c1094987d1
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>
32 lines
783 B
Makefile
32 lines
783 B
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Kbuild for top-level directory of U-Boot
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#####
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# Generate generic-asm-offsets.h
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generic-offsets-file := include/generated/generic-asm-offsets.h
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always := $(generic-offsets-file)
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targets := lib/asm-offsets.s
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CFLAGS_REMOVE_asm-offsets.o := $(LTO_CFLAGS)
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$(obj)/$(generic-offsets-file): $(obj)/lib/asm-offsets.s FORCE
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$(call filechk,offsets,__GENERIC_ASM_OFFSETS_H__)
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#####
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# Generate asm-offsets.h
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ifneq ($(wildcard $(srctree)/arch/$(ARCH)/lib/asm-offsets.c),)
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offsets-file := include/generated/asm-offsets.h
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endif
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always += $(offsets-file)
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targets += arch/$(ARCH)/lib/asm-offsets.s
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CFLAGS_asm-offsets.o := -DDO_DEPS_ONLY
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$(obj)/$(offsets-file): $(obj)/arch/$(ARCH)/lib/asm-offsets.s FORCE
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$(call filechk,offsets,__ASM_OFFSETS_H__)
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