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| author | Marek Behún <marek.behun@nic.cz> | 2021-05-20 14:24:03 +0300 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2021-05-24 21:21:30 +0300 |
| commit | c1094987d1dc4701646c5f3aa254e7a92a02d305 (patch) | |
| tree | 5d2bbcee39b8adff66ac767d8bde1bcb6283dfe7 /Makefile | |
| parent | 958f2e57eff72b5156f7b08b9c1415fb7e12833d (diff) | |
| download | u-boot-c1094987d1dc4701646c5f3aa254e7a92a02d305.tar.xz | |
build: support building with Link Time Optimizations
Add plumbing for building U-Boot with Link Time Optimizations.
When building with LTO, $(PLATFORM_LIBS) has to be in --whole-archive /
--no-whole-archive group, otherwise some functions declared in assembly
may not be resolved and linking may fail.
Note: clang may throw away linker list symbols it thinks are unused when
compiling with LTO. To force these symbols to be included, we refer to
them via the __ADDRESSABLE macro in a C file generated from compiled
built-in.o files before linking.
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'Makefile')
| -rw-r--r-- | Makefile | 67 |
1 files changed, 65 insertions, 2 deletions
@@ -676,6 +676,31 @@ else KBUILD_CFLAGS += -O2 endif +LTO_CFLAGS := +LTO_FINAL_LDFLAGS := +export LTO_CFLAGS LTO_FINAL_LDFLAGS +ifdef CONFIG_LTO + ifeq ($(cc-name),clang) + LTO_CFLAGS += -flto + LTO_FINAL_LDFLAGS += -flto + + AR = $(shell $(CC) -print-prog-name=llvm-ar) + NM = $(shell $(CC) -print-prog-name=llvm-nm) + else + NPROC := $(shell nproc 2>/dev/null || echo 1) + LTO_CFLAGS += -flto=$(NPROC) + LTO_FINAL_LDFLAGS += -fuse-linker-plugin -flto=$(NPROC) + + # use plugin aware tools + AR = $(CROSS_COMPILE)gcc-ar + NM = $(CROSS_COMPILE)gcc-nm + endif + + CFLAGS_NON_EFI += $(LTO_CFLAGS) + + KBUILD_CFLAGS += $(LTO_CFLAGS) +endif + ifeq ($(CONFIG_STACKPROTECTOR),y) KBUILD_CFLAGS += $(call cc-option,-fstack-protector-strong) CFLAGS_EFI += $(call cc-option,-fno-stack-protector) @@ -1708,8 +1733,45 @@ u-boot-swap.bin: u-boot.bin FORCE ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(ARCH)/Makefile.postlink) +# Generate linker list symbols references to force compiler to not optimize +# them away when compiling with LTO +ifdef CONFIG_LTO +u-boot-keep-syms-lto := keep-syms-lto.o +u-boot-keep-syms-lto_c := $(patsubst %.o,%.c,$(u-boot-keep-syms-lto)) + +quiet_cmd_keep_syms_lto = KSL $@ + cmd_keep_syms_lto = \ + NM=$(NM) $(srctree)/scripts/gen_ll_addressable_symbols.sh $^ >$@ + +quiet_cmd_keep_syms_lto_cc = KSLCC $@ + cmd_keep_syms_lto_cc = \ + $(CC) $(filter-out $(LTO_CFLAGS),$(c_flags)) -c -o $@ $< + +$(u-boot-keep-syms-lto_c): $(u-boot-main) + $(call if_changed,keep_syms_lto) +$(u-boot-keep-syms-lto): $(u-boot-keep-syms-lto_c) + $(call if_changed,keep_syms_lto_cc) +else +u-boot-keep-syms-lto := +endif + # Rule to link u-boot # May be overridden by arch/$(ARCH)/config.mk +ifdef CONFIG_LTO +quiet_cmd_u-boot__ ?= LTO $@ + cmd_u-boot__ ?= \ + $(CC) -nostdlib -nostartfiles \ + $(LTO_FINAL_LDFLAGS) $(c_flags) \ + $(KBUILD_LDFLAGS:%=-Wl,%) $(LDFLAGS_u-boot:%=-Wl,%) -o $@ \ + -T u-boot.lds $(u-boot-init) \ + -Wl,--whole-archive \ + $(u-boot-main) \ + $(u-boot-keep-syms-lto) \ + $(PLATFORM_LIBS) \ + -Wl,--no-whole-archive \ + -Wl,-Map,u-boot.map; \ + $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) +else quiet_cmd_u-boot__ ?= LD $@ cmd_u-boot__ ?= $(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_u-boot) -o $@ \ -T u-boot.lds $(u-boot-init) \ @@ -1718,6 +1780,7 @@ quiet_cmd_u-boot__ ?= LD $@ --no-whole-archive \ $(PLATFORM_LIBS) -Map u-boot.map; \ $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) +endif quiet_cmd_smap = GEN common/system_map.o cmd_smap = \ @@ -1726,7 +1789,7 @@ cmd_smap = \ $(CC) $(c_flags) -DSYSTEM_MAP="\"$${smap}\"" \ -c $(srctree)/common/system_map.c -o common/system_map.o -u-boot: $(u-boot-init) $(u-boot-main) u-boot.lds FORCE +u-boot: $(u-boot-init) $(u-boot-main) $(u-boot-keep-syms-lto) u-boot.lds FORCE +$(call if_changed,u-boot__) ifeq ($(CONFIG_KALLSYMS),y) $(call cmd,smap) @@ -2009,7 +2072,7 @@ CLEAN_FILES += include/bmp_logo.h include/bmp_logo_data.h tools/version.h \ boot* u-boot* MLO* SPL System.map fit-dtb.blob* \ u-boot-ivt.img.log u-boot-dtb.imx.log SPL.log u-boot.imx.log \ lpc32xx-* bl31.c bl31.elf bl31_*.bin image.map tispl.bin* \ - idbloader.img flash.bin flash.log defconfig + idbloader.img flash.bin flash.log defconfig keep-syms-lto.c # Directories & files removed with 'make mrproper' MRPROPER_DIRS += include/config include/generated spl tpl \ |