WIP: Run `makedepend` in parallel by using `make`

This moves the per-file loop body of `makedepend` into a separate
file named `makedepend_file` and then uses `make` to launch
the `makedepend_file` processes for each target potentially in parallel.

This reduces the time for

  time sh ./makedepend MAKE=make cflags

from 5 seconds to 2 seconds with MAKEFLAGS=-j8

1 files changed, 177 insertions, 0 deletions

diff --git a/makedepend_file.SH b/makedepend_file.SH
new file mode 100644
index 0000000000..51f5191fe9
--- /dev/null
+++ b/makedepend_file.SH
@@ -0,0 +1,177 @@
+#! /bin/sh
+case $PERL_CONFIG_SH in
+'')
+	if test -f config.sh; then TOP=.;
+	elif test -f ../config.sh; then TOP=..;
+	elif test -f ../../config.sh; then TOP=../..;
+	elif test -f ../../../config.sh; then TOP=../../..;
+	elif test -f ../../../../config.sh; then TOP=../../../..;
+	else
+		echo "Can't find config.sh."; exit 1
+	fi
+	. $TOP/config.sh
+	;;
+esac
+: This forces SH files to create target in same directory as SH file.
+: This is so that make depend always knows where to find SH derivatives.
+case "$0" in
+*/*) cd `expr X$0 : 'X\(.*\)/'` ;;
+esac
+
+echo "Extracting makedepend_file (with variable substitutions)"
+rm -f makedepend_file
+$spitshell >makedepend_file <<!GROK!THIS!
+$startsh
+# makedepend_file.SH
+#
+MAKE=$make
+trnl='$trnl'
+!GROK!THIS!
+$spitshell >>makedepend_file <<'!NO!SUBS!'
+
+file=$1
+shift
+outfile=$1
+shift
+
+case $PERL_CONFIG_SH in
+'')
+	if test -f config.sh; then TOP=.;
+	elif test -f ../config.sh; then TOP=..;
+	elif test -f ../../config.sh; then TOP=../..;
+	elif test -f ../../../config.sh; then TOP=../../..;
+	elif test -f ../../../../config.sh; then TOP=../../../..;
+	else
+		echo "Can't find config.sh."; exit 1
+	fi
+	. $TOP/config.sh
+	;;
+esac
+
+# Avoid localized gcc messages
+case "$ccname" in
+    gcc) LC_ALL=C ; export LC_ALL ;;
+esac
+
+# We need .. when we are in the x2p directory if we are using the
+# cppstdin wrapper script.
+# Put .. and . first so that we pick up the present cppstdin, not
+# an older one lying about in /usr/local/bin.
+PATH=".$path_sep..$path_sep$PATH"
+export PATH
+
+case "$osname" in
+amigaos) cat=/bin/cat ;; # must be absolute
+esac
+
+    case "$osname" in
+    uwin)     uwinfix="-e s,\\\\\\\\,/,g -e s,\\([a-zA-Z]\\):/,/\\1/,g" ;;
+    os2)      uwinfix="-e s,\\\\\\\\,/,g" ;;
+    cygwin)   uwinfix="-e s,\\\\\\\\,/,g" ;;
+    posix-bc) uwinfix="-e s/\\*POSIX(\\(.*\\))/\\1/" ;;
+    vos)      uwinfix="-e s/\#/\\\#/" ;;
+    *)        uwinfix="" ;;
+    esac
+    case "$file" in
+    *.c) filebase=`basename $file .c` ;;
+    *.y) filebase=`basename $file .y` ;;
+    esac
+    case "$file" in
+    */*) finc="-I`echo $file | sed 's#/[^/]*$##'`" ;;
+    *)   finc= ;;
+    esac
+    $echo "Finding dependencies for $filebase$_o"
+    # Below, we strip out all but preprocessor directives.
+    # We have to take care of situations like
+    #       #if defined(FOO) BAR   /* comment line 1
+    #                                 more comment lines */
+    # If we just delete text starting from the '/*' to the end of line, we will
+    # screw up cases like
+    #      #if defined(FOO)    /* comment */ \
+    #          && defined(BAR) /* comment */ \
+    #          && defined(BAZ) /* comment */ \
+    #               etc.
+    # Also, in lines like
+    #      #defined FOO(a,b)    a/**/b
+    # the comment may be important and so needs to be retained.
+    # This code processes the single-line comments first; it assumes there is
+    # at most one straightforward comment per continued preprocessor line,
+    # replacing each non-empty comment (and its surrounding white space) by a
+    # single space.  (sed only has a greedy '*' quantifier, so this doesn't
+    # work right if there are multiple comments per line, and strings can look
+    # like comments to it; both are unlikely in a preprocessor statement.) Any
+    # continuation line is joined, and the process repeated on the enlarged
+    # line as long as there are continuations.  At the end, if there are any
+    # comments remaining, they are either completely empty or are like the
+    # first situation.  The latter are just deleted by first deleting to the
+    # end of line (including preceding white space) things that start with '/*'
+    # and the next char isn't a '*'; then things that start with '/**', but the
+    # next char isn't a '/'.  (Subsequent lines of the comment are irrelevant
+    # and get dropped.)  At the end, we unjoin very long lines to avoid
+    # preprocessor limitations
+    ( $echo "#line 2 \"$file\"";                               \
+      $sed -n <$file                                           \
+	-e "/^${filebase}_init(/q"                             \
+        -e ': tstcont'                                         \
+	-e '/^[ 	]*#/s|[ 	]*/\*..*\*/[ 	]*| |' \
+        -e '/\\$/{'                                            \
+            -e 'N'                                             \
+            -e 'b tstcont'                                     \
+        -e '}'                                                 \
+	-e 's/\\\n//g'                                         \
+	-e '/^#line/d'                                         \
+	-e '/^[ 	]*#/{'                                 \
+	    -e 's|[ 	]*/\*[^*].*$||'                        \
+	    -e 's|[ 	]*/\*\*[^/].*$||'                      \
+            -e 's/.\{255\}/&\\\n/g'                           \
+	    -e p                                               \
+	-e '}' | $grep -v ":" ) >UU/$file.c
+
+    # We're not sure why this was there; the #endif is extraneous on modern z/OS
+    #if [ "$osname" = os390 -a "$file" = perly.c ]; then
+    #   $echo '#endif' >>UU/$file.c
+    #fi
+
+    if [ "$osname" = os390 ]; then
+        $cppstdin $finc -I. $cppflags $cppminus <UU/$file.c |
+        $sed \
+    	    -e '/^#.*<stdin>/d' \
+	    -e '/^#.*"-"/d' \
+	    -e '/^#.*git_version\.h/d' \
+	    -e 's#\.[0-9][0-9]*\.c#'"$file.c#" \
+	    -e 's/^[	 ]*#[	 ]*line/#/' \
+	    -e '/^# *[0-9][0-9]* *[".\/]/!d' \
+	    -e 's/^.*"\(.*\)".*$/'$filebase'\$(OBJ_EXT): \1/' \
+	    -e 's/^# *[0-9][0-9]* \(.*\)$/'$filebase'\$(OBJ_EXT): \1/' \
+	    -e 's|: \./|: |' \
+	    -e 's|\.c\.c|.c|' $uwinfix | \
+        $uniq | $sort | $uniq >>$outfile
+    else
+        $cppstdin $finc -I. $cppflags $cppminus <UU/$file.c >$$.cout 2>$$.cerr
+        $sed \
+	    -e '1d' \
+	    -e '/^#.*<stdin>/d' \
+            -e '/^#.*<builtin>/d' \
+            -e '/^#.*<built-in>/d' \
+            -e '/^#.*<command line>/d' \
+            -e '/^#.*<command-line>/d' \
+	    -e '/^#.*"-"/d' \
+	    -e '/^#.*"\/.*\/"/d' \
+	    -e '/: file path prefix .* never used$/d' \
+	    -e '/^#.*git_version\.h/d' \
+	    -e 's#\.[0-9][0-9]*\.c#'"$file.c#" \
+	    -e 's/^[	 ]*#[	 ]*line/#/' \
+	    -e '/^# *[0-9][0-9]* *[".\/]/!d' \
+	    -e 's/^.*"\(.*\)".*$/'$filebase'\$(OBJ_EXT): \1/' \
+	    -e 's/^# *[0-9][0-9]* \(.*\)$/'$filebase'\$(OBJ_EXT): \1/' \
+	    -e 's|: \./|: |' \
+           -e 's|\.c\.c|.c|' $uwinfix $$.cout $$.cerr| \
+        $uniq | $sort | $uniq >>$outfile
+        rm $$.cout
+        rm $$.cerr
+    fi
+    $echo "$filebase\$(OBJ_EXT): $@" >>$outfile
+
+!NO!SUBS!
+$eunicefix makedepend_file
+chmod +x makedepend_file