(build_binary_op, case *_DIV_EXPR): Use same shorten

condition as for TRUNC_MOD_EXPR.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@6353 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/c-typeck.c b/gcc/c-typeck.c
index bc95508..b952828 100644 (file)
--- a/gcc/c-typeck.c
+++ b/gcc/c-typeck.c
@@ -1940,9 +1940,17 @@ build_binary_op (code, orig_op0, orig_op1, convert_p)
          if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
            resultcode = RDIV_EXPR;
          else
-           /* When dividing two signed integers, you have to promote to int.
-              E.g. (short) -32768 / (short) -1 doesn't fit in a short.  */
-           shorten = TREE_UNSIGNED (orig_op0);
+           {
+             /* Although it would be tempting to shorten always here, that
+                loses on some targets, since the modulo instruction is
+                undefined if the quotient can't be represented in the
+                computation mode.  We shorten only if unsigned or if
+                dividing by something we know != -1.  */
+             shorten = (TREE_UNSIGNED (orig_op0)
+                        || (TREE_CODE (op1) == INTEGER_CST
+                            && (TREE_INT_CST_LOW (op1) != -1
+                                || TREE_INT_CST_HIGH (op1) != -1)));
+           }
          common = 1;
        }
       break;