From 28c008bb89e0ab798c2d16c68f51fb01fdccb135 Mon Sep 17 00:00:00 2001 From: Jeff Law Date: Mon, 19 Jul 2004 13:01:55 -0600 Subject: [PATCH] tree-ssa-dom.c (single_incoming_edge_ignoring_loop_edges): New. * tree-ssa-dom.c (single_incoming_edge_ignoring_loop_edges): New. (get_eq_expr_value): Use it. Simplify slightly. From-SVN: r84927 --- gcc/ChangeLog | 5 ++++ gcc/tree-ssa-dom.c | 58 ++++++++++++++++++++++++++++++++-------------- 2 files changed, 46 insertions(+), 17 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 04038313a1b..a9e147cca60 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2004-07-19 Jeff Law + + * tree-ssa-dom.c (single_incoming_edge_ignoring_loop_edges): New. + (get_eq_expr_value): Use it. Simplify slightly. + 2004-07-19 Maciej W. Rozycki * config/mips/mips.md (mulsidi3_32bit_r4000): Fix the clobber list. diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c index 740fe9bc9b2..90e11b76410 100644 --- a/gcc/tree-ssa-dom.c +++ b/gcc/tree-ssa-dom.c @@ -268,6 +268,7 @@ static void restore_currdefs_to_original_value (varray_type locals, unsigned limit); static void register_definitions_for_stmt (stmt_ann_t, varray_type *); static void redirect_edges_and_update_ssa_graph (varray_type); +static edge single_incoming_edge_ignoring_loop_edges (basic_block); /* Local version of fold that doesn't introduce cruft. */ @@ -1407,6 +1408,34 @@ record_equivalences_from_phis (struct dom_walk_data *walk_data, basic_block bb) } } +/* Ignoring loop backedges, if BB has precisely one incoming edge then + return that edge. Otherwise return NULL. */ +static edge +single_incoming_edge_ignoring_loop_edges (basic_block bb) +{ + edge retval = NULL; + edge e; + + for (e = bb->pred; e; e = e->pred_next) + { + /* A loop back edge can be identified by the destination of + the edge dominating the source of the edge. */ + if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) + continue; + + /* If we have already seen a non-loop edge, then we must have + multiple incoming non-loop edges and thus we return NULL. */ + if (retval) + return NULL; + + /* This is the first non-loop incoming edge we have found. Record + it. */ + retval = e; + } + + return retval; +} + /* Record any equivalences created by the incoming edge to BB. If BB has more than one incoming edge, then no equivalence is created. */ @@ -1435,21 +1464,20 @@ record_equivalences_from_incoming_edge (struct dom_walk_data *walk_data, eq_expr_value.src = NULL; eq_expr_value.dst = NULL; - /* If we have a single predecessor, then extract EDGE_FLAGS from - our single incoming edge. Otherwise clear EDGE_FLAGS and - PARENT_BLOCK_LAST_STMT since they're not needed. */ + /* If we have a single predecessor (ignoring loop backedges), then extract + EDGE_FLAGS from the single incoming edge. Otherwise just return as + there is nothing to do. */ if (bb->pred - && ! bb->pred->pred_next - && parent_block_last_stmt - && bb_for_stmt (parent_block_last_stmt) == bb->pred->src) + && parent_block_last_stmt) { - edge_flags = bb->pred->flags; + edge e = single_incoming_edge_ignoring_loop_edges (bb); + if (e && bb_for_stmt (parent_block_last_stmt) == e->src) + edge_flags = e->flags; + else + return; } else - { - edge_flags = 0; - parent_block_last_stmt = NULL; - } + return; /* If our parent block ended in a COND_EXPR, add any equivalences created by the COND_EXPR to the hash table and initialize @@ -1462,9 +1490,7 @@ record_equivalences_from_incoming_edge (struct dom_walk_data *walk_data, conditional. This assignment is inserted in CONST_AND_COPIES so that the copy and constant propagator can find more propagation opportunities. */ - if (parent_block_last_stmt - && bb->pred->pred_next == NULL - && TREE_CODE (parent_block_last_stmt) == COND_EXPR + if (TREE_CODE (parent_block_last_stmt) == COND_EXPR && (edge_flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) eq_expr_value = get_eq_expr_value (parent_block_last_stmt, (edge_flags & EDGE_TRUE_VALUE) != 0, @@ -1474,9 +1500,7 @@ record_equivalences_from_incoming_edge (struct dom_walk_data *walk_data, /* Similarly when the parent block ended in a SWITCH_EXPR. We can only know the value of the switch's condition if the dominator parent is also the only predecessor of this block. */ - else if (parent_block_last_stmt - && bb->pred->pred_next == NULL - && bb->pred->src == parent + else if (bb->pred->src == parent && TREE_CODE (parent_block_last_stmt) == SWITCH_EXPR) { tree switch_cond = SWITCH_COND (parent_block_last_stmt); -- 2.30.2