sim: testsuite: support basic vars in flags

Sometimes in tests, we need supplemental files like linker scripts or
board helper files.  There's no way to set those flags in the tests
currently and relative paths don't work (breaks out of tree builds).

Update the main option parser to replace some strings on the fly.  Now
tests can do things like:

Long term we'll want to switch the framework to use the dejagnu helpers
like dg-xxx that gcc & gdb utilize.  But that'll require more rework.

sim/testsuite/ChangeLog

@@ -1,6 +1,11 @@
+2015-11-14  Mike Frysinger  <vapier@gentoo.org>
+
+	* lib/sim-defs.exp (slurp_options): Pull in global subdir/srcdir.
+	Replace $srcdir and $subdir in the read option.
+
 2015-04-13  Hans-Peter Nilsson  <hp@axis.com>
 
-	* sim-defs.exp (sim_init): Unset target ldscript here.
+	* lib/sim-defs.exp (sim_init): Unset target ldscript here.
 
 2015-03-30  Mike Frysinger  <vapier@gentoo.org>
 

sim/testsuite/lib/sim-defs.exp

@@ -1,4 +1,5 @@
 # Simulator dejagnu utilities.
+# TODO: Switch to using dg-xxx helpers rather than parsing the files directly.
 
 # Communicate simulator path from sim_init to sim_version.
 # For some reason [board_info target sim] doesn't work in sim_version.
@@ -423,6 +424,7 @@ proc run_sim_test { name requested_machs } {
 # Subroutine of run_sim_test to process options in FILE.
 
 proc slurp_options { file } {
+    global subdir srcdir
     if [catch { set f [open $file r] } x] {
 	#perror "couldn't open `$file': $x"
 	perror "$x"
@@ -442,6 +444,10 @@ proc slurp_options { file } {
 	# Whitespace here is space-tab.
 	if [regexp $pat $line xxx opt_name opt_machs opt_val] {
 	    # match!
+	    set opt_val [string map [list \
+		{$srcdir} "$srcdir" \
+		{$subdir} "$subdir" \
+	    ] "$opt_val"]
 	    lappend opt_array [list $opt_name $opt_machs $opt_val]
 	    set seen_opt 1
 	} else {