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>
1 parent 958f2e5 commit c1094987d1dc4701646c5f3aa254e7a92a02d305
@Marek Behún Marek Behún authored on 20 May 2021
Tom Rini committed on 24 May 2021
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scripts/Makefile.spl
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scripts/gen_ll_addressable_symbols.sh 0 → 100755