tidy setup_incoming_promotions

[Richard Henderson <rth at redhat dot com>]

While looking at how FUNCTION_ARG_REGNO_P is used, I noticed this
bit of silliness, spanning two functions:

	for each hardreg
	  for each function argument
	    if argument = hardreg
	      do something

I've rearranged it to the much more straightforward

	for each function argument
	  if argument isa hardreg
	    do something

Tested on alpha and x86_64 linux.


r~



        * expr.h (promoted_input_arg): Remove decl.
        * function.c (promoted_input_arg): Merge into ...
        * combine.c (setup_incoming_promotions): ... only caller.
        Rearrange to avoid double loop. 

--- combine.c	(revision 122488)
+++ combine.c	(local)
@@ -1014,27 +1014,36 @@ init_reg_last (void)
 static void
 setup_incoming_promotions (void)
 {
-  unsigned int regno;
-  rtx reg;
-  enum machine_mode mode;
-  int unsignedp;
-  rtx first = get_insns ();
+  rtx first;
+  tree arg;
+
+  if (!targetm.calls.promote_function_args (TREE_TYPE (cfun->decl)))
+    return;
 
-  if (targetm.calls.promote_function_args (TREE_TYPE (cfun->decl)))
+  first = get_insns ();
+
+  for (arg = DECL_ARGUMENTS (current_function_decl); arg;
+       arg = TREE_CHAIN (arg))
     {
-      for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
-	/* Check whether this register can hold an incoming pointer
-	   argument.  FUNCTION_ARG_REGNO_P tests outgoing register
-	   numbers, so translate if necessary due to register windows.  */
-	if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (regno))
-	    && (reg = promoted_input_arg (regno, &mode, &unsignedp)) != 0)
-	  {
-	    record_value_for_reg
-	      (reg, first, gen_rtx_fmt_e ((unsignedp ? ZERO_EXTEND
-					   : SIGN_EXTEND),
-					  GET_MODE (reg),
-					  gen_rtx_CLOBBER (mode, const0_rtx)));
-	  }
+      rtx reg = DECL_INCOMING_RTL (arg);
+
+      if (!REG_P (reg))
+	continue;
+
+      if (TYPE_MODE (DECL_ARG_TYPE (arg)) == TYPE_MODE (TREE_TYPE (arg)))
+	{
+	  enum machine_mode mode = TYPE_MODE (TREE_TYPE (arg));
+	  int uns = TYPE_UNSIGNED (TREE_TYPE (arg));
+
+	  mode = promote_mode (TREE_TYPE (arg), mode, &uns, 1);
+	  if (mode == GET_MODE (reg) && mode != DECL_MODE (arg))
+	    {
+	      rtx x;
+	      x = gen_rtx_CLOBBER (DECL_MODE (arg), const0_rtx);
+	      x = gen_rtx_fmt_e ((uns ? ZERO_EXTEND : SIGN_EXTEND), mode, x);
+	      record_value_for_reg (reg, first, x);
+	    }
+	}
     }
 }
 
--- expr.h	(revision 122488)
+++ expr.h	(local)
@@ -597,9 +597,6 @@ extern rtx label_rtx (tree);
    if how is not obvious).  */
 extern rtx force_label_rtx (tree);
 
-/* Indicate how an input argument register was promoted.  */
-extern rtx promoted_input_arg (unsigned int, enum machine_mode *, int *);
-
 /* Return an rtx like arg but sans any constant terms.
    Returns the original rtx if it has no constant terms.
    The constant terms are added and stored via a second arg.  */
--- function.c	(revision 122488)
+++ function.c	(local)
@@ -3229,40 +3229,6 @@ gimplify_parameters (void)
   return stmts;
 }
 
-/* Indicate whether REGNO is an incoming argument to the current function
-   that was promoted to a wider mode.  If so, return the RTX for the
-   register (to get its mode).  PMODE and PUNSIGNEDP are set to the mode
-   that REGNO is promoted from and whether the promotion was signed or
-   unsigned.  */
-
-rtx
-promoted_input_arg (unsigned int regno, enum machine_mode *pmode, int *punsignedp)
-{
-  tree arg;
-
-  for (arg = DECL_ARGUMENTS (current_function_decl); arg;
-       arg = TREE_CHAIN (arg))
-    if (REG_P (DECL_INCOMING_RTL (arg))
-	&& REGNO (DECL_INCOMING_RTL (arg)) == regno
-	&& TYPE_MODE (DECL_ARG_TYPE (arg)) == TYPE_MODE (TREE_TYPE (arg)))
-      {
-	enum machine_mode mode = TYPE_MODE (TREE_TYPE (arg));
-	int unsignedp = TYPE_UNSIGNED (TREE_TYPE (arg));
-
-	mode = promote_mode (TREE_TYPE (arg), mode, &unsignedp, 1);
-	if (mode == GET_MODE (DECL_INCOMING_RTL (arg))
-	    && mode != DECL_MODE (arg))
-	  {
-	    *pmode = DECL_MODE (arg);
-	    *punsignedp = unsignedp;
-	    return DECL_INCOMING_RTL (arg);
-	  }
-      }
-
-  return 0;
-}
-
-
 /* Compute the size and offset from the start of the stacked arguments for a
    parm passed in mode PASSED_MODE and with type TYPE.