* predict.c (expr_expected_value_1): Assume compare-and-swap builtin

        boolean return is true.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@181862 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1e06e7f..dceaefc 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2011-11-30  Richard Henderson  <rth@redhat.com>
+
+       * predict.c (expr_expected_value_1): Assume compare-and-swap builtin
+       boolean return is true.
+
 2011-11-30  Jakub Jelinek  <jakub@redhat.com>
 
        PR rtl-optimization/51044

diff --git a/gcc/predict.c b/gcc/predict.c
index eeca172..9236531 100644 (file)
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -1190,7 +1190,8 @@ static tree expr_expected_value (tree, bitmap);
 /* Helper function for expr_expected_value.  */
 
 static tree
-expr_expected_value_1 (tree type, tree op0, enum tree_code code, tree op1, bitmap visited)
+expr_expected_value_1 (tree type, tree op0, enum tree_code code,
+                      tree op1, bitmap visited)
 {
   gimple def;
 
@@ -1255,17 +1256,36 @@ expr_expected_value_1 (tree type, tree op0, enum tree_code code, tree op1, bitma
          tree decl = gimple_call_fndecl (def);
          if (!decl)
            return NULL;
-         if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
-             && DECL_FUNCTION_CODE (decl) == BUILT_IN_EXPECT)
-           {
-             tree val;
+         if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL)
+           switch (DECL_FUNCTION_CODE (decl))
+             {
+             case BUILT_IN_EXPECT:
+               {
+                 tree val;
+                 if (gimple_call_num_args (def) != 2)
+                   return NULL;
+                 val = gimple_call_arg (def, 0);
+                 if (TREE_CONSTANT (val))
+                   return val;
+                 return gimple_call_arg (def, 1);
+               }
 
-             if (gimple_call_num_args (def) != 2)
-               return NULL;
-             val = gimple_call_arg (def, 0);
-             if (TREE_CONSTANT (val))
-               return val;
-             return gimple_call_arg (def, 1);
+             case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N:
+             case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1:
+             case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2:
+             case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4:
+             case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8:
+             case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16:
+             case BUILT_IN_ATOMIC_COMPARE_EXCHANGE:
+             case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N:
+             case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1:
+             case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2:
+             case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4:
+             case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8:
+             case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16:
+               /* Assume that any given atomic operation has low contention,
+                  and thus the compare-and-swap operation succeeds.  */
+               return boolean_true_node;
            }
        }