From c1094987d1dc4701646c5f3aa254e7a92a02d305 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marek=20Beh=C3=BAn?= Date: Thu, 20 May 2021 13:24:03 +0200 Subject: build: support building with Link Time Optimizations MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Simon Glass --- Kbuild | 2 ++ 1 file changed, 2 insertions(+) (limited to 'Kbuild') diff --git a/Kbuild b/Kbuild index 1eac091..bf52e54 100644 --- a/Kbuild +++ b/Kbuild @@ -10,6 +10,8 @@ generic-offsets-file := include/generated/generic-asm-offsets.h always := $(generic-offsets-file) targets := lib/asm-offsets.s +CFLAGS_REMOVE_asm-offsets.o := $(LTO_CFLAGS) + $(obj)/$(generic-offsets-file): $(obj)/lib/asm-offsets.s FORCE $(call filechk,offsets,__GENERIC_ASM_OFFSETS_H__) -- cgit v1.1