[PATCH 07/10] tools: Use -Og for debug builds when available

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The recommended optimisation level for debugging is -Og, and is what tools
such as gdb prefer.  In practice, it equates to -01 with a few specific
optimisations turned off.

abi-dumper in particular wants the libraries it inspects in this form.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Ian Jackson <iwj@xxxxxxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Juergen Gross <jgross@xxxxxxxx>
---
 tools/Rules.mk | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/Rules.mk b/tools/Rules.mk
index f61da81f4a..2907ed2d39 100644
--- a/tools/Rules.mk
+++ b/tools/Rules.mk
@@ -106,8 +106,9 @@ endif
 CFLAGS_libxenlight += $(CFLAGS_libxenctrl)
 
 ifeq ($(debug),y)
-# Disable optimizations
-CFLAGS += -O0 -fno-omit-frame-pointer
+# Use -Og if available, -O0 otherwise
+dbg_opt_level := $(call cc-option,$(CC),-Og,-O0)
+CFLAGS += $(dbg_opt_level) -fno-omit-frame-pointer
 # But allow an override to -O0 in case Python enforces -D_FORTIFY_SOURCE=<n>.
 PY_CFLAGS += $(PY_NOOPT_CFLAGS)
 else
-- 
2.11.0