new approach for generating sysimport.c

(renamed to avoid any conflict with old p4 copies).

this approach doesn't require auto-generating
files also kept in p4, so it should be easier on
go users who don't sync very often.

this approach will be more work for go developers:
builtin.c needs to be copied to builtin.c.boot in p4
as new functions are added.  mkbuiltin does this
for certain $USERs to help us remember.

R=r
DELTA=343  (176 added, 162 deleted, 5 changed)
OCL=25803
CL=25805

src/cmd/gc/Makefile

@@ -26,7 +26,7 @@ OFILES=\
 	mparith1.$O\
 	mparith2.$O\
 	mparith3.$O\
-	sysimport.$O\
+	builtin.$O\
 	compat.$O\
 
 $(LIB): $(OFILES)
@@ -40,25 +40,11 @@ y.tab.h: $(YFILES)
 y.tab.c: y.tab.h
 	test -f y.tab.c && touch y.tab.c
 
-# the test here checks whether we have 6g at all.
-# if so, use it.  if not, just use the sysimport.c we have.
-# this happens on fresh perforce checkouts where
-# sysimport.c ends up with an older time stamp
-# than sys.go (or unsafe.go or mksys.c).
-sysimport.c:	sys.go unsafe.go mksys.c
-	if test -x $(BIN)/6g; then \
-		p4 open sysimport.c; \
-		gcc -o mksys mksys.c; \
-		6g sys.go; \
-		6g unsafe.go; \
-		./mksys sys >_sysimport.c && \
-		./mksys unsafe >>_sysimport.c && \
-		mv _sysimport.c sysimport.c; \
-	elif test -f sysimport.c; then \
-		touch sysimport.c; \
-	fi
+builtin.c:	sys.go unsafe.go mkbuiltin1.c mkbuiltin
+	mkbuiltin >builtin.c || \
+	(echo 'mkbuiltin failed; using bootstrap copy of builtin.c'; cp builtin.c.boot builtin.c)
 
 clean:
-	rm -f $(OFILES) *.6 enam.c 6.out a.out y.tab.h y.tab.c $(LIB) _sysimport.c
+	rm -f $(OFILES) *.6 enam.c 6.out a.out y.tab.h y.tab.c $(LIB) mkbuiltin1 builtin.c _builtin.c
 
 install: $(LIB)

src/cmd/gc/mkbuiltin

@@ -0,0 +1,31 @@
+#!/bin/sh
+# 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.
+
+set -e
+gcc -o mkbuiltin1 mkbuiltin1.c
+6g sys.go
+6g unsafe.go
+rm -f _builtin.c
+./mkbuiltin1 sys >_builtin.c
+./mkbuiltin1 unsafe >>_builtin.c
+
+# If _builtin.c has changed vs builtin.c.boot,
+# check in the new change if being run by
+# one of the people who tends to work on
+# the compiler.  This makes sure that changes
+# don't get forgotten, without causing problems
+# in end user Go repositories.
+case "$USER" in
+ken | r | rsc)
+	if ! cmp _builtin.c builtin.c.boot
+	then
+		p4 open builtin.c.boot
+		cp _builtin.c builtin.c.boot
+	fi
+esac
+
+cat _builtin.c
+rm -f _builtin.c
+

src/cmd/gc/mkbuiltin1.c

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Extract import data from sys.6 and generate C string version.
+// Compile .go file, import data from .6 file, and generate C string version.
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -18,7 +18,7 @@ main(int argc, char **argv)
 	char buf[1024], initfunc[1024], *p, *q;
 
 	if(argc != 2) {
-		fprintf(stderr, "usage: sys sys\n");
+		fprintf(stderr, "usage: mkbuiltin1 sys\n");
 		fprintf(stderr, "in file $1.6 s/PACKAGE/$1/\n");
 		exit(1);
 	}