trunk/gcc/symtab.c:1204^M

where a callgraph edge references a removed stmt (the folded call).  Because

static void
cgraph_update_edges_for_call_stmt_node (cgraph_node *node,
                                        gimple *old_stmt, tree old_call,
                                        gimple *new_stmt)
{
  tree new_call = (new_stmt && is_gimple_call (new_stmt))
                  ? gimple_call_fndecl (new_stmt) : 0;

  /* We are seeing indirect calls, then there is nothing to update.  */
  if (!new_call && !old_call)
    return;

we turned an indirect call into a non-call (the LHS effect of it after
a __builtin_unreachable ()).

Testing an updated patch.