[PATCH V2] IRA: Speed up setup_left_conflict_sizes_p

[Zhouyi Zhou]

From: Zhouyi Zhou <zhouzho...@gmail.com>

In function setup_left_conflict_sizes_p, left conflict subnodes sizes
are computed in a bottom-to-up fashion through the regnodes foreast.

Speed up the process from prevent node itself to involve in this 
computation. 

I have no write access to GCC SVN repository, if it OK, can you commit
for me?

(Thanks Richard for reviewing)

Bootstrap and regtest scheduled on x86_64 GNU/Linux
Signed-off-by: Zhouyi Zhou <yizhouz...@ict.ac.cn>
---
 gcc/ChangeLog   |    5 +++++
 gcc/ira-color.c |    8 +++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 53f582b..a495dfc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2015-03-12  Zhouyi Zhou  <yizhouz...@ict.ac.cn> 
+
+       * ira-color.c (setup_left_conflict_sizes_p): Prevent node itself
+       from computing left conflict subnodes size.
+       
 2015-03-10  Jan Hubicka  <hubi...@ucw.cz>
 
        * cgraph.c (cgraph_node::release_body): Free function_in_decl_state.
diff --git a/gcc/ira-color.c b/gcc/ira-color.c
index ff1fe8a..d2d5102 100644
--- a/gcc/ira-color.c
+++ b/gcc/ira-color.c
@@ -938,7 +938,7 @@ setup_left_conflict_sizes_p (ira_allocno_t a)
       subnodes[i].left_conflict_subnodes_size = 0;
     }
   start = node_preorder_num * allocno_hard_regs_nodes_num;
-  for (i = data->hard_regs_subnodes_num - 1; i >= 0; i--)
+  for (i = data->hard_regs_subnodes_num - 1; i > 0; i--)
     {
       int size, parent_i;
       allocno_hard_regs_node_t parent;
@@ -948,12 +948,10 @@ setup_left_conflict_sizes_p (ira_allocno_t a)
                     - subnodes[i].left_conflict_subnodes_size,
                     subnodes[i].left_conflict_size));
       parent = allocno_hard_regs_nodes[i + node_preorder_num]->parent;
-      if (parent == NULL)
-       continue;
+      gcc_checking_assert(parent);
       parent_i
        = allocno_hard_regs_subnode_index[start + parent->preorder_num];
-      if (parent_i < 0)
-       continue;
+      gcc_checking_assert(parent_i >= 0);
       subnodes[parent_i].left_conflict_subnodes_size += size;
     }
   left_conflict_subnodes_size = subnodes[0].left_conflict_subnodes_size;
-- 
1.7.10.4