4423eff71c
Commit 328e7e487a46 ("powerpc: force inlining of csum_partial() to
avoid multiple csum_partial() with GCC10") inlined csum_partial().
Now that csum_partial() is inlined, GCC outlines csum_add() when
called by csum_partial().
c064fb28 <csum_add>:
c064fb28: 7c 63 20 14 addc r3,r3,r4
c064fb2c: 7c 63 01 94 addze r3,r3
c064fb30: 4e 80 00 20 blr
c0665fb8 <csum_add>:
c0665fb8: 7c 63 20 14 addc r3,r3,r4
c0665fbc: 7c 63 01 94 addze r3,r3
c0665fc0: 4e 80 00 20 blr
c066719c: 7c 9a c0 2e lwzx r4,r26,r24
c06671a0: 38 60 00 00 li r3,0
c06671a4: 7f 1a c2 14 add r24,r26,r24
c06671a8: 4b ff ee 11 bl c0665fb8 <csum_add>
c06671ac: 80 98 00 04 lwz r4,4(r24)
c06671b0: 4b ff ee 09 bl c0665fb8 <csum_add>
c06671b4: 80 98 00 08 lwz r4,8(r24)
c06671b8: 4b ff ee 01 bl c0665fb8 <csum_add>
c06671bc: a0 98 00 0c lhz r4,12(r24)
c06671c0: 4b ff ed f9 bl c0665fb8 <csum_add>
c06671c4: 7c 63 18 f8 not r3,r3
c06671c8: 81 3f 00 68 lwz r9,104(r31)
c06671cc: 81 5f 00 a0 lwz r10,160(r31)
c06671d0: 7d 29 18 14 addc r9,r9,r3
c06671d4: 7d 29 01 94 addze r9,r9
c06671d8: 91 3f 00 68 stw r9,104(r31)
c06671dc: 7d 1a 50 50 subf r8,r26,r10
c06671e0: 83 01 00 10 lwz r24,16(r1)
c06671e4: 83 41 00 18 lwz r26,24(r1)
The sum with 0 is useless, should have been skipped.
And there is even one completely unused instance of csum_add().
In file included from ./include/net/checksum.h:22,
from ./include/linux/skbuff.h:28,
from ./include/linux/icmp.h:16,
from net/ipv6/ip6_tunnel.c:23:
./arch/powerpc/include/asm/checksum.h: In function '__ip6_tnl_rcv':
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:172:31: note: called from here
172 | sum = csum_add(sum, (__force __wsum)*(const u32 *)buff);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:177:31: note: called from here
177 | sum = csum_add(sum, (__force __wsum)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
178 | *(const u32 *)(buff + 4));
| ~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:183:31: note: called from here
183 | sum = csum_add(sum, (__force __wsum)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
184 | *(const u32 *)(buff + 8));
| ~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/powerpc/include/asm/checksum.h:94:22: warning: inlining failed in call to 'csum_add': call is unlikely and code size would grow [-Winline]
94 | static inline __wsum csum_add(__wsum csum, __wsum addend)
| ^~~~~~~~
./arch/powerpc/include/asm/checksum.h:186:31: note: called from here
186 | sum = csum_add(sum, (__force __wsum)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
187 | *(const u16 *)(buff + 12));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~
Force inlining of csum_add().
94c: 80 df 00 a0 lwz r6,160(r31)
950: 7d 28 50 2e lwzx r9,r8,r10
954: 7d 48 52 14 add r10,r8,r10
958: 80 aa 00 04 lwz r5,4(r10)
95c: 80 ff 00 68 lwz r7,104(r31)
960: 7d 29 28 14 addc r9,r9,r5
964: 7d 29 01 94 addze r9,r9
968: 7d 08 30 50 subf r8,r8,r6
96c: 80 aa 00 08 lwz r5,8(r10)
970: a1 4a 00 0c lhz r10,12(r10)
974: 7d 29 28 14 addc r9,r9,r5
978: 7d 29 01 94 addze r9,r9
97c: 7d 29 50 14 addc r9,r9,r10
980: 7d 29 01 94 addze r9,r9
984: 7d 29 48 f8 not r9,r9
988: 7c e7 48 14 addc r7,r7,r9
98c: 7c e7 01 94 addze r7,r7
990: 90 ff 00 68 stw r7,104(r31)
In the non-inlined version, the first sum with 0 was performed.
Here it is skipped.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f7f4d4e364de6e473da874468b903da6e5d97adc.1620713272.git.christophe.leroy@csgroup.eu
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.