reload.c (find_reloads_subreg_address): Check the original req_equiv_mem address...

	* reload.c (find_reloads_subreg_address): Check the original
	req_equiv_mem address to detect the case where an address is
	not valid in the outer mode.

From-SVN: r150649

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1938c39..8aaa865 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2009-08-11  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>
+
+       * reload.c (find_reloads_subreg_address): Check the original
+       req_equiv_mem address to detect the case where an address is
+       not valid in the outer mode.
+
 2009-08-11  Richard Guenther  <rguenther@suse.de>
         
         PR bootstrap/40788

diff --git a/gcc/reload.c b/gcc/reload.c
index 64024a7..257acd0 100644 (file)
--- a/gcc/reload.c
+++ b/gcc/reload.c
@@ -6133,18 +6133,26 @@ find_reloads_subreg_address (rtx x, int force_replace, int opnum,
              /* For some processors an address may be valid in the
                 original mode but not in a smaller mode.  For
                 example, ARM accepts a scaled index register in
-                SImode but not in HImode.  Similarly, the address may
-                have been valid before the subreg offset was added,
-                but not afterwards.  find_reloads_address
-                assumes that we pass it a valid address, and doesn't
-                force a reload.  This will probably be fine if
-                find_reloads_address finds some reloads.  But if it
-                doesn't find any, then we may have just converted a
-                valid address into an invalid one.  Check for that
-                here.  */
+                SImode but not in HImode.  Note that this is only
+                a problem if the address in reg_equiv_mem is already
+                invalid in the new mode; other cases would be fixed
+                by find_reloads_address as usual.
+
+                ??? We attempt to handle such cases here by doing an
+                additional reload of the full address after the
+                usual processing by find_reloads_address.  Note that
+                this may not work in the general case, but it seems
+                to cover the cases where this situation currently
+                occurs.  A more general fix might be to reload the
+                *value* instead of the address, but this would not
+                be expected by the callers of this routine as-is.
+
+                If find_reloads_address already completed replaced
+                the address, there is nothing further to do.  */
              if (reloaded == 0
-                 && !strict_memory_address_p (GET_MODE (tem),
-                                              XEXP (tem, 0)))
+                 && reg_equiv_mem[regno] != 0
+                 && !strict_memory_address_p (GET_MODE (x),
+                                              XEXP (reg_equiv_mem[regno], 0)))
                push_reload (XEXP (tem, 0), NULL_RTX, &XEXP (tem, 0), (rtx*) 0,
                             base_reg_class (GET_MODE (tem), MEM, SCRATCH),
                             GET_MODE (XEXP (tem, 0)), VOIDmode, 0, 0,