Author: delphij
Date: Wed Feb 13 17:30:54 2013
New Revision: 246768
URL: http://svnweb.freebsd.org/changeset/base/246768
Log:
Restore De Bruijn algorithm for sparc64 where the compiler rely on a
library function for __builtin_c?z.
Tested by: Michael Moll <kvedulv kvedulv de>
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c Wed Feb 13
17:03:35 2013 (r246767)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c Wed Feb 13
17:30:54 2013 (r246768)
@@ -238,6 +238,16 @@ lz4_decompress(void *s_start, void *d_st
#endif
/*
+ * FreeBSD: can't use GCC's __builtin_ctz when using sparc64 because
+ * gcc currently rely on libcompiler_rt.
+ *
+ * TODO: revisit this when situation changes.
+ */
+#if defined(__sparc64__)
+#define LZ4_FORCE_SW_BITCOUNT
+#endif
+
+/*
* Compiler Options
*/
#if __STDC_VERSION__ >= 199901L /* C99 */
@@ -378,9 +388,38 @@ static inline int
LZ4_NbCommonBytes(register U64 val)
{
#if defined(LZ4_BIG_ENDIAN)
+#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_clzll(val) >> 3);
#else
+ int r;
+ if (!(val >> 32)) {
+ r = 4;
+ } else {
+ r = 0;
+ val >>= 32;
+ }
+ if (!(val >> 16)) {
+ r += 2;
+ val >>= 8;
+ } else {
+ val >>= 24;
+ }
+ r += (!val);
+ return (r);
+#endif
+#else
+#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_ctzll(val) >> 3);
+#else
+ static const int DeBruijnBytePos[64] =
+ { 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5,
+ 3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5,
+ 5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4,
+ 4, 5, 7, 2, 6, 5, 7, 6, 7, 7
+ };
+ return DeBruijnBytePos[((U64) ((val & -val) * 0x0218A392CDABBD3F)) >>
+ 58];
+#endif
#endif
}
@@ -390,9 +429,33 @@ static inline int
LZ4_NbCommonBytes(register U32 val)
{
#if defined(LZ4_BIG_ENDIAN)
+#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_clz(val) >> 3);
#else
+ int r;
+ if (!(val >> 16)) {
+ r = 2;
+ val >>= 8;
+ } else {
+ r = 0;
+ val >>= 24;
+ }
+ r += (!val);
+ return (r);
+#endif
+#else
+#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_ctz(val) >> 3);
+#else
+ static const int DeBruijnBytePos[32] = {
+ 0, 0, 3, 0, 3, 1, 3, 0,
+ 3, 2, 2, 1, 3, 2, 0, 1,
+ 3, 3, 1, 2, 2, 2, 2, 0,
+ 3, 1, 2, 0, 1, 0, 1, 1
+ };
+ return DeBruijnBytePos[((U32) ((val & -(S32) val) * 0x077CB531U)) >>
+ 27];
+#endif
#endif
}
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