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| author | Tom Rini <trini@konsulko.com> | 2021-05-24 23:12:31 +0300 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2021-05-24 23:12:31 +0300 |
| commit | 27c6d9663c3f42059514e47c17652304a1cfcfc9 (patch) | |
| tree | 15e7a1deb449053a3ffca9b708813cce2da366ec /Makefile | |
| parent | eb53b943be2949ca111140a8e05532cd74cda058 (diff) | |
| parent | 2fc62f2991744dfeec65f8619092c359d8ecbcb0 (diff) | |
| download | u-boot-27c6d9663c3f42059514e47c17652304a1cfcfc9.tar.xz | |
Merge branch '2021-05-24-add-lto-support'
- Add LTO (link time optimization) support to the build system and
enable it on a few boards. This is an alternative to using
-ffunction-sections/-fdata-sections and --gc-sections at link time to
remove unused code. This can result in notable savings, but needs
testing on each platform before use as it can expose problems by
optimizing away various functionally necessary calls.
Diffstat (limited to 'Makefile')
| -rw-r--r-- | Makefile | 81 |
1 files changed, 74 insertions, 7 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) @@ -972,6 +997,8 @@ LDFLAGS_u-boot += $(LDFLAGS_FINAL) # Avoid 'Not enough room for program headers' error on binutils 2.28 onwards. LDFLAGS_u-boot += $(call ld-option, --no-dynamic-linker) +LDFLAGS_u-boot += --build-id=none + ifeq ($(CONFIG_ARC)$(CONFIG_NIOS2)$(CONFIG_X86)$(CONFIG_XTENSA),) LDFLAGS_u-boot += -Ttext $(CONFIG_SYS_TEXT_BASE) endif @@ -1708,14 +1735,54 @@ 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) \ - --start-group $(u-boot-main) --end-group \ - $(PLATFORM_LIBS) -Map u-boot.map; \ - $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) + cmd_u-boot__ ?= $(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_u-boot) -o $@ \ + -T u-boot.lds $(u-boot-init) \ + --whole-archive \ + $(u-boot-main) \ + --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 = \ @@ -1724,7 +1791,7 @@ 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) @@ -2007,7 +2074,7 @@ 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 \ |