[PR99680] Check empty constraint before using CONSTRAINT_LEN.

It seems CONSTRAINT_LEN treats constraint '\0' as one having length 1.  Therefore we
read after the constraint string.  The patch fixes it.

gcc/ChangeLog:

	PR rtl-optimization/99680
	* lra-constraints.c (skip_contraint_modifiers): Rename to skip_constraint_modifiers.
	(process_address_1): Check empty constraint before using
	CONSTRAINT_LEN.

gcc/lra-constraints.c

@@ -3395,12 +3395,12 @@ equiv_address_substitution (struct address_info *ad)
 /* Skip all modifiers and whitespaces in constraint STR and return the
    result.  */
 static const char *
-skip_contraint_modifiers (const char *str)
+skip_constraint_modifiers (const char *str)
 {
   for (;;str++)
     switch (*str)
       {
-      case '+' : case '&' : case '=': case '*': case ' ': case '\t':
+      case '+': case '&' : case '=': case '*': case ' ': case '\t':
       case '$': case '^' : case '%': case '?': case '!':
 	break;
       default: return str;
@@ -3451,24 +3451,24 @@ process_address_1 (int nop, bool check_only_p,
     return false;
 
   constraint
-    = skip_contraint_modifiers (curr_static_id->operand[nop].constraint);
+    = skip_constraint_modifiers (curr_static_id->operand[nop].constraint);
   if (IN_RANGE (constraint[0], '0', '9'))
     {
       char *end;
       unsigned long dup = strtoul (constraint, &end, 10);
       constraint
-	= skip_contraint_modifiers (curr_static_id->operand[dup].constraint);
+	= skip_constraint_modifiers (curr_static_id->operand[dup].constraint);
     }
   cn = lookup_constraint (*constraint == '\0' ? "X" : constraint);
   /* If we have several alternatives or/and several constraints in an
      alternative and we can not say at this stage what constraint will be used,
      use unknown constraint.  The exception is an address constraint.  If
      operand has one address constraint, probably all others constraints are
      address ones.  */
-  if (get_constraint_type (cn) != CT_ADDRESS
-      && *skip_contraint_modifiers (constraint
-				    + CONSTRAINT_LEN (constraint[0],
-						      constraint)) != '\0')
+  if (constraint[0] != '\0' && get_constraint_type (cn) != CT_ADDRESS
+      && *skip_constraint_modifiers (constraint
+				     + CONSTRAINT_LEN (constraint[0],
+						       constraint)) != '\0')
     cn = CONSTRAINT__UNKNOWN;
   if (insn_extra_address_constraint (cn)
       /* When we find an asm operand with an address constraint that