Dependency generation now uses all cores on multi-core machines.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22021 a1c6a512-1295-4272-9138-f99709370657

tools/functions.make

@@ -33,7 +33,7 @@ c2obj = $(addsuffix .o,$(basename $(subst $(ROOTDIR),$(BUILDDIR),$(1))))
 # calculate dependencies for a list of source files $(2) and output them
 # to a file $(1)_, to be later renamed to $(1).
 mkdepfile = $(shell \
-	$(CC) $(PPCFLAGS) $(OTHER_INC) -MG -MM -include config.h $(2) | \
+	perl $(TOOLSDIR)/multigcc.pl $(CC) $(PPCFLAGS) $(OTHER_INC) -MG -MM -include config.h -- $(2) | \
 	sed -e "s: lang.h: lang/lang_core.o:" \
 	-e 's:_asmdefs.o:_asmdefs.h:' \
 	-e "s: max_language_size.h: lang/max_language_size.h:" | \

tools/multigcc.pl

@@ -0,0 +1,72 @@
+#!/usr/bin/perl
+use List::Util 'shuffle'; # standard from Perl 5.8 and later
+
+my $tempfile = "multigcc.out";
+my @params;
+my @files;
+my $list = \@params;
+
+# parse command line arguments
+for my $a (@ARGV) {
+    if ($a eq "--") {
+        $list = \@files;
+        next;
+    }
+
+    push @{$list}, $a;
+}
+
+my $command = join " ", @params;
+
+# shuffle the file list to spread the load as evenly as we can
+@files = shuffle(@files);  
+
+# count number of cores
+my $cores = 1;
+if (open CPUINFO, "</proc/cpuinfo") {
+    $cores = scalar grep /^processor/i, <CPUINFO>;
+    close CPUINFO;
+}
+
+# don't run empty children
+if (scalar @files < $cores)
+{
+    $cores = 1;
+}
+
+# fork children
+my @pids;
+my $slice = int((scalar @files / $cores) + 0.5);
+for my $i (0 .. $cores-1)
+{
+    my $pid = fork;
+    if ($pid)
+    {
+        # mother
+        $pids[$i] = $pid;
+    }
+    else
+    {
+        # get my slice of the files
+        my @list = @files[$i * $slice .. $i * $slice + $slice - 1];
+
+        # run command
+        system("$command @list > $tempfile.$$");
+
+        exit;
+    }
+}
+
+for my $i (0 .. $cores - 1)
+{
+    # wait for child to complete
+    waitpid $pids[$i], 0;
+
+    # read & print result
+    if (open F, "<$tempfile.$pids[$i]")
+    {
+        print <F>;
+        close F;
+        unlink "$tempfile.$pids[$i]";
+    }
+}