Messages in this thread Patch in this message | | | Date | Tue, 1 Dec 2020 13:36:55 -0800 | Subject | [PATCH v8 04/16] kbuild: lto: limit inlining | From | Sami Tolvanen <> |
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This change limits function inlining across translation unit boundaries in order to reduce the binary size with LTO. The -import-instr-limit flag defines a size limit, as the number of LLVM IR instructions, for importing functions from other TUs, defaulting to 100.
Based on testing with arm64 defconfig, we found that a limit of 5 is a reasonable compromise between performance and binary size, reducing the size of a stripped vmlinux by 11%.
Suggested-by: George Burgess IV <gbiv@google.com> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> --- Makefile | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile index 222ae96d179d..ac836907d8b1 100644 --- a/Makefile +++ b/Makefile @@ -899,6 +899,9 @@ else CC_FLAGS_LTO += -flto endif CC_FLAGS_LTO += -fvisibility=default + +# Limit inlining across translation units to reduce binary size +KBUILD_LDFLAGS += -mllvm -import-instr-limit=5 endif ifdef CONFIG_LTO -- 2.29.2.576.ga3fc446d84-goog
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