Messages in this thread Patch in this message |  | | Date | Tue, 29 Sep 2020 14:46:16 -0700 | Subject | [PATCH v4 14/29] 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 23cdb475c445..d6510ee99ffc 100644 --- a/Makefile +++ b/Makefile @@ -894,6 +894,9 @@ 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 -- 2.28.0.709.gb0816b6eb0-goog
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