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

gcc/ChangeLog

@@ -6,6 +6,13 @@
 
 Wed Jun 17 08:38:13 1998  Jeffrey A Law  (law@cygnus.com)
 
+	* 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.
+
 	* configure.in (nm): Make a link to "nm" in the build tree too.
 
 	* mn10300.md (andsi3): Fix typo.

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)

gcc/fold-const.c

@@ -3797,6 +3797,10 @@ fold (expr)
       return t;
     }
   
+#ifdef MAX_INTEGER_COMPUTATION_MODE
+  check_max_integer_computation_mode (expr);
+#endif
+
   kind = TREE_CODE_CLASS (code);
   if (code == NOP_EXPR || code == FLOAT_EXPR || code == CONVERT_EXPR)
     {

gcc/tm.texi

@@ -7417,4 +7417,12 @@ A C expression that returns how many instructions can be issued at the
 same time if the machine is a superscalar machine.  This is only used by
 the @samp{Haifa} scheduler, and not the traditional scheduler.
 
+@findex MAX_INTEGER_COMPUTATION_MODE
+@item MAX_INTEGER_COMPUTATION_MODE
+Define this to the largest integer machine mode which can be used for
+operations other than load, store and copy operations.
+
+You need only define this macro if the target holds values larger than
+@code{word_mode} in general purpose registers.  Most targets should not define
+this macro.
 @end table

gcc/tree.h

@@ -2123,6 +2123,7 @@ extern void do_pending_stack_adjust		PROTO ((void));
 extern struct rtx_def *expand_assignment	PROTO ((tree, tree, int, int));
 extern struct rtx_def *store_expr		PROTO ((tree, struct rtx_def *,
 							int));
+extern void check_max_integer_computation_mode	PROTO ((tree));
 
 /* In emit-rtl.c */
 extern void start_sequence_for_rtl_expr		PROTO ((tree));