diff options
| -rw-r--r-- | gcc/tree-ssa-threadbackward.c | 41 |
1 files changed, 35 insertions, 6 deletions
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c index 7c2c111..8cc92a4 100644 --- a/gcc/tree-ssa-threadbackward.c +++ b/gcc/tree-ssa-threadbackward.c @@ -77,7 +77,7 @@ private: class back_threader { public: - back_threader (bool speed_p); + back_threader (bool speed_p, bool resolve); ~back_threader (); void maybe_thread_block (basic_block bb); bool thread_through_all_blocks (bool may_peel_loop_headers); @@ -112,17 +112,22 @@ private: tree m_name; // Marker to differentiate unreachable edges. static const edge UNREACHABLE_EDGE; + // Set to TRUE if unknown SSA names along a path should be resolved + // with the ranger. Otherwise, unknown SSA names are assumed to be + // VARYING. Setting to true more precise but slower. + bool m_resolve; }; // Used to differentiate unreachable edges, so we may stop the search // in a the given direction. const edge back_threader::UNREACHABLE_EDGE = (edge) -1; -back_threader::back_threader (bool speed_p) +back_threader::back_threader (bool speed_p, bool resolve) : m_profit (speed_p), - m_solver (m_ranger, /*resolve=*/false) + m_solver (m_ranger, resolve) { m_last_stmt = NULL; + m_resolve = resolve; } back_threader::~back_threader () @@ -295,7 +300,23 @@ back_threader::resolve_phi (gphi *phi, bitmap interesting) bitmap_set_bit (interesting, v); bitmap_set_bit (m_imports, v); - done |= find_paths_to_names (e->src, interesting); + + // When resolving unknowns, see if the incoming SSA can be + // resolved on entry without having to keep looking back. + bool keep_looking = true; + if (m_resolve) + { + m_path.safe_push (e->src); + if (maybe_register_path ()) + { + keep_looking = false; + m_visited_bbs.add (e->src); + } + m_path.pop (); + } + if (keep_looking) + done |= find_paths_to_names (e->src, interesting); + bitmap_clear_bit (interesting, v); } else if (TREE_CODE (arg) == INTEGER_CST) @@ -360,6 +381,14 @@ back_threader::find_paths_to_names (basic_block bb, bitmap interesting) return false; } + // Try to resolve the path with nothing but ranger knowledge. + if (m_resolve && m_path.length () > 1 && maybe_register_path ()) + { + m_path.pop (); + m_visited_bbs.remove (bb); + return true; + } + auto_bitmap processed; unsigned i; bool done = false; @@ -936,7 +965,7 @@ static bool try_thread_blocks (function *fun) { /* Try to thread each block with more than one successor. */ - back_threader threader (/*speed_p=*/true); + back_threader threader (/*speed=*/true, /*resolve=*/false); basic_block bb; FOR_EACH_BB_FN (bb, fun) { @@ -1005,7 +1034,7 @@ pass_early_thread_jumps::execute (function *fun) loop_optimizer_init (AVOID_CFG_MODIFICATIONS); /* Try to thread each block with more than one successor. */ - back_threader threader (/*speed_p=*/false); + back_threader threader (/*speed_p=*/false, /*resolve=*/false); basic_block bb; FOR_EACH_BB_FN (bb, fun) { |