Add default debug flags for tests

Include debugging symbols in tests by default to improve stack traces
and also set the compiler optimisation level to improve the debugging
experience.

Signed-off-by: Thomas Wood <thomas.wood@intel.com>

configure.ac

@@ -196,6 +196,19 @@ if test "x$with_libunwind" = xyes; then
 			  AC_MSG_ERROR([libunwind not found. Use --without-libunwind to disable libunwind support.]))
 fi
 
+# enable debug symbols
+AC_ARG_ENABLE(debug,
+	      AS_HELP_STRING([--disable-debug],
+			     [Build tests without debug symbols]),
+	      [], [enable_debug=yes])
+
+if test "x$enable_debug" = xyes; then
+	AS_COMPILER_FLAG([-g3], [DEBUG_CFLAGS="-g3"], [DEBUG_CFLAGS="-g"])
+	AS_COMPILER_FLAG([-Og], [DEBUG_CFLAGS+=" -Og -Wno-maybe-uninitialized"], # disable maybe-uninitialized due to false positives
+			 [DEBUG_CFLAGS+=" -O0"])
+	AC_SUBST([DEBUG_CFLAGS])
+fi
+
 # -----------------------------------------------------------------------------
 
 # To build multithread code, gcc uses -pthread, Solaris Studio cc uses -mt
@@ -253,6 +266,7 @@ echo " • Tests:"
 echo "       Build tests        : ${BUILD_TESTS}"
 echo "       Compile prime tests: ${NOUVEAU}"
 echo "       Print stack traces : ${with_libunwind}"
+echo "       Debug flags        : ${DEBUG_CFLAGS}"
 echo ""
 echo " • Tools:"
 echo "       Assembler          : ${enable_assembler}"

m4/as-compiler-flag.m4

@@ -0,0 +1,62 @@
+dnl as-compiler-flag.m4 0.1.0
+
+dnl autostars m4 macro for detection of compiler flags
+
+dnl David Schleef <ds@schleef.org>
+
+dnl $Id: as-compiler-flag.m4,v 1.1 2005/12/15 23:35:19 ds Exp $
+
+dnl AS_COMPILER_FLAG(CFLAGS, ACTION-IF-ACCEPTED, [ACTION-IF-NOT-ACCEPTED])
+dnl Tries to compile with the given CFLAGS.
+dnl Runs ACTION-IF-ACCEPTED if the compiler can compile with the flags,
+dnl and ACTION-IF-NOT-ACCEPTED otherwise.
+
+AC_DEFUN([AS_COMPILER_FLAG],
+[
+  AC_MSG_CHECKING([to see if compiler understands $1])
+
+  save_CFLAGS="$CFLAGS"
+  CFLAGS="$CFLAGS $1"
+
+  AC_TRY_COMPILE([ ], [], [flag_ok=yes], [flag_ok=no])
+  CFLAGS="$save_CFLAGS"
+
+  if test "X$flag_ok" = Xyes ; then
+    m4_ifvaln([$2],[$2])
+    true
+  else
+    m4_ifvaln([$3],[$3])
+    true
+  fi
+  AC_MSG_RESULT([$flag_ok])
+])
+
+dnl AS_COMPILER_FLAGS(VAR, FLAGS)
+dnl Tries to compile with the given CFLAGS.
+
+AC_DEFUN([AS_COMPILER_FLAGS],
+[
+  list=$2
+  flags_supported=""
+  flags_unsupported=""
+  AC_MSG_CHECKING([for supported compiler flags])
+  for each in $list
+  do
+    save_CFLAGS="$CFLAGS"
+    CFLAGS="$CFLAGS $each"
+    AC_TRY_COMPILE([ ], [], [flag_ok=yes], [flag_ok=no])
+    CFLAGS="$save_CFLAGS"
+
+    if test "X$flag_ok" = Xyes ; then
+      flags_supported="$flags_supported $each"
+    else
+      flags_unsupported="$flags_unsupported $each"
+    fi
+  done
+  AC_MSG_RESULT([$flags_supported])
+  if test "X$flags_unsupported" != X ; then
+    AC_MSG_WARN([unsupported compiler flags: $flags_unsupported])
+  fi
+  $1="$$1 $flags_supported"
+])
+

tests/Makefile.am

@@ -32,7 +32,7 @@ EXTRA_DIST = $(TESTS_scripts) $(TESTS_scripts_M) $(scripts) $(IMAGES) $(common_f
 
 CLEANFILES = $(EXTRA_PROGRAMS) single-tests.txt multi-tests.txt
 
-AM_CFLAGS = $(DRM_CFLAGS) $(CWARNFLAGS) \
+AM_CFLAGS = $(DRM_CFLAGS) $(CWARNFLAGS) $(DEBUG_CFLAGS)\
 	-I$(srcdir)/.. \
 	-I$(srcdir)/../lib \
 	-include "$(srcdir)/../lib/check-ndebug.h" \