| Date | Thu, 3 Sep 2020 13:30:37 -0700 | Subject | [PATCH v2 12/28] kbuild: lto: limit inlining | From | Sami Tolvanen <> |
| |
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> --- Makefile | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/Makefile b/Makefile index 2752be67b460..c69e07bd506a 100644 --- a/Makefile +++ b/Makefile @@ -917,6 +917,10 @@ else CC_FLAGS_LTO_CLANG := -flto endif CC_FLAGS_LTO_CLANG += -fvisibility=default + +# Limit inlining across translation units to reduce binary size +LD_FLAGS_LTO_CLANG := -mllvm -import-instr-limit=5 +KBUILD_LDFLAGS += $(LD_FLAGS_LTO_CLANG) endif ifdef CONFIG_LTO -- 2.28.0.402.g5ffc5be6b7-goog
|