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arm: Have the linker garbage-collect unused functions and variables

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This patch activates -ffunction-sections and -fdata-sections for the
compiler and --gc-sections for the linker. This will strip out all
unused functions and static/global variables from the final binaries and
reduce the amount of data we need to read over SPI.

A quick test with ToT images shows a 2.5k (13%) / 10k (29%) / 12k (28%)
reduction on Nyan and 3k (38%) / 23k (50%) / 13k (29%) on Pit,
respectively for bootblock / romstage / ramstage.

Change-Id: I052411d4ad190d0395921ac4d4677341fb91568a
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/177111
(cherry picked from commit 5635b138778dea67a5f179e13003132be07f7e59)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6904
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
This commit is contained in:
Julius Werner
2013-10-15 17:36:17 -07:00
committed by Isaac Christensen
parent 08539b3b98
commit c505837e67
5 changed files with 36 additions and 35 deletions
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12
src/arch/arm/Makefile.inc
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@@ -62,9 +62,9 @@ bootblock-y += memmove.S
$(objcbfs)/bootblock.debug: $(src)/arch/arm/bootblock.ld $(obj)/ldoptions $$(bootblock-objs)
@printf " LINK $(subst $(obj)/,,$(@))\n"
ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
$(LD_bootblock) -m armelf_linux_eabi -static -o $@ -L$(obj) $< -T $(src)/arch/arm/bootblock.ld
$(LD_bootblock) -m armelf_linux_eabi --gc-sections -static -o $@ -L$(obj) $< -T $(src)/arch/arm/bootblock.ld
else
$(CC_bootblock) $(CFLAGS_bootblock) -nostartfiles -static -o $@ -L$(obj) -T $(src)/arch/arm/bootblock.ld -Wl,--start-group $(bootblock-objs) $(LIBGCC_FILE_NAME_bootblock) -Wl,--end-group
$(CC_bootblock) $(CFLAGS_bootblock) -nostartfiles -Wl,--gc-sections -static -o $@ -L$(obj) -T $(src)/arch/arm/bootblock.ld -Wl,--start-group $(bootblock-objs) $(LIBGCC_FILE_NAME_bootblock) -Wl,--end-group
endif
endif # CONFIG_ARCH_BOOTBLOCK_ARM
@@ -87,9 +87,9 @@ VBOOT_STUB_DEPS += $(obj)/arch/arm/eabi_compat.rmodules_arm.o
$(objcbfs)/romstage.debug: $$(romstage-objs) $(src)/arch/arm/romstage.ld $(obj)/ldoptions
@printf " LINK $(subst $(obj)/,,$(@))\n"
ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
$(LD_romstage) -nostdlib -nostartfiles -static -o $@ -L$(obj) $(romstage-objs) -T $(src)/arch/arm/romstage.ld
$(LD_romstage) -nostdlib -nostartfiles --gc-sections -static -o $@ -L$(obj) $(romstage-objs) -T $(src)/arch/arm/romstage.ld
else
$(CC_romstage) $(CFLAGS_romstage) -nostartfiles -static -o $@ -L$(obj) -T $(src)/arch/arm/romstage.ld -Wl,--start-group $(romstage-objs) $(LIBGCC_FILE_NAME_romstage) -Wl,--end-group
$(CC_romstage) $(CFLAGS_romstage) -nostartfiles -Wl,--gc-sections -static -o $@ -L$(obj) -T $(src)/arch/arm/romstage.ld -Wl,--start-group $(romstage-objs) $(LIBGCC_FILE_NAME_romstage) -Wl,--end-group
endif
endif # CONFIG_ARCH_ROMSTAGE_ARM
@@ -122,9 +122,9 @@ endif
$(objgenerated)/ramstage.o: $(stages_o) $$(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage)
@printf " CC $(subst $(obj)/,,$(@))\n"
ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
$(LD_ramstage) -m -m armelf_linux_eabi -r -o $@ --wrap __divdi3 --wrap __udivdi3 --wrap __moddi3 --wrap __umoddi3 --wrap __uidiv --start-group $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) --end-group
$(LD_ramstage) -m -m armelf_linux_eabi --gc-sections -r -o $@ --wrap __divdi3 --wrap __udivdi3 --wrap __moddi3 --wrap __umoddi3 --wrap __uidiv --start-group $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) --end-group
else
$(CC_ramstage) $(CFLAGS_ramstage) $(CPPFLAGS_ramstage) -nostdlib -r -o $@ -Wl,--start-group $(stages_o) $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) -Wl,--end-group
$(CC_ramstage) $(CFLAGS_ramstage) $(CPPFLAGS_ramstage) -nostdlib -Wl,--gc-sections -r -o $@ -Wl,--start-group $(stages_o) $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) -Wl,--end-group
endif
endif # CONFIG_ARCH_RAMSTAGE_ARM