expr.c (check_max_integer_computation_mode): New function.

        * expr.c (check_max_integer_computation_mode): New function.
        (expand_expr): Avoid integer computations in modes wider than
        MAX_INTEGER_COMPUTATION_MODE.
        * fold-const.c (fold): Likewise.
        * tree.h (check_max_integer_computation_mode): Declare.
        * tm.texi (MAX_INTEGER_COMPUTATION_MODE): Document it.

From-SVN: r20538

1 files changed, 67 insertions, 0 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 657737f..aad427d 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -4919,6 +4919,52 @@ var_rtx (exp)
       return 0;
     }
 }
+
+#ifdef MAX_INTEGER_COMPUTATION_MODE
+void
+check_max_integer_computation_mode (exp)
+    tree exp;
+{
+  enum tree_code code = TREE_CODE (exp);
+  enum machine_mode mode;
+
+  /* First check the type of the overall operation.   We need only look at
+     unary, binary and relational operations.  */
+  if (TREE_CODE_CLASS (code) == '1'
+      || TREE_CODE_CLASS (code) == '2'
+      || TREE_CODE_CLASS (code) == '<')
+    {
+      mode = TYPE_MODE (TREE_TYPE (exp));
+      if (GET_MODE_CLASS (mode) == MODE_INT
+	  && mode > MAX_INTEGER_COMPUTATION_MODE)
+	fatal ("unsupported wide integer operation");
+    }
+
+  /* Check operand of a unary op.  */
+  if (TREE_CODE_CLASS (code) == '1')
+    {
+      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
+      if (GET_MODE_CLASS (mode) == MODE_INT
+	  && mode > MAX_INTEGER_COMPUTATION_MODE)
+	fatal ("unsupported wide integer operation");
+    }
+	
+  /* Check operands of a binary/comparison op.  */
+  if (TREE_CODE_CLASS (code) == '2' || TREE_CODE_CLASS (code) == '<')
+    {
+      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
+      if (GET_MODE_CLASS (mode) == MODE_INT
+	  && mode > MAX_INTEGER_COMPUTATION_MODE)
+	fatal ("unsupported wide integer operation");
+
+      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 1)));
+      if (GET_MODE_CLASS (mode) == MODE_INT
+	  && mode > MAX_INTEGER_COMPUTATION_MODE)
+	fatal ("unsupported wide integer operation");
+    }
+}
+#endif
+
 
 /* expand_expr: generate code for computing expression EXP.
    An rtx for the computed value is returned.  The value is never null.
@@ -5041,6 +5087,23 @@ expand_expr (exp, target, tmode, modifier)
       target = 0;
     }
 
+#ifdef MAX_INTEGER_COMPUTATION_MODE
+  if (target)
+    {
+      enum machine_mode mode = GET_MODE (target);
+
+      if (GET_MODE_CLASS (mode) == MODE_INT
+	  && mode > MAX_INTEGER_COMPUTATION_MODE)
+	fatal ("unsupported wide integer operation");
+    }
+
+  if (GET_MODE_CLASS (tmode) == MODE_INT
+      && tmode > MAX_INTEGER_COMPUTATION_MODE)
+    fatal ("unsupported wide integer operation");
+
+  check_max_integer_computation_mode (exp);
+#endif
+
   /* If will do cse, generate all results into pseudo registers
      since 1) that allows cse to find more things
      and 2) otherwise cse could produce an insn the machine
@@ -9816,6 +9879,10 @@ do_jump (exp, if_false_label, if_true_label)
   tree type;
   enum machine_mode mode;
 
+#ifdef MAX_INTEGER_COMPUTATION_MODE
+  check_max_integer_computation_mode (exp);
+#endif
+
   emit_queue ();
 
   switch (code)