emit-rtl.c (copy_rtx_if_shared): Don't allow MEMs with constant addresses to be shared.

	* emit-rtl.c (copy_rtx_if_shared): Don't allow MEMs with constant
	addresses to be shared.
	(force_const_mem): Return a copy of the pool entry.

From-SVN: r73248

gcc/ChangeLog

+2003-11-04  Richard Sandiford  <rsandifo@redhat.com>
+
+	* emit-rtl.c (copy_rtx_if_shared): Don't allow MEMs with constant
+	addresses to be shared.
+	(force_const_mem): Return a copy of the pool entry.
+
 2003-11-03  Andreas Jaeger  <aj@suse.de>
 
 	* Makefile.in (GCC_CFLAGS): Remove @WERROR@ again.

gcc/emit-rtl.c

@@ -2690,20 +2690,6 @@ copy_rtx_if_shared (rtx orig)
       /* The chain of insns is not being copied.  */
       return x;
 
-    case MEM:
-      /* A MEM is allowed to be shared if its address is constant.
-
-	 We used to allow sharing of MEMs which referenced
-	 virtual_stack_vars_rtx or virtual_incoming_args_rtx, but
-	 that can lose.  instantiate_virtual_regs will not unshare
-	 the MEMs, and combine may change the structure of the address
-	 because it looks safe and profitable in one context, but
-	 in some other context it creates unrecognizable RTL.  */
-      if (CONSTANT_ADDRESS_P (XEXP (x, 0)))
-	return x;
-
-      break;
-
     default:
       break;
     }

gcc/varasm.c

@@ -2915,7 +2915,7 @@ force_const_mem (enum machine_mode mode, rtx x)
   hash = const_hash_rtx (mode, x);
   for (desc = const_rtx_hash_table[hash]; desc; desc = desc->next)
     if (compare_constant_rtx (mode, x, desc))
-      return desc->rtl;
+      return copy_rtx (desc->rtl);
 
   /* No constant equal to X is known to have been output.
      Make a constant descriptor to enter X in the hash table
@@ -2983,7 +2983,7 @@ force_const_mem (enum machine_mode mode, rtx x)
   SYMBOL_REF_FLAGS (symbol) = SYMBOL_FLAG_LOCAL;
   current_function_uses_const_pool = 1;
 
-  return def;
+  return copy_rtx (def);
 }
 
 /* Given a SYMBOL_REF with CONSTANT_POOL_ADDRESS_P true, return a pointer to