s390: Fix AQ and AR constraints

Ensure for AQ and AR constraints that the resulting displacement after
adding any positive offset less than the size of the object being
referenced is still valid.

gcc/ChangeLog:

	* config/s390/s390.cc (s390_mem_constraint): Check displacement
	for AQ and AR constraints.

diff --git a/gcc/config/s390/s390.cc b/gcc/config/s390/s390.cc
index c1649ca49bd13f50e818cc61e514d4799a24b8b5..926987113dd47f440396c587f9e56e07c7cf0a0b 100644 (file)
--- a/gcc/config/s390/s390.cc
+++ b/gcc/config/s390/s390.cc
@@ -3689,6 +3689,18 @@ s390_mem_constraint (const char *str, rtx op)
       if ((reload_completed || reload_in_progress)
          ? !offsettable_memref_p (op) : !offsettable_nonstrict_memref_p (op))
        return 0;
+      /* offsettable_memref_p ensures only that any positive offset added to
+        the address forms a valid general address.  For AQ and AR constraints
+        we also have to verify that the resulting displacement after adding
+        any positive offset less than the size of the object being referenced
+        is still valid.  */
+      if (str[1] == 'Q' || str[1] == 'R')
+       {
+         int o = GET_MODE_SIZE (GET_MODE (op)) - 1;
+         rtx tmp = adjust_address (op, QImode, o);
+         if (!s390_check_qrst_address (str[1], XEXP (tmp, 0), true))
+           return 0;
+       }
       return s390_check_qrst_address (str[1], XEXP (op, 0), true);
     case 'B':
       /* Check for non-literal-pool variants of memory constraints.  */