[CF 5726] v8 - Enable auto-vectorization for page checksum calculations

This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5726

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/CAK64mnejn9AZMYz03e7HX8Uui35PihUuOy=b+iBG=YtRKx0Log@mail.gmail.com
Author(s): Matthew Sterrett, Andrew Kim

Author: Commitfest Bot

config/c-compiler.m4

@@ -581,6 +581,32 @@ fi
 undefine([Ac_cachevar])dnl
 ])# PGAC_SSE42_CRC32_INTRINSICS
 
+# PGAC_AVX2_SUPPORT
+# ---------------------------
+# Check if the compiler supports AVX2 target attribute.
+# This is used for optimized checksum calculations with runtime detection.
+#
+# If AVX2 target attribute is supported, sets pgac_avx2_support.
+AC_DEFUN([PGAC_AVX2_SUPPORT],
+[define([Ac_cachevar], [AS_TR_SH([pgac_cv_avx2_support])])dnl
+AC_CACHE_CHECK([for AVX2 target attribute support], [Ac_cachevar],
+[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <stdint.h>
+    #if defined(__has_attribute) && __has_attribute (target)
+    __attribute__((target("avx2")))
+    static int avx2_test(void)
+    {
+      return 0;
+    }
+    #endif],
+  [return avx2_test();])],
+  [Ac_cachevar=yes],
+  [Ac_cachevar=no])])
+if test x"$Ac_cachevar" = x"yes"; then
+  pgac_avx2_support=yes
+fi
+undefine([Ac_cachevar])dnl
+])# PGAC_AVX2_SUPPORT
+
 # PGAC_AVX512_PCLMUL_INTRINSICS
 # ---------------------------
 # Check if the compiler supports AVX-512 carryless multiplication

configure

@@ -17552,6 +17552,58 @@ $as_echo "#define HAVE_XSAVE_INTRINSICS 1" >>confdefs.h
 
 fi
 
+# Check for AVX2 target and intrinsic support
+#
+if test x"$host_cpu" = x"x86_64"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for AVX2 support" >&5
+$as_echo_n "checking for AVX2 support... " >&6; }
+if ${pgac_cv_avx2_support+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <immintrin.h>
+    #include <stdint.h>
+    #if defined(__has_attribute) && __has_attribute (target)
+    __attribute__((target("avx2")))
+    #endif
+    static int avx2_test(void)
+    {
+      const char buf[sizeof(__m256i)];
+      __m256i accum = _mm256_loadu_si256((const __m256i *) buf);
+	  accum = _mm256_add_epi32(accum, accum);
+      int result = _mm256_extract_epi32(accum, 0);
+      return (int) result;
+    }
+int
+main ()
+{
+return avx2_test();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv_avx2_support=yes
+else
+  pgac_cv_avx2_support=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_avx2_support" >&5
+$as_echo "$pgac_cv_avx2_support" >&6; }
+if test x"$pgac_cv_avx2_support" = x"yes"; then
+  pgac_avx2_support=yes
+fi
+
+  if test x"$pgac_avx2_support" = x"yes"; then
+
+$as_echo "#define USE_AVX2_WITH_RUNTIME_CHECK 1" >>confdefs.h
+
+  fi
+fi
+
 # Check for AVX-512 popcount intrinsics
 #
 if test x"$host_cpu" = x"x86_64"; then

configure.ac

@@ -2077,6 +2077,15 @@ else
   fi
 fi
 
+# Check for AVX2 target and intrinsic support
+#
+if test x"$host_cpu" = x"x86_64"; then
+  PGAC_AVX2_SUPPORT()
+  if test x"$pgac_avx2_support" = x"yes"; then
+    AC_DEFINE(USE_AVX2_WITH_RUNTIME_CHECK, 1, [Define to 1 to use AVX2 instructions with a runtime check.])
+  fi
+fi
+
 # Check for XSAVE intrinsics
 #
 PGAC_XSAVE_INTRINSICS()

contrib/meson.build

@@ -12,6 +12,7 @@ contrib_doc_args = {
   'install_dir': contrib_doc_dir,
 }
 
+subdir('pg_checksum_bench')
 subdir('amcheck')
 subdir('auth_delay')
 subdir('auto_explain')

contrib/pageinspect/rawpage.c

@@ -23,7 +23,7 @@
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "storage/bufmgr.h"
-#include "storage/checksum.h"
+#include "port/checksum.h"
 #include "utils/builtins.h"
 #include "utils/pg_lsn.h"
 #include "utils/rel.h"

contrib/pg_checksum_bench/meson.build

@@ -0,0 +1,23 @@
+# Copyright (c) 2022-2025, PostgreSQL Global Development Group
+
+pg_checksum_bench_sources = files(
+  'pg_checksum_bench.c',
+)
+
+if host_system == 'windows'
+  pg_checksum_bench_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'pg_checksum_bench',
+    '--FILEDESC', 'pg_checksum_bench',])
+endif
+
+pg_checksum_bench = shared_module('pg_checksum_bench',
+  pg_checksum_bench_sources,
+  kwargs: contrib_mod_args,
+)
+contrib_targets += pg_checksum_bench
+
+install_data(
+  'pg_checksum_bench--1.0.sql',
+  'pg_checksum_bench.control',
+  kwargs: contrib_data_args,
+)

contrib/pg_checksum_bench/pg_checksum_bench--1.0.sql

@@ -0,0 +1,8 @@
+/* contrib/pg_checksum_bench/pg_checksum_bench--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+-- \echo Use "CREATE EXTENSION pg_checksum_bench" to load this file. \quit
+
+CREATE FUNCTION drive_pg_checksum(page_count int)
+	RETURNS pg_catalog.void
+	AS 'MODULE_PATHNAME' LANGUAGE C;

contrib/pg_checksum_bench/pg_checksum_bench.c

@@ -0,0 +1,34 @@
+#include "postgres.h"
+#include "fmgr.h"
+#include "port/checksum_impl.h"
+
+#include <stdio.h>
+#include <assert.h>
+
+PG_MODULE_MAGIC;
+
+#define REPEATS 1000000
+
+PG_FUNCTION_INFO_V1(drive_pg_checksum);
+Datum
+drive_pg_checksum(PG_FUNCTION_ARGS)
+{
+	int page_count = PG_GETARG_INT32(0);
+
+	PGChecksummablePage * pages = palloc(page_count * sizeof(PGChecksummablePage));
+	srand(0);
+	for (size_t i = 0; i < page_count * sizeof(PGChecksummablePage); i++){
+		char * byte_ptr = (char *) pages;
+		byte_ptr[i] = rand() % 256;
+	}
+
+	for (int i = 0; i < REPEATS; i++){
+		const PGChecksummablePage * test_page = pages + (i % page_count);
+		volatile uint32 result = pg_checksum_block(test_page);
+		(void) result;
+	}
+
+	pfree((void *) pages);
+
+	PG_RETURN_VOID();
+}

contrib/pg_checksum_bench/pg_checksum_bench.control

@@ -0,0 +1,4 @@
+comment = 'pg_checksum benchmark'
+default_version = '1.0'
+module_pathname = '$libdir/pg_checksum_bench'
+relocatable = true

contrib/pg_checksum_bench/sql/pg_checksum_bench.sql

@@ -0,0 +1,17 @@
+CREATE EXTENSION pg_checksum_bench;
+
+SELECT drive_pg_checksum(-1);
+
+\timing on
+
+SELECT drive_pg_checksum(1);
+SELECT drive_pg_checksum(2);
+SELECT drive_pg_checksum(4);
+SELECT drive_pg_checksum(8);
+SELECT drive_pg_checksum(16);
+SELECT drive_pg_checksum(32);
+SELECT drive_pg_checksum(64);
+SELECT drive_pg_checksum(128);
+SELECT drive_pg_checksum(256);
+SELECT drive_pg_checksum(512);
+SELECT drive_pg_checksum(1024);