kbuild: Prefer -Oz over -Os
-Oz Optimize aggressively for size rather than speed.
with gcc-12 so far (i think only https://gcc.gnu.org/PR32803 and 103773 )
"shorter load imm on x86_64":
(add/remove: 0/0 grow/shrink: 4/1670 up/down: 6/-13196) Total: -13190 bytes
text data bss dec hex filename
975753 4227 1816 981796 efb24 busybox_old
962442 4227 1816 968485 ec725 busybox_unstripped
with clang-15:
(add/remove: 394/34 grow/shrink: 161/1856 up/down: 18644/-98946)Total: -80302 bytes
text data bss dec hex filename
1120994 16066 1696 1138756 116044 busybox_old
1040689 16026 1696 1058411 10266b busybox_unstripped
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
diff --git a/Makefile.flags b/Makefile.flags
index c343562..84cb00a 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -87,14 +87,14 @@
#CFLAGS += $(call cc-option,-Wconversion,)
ifneq ($(CONFIG_DEBUG),y)
-CFLAGS += $(call cc-option,-Os,$(call cc-option,-O2,))
+CFLAGS += $(call cc-option,-Oz,$(call cc-option,-Os,$(call cc-option,-O2,)))
else
CFLAGS += $(call cc-option,-g,)
#CFLAGS += "-D_FORTIFY_SOURCE=2"
ifeq ($(CONFIG_DEBUG_PESSIMIZE),y)
CFLAGS += $(call cc-option,-O0,)
else
-CFLAGS += $(call cc-option,-Os,$(call cc-option,-O2,))
+CFLAGS += $(call cc-option,-Oz,$(call cc-option,-Os,$(call cc-option,-O2,)))
endif
endif
ifeq ($(CONFIG_DEBUG_SANITIZE),y)