5506 cstyle: warn about #if enumerating ISA defines

*** 20,32 ****
  # CDDL HEADER END
  #
  #
  # Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  # Use is subject to license terms.
! #
! # @(#)cstyle 1.58 98/09/09 (from shannon)
! #ident  "%Z%%M% %I%     %E% SMI"
  #
  # cstyle - check for some common stylistic errors.
  #
  #       cstyle is a sort of "lint" for C coding style.
  #       It attempts to check for the style used in the
--- 20,30 ----
  # CDDL HEADER END
  #
  #
  # Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  # Use is subject to license terms.
! # Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
  #
  # cstyle - check for some common stylistic errors.
  #
  #       cstyle is a sort of "lint" for C coding style.
  #       It attempts to check for the style used in the
*** 482,491 ****
--- 480,507 ----
          # declaration.
          if (/\S.*\/\*/ && !/\S.*\/\*.*\*\// && !/\(\/\*/) {
                  err("unterminated single line comment");
          }
  
+         # check that #if and #elif don't enumerate ISA defines when there
+         # are more concise ways of checking.  E.g., don't do:
+         #     #if defined(__amd64) || defined(__i386)
+         # when there is:
+         #     #ifdef __x86
+         if ((/^(#if|#elif)\sdefined\((.*)\)\s\|\|\sdefined\((.*)\)/) ||
+             (/^(#if|#elif)\s!defined\((.*)\)\s&&\s!defined\((.*)\)/)) {
+                 my $directive = $1;
+                 my $first = $2;
+                 my $second = $3;
+                 ($first, $second) = ($second, $first) if ($first gt $second);
+ 
+                 if (($first eq "__amd64") && ($second eq "__i386")) {
+                         err("$directive checking for $first or $second " .
+                             "instead of __x86");
+                 }
+         }
+ 
          if (/^(#else|#endif|#include)(.*)$/) {
                  $prev = $line;
                  if ($picky) {
                          my $directive = $1;
                          my $clause = $2;