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With both gcc 4.7.2 and 4.9.2, sometimes gcc mysteriously doesn't inline
very small functions we expect to be inlined. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
With this .config:
http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os,
set_buffer_foo(), clear_buffer_foo() and similar functions get deinlined
about 60 times. Examples of disassembly:
<set_buffer_mapped> (14 copies, 43 calls):
55 push %rbp
48 89 e5 mov %rsp,%rbp
f0 80 0f 20 lock orb $0x20,(%rdi)
5d pop %rbp
c3 retq
<buffer_mapped> (3 copies, 34 calls):
48 8b 07 mov (%rdi),%rax
55 push %rbp
48 89 e5 mov %rsp,%rbp
48 c1 e8 05 shr $0x5,%rax
83 e0 01 and $0x1,%eax
5d pop %rbp
c3 retq
<set_buffer_new> (5 copies, 13 calls):
55 push %rbp
48 89 e5 mov %rsp,%rbp
f0 80 0f 40 lock orb $0x40,(%rdi)
5d pop %rbp
c3 retq
This patch fixes this via s/inline/__always_inline/.
This decreases vmlinux by about 3 kbytes.
text data bss dec hex filename
88200439 19905208 36421632 144527279 89d4faf vmlinux2
88197239
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