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-rw-r--r--gcc/tree-cfg.c128
1 files changed, 41 insertions, 87 deletions
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 119d51f3194..6bba74b0142 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -790,7 +790,7 @@ main_block_label (tree label)
return label_for_bb[bb->index];
}
-/* Cleanup redundant labels. This is a three-steo process:
+/* Cleanup redundant labels. This is a three-step process:
1) Find the leading label for each block.
2) Redirect all references to labels to the leading labels.
3) Cleanup all useless labels. */
@@ -1843,69 +1843,6 @@ remove_bb (basic_block bb)
remove_phi_nodes_and_edges_for_unreachable_block (bb);
}
-
-/* Examine BB to determine if it is a forwarding block (a block which only
- transfers control to a new destination). If BB is a forwarding block,
- then return the edge leading to the ultimate destination. */
-
-edge
-tree_block_forwards_to (basic_block bb)
-{
- block_stmt_iterator bsi;
- bb_ann_t ann = bb_ann (bb);
- tree stmt;
-
- /* If this block is not forwardable, then avoid useless work. */
- if (! ann->forwardable)
- return NULL;
-
- /* Set this block to not be forwardable. This prevents infinite loops since
- any block currently under examination is considered non-forwardable. */
- ann->forwardable = 0;
-
- /* No forwarding is possible if this block is a special block (ENTRY/EXIT),
- this block has more than one successor, this block's single successor is
- reached via an abnormal edge, this block has phi nodes, or this block's
- single successor has phi nodes. */
- if (bb == EXIT_BLOCK_PTR
- || bb == ENTRY_BLOCK_PTR
- || EDGE_COUNT (bb->succs) != 1
- || EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
- || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) != 0
- || phi_nodes (bb)
- || phi_nodes (EDGE_SUCC (bb, 0)->dest))
- return NULL;
-
- /* Walk past any labels at the start of this block. */
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
- {
- stmt = bsi_stmt (bsi);
- if (TREE_CODE (stmt) != LABEL_EXPR)
- break;
- }
-
- /* If we reached the end of this block we may be able to optimize this
- case. */
- if (bsi_end_p (bsi))
- {
- edge dest;
-
- /* Recursive call to pick up chains of forwarding blocks. */
- dest = tree_block_forwards_to (EDGE_SUCC (bb, 0)->dest);
-
- /* If none found, we forward to bb->succs[0] at minimum. */
- if (!dest)
- dest = EDGE_SUCC (bb, 0);
-
- ann->forwardable = 1;
- return dest;
- }
-
- /* No forwarding possible. */
- return NULL;
-}
-
-
/* Try to remove superfluous control structures. */
static bool
@@ -2713,6 +2650,24 @@ stmt_for_bsi (tree stmt)
gcc_unreachable ();
}
+/* Mark statement T as modified, and update it. */
+static inline void
+update_modified_stmts (tree t)
+{
+ if (TREE_CODE (t) == STATEMENT_LIST)
+ {
+ tree_stmt_iterator i;
+ tree stmt;
+ for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
+ {
+ stmt = tsi_stmt (i);
+ update_stmt_if_modified (stmt);
+ }
+ }
+ else
+ update_stmt_if_modified (t);
+}
+
/* Insert statement (or statement list) T before the statement
pointed-to by iterator I. M specifies how to update iterator I
after insertion (see enum bsi_iterator_update). */
@@ -2721,8 +2676,8 @@ void
bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
{
set_bb_for_stmt (t, i->bb);
+ update_modified_stmts (t);
tsi_link_before (&i->tsi, t, m);
- modify_stmt (t);
}
@@ -2734,8 +2689,8 @@ void
bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
{
set_bb_for_stmt (t, i->bb);
+ update_modified_stmts (t);
tsi_link_after (&i->tsi, t, m);
- modify_stmt (t);
}
@@ -2747,7 +2702,9 @@ bsi_remove (block_stmt_iterator *i)
{
tree t = bsi_stmt (*i);
set_bb_for_stmt (t, NULL);
+ delink_stmt_imm_use (t);
tsi_delink (&i->tsi);
+ mark_stmt_modified (t);
}
@@ -2811,7 +2768,7 @@ bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
}
*bsi_stmt_ptr (*bsi) = stmt;
- modify_stmt (stmt);
+ update_modified_stmts (stmt);
}
@@ -3757,7 +3714,10 @@ tree_make_forwarder_block (edge fallthru)
/* Return true if basic block BB does nothing except pass control
flow to another block and that we can safely insert a label at
- the start of the successor block. */
+ the start of the successor block.
+
+ As a precondition, we require that BB be not equal to
+ ENTRY_BLOCK_PTR. */
static bool
tree_forwarder_block_p (basic_block bb)
@@ -3771,17 +3731,25 @@ tree_forwarder_block_p (basic_block bb)
if (! bb_ann (bb)->forwardable)
return false;
- /* BB must have a single outgoing normal edge. Otherwise it can not be
- a forwarder block. */
+ /* BB must have a single outgoing edge. */
if (EDGE_COUNT (bb->succs) != 1
+ /* BB can not have any PHI nodes. This could potentially be
+ relaxed early in compilation if we re-rewrote the variables
+ appearing in any PHI nodes in forwarder blocks. */
+ || phi_nodes (bb)
+ /* BB may not be a predecessor of EXIT_BLOCK_PTR. */
|| EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
- || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL)
- || bb == ENTRY_BLOCK_PTR)
+ /* BB may not have an abnormal outgoing edge. */
+ || (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL))
{
bb_ann (bb)->forwardable = 0;
return false;
}
+#if ENABLE_CHECKING
+ gcc_assert (bb != ENTRY_BLOCK_PTR);
+#endif
+
/* Successors of the entry block are not forwarders. */
FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
if (e->dest == bb)
@@ -3790,15 +3758,6 @@ tree_forwarder_block_p (basic_block bb)
return false;
}
- /* BB can not have any PHI nodes. This could potentially be relaxed
- early in compilation if we re-rewrote the variables appearing in
- any PHI nodes in forwarder blocks. */
- if (phi_nodes (bb))
- {
- bb_ann (bb)->forwardable = 0;
- return false;
- }
-
/* Now walk through the statements. We can ignore labels, anything else
means this is not a forwarder block. */
for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
@@ -3884,12 +3843,7 @@ thread_jumps (void)
tree_forwarder_block_p (dest);
last = EDGE_SUCC (dest, 0),
dest = EDGE_SUCC (dest, 0)->dest)
- {
- if (EDGE_SUCC (dest, 0)->dest == EXIT_BLOCK_PTR)
- break;
-
- bb_ann (dest)->forwardable = 0;
- }
+ bb_ann (dest)->forwardable = 0;
/* Reset the forwardable marks to 1. */
for (tmp = e->dest;
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-18 00:13:58 +0000