blob: fc91b82c7380c325a131c7e042f7c33a8c3c04ac (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
From ba6bd6d4f05dc173ddcf5ff7365a7964c7769349 Mon Sep 17 00:00:00 2001
From: Sami Tolvanen <samitolvanen@google.com>
Date: Wed, 4 Dec 2019 15:57:39 -0800
Subject: [PATCH 08/24] kbuild: lto: limit inlining
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 19e2bf26c52c..498d281aa318 100644
--- a/Makefile
+++ b/Makefile
@@ -895,6 +895,10 @@ 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
|