*
*------------------------------------------------------------------------ -
*/
-
#ifndef PG_BITUTILS_H
#define PG_BITUTILS_H
-extern int (*pg_popcount32) (uint32 word);
-extern int (*pg_popcount64) (uint64 word);
-extern int (*pg_rightmost_one32) (uint32 word);
-extern int (*pg_rightmost_one64) (uint64 word);
-extern int (*pg_leftmost_one32) (uint32 word);
-extern int (*pg_leftmost_one64) (uint64 word);
-
+extern int (*pg_popcount32) (uint32 word);
+extern int (*pg_popcount64) (uint64 word);
extern uint64 pg_popcount(const char *buf, int bytes);
+/* in pg_bitutils_hwpopcnt.c */
+extern int pg_popcount32_hw(uint32 word);
+extern int pg_popcount64_hw(uint64 word);
+
+
+#ifndef HAVE__BUILTIN_CTZ
+/*
+ * Array marking the position of the right-most set bit for each value of
+ * 1-255. We count the right-most position as the 0th bit, and the
+ * left-most the 7th bit. The 0th index of the array must not be used.
+ */
+static const uint8 rightmost_one_pos[256] = {
+ 0, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
+ 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
+};
+#endif /* !HAVE__BUILTIN_CTZ */
+
+/*
+ * pg_rightmost_one32
+ * Returns the number of trailing 0-bits in word, starting at the least
+ * significant bit position. word must not be 0.
+ */
+static inline int
+pg_rightmost_one32(uint32 word)
+{
+ int result = 0;
+
+ Assert(word != 0);
+
+#ifdef HAVE__BUILTIN_CTZ
+ result = __builtin_ctz(word);
+#else
+ while ((word & 255) == 0)
+ {
+ word >>= 8;
+ result += 8;
+ }
+ result += rightmost_one_pos[word & 255];
+#endif /* HAVE__BUILTIN_CTZ */
+
+ return result;
+}
+
+/*
+ * pg_rightmost_one64
+ * Returns the number of trailing 0-bits in word, starting at the least
+ * significant bit position. word must not be 0.
+ */
+static inline int
+pg_rightmost_one64(uint64 word)
+{
+ int result = 0;
+
+ Assert(word != 0);
+#ifdef HAVE__BUILTIN_CTZ
+#if defined(HAVE_LONG_INT_64)
+ return __builtin_ctzl(word);
+#elif defined(HAVE_LONG_LONG_INT_64)
+ return __builtin_ctzll(word);
+#else
+#error must have a working 64-bit integer datatype
+#endif
+#else /* HAVE__BUILTIN_CTZ */
+ while ((word & 255) == 0)
+ {
+ word >>= 8;
+ result += 8;
+ }
+ result += rightmost_one_pos[word & 255];
+#endif
+
+ return result;
+}
+
+#ifndef HAVE__BUILTIN_CLZ
+/*
+ * Array marking the position of the left-most set bit for each value of
+ * 1-255. We count the right-most position as the 0th bit, and the
+ * left-most the 7th bit. The 0th index of the array must not be used.
+ */
+static const uint8 leftmost_one_pos[256] = {
+ 0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
+ 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+ 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+ 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+ 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+ 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+ 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+ 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
+};
+#endif /* !HAVE_BUILTIN_CLZ */
+
+/*
+ * pg_leftmost_one32
+ * Returns the 0-based position of the most significant set bit in word
+ * measured from the least significant bit. word must not be 0.
+ */
+static inline int
+pg_leftmost_one32(uint32 word)
+{
+#ifdef HAVE__BUILTIN_CLZ
+ Assert(word != 0);
+
+ return 31 - __builtin_clz(word);
+#else
+ int shift = 32 - 8;
+
+ Assert(word != 0);
+
+ while ((word >> shift) == 0)
+ shift -= 8;
+
+ return shift + leftmost_one_pos[(word >> shift) & 255];
+#endif /* HAVE__BUILTIN_CLZ */
+}
+
+/*
+ * pg_leftmost_one64
+ * Returns the 0-based position of the most significant set bit in word
+ * measured from the least significant bit. word must not be 0.
+ */
+static inline int
+pg_leftmost_one64(uint64 word)
+{
+#ifdef HAVE__BUILTIN_CLZ
+ Assert(word != 0);
+#if defined(HAVE_LONG_INT_64)
+ return 63 - __builtin_clzl(word);
+#elif defined(HAVE_LONG_LONG_INT_64)
+ return 63 - __builtin_clzll(word);
+#else
+#error must have a working 64-bit integer datatype
+#endif
+#else /* HAVE__BUILTIN_CLZ */
+ int shift = 64 - 8;
+
+ Assert(word != 0);
+ while ((word >> shift) == 0)
+ shift -= 8;
+
+ return shift + leftmost_one_pos[(word >> shift) & 255];
+#endif /* !HAVE__BUIILTIN_CLZ */
+}
+
#endif /* PG_BITUTILS_H */
*
*-------------------------------------------------------------------------
*/
-
#include "postgres.h"
#ifdef HAVE__GET_CPUID
#include "port/pg_bitutils.h"
-#if defined(HAVE__BUILTIN_POPCOUNT) && defined(HAVE__GET_CPUID)
+#ifdef HAVE__BUILTIN_POPCOUNT
static bool pg_popcount_available(void);
-static int pg_popcount32_choose(uint32 word);
-static int pg_popcount32_sse42(uint32 word);
-static int pg_popcount64_choose(uint64 word);
-static int pg_popcount64_sse42(uint64 word);
-#endif
-static int pg_popcount32_slow(uint32 word);
-static int pg_popcount64_slow(uint64 word);
-
-#if defined(HAVE__GET_CPUID) && (defined(HAVE__BUILTIN_CTZ) || defined(HAVE__BUILTIN_CLZ))
-static bool pg_lzcnt_available(void);
-#endif
-
-#if defined(HAVE__BUILTIN_CTZ) && defined(HAVE__GET_CPUID)
-static int pg_rightmost_one32_choose(uint32 word);
-static int pg_rightmost_one32_abm(uint32 word);
-static int pg_rightmost_one64_choose(uint64 word);
-static int pg_rightmost_one64_abm(uint64 word);
-#endif
-static int pg_rightmost_one32_slow(uint32 word);
-static int pg_rightmost_one64_slow(uint64 word);
-
-#if defined(HAVE__BUILTIN_CLZ) && defined(HAVE__GET_CPUID)
-static int pg_leftmost_one32_choose(uint32 word);
-static int pg_leftmost_one32_abm(uint32 word);
-static int pg_leftmost_one64_choose(uint64 word);
-static int pg_leftmost_one64_abm(uint64 word);
-#endif
-static int pg_leftmost_one32_slow(uint32 word);
-static int pg_leftmost_one64_slow(uint64 word);
-
-#if defined(HAVE__BUILTIN_POPCOUNT) && defined(HAVE__GET_CPUID)
-int (*pg_popcount32) (uint32 word) = pg_popcount32_choose;
-int (*pg_popcount64) (uint64 word) = pg_popcount64_choose;
-#else
-int (*pg_popcount32) (uint32 word) = pg_popcount32_slow;
-int (*pg_popcount64) (uint64 word) = pg_popcount64_slow;
-#endif
-
-#if defined(HAVE__BUILTIN_CTZ) && defined(HAVE__GET_CPUID)
-int (*pg_rightmost_one32) (uint32 word) = pg_rightmost_one32_choose;
-int (*pg_rightmost_one64) (uint64 word) = pg_rightmost_one64_choose;
+static int pg_popcount32_choose(uint32 word);
+static int pg_popcount32_builtin(uint32 word);
+static int pg_popcount64_choose(uint64 word);
+static int pg_popcount64_builtin(uint64 word);
+int (*pg_popcount32) (uint32 word) = pg_popcount32_choose;
+int (*pg_popcount64) (uint64 word) = pg_popcount64_choose;
#else
-int (*pg_rightmost_one32) (uint32 word) = pg_rightmost_one32_slow;
-int (*pg_rightmost_one64) (uint64 word) = pg_rightmost_one64_slow;
-#endif
+static int pg_popcount32_slow(uint32 word);
+static int pg_popcount64_slow(uint64 word);
+int (*pg_popcount32) (uint32 word) = pg_popcount32_slow;
+int (*pg_popcount64) (uint64 word) = pg_popcount64_slow;
+#endif /* !HAVE_BUILTIN_POPCOUNT */
-#if defined(HAVE__BUILTIN_CLZ) && defined(HAVE__GET_CPUID)
-int (*pg_leftmost_one32) (uint32 word) = pg_leftmost_one32_choose;
-int (*pg_leftmost_one64) (uint64 word) = pg_leftmost_one64_choose;
-#else
-int (*pg_leftmost_one32) (uint32 word) = pg_leftmost_one32_slow;
-int (*pg_leftmost_one64) (uint64 word) = pg_leftmost_one64_slow;
-#endif
/* Array marking the number of 1-bits for each value of 0-255. */
static const uint8 number_of_ones[256] = {
};
/*
- * Array marking the position of the right-most set bit for each value of
- * 1-255. We count the right-most position as the 0th bit, and the
- * left-most the 7th bit. The 0th index of the array must not be used.
+ * Return true iff we have CPUID support and it indicates that the POPCNT
+ * instruction is available.
*/
-static const uint8 rightmost_one_pos[256] = {
- 0, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
- 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
-};
-
-/*
- * Array marking the position of the left-most set bit for each value of
- * 1-255. We count the right-most position as the 0th bit, and the
- * left-most the 7th bit. The 0th index of the array must not be used.
- */
-static const uint8 leftmost_one_pos[256] = {
- 0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
- 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
- 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
- 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
- 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
- 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
- 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
- 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
- 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
-};
-
-#if defined(HAVE__GET_CPUID) && defined(HAVE__BUILTIN_POPCOUNT)
-
static bool
pg_popcount_available(void)
{
- unsigned int exx[4] = { 0, 0, 0, 0 };
+#if defined(HAVE__GET_CPUID) || defined(HAVE__CPUID)
+ unsigned int exx[4] = {0, 0, 0, 0};
#if defined(HAVE__GET_CPUID)
__get_cpuid(1, &exx[0], &exx[1], &exx[2], &exx[3]);
#elif defined(HAVE__CPUID)
__cpuid(exx, 1);
-#else
-#error cpuid instruction not available
#endif
return (exx[2] & (1 << 23)) != 0; /* POPCNT */
-}
-#endif
+#else /* HAVE__GET_CPUID || HAVE__CPUID */
-#if defined(HAVE__GET_CPUID) && defined(HAVE__BUILTIN_POPCOUNT)
+ return false;
+#endif
+}
+#ifdef HAVE__BUILTIN_POPCOUNT
/*
- * This gets called on the first call. It replaces the function pointer
- * so that subsequent calls are routed directly to the chosen implementation.
+ * This gets called on the first call to pg_popcount32. It replaces the
+ * function pointer so that subsequent calls are routed directly to the chosen
+ * implementation.
*/
static int
pg_popcount32_choose(uint32 word)
{
if (pg_popcount_available())
- pg_popcount32 = pg_popcount32_sse42;
+ pg_popcount32 = pg_popcount32_hw;
else
- pg_popcount32 = pg_popcount32_slow;
+ pg_popcount32 = pg_popcount32_builtin;
return pg_popcount32(word);
}
static int
-pg_popcount32_sse42(uint32 word)
+pg_popcount32_builtin(uint32 word)
{
return __builtin_popcount(word);
}
-#endif
-
+#else /* HAVE__BUILTIN_POPCOUNT */
/*
* pg_popcount32_slow
* Return the number of 1 bits set in word
static int
pg_popcount32_slow(uint32 word)
{
- int result = 0;
+ int result = 0;
while (word != 0)
{
return result;
}
+#endif
/*
* pg_popcount
uint64
pg_popcount(const char *buf, int bytes)
{
- uint64 popcnt = 0;
+ uint64 popcnt = 0;
#if SIZEOF_VOID_P >= 8
/* Process in 64-bit chunks if the buffer is aligned. */
if (buf == (char *) TYPEALIGN(8, buf))
{
- uint64 *words = (uint64 *) buf;
+ uint64 *words = (uint64 *) buf;
while (bytes >= 8)
{
/* Process in 32-bit chunks if the buffer is aligned. */
if (buf == (char *) TYPEALIGN(4, buf))
{
- uint32 *words = (uint32 *) buf;
+ uint32 *words = (uint32 *) buf;
while (bytes >= 4)
{
return popcnt;
}
-#if defined(HAVE__GET_CPUID) && defined(HAVE__BUILTIN_POPCOUNT)
-
+#ifdef HAVE__BUILTIN_POPCOUNT
/*
- * This gets called on the first call. It replaces the function pointer
- * so that subsequent calls are routed directly to the chosen implementation.
+ * This gets called on the first call to pg_popcount64. It replaces the
+ * function pointer so that subsequent calls are routed directly to the chosen
+ * implementation.
*/
static int
pg_popcount64_choose(uint64 word)
{
if (pg_popcount_available())
- pg_popcount64 = pg_popcount64_sse42;
+ pg_popcount64 = pg_popcount64_hw;
else
- pg_popcount64 = pg_popcount64_slow;
+ pg_popcount64 = pg_popcount64_builtin;
return pg_popcount64(word);
}
static int
-pg_popcount64_sse42(uint64 word)
+pg_popcount64_builtin(uint64 word)
{
#if defined(HAVE_LONG_INT_64)
return __builtin_popcountl(word);
#elif defined(HAVE_LONG_LONG_INT_64)
return __builtin_popcountll(word);
#else
- /* shouldn't happen */
#error must have a working 64-bit integer datatype
#endif
}
-#endif
-
+#else /* HAVE__BUILTIN_POPCOUNT */
/*
* pg_popcount64_slow
* Return the number of 1 bits set in word
static int
pg_popcount64_slow(uint64 word)
{
- int result = 0;
+ int result = 0;
while (word != 0)
{
return result;
}
-
-#if defined(HAVE__GET_CPUID) && (defined(HAVE__BUILTIN_CTZ) || defined(HAVE__BUILTIN_CLZ))
-
-static bool
-pg_lzcnt_available(void)
-{
-
- unsigned int exx[4] = { 0, 0, 0, 0 };
-
-#if defined(HAVE__GET_CPUID)
- __get_cpuid(0x80000001, &exx[0], &exx[1], &exx[2], &exx[3]);
-#elif defined(HAVE__CPUID)
- __cpuid(exx, 0x80000001);
-#else
-#error cpuid instruction not available
-#endif
-
- return (exx[2] & (1 << 5)) != 0; /* LZCNT */
-}
-#endif
-
-#if defined(HAVE__GET_CPUID) && defined(HAVE__BUILTIN_CTZ)
-/*
- * This gets called on the first call. It replaces the function pointer
- * so that subsequent calls are routed directly to the chosen implementation.
- */
-static int
-pg_rightmost_one32_choose(uint32 word)
-{
- if (pg_lzcnt_available())
- pg_rightmost_one32 = pg_rightmost_one32_abm;
- else
- pg_rightmost_one32 = pg_rightmost_one32_slow;
-
- return pg_rightmost_one32(word);
-}
-
-static int
-pg_rightmost_one32_abm(uint32 word)
-{
- return __builtin_ctz(word);
-}
-
#endif
-
-/*
- * pg_rightmost_one32_slow
- * Returns the number of trailing 0-bits in word, starting at the least
- * significant bit position. word must not be 0.
- */
-static int
-pg_rightmost_one32_slow(uint32 word)
-{
- int result = 0;
-
- Assert(word != 0);
-
- while ((word & 255) == 0)
- {
- word >>= 8;
- result += 8;
- }
- result += rightmost_one_pos[word & 255];
-
- return result;
-}
-
-#if defined(HAVE__GET_CPUID) && defined(HAVE__BUILTIN_CTZ)
-/*
- * This gets called on the first call. It replaces the function pointer
- * so that subsequent calls are routed directly to the chosen implementation.
- */
-static int
-pg_rightmost_one64_choose(uint64 word)
-{
- if (pg_lzcnt_available())
- pg_rightmost_one64 = pg_rightmost_one64_abm;
- else
- pg_rightmost_one64 = pg_rightmost_one64_slow;
-
- return pg_rightmost_one64(word);
-}
-
-static int
-pg_rightmost_one64_abm(uint64 word)
-{
-#if defined(HAVE_LONG_INT_64)
- return __builtin_ctzl(word);
-#elif defined(HAVE_LONG_LONG_INT_64)
- return __builtin_ctzll(word);
-#else
- /* shouldn't happen */
-#error must have a working 64-bit integer datatype
-#endif
-}
-#endif
-
-/*
- * pg_rightmost_one64_slow
- * Returns the number of trailing 0-bits in word, starting at the least
- * significant bit position. word must not be 0.
- */
-static int
-pg_rightmost_one64_slow(uint64 word)
-{
- int result = 0;
-
- Assert(word != 0);
-
- while ((word & 255) == 0)
- {
- word >>= 8;
- result += 8;
- }
- result += rightmost_one_pos[word & 255];
-
- return result;
-}
-
-#if defined(HAVE__GET_CPUID) && defined(HAVE__BUILTIN_CLZ)
-/*
- * This gets called on the first call. It replaces the function pointer
- * so that subsequent calls are routed directly to the chosen implementation.
- */
-static int
-pg_leftmost_one32_choose(uint32 word)
-{
- if (pg_lzcnt_available())
- pg_leftmost_one32 = pg_leftmost_one32_abm;
- else
- pg_leftmost_one32 = pg_leftmost_one32_slow;
-
- return pg_leftmost_one32(word);
-}
-
-static int
-pg_leftmost_one32_abm(uint32 word)
-{
- return 31 - __builtin_clz(word);
-}
-#endif
-
-/*
- * pg_leftmost_one32_slow
- * Returns the 0-based position of the most significant set bit in word
- * measured from the least significant bit. word must not be 0.
- */
-static int
-pg_leftmost_one32_slow(uint32 word)
-{
- int shift = 32 - 8;
-
- Assert(word != 0);
-
- while ((word >> shift) == 0)
- shift -= 8;
-
- return shift + leftmost_one_pos[(word >> shift) & 255];
-}
-
-#if defined(HAVE__GET_CPUID) && defined(HAVE__BUILTIN_CLZ)
-/*
- * This gets called on the first call. It replaces the function pointer
- * so that subsequent calls are routed directly to the chosen implementation.
- */
-static int
-pg_leftmost_one64_choose(uint64 word)
-{
- if (pg_lzcnt_available())
- pg_leftmost_one64 = pg_leftmost_one64_abm;
- else
- pg_leftmost_one64 = pg_leftmost_one64_slow;
-
- return pg_leftmost_one64(word);
-}
-
-static int
-pg_leftmost_one64_abm(uint64 word)
-{
-#if defined(HAVE_LONG_INT_64)
- return 63 - __builtin_clzl(word);
-#elif defined(HAVE_LONG_LONG_INT_64)
- return 63 - __builtin_clzll(word);
-#else
- /* shouldn't happen */
-#error must have a working 64-bit integer datatype
-#endif
-
-}
-#endif
-
-/*
- * pg_leftmost_one64_slow
- * Returns the 0-based position of the most significant set bit in word
- * measured from the least significant bit. word must not be 0.
- */
-static int
-pg_leftmost_one64_slow(uint64 word)
-{
- int shift = 64 - 8;
-
- Assert(word != 0);
-
- while ((word >> shift) == 0)
- shift -= 8;
-
- return shift + leftmost_one_pos[(word >> shift) & 255];
-}
projects / postgresql / commitdiff