# Make variables (CC, etc...)
AS = $(CROSS_COMPILE)as
LD = $(CROSS_COMPILE)ld
+LDFINAL = $(LD)
CC = $(CROSS_COMPILE)gcc
CPP = $(CC) -E
+ifdef CONFIG_LTO
+AR = $(CROSS_COMPILE)gcc-ar
+else
AR = $(CROSS_COMPILE)ar
+endif
NM = $(CROSS_COMPILE)nm
STRIP = $(CROSS_COMPILE)strip
OBJCOPY = $(CROSS_COMPILE)objcopy
export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
-export CPP AR NM STRIP OBJCOPY OBJDUMP
+export CPP AR NM STRIP OBJCOPY OBJDUMP LDFINAL
export MAKE AWK GENKSYMS INSTALLKERNEL PERL UTS_MACHINE
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
export KBUILD_ARFLAGS
+ifdef CONFIG_LTO
+# LTO gcc creates a lot of files in TMPDIR, and with /tmp as tmpfs
+# it's easy to drive the machine OOM. Use the object directory
+# instead.
+ifndef TMPDIR
+TMPDIR ?= $(objtree)
+export TMPDIR
+$(info setting TMPDIR=$(objtree) for LTO build)
+endif
+endif
+
# When compiling out-of-tree modules, put MODVERDIR in the module
# tree rather than in the kernel tree. The kernel tree might
# even be read-only.
KBUILD_CFLAGS += -O2
endif
+# Tell gcc to never replace conditional load with a non-conditional one
+KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)
+
ifdef CONFIG_READABLE_ASM
# Disable optimizations that make assembler listings hard to read.
# reorder blocks reorders the control in the function
endif
include $(srctree)/scripts/Makefile.extrawarn
+include ${srctree}/scripts/Makefile.lto
# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
KBUILD_CPPFLAGS += $(KCPPFLAGS)