* fold-const.c (fold): Recognise a rotate by an unsigned amount.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@25937 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index def552b..d05eba8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+Wed Mar 24 01:35:01 1999  Geoff Keating  <geoffk@ozemail.com.au>
+
+       * fold-const.c (fold): Recognise a rotate by an unsigned amount.
+
 Tue Mar 23 23:32:14 1999  Jeffrey A Law  (law@cygnus.com)
 
        * pa.md (rotlsi3): New expander.  Synthesize a variable rotate

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 492f1b8..4faac0c 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -5007,6 +5007,8 @@ fold (expr)
 
          tree01 = TREE_OPERAND (arg0, 1);
          tree11 = TREE_OPERAND (arg1, 1);
+         STRIP_NOPS (tree01);
+         STRIP_NOPS (tree11);
          code01 = TREE_CODE (tree01);
          code11 = TREE_CODE (tree11);
          if (code01 == INTEGER_CST
@@ -5017,22 +5019,40 @@ fold (expr)
              == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0)))))
            return build (LROTATE_EXPR, type, TREE_OPERAND (arg0, 0),
                      code0 == LSHIFT_EXPR ? tree01 : tree11);
-         else if (code11 == MINUS_EXPR
-               && TREE_CODE (TREE_OPERAND (tree11, 0)) == INTEGER_CST
-               && TREE_INT_CST_HIGH (TREE_OPERAND (tree11, 0)) == 0
-               && TREE_INT_CST_LOW (TREE_OPERAND (tree11, 0))
-                 == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0)))
-               && operand_equal_p (tree01, TREE_OPERAND (tree11, 1), 0))
-           return build (code0 == LSHIFT_EXPR ? LROTATE_EXPR : RROTATE_EXPR,
-                       type, TREE_OPERAND (arg0, 0), tree01);
-         else if (code01 == MINUS_EXPR
-               && TREE_CODE (TREE_OPERAND (tree01, 0)) == INTEGER_CST
-               && TREE_INT_CST_HIGH (TREE_OPERAND (tree01, 0)) == 0
-               && TREE_INT_CST_LOW (TREE_OPERAND (tree01, 0))
-                 == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0)))
-               && operand_equal_p (tree11, TREE_OPERAND (tree01, 1), 0))
-           return build (code0 != LSHIFT_EXPR ? LROTATE_EXPR : RROTATE_EXPR,
-                       type, TREE_OPERAND (arg0, 0), tree11);
+         else if (code11 == MINUS_EXPR)
+           {
+             tree tree110, tree111;
+             tree110 = TREE_OPERAND (tree11, 0);
+             tree111 = TREE_OPERAND (tree11, 1);
+             STRIP_NOPS (tree110);
+             STRIP_NOPS (tree111);
+             if (TREE_CODE (tree110) == INTEGER_CST
+                 && TREE_INT_CST_HIGH (tree110) == 0
+                 && (TREE_INT_CST_LOW (tree110)
+                     == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0))))
+                 && operand_equal_p (tree01, tree111, 0))
+               return build ((code0 == LSHIFT_EXPR 
+                              ? LROTATE_EXPR 
+                              : RROTATE_EXPR),
+                             type, TREE_OPERAND (arg0, 0), tree01);
+           }
+         else if (code01 == MINUS_EXPR)
+           {
+             tree tree010, tree011;
+             tree010 = TREE_OPERAND (tree01, 0);
+             tree011 = TREE_OPERAND (tree01, 1);
+             STRIP_NOPS (tree010);
+             STRIP_NOPS (tree011);
+             if (TREE_CODE (tree010) == INTEGER_CST
+                 && TREE_INT_CST_HIGH (tree010) == 0
+                 && (TREE_INT_CST_LOW (tree010)
+                     == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0))))
+                 && operand_equal_p (tree11, tree011, 0))
+               return build ((code0 != LSHIFT_EXPR 
+                              ? LROTATE_EXPR 
+                              : RROTATE_EXPR),
+                              type, TREE_OPERAND (arg0, 0), tree11);
+           }
        }
 
       goto associate;