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Diffstat (limited to 'gcc/tree-ssa-structalias.c')
| -rw-r--r-- | gcc/tree-ssa-structalias.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c index 529ec3a..a023871 100644 --- a/gcc/tree-ssa-structalias.c +++ b/gcc/tree-ssa-structalias.c @@ -1195,6 +1195,22 @@ add_graph_edge (constraint_graph_t graph, unsigned int to, if (!graph->succs[from]) graph->succs[from] = BITMAP_ALLOC (&pta_obstack); + + /* The graph solving process does not avoid "triangles", thus + there can be multiple paths from a node to another involving + intermediate other nodes. That causes extra copying which is + most difficult to avoid when the intermediate node is ESCAPED + because there are no edges added from ESCAPED. Avoid + adding the direct edge FROM -> TO when we have FROM -> ESCAPED + and TO contains ESCAPED. + ??? Note this is only a heuristic, it does not prevent the + situation from occuring. The heuristic helps PR38474 and + PR99912 significantly. */ + if (to < FIRST_REF_NODE + && bitmap_bit_p (graph->succs[from], find (escaped_id)) + && bitmap_bit_p (get_varinfo (find (to))->solution, escaped_id)) + return false; + if (bitmap_set_bit (graph->succs[from], to)) { r = true; |