On Mon, Aug 22, 2022 at 02:22:29PM -0700, Nathan Bossart wrote:
> On Mon, Aug 22, 2022 at 09:35:34AM +0700, John Naylor wrote:
>> Not at all! However, the 32-bit-element changes are irrelevant for
>> json, and make review more difficult. I would suggest keeping those in
>> the other thread starting with whatever refactoring is needed. I can
>> always rebase over that.
>
> Yeah, I'll remove those to keep this thread focused.
Here's a new version of the patch with the 32-bit changes and calls to
lfind() removed.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
>From dd7b3c3b0567d77a7f171d9cb4b6a8d3ee30ceec Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathandboss...@gmail.com>
Date: Sat, 20 Aug 2022 21:14:01 -0700
Subject: [PATCH v8 1/1] json_lex_string() SIMD
---
src/common/jsonapi.c | 11 +-
src/include/port/pg_lfind.h | 65 +++++++-
src/include/port/simd.h | 143 ++++++++++++++++++
.../test_lfind/expected/test_lfind.out | 18 ++-
.../modules/test_lfind/sql/test_lfind.sql | 4 +-
.../modules/test_lfind/test_lfind--1.0.sql | 10 +-
src/test/modules/test_lfind/test_lfind.c | 91 ++++++++++-
7 files changed, 332 insertions(+), 10 deletions(-)
diff --git a/src/common/jsonapi.c b/src/common/jsonapi.c
index fefd1d24d9..87e1d0b192 100644
--- a/src/common/jsonapi.c
+++ b/src/common/jsonapi.c
@@ -19,6 +19,7 @@
#include "common/jsonapi.h"
#include "mb/pg_wchar.h"
+#include "port/pg_lfind.h"
#ifndef FRONTEND
#include "miscadmin.h"
@@ -844,7 +845,7 @@ json_lex_string(JsonLexContext *lex)
}
else
{
- char *p;
+ char *p = s;
if (hi_surrogate != -1)
return JSON_UNICODE_LOW_SURROGATE;
@@ -853,7 +854,13 @@ json_lex_string(JsonLexContext *lex)
* Skip to the first byte that requires special handling, so we
* can batch calls to appendBinaryStringInfo.
*/
- for (p = s; p < end; p++)
+ while (p < end - sizeof(Vector8) &&
+ !pg_lfind8('\\', (uint8 *) p, sizeof(Vector8)) &&
+ !pg_lfind8('"', (uint8 *) p, sizeof(Vector8)) &&
+ !pg_lfind8_le(0x1F, (uint8 *) p, sizeof(Vector8)))
+ p += sizeof(Vector8);
+
+ for (; p < end; p++)
{
if (*p == '\\' || *p == '"')
break;
diff --git a/src/include/port/pg_lfind.h b/src/include/port/pg_lfind.h
index fb125977b2..86342d71d8 100644
--- a/src/include/port/pg_lfind.h
+++ b/src/include/port/pg_lfind.h
@@ -1,7 +1,8 @@
/*-------------------------------------------------------------------------
*
* pg_lfind.h
- * Optimized linear search routines.
+ * Optimized linear search routines using SIMD intrinsics where
+ * available.
*
* Copyright (c) 2022, PostgreSQL Global Development Group
*
@@ -15,6 +16,68 @@
#include "port/simd.h"
+/*
+ * pg_lfind8
+ *
+ * Return true if there is an element in 'base' that equals 'key', otherwise
+ * return false.
+ */
+static inline bool
+pg_lfind8(uint8 key, uint8 *base, uint32 nelem)
+{
+ uint32 i;
+ /* round down to multiple of vector length */
+ uint32 tail_idx = nelem & ~(sizeof(Vector8) - 1);
+ Vector8 chunk;
+
+ for (i = 0; i < tail_idx; i += sizeof(Vector8))
+ {
+ vector8_load(&chunk, &base[i]);
+ if (vector8_eq(chunk, key))
+ return true;
+ }
+
+ /* Process the remaining elements one at a time. */
+ for (; i < nelem; i++)
+ {
+ if (key == base[i])
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * pg_lfind8_le
+ *
+ * Return true if there is an element in 'base' that is less than or equal to
+ * 'key', otherwise return false.
+ */
+static inline bool
+pg_lfind8_le(uint8 key, uint8 *base, uint32 nelem)
+{
+ uint32 i;
+ /* round down to multiple of vector length */
+ uint32 tail_idx = nelem & ~(sizeof(Vector8) - 1);
+ Vector8 chunk;
+
+ for (i = 0; i < tail_idx; i += sizeof(Vector8))
+ {
+ vector8_load(&chunk, &base[i]);
+ if (vector8_le(chunk, key))
+ return true;
+ }
+
+ /* Process the remaining elements one at a time. */
+ for (; i < nelem; i++)
+ {
+ if (base[i] <= key)
+ return true;
+ }
+
+ return false;
+}
+
/*
* pg_lfind32
*
diff --git a/src/include/port/simd.h b/src/include/port/simd.h
index a571e79f57..23f6269169 100644
--- a/src/include/port/simd.h
+++ b/src/include/port/simd.h
@@ -25,6 +25,149 @@
#if (defined(__x86_64__) || defined(_M_AMD64))
#include <emmintrin.h>
#define USE_SSE2
+typedef __m128i Vector8;
+
+/*
+ * If no SIMD instructions are available, we emulate specialized vector
+ * operations using uint64.
+ */
+#else
+typedef uint64 Vector8;
+#endif
+
+
+static inline void vector8_load(Vector8 *v, const uint8 *s);
+static inline Vector8 vector8_broadcast(const uint8 c);
+static inline bool vector8_has_zero(const Vector8 v);
+static inline bool vector8_eq(const Vector8 v, const uint8 c);
+static inline bool vector8_le(const Vector8 v, const uint8 c);
+
+
+/*
+ * Functions for loading a chunk of memory into a vector.
+ */
+
+static inline void
+vector8_load(Vector8 *v, const uint8 *s)
+{
+#ifdef USE_SSE2
+ *v = _mm_loadu_si128((const __m128i *) s);
+#else
+ memcpy(v, s, sizeof(Vector8));
+#endif
+}
+
+
+/*
+ * Functions for creating a vector with all elements set to the same value.
+ */
+
+static inline Vector8
+vector8_broadcast(const uint8 c)
+{
+#ifdef USE_SSE2
+ return _mm_set1_epi8(c);
+#else
+ return ~UINT64CONST(0) / 0xFF * c;
#endif
+}
+
+
+/*
+ * Functions for comparing vector elements to a given value.
+ */
+
+static inline bool
+vector8_has_zero(const Vector8 v)
+{
+#ifdef USE_SSE2
+ return _mm_movemask_epi8(_mm_cmpeq_epi8(v, _mm_setzero_si128()));
+#else
+ return vector8_le(v, 0);
+#endif
+}
+
+static inline bool
+vector8_eq(const Vector8 v, const uint8 c)
+{
+ bool result;
+
+ /* pre-compute the result for assert checking */
+#ifdef USE_ASSERT_CHECKING
+ bool assert_result = false;
+ for (int i = 0; i < sizeof(Vector8); i++)
+ {
+ if (((const uint8 *) &v)[i] == c)
+ {
+ assert_result = true;
+ break;
+ }
+ }
+#endif /* USE_ASSERT_CHECKING */
+
+#ifdef USE_SSE2
+ result = _mm_movemask_epi8(_mm_cmpeq_epi8(v, vector8_broadcast(c)));
+#else
+ /* any bytes in v equal to c will evaluate to zero via XOR */
+ result = vector8_has_zero(v ^ vector8_broadcast(c));
+#endif
+
+ Assert(assert_result == result);
+ return result;
+}
+
+static inline bool
+vector8_le(const Vector8 v, const uint8 c)
+{
+ bool result = false;
+#ifdef USE_SSE2
+ __m128i sub;
+#endif
+
+ /* pre-compute the result for assert checking */
+#ifdef USE_ASSERT_CHECKING
+ bool assert_result = false;
+ for (int i = 0; i < sizeof(Vector8); i++)
+ {
+ if (((const uint8 *) &v)[i] <= c)
+ {
+ assert_result = true;
+ break;
+ }
+ }
+#endif /* USE_ASSERT_CHECKING */
+
+#ifdef USE_SSE2
+ /*
+ * Use saturating subtraction to find bytes <= c, which will present as
+ * NUL bytes in 'sub'.
+ */
+ sub = _mm_subs_epu8(v, vector8_broadcast(c));
+ result = vector8_has_zero(sub);
+#else
+ /*
+ * To find bytes <= c, we can use bitwise operations to find bytes < c + 1,
+ * but it only works if c + 1 <= 128 and if the highest bit in v is not set
+ * (from https://graphics.stanford.edu/~seander/bithacks.html).
+ */
+ if ((int64) v >= 0 && c < 0x80)
+ result = (v - vector8_broadcast(c + 1)) & ~v & vector8_broadcast(0x80);
+ else
+ {
+ /* one byte at a time */
+ for (int i = 0; i < sizeof(Vector8); i++)
+ {
+ if (((const uint8 *) &v)[i] <= c)
+ {
+ result = true;
+ break;
+ }
+ }
+ }
+#endif
+
+ Assert(assert_result == result);
+ return result;
+}
#endif /* SIMD_H */
diff --git a/src/test/modules/test_lfind/expected/test_lfind.out b/src/test/modules/test_lfind/expected/test_lfind.out
index 222c8fd7ff..1d4b14e703 100644
--- a/src/test/modules/test_lfind/expected/test_lfind.out
+++ b/src/test/modules/test_lfind/expected/test_lfind.out
@@ -4,9 +4,21 @@ CREATE EXTENSION test_lfind;
-- the operations complete without crashing or hanging and that none of their
-- internal sanity tests fail.
--
-SELECT test_lfind();
- test_lfind
-------------
+SELECT test_lfind8();
+ test_lfind8
+-------------
+
+(1 row)
+
+SELECT test_lfind8_le();
+ test_lfind8_le
+----------------
+
+(1 row)
+
+SELECT test_lfind32();
+ test_lfind32
+--------------
(1 row)
diff --git a/src/test/modules/test_lfind/sql/test_lfind.sql b/src/test/modules/test_lfind/sql/test_lfind.sql
index 899f1dd49b..766c640831 100644
--- a/src/test/modules/test_lfind/sql/test_lfind.sql
+++ b/src/test/modules/test_lfind/sql/test_lfind.sql
@@ -5,4 +5,6 @@ CREATE EXTENSION test_lfind;
-- the operations complete without crashing or hanging and that none of their
-- internal sanity tests fail.
--
-SELECT test_lfind();
+SELECT test_lfind8();
+SELECT test_lfind8_le();
+SELECT test_lfind32();
diff --git a/src/test/modules/test_lfind/test_lfind--1.0.sql b/src/test/modules/test_lfind/test_lfind--1.0.sql
index d82ab0567e..81801926ae 100644
--- a/src/test/modules/test_lfind/test_lfind--1.0.sql
+++ b/src/test/modules/test_lfind/test_lfind--1.0.sql
@@ -3,6 +3,14 @@
-- complain if script is sourced in psql, rather than via CREATE EXTENSION
\echo Use "CREATE EXTENSION test_lfind" to load this file. \quit
-CREATE FUNCTION test_lfind()
+CREATE FUNCTION test_lfind32()
+ RETURNS pg_catalog.void
+ AS 'MODULE_PATHNAME' LANGUAGE C;
+
+CREATE FUNCTION test_lfind8()
+ RETURNS pg_catalog.void
+ AS 'MODULE_PATHNAME' LANGUAGE C;
+
+CREATE FUNCTION test_lfind8_le()
RETURNS pg_catalog.void
AS 'MODULE_PATHNAME' LANGUAGE C;
diff --git a/src/test/modules/test_lfind/test_lfind.c b/src/test/modules/test_lfind/test_lfind.c
index a000746fb8..efe6b60bc5 100644
--- a/src/test/modules/test_lfind/test_lfind.c
+++ b/src/test/modules/test_lfind/test_lfind.c
@@ -18,10 +18,97 @@
PG_MODULE_MAGIC;
-PG_FUNCTION_INFO_V1(test_lfind);
+/* workhorse for test_lfind8 */
+static void
+test_lfind8_internal(uint8 key)
+{
+ /* The byte searched for shouldn't be in the first vector-sized chunk, to make sure iteration works */
+#define LEN_NO_TAIL (2 * sizeof(Vector8))
+#define LEN_WITH_TAIL (LEN_NO_TAIL + 3)
+
+ uint8 charbuf[LEN_WITH_TAIL];
+
+ memset(charbuf, 0xFF, LEN_WITH_TAIL);
+ /* search tail to test one-byte-at-a-time path */
+ charbuf[LEN_WITH_TAIL - 1] = key;
+ if (key > 0x00 && pg_lfind8(key - 1, charbuf, LEN_WITH_TAIL))
+ elog(ERROR, "pg_lfind8() found nonexistent element <= '0x%x'", key - 1);
+ if (key < 0xFF && !pg_lfind8(key, charbuf, LEN_WITH_TAIL))
+ elog(ERROR, "pg_lfind8() did not find existing element <= '0x%x'", key);
+ if (key < 0xFE && pg_lfind8(key + 1, charbuf, LEN_WITH_TAIL))
+ elog(ERROR, "pg_lfind8() found nonexistent element <= '0x%x'", key + 1);
+
+ memset(charbuf, 0xFF, LEN_WITH_TAIL);
+ /* search with vector operations */
+ charbuf[LEN_NO_TAIL - 1] = key;
+ if (key > 0x00 && pg_lfind8(key - 1, charbuf, LEN_NO_TAIL))
+ elog(ERROR, "pg_lfind8() found nonexistent element <= '0x%x'", key - 1);
+ if (key < 0xFF && !pg_lfind8(key, charbuf, LEN_NO_TAIL))
+ elog(ERROR, "pg_lfind8() did not find existing element <= '0x%x'", key);
+ if (key < 0xFE && pg_lfind8(key + 1, charbuf, LEN_NO_TAIL))
+ elog(ERROR, "pg_lfind8() found nonexistent element <= '0x%x'", key + 1);
+}
+
+PG_FUNCTION_INFO_V1(test_lfind8);
+Datum
+test_lfind8(PG_FUNCTION_ARGS)
+{
+ test_lfind8_internal(0);
+ test_lfind8_internal(1);
+ test_lfind8_internal(0x7F);
+ test_lfind8_internal(0x80);
+ test_lfind8_internal(0xFD);
+
+ PG_RETURN_VOID();
+}
+
+/* workhorse for test_lfind8_le */
+static void
+test_lfind8_le_internal(uint8 key)
+{
+ /* The byte searched for shouldn't be in the first vector-sized chunk, to make sure iteration works */
+#define LEN_NO_TAIL (2 * sizeof(Vector8))
+#define LEN_WITH_TAIL (LEN_NO_TAIL + 3)
+
+ uint8 charbuf[LEN_WITH_TAIL];
+
+ memset(charbuf, 0xFF, LEN_WITH_TAIL);
+ /* search tail to test one-byte-at-a-time path */
+ charbuf[LEN_WITH_TAIL - 1] = key;
+ if (key > 0x00 && pg_lfind8_le(key - 1, charbuf, LEN_WITH_TAIL))
+ elog(ERROR, "pg_lfind8_le() found nonexistent element <= '0x%x'", key - 1);
+ if (key < 0xFF && !pg_lfind8_le(key, charbuf, LEN_WITH_TAIL))
+ elog(ERROR, "pg_lfind8_le() did not find existing element <= '0x%x'", key);
+ if (key < 0xFE && !pg_lfind8_le(key + 1, charbuf, LEN_WITH_TAIL))
+ elog(ERROR, "pg_lfind8_le() did not find existing element <= '0x%x'", key + 1);
+
+ memset(charbuf, 0xFF, LEN_WITH_TAIL);
+ /* search with vector operations */
+ charbuf[LEN_NO_TAIL - 1] = key;
+ if (key > 0x00 && pg_lfind8_le(key - 1, charbuf, LEN_NO_TAIL))
+ elog(ERROR, "pg_lfind8_le() found nonexistent element <= '0x%x'", key - 1);
+ if (key < 0xFF && !pg_lfind8_le(key, charbuf, LEN_NO_TAIL))
+ elog(ERROR, "pg_lfind8_le() did not find existing element <= '0x%x'", key);
+ if (key < 0xFE && !pg_lfind8_le(key + 1, charbuf, LEN_NO_TAIL))
+ elog(ERROR, "pg_lfind8_le() did not find existing element <= '0x%x'", key + 1);
+}
+
+PG_FUNCTION_INFO_V1(test_lfind8_le);
+Datum
+test_lfind8_le(PG_FUNCTION_ARGS)
+{
+ test_lfind8_le_internal(0);
+ test_lfind8_le_internal(1);
+ test_lfind8_le_internal(0x7F);
+ test_lfind8_le_internal(0x80);
+ test_lfind8_le_internal(0xFD);
+
+ PG_RETURN_VOID();
+}
+PG_FUNCTION_INFO_V1(test_lfind32);
Datum
-test_lfind(PG_FUNCTION_ARGS)
+test_lfind32(PG_FUNCTION_ARGS)
{
#define TEST_ARRAY_SIZE 135
uint32 test_array[TEST_ARRAY_SIZE] = {0};
--
2.25.1
