diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d6a9c4da70dd8f61b048955b9f7e608fac9c5731..af01b0e7f947e89d5c2de2e61ad836205e922ede 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2011-11-01 Tom de Vries <tom@codesourcery.com>
+
+ PR tree-optimization/50908
+ * tree-ssa-tail-merge.c (update_vuses): Now that edges are removed
+ before update_vuses, test for 1 predecessor rather than two.
+ (delete_block_update_dominator_info): New function, part of it factored
+ out of ...
+ (replace_block_by): Use delete_block_update_dominator_info. Call
+ update_vuses after deleting bb1 and updating dominator info, instead of
+ before.
+
2011-11-01 David S. Miller <davem@davemloft.net>
* config/sparc/sparc.c (sparc_expand_vcond): New function.
diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index eb4bc92bd62154c0f664383c49d0770c3c37aee9..17e7f374b05a1ec2b736dc6363908e32326344ed 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -1458,7 +1458,7 @@ update_vuses (bool vuse1_phi_args, tree vuse1, tree vuse2, basic_block bb2,
if (!dominated_by_p (CDI_DOMINATORS, pred, bb2))
continue;
- if (pred == bb2 && EDGE_COUNT (gimple_bb (stmt)->preds) == 2)
+ if (pred == bb2 && EDGE_COUNT (gimple_bb (stmt)->preds) == 1)
{
gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
unlink_virtual_phi (stmt, lhs);
@@ -1526,6 +1526,88 @@ vop_at_entry (basic_block bb)
: NULL_TREE);
}
+/* Given that all incoming edges of BB1 have been redirected to BB2, delete BB1
+ and recompute dominator info. */
+
+static void
+delete_block_update_dominator_info (basic_block bb1, basic_block bb2)
+{
+ VEC (basic_block,heap) *fix_dom_bb;
+ unsigned int i;
+ basic_block bb, dom;
+ edge e;
+ edge_iterator ei;
+
+ /* Consider the following cfg, where A is the direct dominator of I:
+
+ A
+ / \
+ B \
+ / \ \
+ C D
+ /| |\
+ E F
+ |\ /|
+ | x |
+ |/ \|
+ G H
+ \ /
+ I
+
+ Say E and F are duplicates, and F is removed. The cfg then looks like
+ this:
+
+ A
+ / \
+ B \
+ / \ \
+ C D
+ / \ / \
+ E
+ / \
+ G H
+ \ /
+ I
+
+ E is now the new direct dominator of I.
+
+ In order to calculate the new dominator info, we take the nearest common
+ dominator (A) of bb1 (F) and bb2 (E), and get the set of bbs immediately
+ dominated by it. Some of this set may now be directly dominated by bb2.
+
+ Ideally we would have a means to determine which bbs in the set are now
+ dominated by bb2, and call set_immediate_dominator for those bbs, but we
+ don't, so instead we let iterate_fix_dominators figure it out. */
+
+ /* Add bbs immediately dominated by the most common dominator. */
+ dom = nearest_common_dominator (CDI_DOMINATORS, bb1, bb2);
+ fix_dom_bb = get_dominated_by (CDI_DOMINATORS, dom);
+
+ if (get_immediate_dominator (CDI_DOMINATORS, bb1) == dom)
+ for (i = 0; VEC_iterate (basic_block, fix_dom_bb, i, bb); ++i)
+ {
+ if (bb != bb1)
+ continue;
+ VEC_unordered_remove (basic_block, fix_dom_bb, i);
+ break;
+ }
+
+ /* Add bb2, but not twice. */
+ if (get_immediate_dominator (CDI_DOMINATORS, bb2) != dom)
+ VEC_safe_push (basic_block, heap, fix_dom_bb, bb2);
+ /* Add succs of bb2, but not twice. */
+ FOR_EACH_EDGE (e, ei, bb2->succs)
+ if (get_immediate_dominator (CDI_DOMINATORS, e->dest) != dom)
+ VEC_safe_push (basic_block, heap, fix_dom_bb, e->dest);
+
+ delete_basic_block (bb1);
+ iterate_fix_dominators (CDI_DOMINATORS, fix_dom_bb, false);
+#if defined (ENABLE_CHECKING)
+ verify_dominators (CDI_DOMINATORS);
+#endif
+ VEC_free (basic_block, heap, fix_dom_bb);
+}
+
/* Redirect all edges from BB1 to BB2, marks BB1 for removal, and if
UPDATE_VOPS, inserts vop phis. */
@@ -1539,7 +1621,6 @@ replace_block_by (basic_block bb1, basic_block bb2, bool update_vops)
edge e;
edge_iterator ei;
bool vuse1_phi_args = false;
- VEC (basic_block,heap) *fix_dom_bb;
phi_vuse2 = vop_at_entry (bb2);
if (phi_vuse2 != NULL_TREE && TREE_CODE (phi_vuse2) != SSA_NAME)
@@ -1550,7 +1631,8 @@ replace_block_by (basic_block bb1, basic_block bb2, bool update_vops)
/* Find the vops at entry of bb1 and bb2. */
phi_vuse1 = vop_at_entry (bb1);
- /* If both are not found, it means there's no need to update. */
+ /* If both are not found, it means there's no need to update. Uses old
+ dominator info. */
if (phi_vuse1 == NULL_TREE && phi_vuse2 == NULL_TREE)
update_vops = false;
else if (phi_vuse1 == NULL_TREE)
@@ -1591,25 +1673,20 @@ replace_block_by (basic_block bb1, basic_block bb2, bool update_vops)
pred_edge, UNKNOWN_LOCATION);
}
- /* Update the vops. */
+ /* Do updates that use bb1, before deleting bb1. */
+ if (!update_vops)
+ release_last_vdef (bb1);
+ same_succ_flush_bb (bb1);
+
+ delete_block_update_dominator_info (bb1, bb2);
+
+ /* Update the vops. Uses new dominator info. */
if (update_vops)
{
update_vuses (vuse1_phi_args, phi_vuse1, phi_vuse2, bb2,
redirected_edges);
VEC_free (edge, heap, redirected_edges);
}
- else
- release_last_vdef (bb1);
-
- same_succ_flush_bb (bb1);
- delete_basic_block (bb1);
-
- fix_dom_bb = VEC_alloc (basic_block, heap, 2);
- VEC_safe_push (basic_block, heap, fix_dom_bb, bb2);
- FOR_EACH_EDGE (e, ei, bb2->succs)
- VEC_safe_push (basic_block, heap, fix_dom_bb, e->dest);
- iterate_fix_dominators (CDI_DOMINATORS, fix_dom_bb, false);
- VEC_free (basic_block, heap, fix_dom_bb);
}
/* Bbs for which update_debug_stmt need to be called. */