On Wed, Jun 24, 2020 at 01:31:44PM -0700, Sami Tolvanen wrote: > 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. > The default value is 100, and decreasing it to 5 reduces the size > of a stripped arm64 defconfig vmlinux by 11%. Is that also the right number for x86? What about the effect on performance? What did 6 do? or 4? > Suggested-by: George Burgess IV <gbiv@xxxxxxxxxx> > Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx> > --- > Makefile | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Makefile b/Makefile > index 3a7e5e5c17b9..ee66513a5b66 100644 > --- a/Makefile > +++ b/Makefile > @@ -894,6 +894,10 @@ 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 > -- > 2.27.0.212.ge8ba1cc988-goog >
