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| author | Marek Behún <marek.behun@nic.cz> | 2021-05-20 13:24:03 +0200 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2021-05-24 14:21:30 -0400 |
| commit | c1094987d1dc4701646c5f3aa254e7a92a02d305 (patch) | |
| tree | 5d2bbcee39b8adff66ac767d8bde1bcb6283dfe7 /scripts/gen_ll_addressable_symbols.sh | |
| parent | 958f2e57eff72b5156f7b08b9c1415fb7e12833d (diff) | |
| download | u-boot-c1094987d1dc4701646c5f3aa254e7a92a02d305.tar.gz u-boot-c1094987d1dc4701646c5f3aa254e7a92a02d305.tar.xz u-boot-c1094987d1dc4701646c5f3aa254e7a92a02d305.zip | |
build: support building with Link Time Optimizations
Add plumbing for building U-Boot with Link Time Optimizations.
When building with LTO, $(PLATFORM_LIBS) has to be in --whole-archive /
--no-whole-archive group, otherwise some functions declared in assembly
may not be resolved and linking may fail.
Note: clang may throw away linker list symbols it thinks are unused when
compiling with LTO. To force these symbols to be included, we refer to
them via the __ADDRESSABLE macro in a C file generated from compiled
built-in.o files before linking.
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'scripts/gen_ll_addressable_symbols.sh')
| -rwxr-xr-x | scripts/gen_ll_addressable_symbols.sh | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/scripts/gen_ll_addressable_symbols.sh b/scripts/gen_ll_addressable_symbols.sh new file mode 100755 index 0000000000..3978a39d97 --- /dev/null +++ b/scripts/gen_ll_addressable_symbols.sh @@ -0,0 +1,12 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0+ +# Copyright (C) 2020 Marek Behún <marek.behun@nic.cz> + +# Generate __ADDRESSABLE(symbol) for every linker list entry symbol, so that LTO +# does not optimize these symbols away + +set -e + +echo '#include <common.h>' +$NM "$@" 2>/dev/null | grep -oe '_u_boot_list_2_[a-zA-Z0-9_]*_2_[a-zA-Z0-9_]*' | \ + sort -u | sed -e 's/^\(.*\)/extern char \1[];\n__ADDRESSABLE(\1);/' |