code review 3816043: syscall: Plan 9 support for x86.

src/pkg/syscall/mksyscall.pl

 #!/usr/bin/perl
 # Copyright 2009 The Go Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
 # This program reads a file containing function prototypes
 # (like syscall_darwin.go) and generates system call bodies.
 # The prototypes are marked by lines beginning with "//sys"
 # and read like func declarations if //sys is replaced by func, but:
 #       * The parameter lists must give a name for each argument.
 #         This includes return parameters.
 #       * The parameter lists must give a type for each argument:
 #         the (x, y, z int) shorthand is not allowed.
 #       * If the return parameter is an error number, it must be named errno.
 
 # A line beginning with //sysnb is like //sys, except that the
 # goroutine will not be suspended during the execution of the system
 # call.  This must only be used for system calls which can never
 # block, as otherwise the system call could cause all goroutines to
 # hang.
 
 $cmdline = "mksyscall.pl " . join(' ', @ARGV);
 $errors = 0;
 $_32bit = "";
 $nacl = 0;
+$plan9 = 0;
 
 if($ARGV[0] eq "-b32") {
         $_32bit = "big-endian";
         shift;
 } elsif($ARGV[0] eq "-l32") {
         $_32bit = "little-endian";
         shift;
 }
 if($ARGV[0] eq "-nacl") {
         $nacl = 1;
+        shift;
+}
+if($ARGV[0] eq "-plan9") {
+        $plan9 = 1;
         shift;
 }
 
 if($ARGV[0] =~ /^-/) {
         print STDERR "usage: mksyscall.pl [-b32 | -l32] [file ...]\n";
         exit 1;
 }
 
 sub parseparamlist($) {
         my ($list) = @_;
@@ skipping 107 matching lines @@
         my $args = join(', ', @args);
         my $call = "$asm($sysname, $args)";
 
         # Assign return values.
         my $body = "";
         my @ret = ("_", "_", "_");
         for(my $i=0; $i<@out; $i++) {
                 my $p = $out[$i];
                 my ($name, $type) = parseparam($p);
                 my $reg = "";
-                if($name eq "errno") {
+                if($name eq "errno" && !$plan9) {
                         $reg = "e1";
                         $ret[2] = $reg;
+                } elsif ($name eq "err" && $plan9) {
+                        $ret[0] = "r0";·················
+                        $ret[2] = "e1";
+                        next;
                 } else {
                         $reg = sprintf("r%d", $i);
                         $ret[$i] = $reg;
                 }
                 if($type eq "bool") {
                         $reg = "$reg != 0";
                 }
                 if($type eq "int64" && $_32bit ne "") {
                         # 64-bit number in r1:r0 or r0:r1.
                         if($i+2 > @out) {
                                 print STDERR "$ARGV:$.: not enough registers for int64 return\n";
                         }
                         if($_32bit eq "big-endian") {
                                 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1);
                         } else {
                                 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i);
                         }
                         $ret[$i] = sprintf("r%d", $i);
                         $ret[$i+1] = sprintf("r%d", $i+1);
                 }
                 $body .= "\t$name = $type($reg)\n";
         }
         if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
                 $text .= "\t$call\n";
         } else {
                 $text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
         }
         $text .= $body;
+········
+        if ($plan9 && $ret[2] eq "e1") {
+                $text .= "\terr = nil\n";
+                $text .= "\tif int(r0) == -1 {\n";
+                $text .= "\t\t err = NewError(e1)\n";
+                $text .= "\t}\n";
+        }
 
         $text .= "\treturn\n";
         $text .= "}\n\n";
 }
 
 chomp $text;
 chomp $text;
 
 if($errors) {
         exit 1;
 }
 
 print <<EOF;
 // $cmdline
 // MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
 
 package syscall
 
 import "unsafe"
 
 $text
 EOF
 exit 0;