struct cgraph_edge *edge = cgraph_edge (id->src_node, orig_stmt);
POINT_A
int flags;
switch (id->transform_call_graph_edges)
{
case CB_CGE_DUPLICATE:
if (edge)
cgraph_clone_edge (edge, id->dst_node, stmt,
REG_BR_PROB_BASE, 1,
edge->frequency, true);
break;
case CB_CGE_MOVE_CLONES:
cgraph_set_call_stmt_including_clones (id->dst_node, orig_stmt,
stmt);
break;
case CB_CGE_MOVE:
if (edge)
cgraph_set_call_stmt (edge, stmt);
POINT_B
break;
default:
gcc_unreachable ();
}
edge = cgraph_edge (id->src_node, orig_stmt);
POINT_C
/* Constant propagation on argument done during inlining
may create new direct call. Produce an edge for it. */
if ((!edge
|| (edge->indirect_call
&& id->transform_call_graph_edges == CB_CGE_MOVE_CLONES))
&& is_gimple_call (stmt)
&& (fn = gimple_call_fndecl (stmt)) != NULL)
POINT_D
This code cannot possibly work.
We begin by looking up the edge at POINT_A.
We then move the edge at POINT_B.
We then look up the edge *again* at POINT_C.
Ought we be surprised when we do not find the edge at POINT_D?
After POINT_D, we "fix" the missing edge by creating a new one, which of
course is a duplicate, which then of course leads to verification failure.
I think POINT_B is additionally buggy in that we've just corrupted
the cgraph node for the source function when we wanted to change the
destination function. I believe we should have done
case CB_CGE_MOVE:
edge = cgraph_edge (id->dst_node, orig_stmt);
cgraph_set_call_stmt (edge, stmt);
// Possibly fix up indirect->direct call here.
Although, frankly I think it would be easiest to *only* create edges
here. There ought to be no problem doing the cgraph_clone_edge here
instead of in cgraph_copy_node_for_versioning. That would still
preserve all of the information you wanted that's attached to the edges.
Thoughts?
r~
