tests: robustify -k test

Split stack-fcall.c into several compilation units so that intermediate
function calls would not be optimized out by compiler.

* tests/stack-fcall.c: Move intermediate functions to ...
* tests/stack-fcall-*.c: ... new files.
* tests/Makefile.am (stack_fcall_SOURCES): Add stack-fcall-*.c.

tests/Makefile.am

@@ -11,6 +11,8 @@ check_PROGRAMS = \
 	uio
 
 uio_CFLAGS = $(AM_CFLAGS) -D_FILE_OFFSET_BITS=64
+stack_fcall_SOURCES = stack-fcall.c \
+	stack-fcall-0.c stack-fcall-1.c stack-fcall-2.c stack-fcall-3.c
 
 TESTS = \
 	ptrace_setoptions.test \

tests/stack-fcall-0.c

@@ -0,0 +1,6 @@
+int f1(int i);
+
+int f0(int i)
+{
+	return f1(i) - i;
+}

tests/stack-fcall-1.c

@@ -0,0 +1,6 @@
+int f2(int i);
+
+int f1(int i)
+{
+	return f2(i) + i;
+}

tests/stack-fcall-2.c

@@ -0,0 +1,6 @@
+int f3(int i);
+
+int f2(int i)
+{
+	return f3(i) - i;
+}

tests/stack-fcall-3.c

@@ -0,0 +1,6 @@
+#include <unistd.h>
+
+int f3(int i)
+{
+	return getpid() + i;
+}

tests/stack-fcall.c

@@ -1,35 +1,7 @@
-#include <unistd.h>
-#include <sys/types.h>
-
-/* Use "volatile" to avoid compiler optimization. */
-
-int f3(int i)
-{
-	static pid_t (* volatile g)(void) = getpid;
-	return g() + i;
-}
-
-int f2(volatile int i)
-{
-	static int (* volatile g)(int) = f3;
-	return g(i) - i;
-}
-
-int f1(volatile int i)
-{
-	static int (* volatile g)(int) = f2;
-	return g(i) + i;
-}
-
-int f0(volatile int i)
-{
-	static int (* volatile g)(int) = f1;
-	return g(i) - i;
-}
+int f0(int i);
 
 int main(int argc, char** argv)
 {
-	static int (* volatile g)(int) = f0;
-	g(argc);
+	f0(argc);
 	return 0;
 }