+ifeq ($(CONFIG_WERROR),y)
+CFLAGS += $(call cc-option,-Werror,)
+## TODO:
+## gcc version 4.4.0 20090506 (Red Hat 4.4.0-4) (GCC) is a PITA:
+## const char *ptr; ... off_t v = *(off_t*)ptr; -> BOOM
+## and no easy way to convince it to shut the hell up.
+## We have a lot of such things all over the place.
+## Classic *(off_t*)(void*)ptr does not work,
+## and I am unwilling to do crazy gcc specific ({ void *ppp = ...; })
+## stuff in macros. This would obfuscate the code too much.
+## Maybe try __attribute__((__may_alias__))?
+#CFLAGS += $(call cc-ifversion, -eq, 0404, -fno-strict-aliasing)
+endif
+# gcc 3.x emits bogus "old style proto" warning on find.c:alloc_action()
+CFLAGS += $(call cc-ifversion, -ge, 0400, -Wold-style-definition)
+
+CFLAGS += $(call cc-option,-fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer -ffunction-sections -fdata-sections,)
+# -fno-guess-branch-probability: prohibit pseudo-random guessing
+# of branch probabilities (hopefully makes bloatcheck more stable):
+CFLAGS += $(call cc-option,-fno-guess-branch-probability,)
+CFLAGS += $(call cc-option,-funsigned-char -static-libgcc,)
+CFLAGS += $(call cc-option,-falign-functions=1 -falign-jumps=1 -falign-labels=1 -falign-loops=1,)
+# Defeat .eh_frame bloat (gcc 4.6.3 x86-32 defconfig: 20% smaller busybox binary):
+CFLAGS += $(call cc-option,-fno-unwind-tables,)
+CFLAGS += $(call cc-option,-fno-asynchronous-unwind-tables,)
+
+# FIXME: These warnings are at least partially to be concerned about and should
+# be fixed..
+#CFLAGS += $(call cc-option,-Wconversion,)
+
+ifneq ($(CONFIG_DEBUG),y)
+CFLAGS += $(call cc-option,-Os,$(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,))
+endif
+endif
+
+# If arch/$(ARCH)/Makefile did not override it (with, say, -fPIC)...
+ARCH_FPIC ?= -fpic
+ARCH_FPIE ?= -fpie
+ARCH_PIE ?= -pie
+
+# Usage: $(eval $(call pkg_check_modules,VARIABLE-PREFIX,MODULES))
+define pkg_check_modules
+$(1)_CFLAGS := $(shell $(PKG_CONFIG) $(PKG_CONFIG_FLAGS) --cflags $(2))
+$(1)_LIBS := $(shell $(PKG_CONFIG) $(PKG_CONFIG_FLAGS) --libs $(2))
+endef
+
+ifeq ($(CONFIG_BUILD_LIBBUSYBOX),y)
+# on i386: 14% smaller libbusybox.so
+# (code itself is 9% bigger, we save on relocs/PLT/GOT)
+CFLAGS += $(ARCH_FPIC)
+# and another 4% reduction of libbusybox.so:
+# (external entry points must be marked EXTERNALLY_VISIBLE)
+CFLAGS += $(call cc-option,-fvisibility=hidden)