RFA: Split address validation out of process_address

[Richard Sandiford <rdsandiford at googlemail dot com>]

Hi Vlad,

This patch splits out the code to verify an address, so that it's
easier to experiment with different approaches.  See the next patch
for one example where this might be useful in future.

Tested on x86_64-linux-gnu.  OK to install?

Richard


gcc/
	* lra-constraints.c (valid_address_p): New function, split out from...
	(process_address): ...here.

Index: gcc/lra-constraints.c
===================================================================
--- gcc/lra-constraints.c	2012-10-25 10:16:51.025280757 +0100
+++ gcc/lra-constraints.c	2012-10-25 10:20:55.314280159 +0100
@@ -2379,6 +2379,41 @@ valid_address_p (enum machine_mode mode
 #endif
 }
 
+/* Return whether address X, described by AD, is valid for mode MODE
+   and address space AS.  */
+
+static bool
+valid_address_p (struct address *ad, enum machine_mode mode, rtx x,
+		 addr_space_t as)
+{
+  /* Some ports do not check displacements for eliminable registers,
+     so we replace them temporarily with the elimination target.  */
+  rtx saved_base_reg = NULL_RTX;
+  rtx saved_index_reg = NULL_RTX;
+  if (ad->base_reg_loc != NULL)
+    {
+      saved_base_reg = *ad->base_reg_loc;
+      lra_eliminate_reg_if_possible (ad->base_reg_loc);
+      if (ad->base_reg_loc2 != NULL)
+	*ad->base_reg_loc2 = *ad->base_reg_loc;
+    }
+  if (ad->index_reg_loc != NULL)
+    {
+      saved_index_reg = *ad->index_reg_loc;
+      lra_eliminate_reg_if_possible (ad->index_reg_loc);
+    }
+  bool ok_p = valid_address_p (mode, x, as);
+  if (saved_base_reg != NULL_RTX)
+    {
+      *ad->base_reg_loc = saved_base_reg;
+      if (ad->base_reg_loc2 != NULL)
+	*ad->base_reg_loc2 = saved_base_reg;
+    }
+  if (saved_index_reg != NULL_RTX)
+    *ad->index_reg_loc = saved_index_reg;
+  return ok_p;
+}
+
 /* Make reload base reg + disp from address AD in space AS of memory
    with MODE into a new pseudo.	 Return the new pseudo.	 */
 static rtx
@@ -2518,8 +2553,7 @@ process_address (int nop, rtx *before, r
 {
   struct address ad;
   enum machine_mode mode;
-  rtx new_reg, *addr_loc, saved_index_reg, saved_base_reg;
-  bool ok_p;
+  rtx new_reg, *addr_loc;
   addr_space_t as;
   rtx op = *curr_id->operand_loc[nop];
   const char *constraint = curr_static_id->operand[nop].constraint;
@@ -2584,38 +2618,7 @@ process_address (int nop, rtx *before, r
 
      All these cases involve a displacement, so there is no point
      revalidating when there is no displacement.  */
-  if (ad.disp_loc == NULL)
-    return change_p;
-
-  /* See whether the address is still valid.  Some ports do not check
-     displacements for eliminable registers, so we replace them
-     temporarily with the elimination target.  */
-  saved_base_reg = saved_index_reg = NULL_RTX;
-  if (ad.base_reg_loc != NULL)
-    {
-      saved_base_reg = *ad.base_reg_loc;
-      lra_eliminate_reg_if_possible (ad.base_reg_loc);
-      if (ad.base_reg_loc2 != NULL)
-	*ad.base_reg_loc2 = *ad.base_reg_loc;
-    }
-  if (ad.index_reg_loc != NULL)
-    {
-      saved_index_reg = *ad.index_reg_loc;
-      lra_eliminate_reg_if_possible (ad.index_reg_loc);
-    }
-  /* Some ports do not check displacements for virtual registers -- so
-     we substitute them temporarily by real registers.	*/
-  ok_p = valid_address_p (mode, *addr_loc, as);
-  if (saved_base_reg != NULL_RTX)
-    {
-      *ad.base_reg_loc = saved_base_reg;
-      if (ad.base_reg_loc2 != NULL)
-	*ad.base_reg_loc2 = saved_base_reg;
-    }
-  if (saved_index_reg != NULL_RTX)
-    *ad.index_reg_loc = saved_index_reg;
-
-  if (ok_p)
+  if (ad.disp_loc == NULL || valid_address_p (&ad, mode, *addr_loc, as))
     return change_p;
 
   /* Any index existed before LRA started, so we can assume that the