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| author |   Heiko Carstens <heiko.carstens@de.ibm.com> | 2009-09-11 10:28:32 +0200 |
|---|---|---|
| committer |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2009-09-11 10:29:43 +0200 |
| commit | 04efc3be767cfed0d348fd598eba8fe5f5bf5fe6 (patch) | |
| tree | 53a6509f836e2f85c34e5a3af66fa9fbff910f77 | |
| parent | [S390] introduce get_clock_monotonic (diff) | |
| download | linux-dev-04efc3be767cfed0d348fd598eba8fe5f5bf5fe6.tar.xz linux-dev-04efc3be767cfed0d348fd598eba8fe5f5bf5fe6.zip | |
[S390] convert/optimize csum_fold() to C
In the meantime gcc generates better code than the old inline
assemblies do. Original inline assembly results in:
lr %r1,%r2
sr %r3,%r3
lr %r2,%r1
srdl %r2,16
alr %r2,%r3
alr %r1,%r2
srl %r1,16
xilf %r1,65535
llghr %r2,%r1
br %r14
Out of the C code gcc generates this:
rll %r1,%r2,16
ar %r1,%r2
srl %r1,16
xilf %r1,65535
llghr %r2,%r1
br %r14
In addition we don't have any static register allocations anymore and
gcc is free to shuffle instructions around for better pipeline usage.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/checksum.h | 25 |
1 files changed, 4 insertions, 21 deletions
diff --git a/arch/s390/include/asm/checksum.h b/arch/s390/include/asm/checksum.h index d5a8e7c1477c..6c00f6800a34 100644 --- a/arch/s390/include/asm/checksum.h +++ b/arch/s390/include/asm/checksum.h @@ -78,28 +78,11 @@ csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum) */ static inline __sum16 csum_fold(__wsum sum) { -#ifndef __s390x__ - register_pair rp; + u32 csum = (__force u32) sum; - asm volatile( - " slr %N1,%N1\n" /* %0 = H L */ - " lr %1,%0\n" /* %0 = H L, %1 = H L 0 0 */ - " srdl %1,16\n" /* %0 = H L, %1 = 0 H L 0 */ - " alr %1,%N1\n" /* %0 = H L, %1 = L H L 0 */ - " alr %0,%1\n" /* %0 = H+L+C L+H */ - " srl %0,16\n" /* %0 = H+L+C */ - : "+&d" (sum), "=d" (rp) : : "cc"); -#else /* __s390x__ */ - asm volatile( - " sr 3,3\n" /* %0 = H*65536 + L */ - " lr 2,%0\n" /* %0 = H L, 2/3 = H L / 0 0 */ - " srdl 2,16\n" /* %0 = H L, 2/3 = 0 H / L 0 */ - " alr 2,3\n" /* %0 = H L, 2/3 = L H / L 0 */ - " alr %0,2\n" /* %0 = H+L+C L+H */ - " srl %0,16\n" /* %0 = H+L+C */ - : "+&d" (sum) : : "cc", "2", "3"); -#endif /* __s390x__ */ - return (__force __sum16) ~sum; + csum += (csum >> 16) + (csum << 16); + csum >>= 16; + return (__force __sum16) ~csum; } /* |