Changeset 1588 for branches/GNU/src/gcc/gcc/convert.c

Timestamp:

Nov 3, 2004, 6:47:21 AM (21 years ago)

Author:

bird

Message:

GCC v3.3.5 - official sources.

File:

• branches/GNU/src/gcc/gcc/convert.c (modified) (1 diff, 1 prop)

branches/GNU/src/gcc/gcc/convert.c

@@ -183 +183 @@
 
       else if (outprec >= inprec)
-        return build1 (NOP_EXPR, type, expr);
+        {
+          enum tree_code code;
+
+          /* If the precision of the EXPR's type is K bits and the
+             destination mode has more bits, and the sign is changing,
+             it is not safe to use a NOP_EXPR.  For example, suppose
+             that EXPR's type is a 3-bit unsigned integer type, the
+             TYPE is a 3-bit signed integer type, and the machine mode
+             for the types is 8-bit QImode.  In that case, the
+             conversion necessitates an explicit sign-extension.  In
+             the signed-to-unsigned case the high-order bits have to
+             be cleared.  */
+          if (TREE_UNSIGNED (type) != TREE_UNSIGNED (TREE_TYPE (expr))
+              && (TYPE_PRECISION (TREE_TYPE (expr))
+                  != GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)))))
+            code = CONVERT_EXPR;
+          else
+            code = NOP_EXPR;
+
+          return build1 (code, type, expr);
+        }
 
       /* If TYPE is an enumeral type or a type with a precision less