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author | Christophe Leroy <christophe.leroy@c-s.fr> | 2017-04-21 13:18:52 +0200 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-06-02 11:23:56 +0200 |
commit | f782ddf297318d544bf71ee1e8afbac8d55f1878 (patch) | |
tree | 9ca9ca219fb8044b40fa84a3a317df10231cfc10 /arch/powerpc/include | |
parent | powerpc: Replace ffz() by equivalent generic function (diff) | |
download | linux-f782ddf297318d544bf71ee1e8afbac8d55f1878.tar.xz linux-f782ddf297318d544bf71ee1e8afbac8d55f1878.zip |
powerpc: Remove __ilog2()s and use generic ones
With the __ilog2() function as defined in
arch/powerpc/include/asm/bitops.h, GCC will not optimise the code
in case of constant parameter.
The generic ilog2() function in include/linux/log2.h is written
to handle the case of the constant parameter.
This patch discards the three __ilog2() functions and
defines __ilog2() as ilog2()
For non constant calls, the generated code is doing the same:
int test__ilog2(unsigned long x)
{
return __ilog2(x);
}
int test__ilog2_u32(u32 n)
{
return __ilog2_u32(n);
}
int test__ilog2_u64(u64 n)
{
return __ilog2_u64(n);
}
On PPC32 before the patch:
00000000 <test__ilog2>:
0: 7c 63 00 34 cntlzw r3,r3
4: 20 63 00 1f subfic r3,r3,31
8: 4e 80 00 20 blr
0000000c <test__ilog2_u32>:
c: 7c 63 00 34 cntlzw r3,r3
10: 20 63 00 1f subfic r3,r3,31
14: 4e 80 00 20 blr
On PPC32 after the patch:
00000000 <test__ilog2>:
0: 7c 63 00 34 cntlzw r3,r3
4: 20 63 00 1f subfic r3,r3,31
8: 4e 80 00 20 blr
0000000c <test__ilog2_u32>:
c: 7c 63 00 34 cntlzw r3,r3
10: 20 63 00 1f subfic r3,r3,31
14: 4e 80 00 20 blr
On PPC64 before the patch:
0000000000000000 <.test__ilog2>:
0: 7c 63 00 74 cntlzd r3,r3
4: 20 63 00 3f subfic r3,r3,63
8: 7c 63 07 b4 extsw r3,r3
c: 4e 80 00 20 blr
0000000000000010 <.test__ilog2_u32>:
10: 7c 63 00 34 cntlzw r3,r3
14: 20 63 00 1f subfic r3,r3,31
18: 7c 63 07 b4 extsw r3,r3
1c: 4e 80 00 20 blr
0000000000000020 <.test__ilog2_u64>:
20: 7c 63 00 74 cntlzd r3,r3
24: 20 63 00 3f subfic r3,r3,63
28: 7c 63 07 b4 extsw r3,r3
2c: 4e 80 00 20 blr
On PPC64 after the patch:
0000000000000000 <.test__ilog2>:
0: 7c 63 00 74 cntlzd r3,r3
4: 20 63 00 3f subfic r3,r3,63
8: 7c 63 07 b4 extsw r3,r3
c: 4e 80 00 20 blr
0000000000000010 <.test__ilog2_u32>:
10: 7c 63 00 34 cntlzw r3,r3
14: 20 63 00 1f subfic r3,r3,31
18: 7c 63 07 b4 extsw r3,r3
1c: 4e 80 00 20 blr
0000000000000020 <.test__ilog2_u64>:
20: 7c 63 00 74 cntlzd r3,r3
24: 20 63 00 3f subfic r3,r3,63
28: 7c 63 07 b4 extsw r3,r3
2c: 4e 80 00 20 blr
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include')
-rw-r--r-- | arch/powerpc/include/asm/bitops.h | 27 |
1 files changed, 1 insertions, 26 deletions
diff --git a/arch/powerpc/include/asm/bitops.h b/arch/powerpc/include/asm/bitops.h index d835cd697d6b..b750ffef83c7 100644 --- a/arch/powerpc/include/asm/bitops.h +++ b/arch/powerpc/include/asm/bitops.h @@ -206,32 +206,7 @@ static __inline__ void __clear_bit_unlock(int nr, volatile unsigned long *addr) * Return the zero-based bit position (LE, not IBM bit numbering) of * the most significant 1-bit in a double word. */ -static __inline__ __attribute__((const)) -int __ilog2(unsigned long x) -{ - int lz; - - asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x)); - return BITS_PER_LONG - 1 - lz; -} - -static inline __attribute__((const)) -int __ilog2_u32(u32 n) -{ - int bit; - asm ("cntlzw %0,%1" : "=r" (bit) : "r" (n)); - return 31 - bit; -} - -#ifdef __powerpc64__ -static inline __attribute__((const)) -int __ilog2_u64(u64 n) -{ - int bit; - asm ("cntlzd %0,%1" : "=r" (bit) : "r" (n)); - return 63 - bit; -} -#endif +#define __ilog2(x) ilog2(x) #include <asm-generic/bitops/ffz.h> |