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bmomjianbmomjian
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Allow MEMSET_LOOP_LIMIT to be set on a per-platform basis, and turn off
MemSet on AIX by setting MEMSET_LOOP_LIMIT to zero. Add optimization to skip MemSet tests in MEMSET_LOOP_LIMIT == 0 case and just call memset() directly.
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-9
lines changed

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lines changed

‎configure

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -21516,6 +21516,17 @@ _ACEOF
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SHMEM_IMPLEMENTATION="src/backend/port/sysv_shmem.c"
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21519+
# If not set in template file, set bytes to use libc memset()
21520+
if test x"$MEMSET_LOOP_LIMIT" = x"" ; then
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MEMSET_LOOP_LIMIT=1024
21522+
fi
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cat >>confdefs.h <<_ACEOF
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#define MEMSET_LOOP_LIMIT ${MEMSET_LOOP_LIMIT}
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_ACEOF
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if test "$enable_nls" = yes ; then
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2152121532
echo "$as_me:$LINENO: checking for library containing gettext" >&5

‎configure.in

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
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dnl Process this file with autoconf to produce a configure script.
2-
dnl $PostgreSQL: pgsql/configure.in,v 1.443 2006/01/17 23:52:30 tgl Exp $
2+
dnl $PostgreSQL: pgsql/configure.in,v 1.444 2006/02/03 13:53:15 momjian Exp $
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dnl
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dnl Developers, please strive to achieve this order:
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dnl
@@ -1249,6 +1249,13 @@ AC_DEFINE(USE_SYSV_SHARED_MEMORY, 1, [Define to select SysV-style shared memory.
12491249
SHMEM_IMPLEMENTATION="src/backend/port/sysv_shmem.c"
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1252+
# If not set in template file, set bytes to use libc memset()
1253+
if test x"$MEMSET_LOOP_LIMIT" = x"" ; then
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MEMSET_LOOP_LIMIT=1024
1255+
fi
1256+
AC_DEFINE_UNQUOTED(MEMSET_LOOP_LIMIT, ${MEMSET_LOOP_LIMIT}, [Define bytes to use libc memset().])
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12521259
if test "$enable_nls" = yes ; then
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PGAC_CHECK_GETTEXT
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fi

‎src/include/c.h

Lines changed: 11 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
15-
* $PostgreSQL: pgsql/src/include/c.h,v 1.194 2006/01/05 03:01:37 momjian Exp $
15+
* $PostgreSQL: pgsql/src/include/c.h,v 1.195 2006/02/03 13:53:15 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -614,9 +614,7 @@ typedef NameData *Name;
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* overhead. However, we have also found that the loop is faster than
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* native libc memset() on some platforms, even those with assembler
616616
* memset() functions. More research needs to be done, perhaps with
617-
* platform-specific MEMSET_LOOP_LIMIT values or tests in configure.
618-
*
619-
* bjm 2002-10-08
617+
* MEMSET_LOOP_LIMIT tests in configure.
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*/
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#define MemSet(start, val, len) \
622620
do \
@@ -629,7 +627,12 @@ typedef NameData *Name;
629627
if ((((long) _vstart) & INT_ALIGN_MASK) == 0 && \
630628
(_len & INT_ALIGN_MASK) == 0 && \
631629
_val == 0 && \
632-
_len <= MEMSET_LOOP_LIMIT) \
630+
_len <= MEMSET_LOOP_LIMIT && \
631+
/* \
632+
* If MEMSET_LOOP_LIMIT == 0, optimizer should find \
633+
* the whole "if" false at compile time. \
634+
*/ \
635+
MEMSET_LOOP_LIMIT != 0) \
633636
{ \
634637
int32 *_start = (int32 *) _vstart; \
635638
int32 *_stop = (int32 *) ((char *) _start + _len); \
@@ -640,8 +643,6 @@ typedef NameData *Name;
640643
memset(_vstart, _val, _len); \
641644
} while (0)
642645

643-
#define MEMSET_LOOP_LIMIT 1024
644-
645646
/*
646647
* MemSetAligned is the same as MemSet except it omits the test to see if
647648
* "start" is word-aligned. This is okay to use if the caller knows a-priori
@@ -657,7 +658,8 @@ typedef NameData *Name;
657658
\
658659
if ((_len & INT_ALIGN_MASK) == 0 && \
659660
_val == 0 && \
660-
_len <= MEMSET_LOOP_LIMIT) \
661+
_len <= MEMSET_LOOP_LIMIT && \
662+
MEMSET_LOOP_LIMIT != 0) \
661663
{ \
662664
int32 *_stop = (int32 *) ((char *) _start + _len); \
663665
while (_start < _stop) \
@@ -679,6 +681,7 @@ typedef NameData *Name;
679681
#define MemSetTest(val, len) \
680682
( ((len) & INT_ALIGN_MASK) == 0 && \
681683
(len) <= MEMSET_LOOP_LIMIT && \
684+
MEMSET_LOOP_LIMIT != 0 && \
682685
(val) == 0 )
683686

684687
#define MemSetLoop(start, val, len) \

‎src/include/pg_config.h.in

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -576,6 +576,9 @@
576576
/* Define as the maximum alignment requirement of any C data type. */
577577
#undef MAXIMUM_ALIGNOF
578578

579+
/* Define bytes to use libc memset(). */
580+
#undef MEMSET_LOOP_LIMIT
581+
579582
/* Define to the address where bug reports for this package should be sent. */
580583
#undef PACKAGE_BUGREPORT
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‎src/template/aix

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -8,3 +8,7 @@ if test "$GCC" != yes ; then
88
;;
99
esac
1010
fi
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12+
# native memset() is faster, 2006-02-03
13+
# XLC 6.0, (IBM's cc), tested on AIX 5.2 and 5.1
14+
MEMSET_LOOP_LIMIT=0

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