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Add assert checking to pg_leftmost_one_pos32() and friends

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Discussion: https://www.postgresql.org/message-id/CAFBsxsEPc%2BFnX_0vmmQ5DHv60sk4rL_RZJ%2BMD6ei%3D76L0kFMvA%40mail.gmail.com
This commit is contained in:
John Naylor 2023-01-24 14:39:26 +07:00
parent 2cb82e2acf
commit 204b0cbecb
1 changed files with 60 additions and 26 deletions
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86
src/include/port/pg_bitutils.h
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@ -26,10 +26,11 @@ static inline int
pg_leftmost_one_pos32(uint32 word) pg_leftmost_one_pos32(uint32 word)
{ {
#ifdef HAVE__BUILTIN_CLZ #ifdef HAVE__BUILTIN_CLZ
Assert(word != 0); int bitscan_result;
#endif
return 31 - __builtin_clz(word); #if !defined(HAVE__BUILTIN_CLZ) || defined(USE_ASSERT_CHECKING)
#else int result;
int shift = 32 - 8; int shift = 32 - 8;
Assert(word != 0); Assert(word != 0);
@ -37,7 +38,15 @@ pg_leftmost_one_pos32(uint32 word)
while ((word >> shift) == 0) while ((word >> shift) == 0)
shift -= 8; shift -= 8;
return shift + pg_leftmost_one_pos[(word >> shift) & 255]; result = shift + pg_leftmost_one_pos[(word >> shift) & 255];
#endif
#if defined(HAVE__BUILTIN_CLZ)
bitscan_result = 31 - __builtin_clz(word);
Assert(bitscan_result == result);
return bitscan_result;
#else
return result;
#endif /* HAVE__BUILTIN_CLZ */ #endif /* HAVE__BUILTIN_CLZ */
} }
@ -49,16 +58,11 @@ static inline int
pg_leftmost_one_pos64(uint64 word) pg_leftmost_one_pos64(uint64 word)
{ {
#ifdef HAVE__BUILTIN_CLZ #ifdef HAVE__BUILTIN_CLZ
Assert(word != 0); int bitscan_result;
#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 #endif
#else /* !HAVE__BUILTIN_CLZ */
#if !defined(HAVE__BUILTIN_CLZ) || defined(USE_ASSERT_CHECKING)
int result;
int shift = 64 - 8; int shift = 64 - 8;
Assert(word != 0); Assert(word != 0);
@ -66,7 +70,21 @@ pg_leftmost_one_pos64(uint64 word)
while ((word >> shift) == 0) while ((word >> shift) == 0)
shift -= 8; shift -= 8;
return shift + pg_leftmost_one_pos[(word >> shift) & 255]; result = shift + pg_leftmost_one_pos[(word >> shift) & 255];
#endif
#if defined(HAVE__BUILTIN_CLZ)
#if defined(HAVE_LONG_INT_64)
bitscan_result = 63 - __builtin_clzl(word);
#elif defined(HAVE_LONG_LONG_INT_64)
bitscan_result = 63 - __builtin_clzll(word);
#else
#error must have a working 64-bit integer datatype
#endif /* HAVE_LONG_INT_64 */
Assert(bitscan_result == result);
return bitscan_result;
#else
return result;
#endif /* HAVE__BUILTIN_CLZ */ #endif /* HAVE__BUILTIN_CLZ */
} }
@ -79,10 +97,11 @@ static inline int
pg_rightmost_one_pos32(uint32 word) pg_rightmost_one_pos32(uint32 word)
{ {
#ifdef HAVE__BUILTIN_CTZ #ifdef HAVE__BUILTIN_CTZ
Assert(word != 0); const uint32 orig_word = word;
int bitscan_result;
#endif
return __builtin_ctz(word); #if !defined(HAVE__BUILTIN_CTZ) || defined(USE_ASSERT_CHECKING)
#else
int result = 0; int result = 0;
Assert(word != 0); Assert(word != 0);
@ -93,6 +112,13 @@ pg_rightmost_one_pos32(uint32 word)
result += 8; result += 8;
} }
result += pg_rightmost_one_pos[word & 255]; result += pg_rightmost_one_pos[word & 255];
#endif
#if defined(HAVE__BUILTIN_CTZ)
bitscan_result = __builtin_ctz(orig_word);
Assert(bitscan_result == result);
return bitscan_result;
#else
return result; return result;
#endif /* HAVE__BUILTIN_CTZ */ #endif /* HAVE__BUILTIN_CTZ */
} }
@ -105,16 +131,11 @@ static inline int
pg_rightmost_one_pos64(uint64 word) pg_rightmost_one_pos64(uint64 word)
{ {
#ifdef HAVE__BUILTIN_CTZ #ifdef HAVE__BUILTIN_CTZ
Assert(word != 0); const uint64 orig_word = word;
int bitscan_result;
#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 #endif
#else /* !HAVE__BUILTIN_CTZ */
#if !defined(HAVE__BUILTIN_CTZ) || defined(USE_ASSERT_CHECKING)
int result = 0; int result = 0;
Assert(word != 0); Assert(word != 0);
@ -125,6 +146,19 @@ pg_rightmost_one_pos64(uint64 word)
result += 8; result += 8;
} }
result += pg_rightmost_one_pos[word & 255]; result += pg_rightmost_one_pos[word & 255];
#endif
#if defined(HAVE__BUILTIN_CTZ)
#if defined(HAVE_LONG_INT_64)
bitscan_result = __builtin_ctzl(orig_word);
#elif defined(HAVE_LONG_LONG_INT_64)
bitscan_result = __builtin_ctzll(orig_word);
#else
#error must have a working 64-bit integer datatype
#endif /* HAVE_LONG_INT_64 */
Assert(bitscan_result == result);
return bitscan_result;
#else
return result; return result;
#endif /* HAVE__BUILTIN_CTZ */ #endif /* HAVE__BUILTIN_CTZ */
} }