Expand gcc tests.
Verify -fwhole-program works at make startup.
Warn when gcc marks global functions as local.
diff --git a/tools/test-gcc.sh b/tools/test-gcc.sh
new file mode 100755
index 0000000..1dce450
--- /dev/null
+++ b/tools/test-gcc.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+# Script to test if gcc's -combine option works properly.
+
+mkdir -p out
+TMPFILE1=out/tmp_testcompile1.c
+TMPFILE1o=out/tmp_testcompile1.o
+TMPFILE2=out/tmp_testcompile2.c
+TMPFILE2o=out/tmp_testcompile2.o
+TMPFILE3o=out/tmp_testcompile3.o
+
+# Test for "-fwhole-program"
+gcc -fwhole-program -S -o /dev/null -xc /dev/null > /dev/null 2>&1
+if [ $? -ne 0 ]; then
+ echo "This version of gcc does not support -fwhole-program." > /dev/fd/2
+ echo "Please upgrade to gcc v4.1 or later" > /dev/fd/2
+ echo -1
+ exit -1
+fi
+
+# Test if "visible" functions are marked global.
+cat - > $TMPFILE1 <<EOF
+void __attribute__((externally_visible)) t1() { }
+EOF
+$CC -c -fwhole-program $TMPFILE1 -o $TMPFILE1o > /dev/null 2>&1
+cat - > $TMPFILE2 <<EOF
+void t1();
+void __attribute__((externally_visible)) main() { t1(); }
+EOF
+$CC -c -fwhole-program $TMPFILE2 -o $TMPFILE2o > /dev/null 2>&1
+$CC $TMPFILE1o $TMPFILE2o -o $TMPFILE3o > /dev/null 2>&1
+if [ $? -ne 0 ]; then
+ echo " Working around non-global functions in -fwhole-program" > /dev/fd/2
+fi
+
+# Test if "-combine" works
+mkdir -p out
+cat - > $TMPFILE1 <<EOF
+struct ts { union { int u1; struct { int u2; }; }; };
+void t1(struct ts *r);
+EOF
+$CC -c -fwhole-program -combine $TMPFILE1 $TMPFILE1 -o $TMPFILE1o > /dev/null 2>&1
+if [ $? -eq 0 ]; then
+ #echo " Setting AVOIDCOMBINE=0" > /dev/fd/2
+ echo 0
+else
+ echo " Enabling AVOIDCOMBINE=1" > /dev/fd/2
+ echo 1
+fi
+
+rm -f $TMPFILE1 $TMPFILE1o $TMPFILE2 $TMPFILE2o $TMPFILE3o