cgraph_node::verify - quite strong condition that was met by IPA-ICF

[Martin Liška]

Hello.

I've been finalizing IPA ICF testing process and I met a condition for 
lto-bootstrap, where cgraph_node::verify encounters error:

In WPA, I prove that gen_vec_initv16qi can be merged with 
gen_vec_initv2sf. In the following case, ale local calls are redirected:

      while (alias->callers)
    {
      cgraph_edge *e = alias->callers;
      e->redirect_callee (local_original);
      push_cfun (DECL_STRUCT_FUNCTION (e->caller->decl));

      if (e->call_stmt)
        e->redirect_call_stmt_to_callee ();

      pop_cfun ();
      redirected = true;
    }

To be more precise, the modification play role in WPA, where 
e->call_stmt == NULL (bodies are not loaded).
And a LTRANS produces following error:

In function ‘gen_rotlv16qi3’:
lto1: error: edge points to wrong declaration:
 <function_decl 0x7fe495b381b0 gen_vec_initv2sf
...
 Instead of: <function_decl 0x7fe495eaed80 gen_vec_initv16qi

As I talked to Martin Jambor, problematic BT:
#0  cgraph_node::verify_node (this=0x7ffff483b5e0) at 
../../gcc/cgraph.c:2837
#1  0x00000000006d5a40 in symtab_node::verify (this=0x7ffff483b5e0) at 
../../gcc/symtab.c:1158
#2  0x0000000000b00c7c in expand_call_inline (bb=0x7ffff2875340, 
stmt=0x7ffff2870990, id=0x7fffffffda70) at ../../gcc/tree-inline.c:4234
#3  0x0000000000b018a3 in gimple_expand_calls_inline (bb=0x7ffff2875340, 
id=0x7fffffffda70) at ../../gcc/tree-inline.c:4522
#4  0x0000000000b01e69 in optimize_inline_calls (fn=0x7ffff624a870) at 
../../gcc/tree-inline.c:4663

Checking code is called from tree_inline, where checking is called right 
after: cg_edge->callee->get_body ();
That means, no redirect_call_stmt_to_callee () hasn't been called for 
the edge.

Possible solutions:
1) We can call get_body in WPA for each caller I do a redirection. So 
that, call_stmt is fixed for the edge. (ugly solution)
2) We can somehow fix edges in tree_inline, I tried:

  cg_edge->callee->get_body ();

  if (cg_edge->callee->decl != id->dst_node->decl)
  {
    xxx = cg_edge->callee->callees;
    while(xxx)
    {
      push_cfun (DECL_STRUCT_FUNCTION (cg_edge->callee->decl));
      xxx->redirect_call_stmt_to_callee ();
      pop_cfun ();
      xxx = xxx->next_callee;
    }

    cg_edge->callee->verify ();
  }

But there's an ICE:
 0x82e03e gsi_start_bb
    ../../gcc/gimple-iterator.h:118
0x82f3f2 gsi_for_stmt(gimple_statement_base*)
    ../../gcc/gimple-iterator.c:623
0x6dcb1e cgraph_edge::redirect_call_stmt_to_callee()
    ../../gcc/cgraph.c:1375

3) We can somehow reduce checking code or remove this sub-condition?

Thank you,
Martin