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Improve style of pg_lfind32().

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This commit simplifies pg_lfind32() a bit by moving the standard
one-by-one linear search code to an inline helper function.

Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20240327013616.GA3940109%40nathanxps13
This commit is contained in:
Nathan Bossart 2024-03-27 20:26:05 -05:00
parent 2d8f56dabb
commit 7188a7806d
1 changed files with 26 additions and 36 deletions
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62
src/include/port/pg_lfind.h
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@ -80,6 +80,24 @@ pg_lfind8_le(uint8 key, uint8 *base, uint32 nelem)
return false; return false;
} }
/*
* pg_lfind32_one_by_one_helper
*
* Searches the array of integers one-by-one. The caller is responsible for
* ensuring that there are at least "nelem" integers in the array.
*/
static inline bool
pg_lfind32_one_by_one_helper(uint32 key, const uint32 *base, uint32 nelem)
{
for (uint32 i = 0; i < nelem; i++)
{
if (key == base[i])
return true;
}
return false;
}
#ifndef USE_NO_SIMD #ifndef USE_NO_SIMD
/* /*
* pg_lfind32_simd_helper * pg_lfind32_simd_helper
@ -88,7 +106,7 @@ pg_lfind8_le(uint8 key, uint8 *base, uint32 nelem)
* ensuring that there are at least 4-registers-worth of integers remaining. * ensuring that there are at least 4-registers-worth of integers remaining.
*/ */
static inline bool static inline bool
pg_lfind32_simd_helper(const Vector32 keys, uint32 *base) pg_lfind32_simd_helper(const Vector32 keys, const uint32 *base)
{ {
const uint32 nelem_per_vector = sizeof(Vector32) / sizeof(uint32); const uint32 nelem_per_vector = sizeof(Vector32) / sizeof(uint32);
Vector32 vals1, Vector32 vals1,
@ -132,11 +150,10 @@ pg_lfind32_simd_helper(const Vector32 keys, uint32 *base)
* return false. * return false.
*/ */
static inline bool static inline bool
pg_lfind32(uint32 key, uint32 *base, uint32 nelem) pg_lfind32(uint32 key, const uint32 *base, uint32 nelem)
{ {
uint32 i = 0;
#ifndef USE_NO_SIMD #ifndef USE_NO_SIMD
uint32 i = 0;
/* /*
* For better instruction-level parallelism, each loop iteration operates * For better instruction-level parallelism, each loop iteration operates
@ -150,25 +167,15 @@ pg_lfind32(uint32 key, uint32 *base, uint32 nelem)
const uint32 tail_idx = nelem & ~(nelem_per_iteration - 1); const uint32 tail_idx = nelem & ~(nelem_per_iteration - 1);
#if defined(USE_ASSERT_CHECKING) #if defined(USE_ASSERT_CHECKING)
bool assert_result = false; bool assert_result = pg_lfind32_one_by_one_helper(key, base, nelem);
/* pre-compute the result for assert checking */
for (int j = 0; j < nelem; j++)
{
if (key == base[j])
{
assert_result = true;
break;
}
}
#endif #endif
/* /*
* If there aren't enough elements for the SIMD code, jump to the standard * If there aren't enough elements for the SIMD code, use the standard
* one-by-one linear search code. * one-by-one linear search code.
*/ */
if (nelem < nelem_per_iteration) if (nelem < nelem_per_iteration)
goto one_by_one; return pg_lfind32_one_by_one_helper(key, base, nelem);
/* /*
* Process as many elements as possible with a block of 4 registers. * Process as many elements as possible with a block of 4 registers.
@ -193,27 +200,10 @@ pg_lfind32(uint32 key, uint32 *base, uint32 nelem)
*/ */
Assert(assert_result == pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration])); Assert(assert_result == pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration]));
return pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration]); return pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration]);
#else
one_by_one:
#endif /* ! USE_NO_SIMD */
/* Process the elements one at a time. */ /* Process the elements one at a time. */
for (; i < nelem; i++) return pg_lfind32_one_by_one_helper(key, base, nelem);
{
if (key == base[i])
{
#ifndef USE_NO_SIMD
Assert(assert_result == true);
#endif #endif
return true;
}
}
#ifndef USE_NO_SIMD
Assert(assert_result == false);
#endif
return false;
} }
#endif /* PG_LFIND_H */ #endif /* PG_LFIND_H */