Micro optimisation of the day: Remove ia32_Test, which tests the high result of ia32_Mul.

[libfirm] / ir / ana / irconsconfirm.c

diff --git a/ir/ana/irconsconfirm.c b/ir/ana/irconsconfirm.c
index c8f9346..57b8f3c 100644 (file)
--- a/ir/ana/irconsconfirm.c
+++ b/ir/ana/irconsconfirm.c
@@ -415,7 +415,31 @@ static void insert_Confirm_in_block(ir_node *block, void *env) {
 }  /* insert_Confirm_in_block */
 
 /**
- * The given will be dereferenced, add non-null confirms.
+ * Checks if a node is a non-null Confirm.
+ */
+static int is_non_null_Confirm(const ir_node *ptr) {
+       /*
+        * While a SymConst is not a Confirm, it is non-null
+        * anyway. This helps to reduce the number of
+        * constructed Confirms.
+        */
+       if (is_SymConst_addr_ent(ptr))
+               return 1;
+       for (;;) {
+               if (! is_Confirm(ptr))
+                       return 0;
+               if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
+                       ir_node *bound = get_Confirm_bound(ptr);
+
+                       if (is_Const(bound) && is_Const_null(bound))
+                               return 1;
+               }
+               ptr = get_Confirm_value(ptr);
+       }
+}  /* is_non_null_Confirm */
+
+/**
+ * The given pointer will be dereferenced, add non-null Confirms.
  *
  * @param ptr    a node representing an address
  * @param block  the block of the dereferencing instruction
@@ -431,6 +455,11 @@ static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env) {
                ir_node *blk;
 
 
+               if (is_Confirm(succ)) {
+                       /* beware of loops */
+                       continue;
+               }
+
                if ((is_Load(succ) || is_Store(succ)) &&
                        get_nodes_block(succ) == block) {
                        /* Ignore Loads and Store in the same block for now,
@@ -443,7 +472,7 @@ static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env) {
                pos = get_edge_src_pos(edge);
                blk = get_effective_use_block(succ, pos);
 
-               if (block_dominates(block, blk)) {
+               if (block_dominates(block, blk) && !is_non_null_Confirm(get_irn_n(succ, pos))) {
                        /*
                         * Ok, we found a usage of ptr in a block
                         * dominated by the Load/Store block.
@@ -465,23 +494,6 @@ static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env) {
        }
 }  /* insert_non_null */
 
-/**
- * Checks if a node is a non-null Confirm.
- */
-static int is_non_null_Confirm(const ir_node *ptr) {
-       for (;;) {
-               if (! is_Confirm(ptr))
-                       return 0;
-               if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
-                       ir_node *bound = get_Confirm_bound(ptr);
-
-                       if (is_Const(bound) && is_Const_null(bound))
-                               return 1;
-               }
-               ptr = get_Confirm_value(ptr);
-       }
-}  /* is_non_null_Confirm */
-
 /**
  * Pre-walker: Called for every node to insert Confirm nodes
  */
@@ -571,7 +583,7 @@ static void rem_Confirm(ir_node *n, void *env) {
                        exchange(n, value);
                else {
                        /*
-                        * Strange: a Confirm is it's own bound. This can happen
+                        * Strange: a Confirm is its own bound. This can happen
                         * in dead blocks when Phi nodes are already removed.
                         */
                        exchange(n, new_Bad());