summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorChristophe Leroy <christophe.leroy@csgroup.eu>2020-12-16 05:42:45 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-16 07:46:15 +0100
commit0a571b085ff6dadf946b248133533d3ba68f6e31 (patch)
tree5c1578cce2e0561b857c36fbefb265796c8b6b56
parentfs/proc: make pde_get() return nothing (diff)
downloadlinux-0a571b085ff6dadf946b248133533d3ba68f6e31.tar.xz
linux-0a571b085ff6dadf946b248133533d3ba68f6e31.zip
asm-generic: force inlining of get_order() to work around gcc10 poor decision
When building mpc885_ads_defconfig with gcc 10.1, the function get_order() appears 50 times in vmlinux: [linux]# ppc-linux-objdump -x vmlinux | grep get_order | wc -l 50 [linux]# size vmlinux text data bss dec hex filename 3842620 675624 135160 4653404 47015c vmlinux In the old days, marking a function 'static inline' was forcing GCC to inline, but since commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING forcibly") GCC may decide to not inline a function. It looks like GCC 10 is taking poor decisions on this. get_order() compiles into the following tiny function, occupying 20 bytes of text. 0000007c <get_order>: 7c: 38 63 ff ff addi r3,r3,-1 80: 54 63 a3 3e rlwinm r3,r3,20,12,31 84: 7c 63 00 34 cntlzw r3,r3 88: 20 63 00 20 subfic r3,r3,32 8c: 4e 80 00 20 blr By forcing get_order() to be __always_inline, the size of text is reduced by 1940 bytes, that is almost twice the space occupied by 50 times get_order() [linux-powerpc]# size vmlinux text data bss dec hex filename 3840680 675588 135176 4651444 46f9b4 vmlinux Link: https://lkml.kernel.org/r/96c6172d619c51acc5c1c4884b80785c59af4102.1602949927.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-by: Joel Stanley <joel@jms.id.au> Cc: Segher Boessenkool <segher@kernel.crashing.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/asm-generic/getorder.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-generic/getorder.h b/include/asm-generic/getorder.h
index e9f20b813a69..f2979e3a96b6 100644
--- a/include/asm-generic/getorder.h
+++ b/include/asm-generic/getorder.h
@@ -26,7 +26,7 @@
*
* The result is undefined if the size is 0.
*/
-static inline __attribute_const__ int get_order(unsigned long size)
+static __always_inline __attribute_const__ int get_order(unsigned long size)
{
if (__builtin_constant_p(size)) {
if (!size)