mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Split MemSet into three parts to constant comparisons can be optimized

Browse Source 
away by the compiler;  used by palloc0.
This commit is contained in:
Bruce Momjian 2002-11-13 00:37:06 +00:00
parent 266c3679f7
commit aaa3a0caa6
3 changed files with 39 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/utils/mmgr/mcxt.c
View File

@ -14,7 +14,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/mcxt.c,v 1.35 2002/11/10 02:17:25 momjian Exp $ * $Header: /cvsroot/pgsql/src/backend/utils/mmgr/mcxt.c,v 1.36 2002/11/13 00:37:06 momjian Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -453,14 +453,14 @@ MemoryContextAlloc(MemoryContext context, Size size)
} }
/* /*
* MemoryContextAllocZero * MemoryContextAllocPalloc0
* Like MemoryContextAlloc, but clears allocated memory * Like MemoryContextAlloc, but clears allocated memory
* *
* We could just call MemoryContextAlloc then clear the memory, but this * We could just call MemoryContextAlloc then clear the memory, but this
* function is called too many times, so we have a separate version. * function is called too many times, so we have a separate version.
*/ */
void * void *
MemoryContextAllocZero(MemoryContext context, Size size) MemoryContextAllocPalloc0(MemoryContext context, Size size)
{ {
void *ret; void *ret;
@ -471,7 +471,7 @@ MemoryContextAllocZero(MemoryContext context, Size size)
(unsigned long) size); (unsigned long) size);
ret = (*context->methods->alloc) (context, size); ret = (*context->methods->alloc) (context, size);
MemSet(ret, 0, size); MemSetLoop(ret, 0, size);
return ret; return ret;
} }

46
src/include/c.h
View File

@ -12,7 +12,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* $Id: c.h,v 1.131 2002/11/11 03:02:19 momjian Exp $ * $Id: c.h,v 1.132 2002/11/13 00:37:06 momjian Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -577,26 +577,36 @@ typedef NameData *Name;
* memset() functions. More research needs to be done, perhaps with * memset() functions. More research needs to be done, perhaps with
* platform-specific MEMSET_LOOP_LIMIT values or tests in configure. * platform-specific MEMSET_LOOP_LIMIT values or tests in configure.
* *
* MemSet has been split into two parts so MemSetTest can be optimized
* away for constant 'val' and 'len'. This is used by palloc0().
*
* Note, arguments are evaluated more than once.
*
* bjm 2002-10-08 * bjm 2002-10-08
*/ */
#define MemSet(start, val, len) \ #define MemSetTest(val, len) \
do \ ( ((len) & INT_ALIGN_MASK) == 0 && \
{ \ (len) <= MEMSET_LOOP_LIMIT && \
int32 * _start = (int32 *) (start); \ (val) == 0 )
int _val = (val); \
Size _len = (len); \ #define MemSetLoop(start, val, len) \
do \
{ \
int32 * _start = (int32 *) (start); \
int32 * _stop = (int32 *) ((char *) _start + (len)); \
\ \
if ((( ((long) _start) | _len) & INT_ALIGN_MASK) == 0 && \ while (_start < _stop) \
_val == 0 && \ *_start++ = 0; \
_len <= MEMSET_LOOP_LIMIT) \ } while (0)
{ \
int32 * _stop = (int32 *) ((char *) _start + _len); \ #define MemSet(start, val, len) \
while (_start < _stop) \ do \
*_start++ = 0; \ { \
} \ if (MemSetTest(val, len) && ((long)(start) & INT_ALIGN_MASK) == 0 ) \
else \ MemSetLoop(start, val, len); \
memset((char *) _start, _val, _len); \ else \
} while (0) memset((char *)(start), (val), (len)); \
} while (0)
#define MEMSET_LOOP_LIMIT 1024 #define MEMSET_LOOP_LIMIT 1024

10
src/include/utils/palloc.h
View File

@ -21,7 +21,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* $Id: palloc.h,v 1.22 2002/11/10 02:17:25 momjian Exp $ * $Id: palloc.h,v 1.23 2002/11/13 00:37:06 momjian Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -46,11 +46,15 @@ extern DLLIMPORT MemoryContext CurrentMemoryContext;
* Fundamental memory-allocation operations (more are in utils/memutils.h) * Fundamental memory-allocation operations (more are in utils/memutils.h)
*/ */
extern void *MemoryContextAlloc(MemoryContext context, Size size); extern void *MemoryContextAlloc(MemoryContext context, Size size);
extern void *MemoryContextAllocZero(MemoryContext context, Size size); extern void *MemoryContextAllocPalloc0(MemoryContext context, Size size);
#define palloc(sz) MemoryContextAlloc(CurrentMemoryContext, (sz)) #define palloc(sz) MemoryContextAlloc(CurrentMemoryContext, (sz))
#define palloc0(sz) MemoryContextAllocZero(CurrentMemoryContext, (sz)) /* We assume palloc() is already int-aligned */
#define palloc0(sz) \
( MemSetTest(0, (sz)) ? \
MemoryContextAllocPalloc0(CurrentMemoryContext, (sz)) : \
memset(palloc(sz), 0, (sz)))
extern void pfree(void *pointer); extern void pfree(void *pointer);