Remove the actual checks that verify that memory pools (such as set up

using SQLITE_CONFIG_HEAP) are 8-byte aligned.  But document that 8-byte
alignment is required. (CVS 6742)

FossilOrigin-Name: e9b55ccc8b6d4f21c9c8f8e7ba053475833fc833

manifest

@@ -1,5 +1,5 @@
-C Fix\scompiler\swarnings\swith\sMSVC\sbuild.\s(CVS\s6741)
-D 2009-06-09T18:58:53
+C Remove\sthe\sactual\schecks\sthat\sverify\sthat\smemory\spools\s(such\sas\sset\sup\nusing\sSQLITE_CONFIG_HEAP)\sare\s8-byte\saligned.\s\sBut\sdocument\sthat\s8-byte\nalignment\sis\srequired.\s(CVS\s6742)
+D 2009-06-09T19:53:58
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 8b8fb7823264331210cddf103831816c286ba446
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -125,7 +125,7 @@ F src/insert.c 69ef88ce30d1f65315b57aba63b2d4e9bdca1090
 F src/journal.c e00df0c0da8413ab6e1bb7d7cab5665d4a9000d0
 F src/legacy.c 9a56cf126ceee332b56061bf16bd0fb4ff9e26c0
 F src/loadext.c 0e88a335665db0b2fb4cece3e49dcb65d832635a
-F src/main.c 839ebfc7fa3b5a9f36223f536f6b5fef2a5ecf63
+F src/main.c a30a4a7faaefb3dbceee60f80caf985f2f38b3ea
 F src/malloc.c 7b3b6423f5b355e5d649b91e16ef252d610bcf19
 F src/mem0.c f2f84062d1f35814d6535c9f9e33de3bfb3b132c
 F src/mem1.c e6d5c23941288df8191b8a98c28e3f57771e2270
@@ -160,7 +160,7 @@ F src/resolve.c f86d3490cf93a12f8a451720defc622cbc79873a
 F src/rowset.c c64dafba1f9fd876836c8db8682966b9d197eb1f
 F src/select.c 2d97084a176a63eabce2d043eb4fbb13c46d6e9f
 F src/shell.c db2643650b9268df89a4bedca3f1c6d9e786f1bb
-F src/sqlite.h.in e23556112022f04c9c49a4fc9871be16223250c3
+F src/sqlite.h.in 9fe53ec7a8310d7d18d482b85e46f5556abfd1de
 F src/sqlite3ext.h 1db7d63ab5de4b3e6b83dd03d1a4e64fef6d2a17
 F src/sqliteInt.h f8d70341d527404c5f162dc7fcc0f005700d0b48
 F src/sqliteLimit.h ffe93f5a0c4e7bd13e70cd7bf84cfb5c3465f45d
@@ -733,7 +733,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl 672f81d693a03f80f5ae60bfefacd8a349e76746
-P 9d3329891c2227a1a3ded1c636ac615864010ca7
-R 29a13eb275900e63ac826d07275d5f9d
-U shane
-Z a716d3bc3c26080c0aad9adc8101d4dd
+P 0bd84e7387802c58c820369ff27ef54adbdf2e96
+R 29fe22cf8f8068919f8b856eca0fa3af
+U drh
+Z 046c2b0883806c0e583e778b10e1f950

manifest.uuid

@@ -1 +1 @@
-0bd84e7387802c58c820369ff27ef54adbdf2e96
+e9b55ccc8b6d4f21c9c8f8e7ba053475833fc833

src/main.c

@@ -14,7 +14,7 @@
 ** other files are for internal use by SQLite and should not be
 ** accessed by users of the library.
 **
-** $Id: main.c,v 1.556 2009/06/09 18:02:10 drh Exp $
+** $Id: main.c,v 1.557 2009/06/09 19:53:58 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -338,11 +338,6 @@ int sqlite3_config(int op, ...){
       sqlite3GlobalConfig.nHeap = va_arg(ap, int);
       sqlite3GlobalConfig.mnReq = va_arg(ap, int);
 
-      /* Must have 8-byte alignment */
-      if( ((sqlite3GlobalConfig.pHeap - (char*)0)&7)!=0 ){
-        return SQLITE_MISUSE;
-      }
-
       if( sqlite3GlobalConfig.pHeap==0 ){
         /* If the heap pointer is NULL, then restore the malloc implementation
         ** back to NULL pointers too.  This will cause the malloc to go

src/sqlite.h.in

@@ -30,7 +30,7 @@
 ** the version number) and changes its name to "sqlite3.h" as
 ** part of the build process.
 **
-** @(#) $Id: sqlite.h.in,v 1.456 2009/06/09 18:02:10 drh Exp $
+** @(#) $Id: sqlite.h.in,v 1.457 2009/06/09 19:53:58 drh Exp $
 */
 #ifndef _SQLITE3_H_
 #define _SQLITE3_H_
@@ -1036,12 +1036,14 @@ struct sqlite3_mem_methods {
 **
 ** <dt>SQLITE_CONFIG_SCRATCH</dt>
 ** <dd>This option specifies a static memory buffer that SQLite can use for
-** scratch memory.  There are three arguments:  A pointer to the memory, the
-** size of each scratch buffer (sz), and the number of buffers (N).  The sz
+** scratch memory.  There are three arguments:  A pointer an 8-byte
+** aligned memory buffer from which the scrach allocations will be
+** drawn, the size of each scratch allocation (sz),
+** and the maximum number of scratch allocations (N).  The sz
 ** argument must be a multiple of 16. The sz parameter should be a few bytes
-** larger than the actual scratch space required due internal overhead.
-** The first
-** argument should point to an allocation of at least sz*N bytes of memory.
+** larger than the actual scratch space required due to internal overhead.
+** The first argument should pointer to an 8-byte aligned buffer
+** of at least sz*N bytes of memory.
 ** SQLite will use no more than one scratch buffer at once per thread, so
 ** N should be set to the expected maximum number of threads.  The sz
 ** parameter should be 6 times the size of the largest database page size.
@@ -1055,31 +1057,37 @@ struct sqlite3_mem_methods {
 ** the database page cache with the default page cache implemenation.  
 ** This configuration should not be used if an application-define page
 ** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
-** There are three arguments to this option: A pointer to the
+** There are three arguments to this option: A pointer to 8-byte aligned
 ** memory, the size of each page buffer (sz), and the number of pages (N).
-** The sz argument must be a power of two between 512 and 32768.  The first
+** The sz argument should be the size of the largest database page
+** (a power of two between 512 and 32768) plus a little extra for each
+** page header.  The page header size is 20 to 40 bytes depending on
+** the host architecture.  It is harmless, apart from the wasted memory,
+** to make sz a little too large.  The first
 ** argument should point to an allocation of at least sz*N bytes of memory.
 ** SQLite will use the memory provided by the first argument to satisfy its
 ** memory needs for the first N pages that it adds to cache.  If additional
 ** page cache memory is needed beyond what is provided by this option, then
 ** SQLite goes to [sqlite3_malloc()] for the additional storage space.
 ** The implementation might use one or more of the N buffers to hold 
-** memory accounting information. </dd>
+** memory accounting information. The pointer in the first argument must
+** be aligned to an 8-byte boundary or subsequent behavior of SQLite
+** will be undefined.</dd>
 **
 ** <dt>SQLITE_CONFIG_HEAP</dt>
 ** <dd>This option specifies a static memory buffer that SQLite will use
 ** for all of its dynamic memory allocation needs beyond those provided
 ** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
-** There are three arguments: A pointer to the memory, the number of
-** bytes in the memory buffer, and the minimum allocation size.  If
-** the first pointer (the memory pointer) is NULL, then SQLite reverts
+** There are three arguments: An 8-byte aligned pointer to the memory,
+** the number of bytes in the memory buffer, and the minimum allocation size.
+** If the first pointer (the memory pointer) is NULL, then SQLite reverts
 ** to using its default memory allocator (the system malloc() implementation),
 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  If the
 ** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
 ** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
 ** allocator is engaged to handle all of SQLites memory allocation needs.
 ** The first pointer (the memory pointer) must be aligned to an 8-byte
-** boundary or the behavior is undefined.</dd>
+** boundary or subsequent behavior of SQLite will be undefined.</dd>
 **
 ** <dt>SQLITE_CONFIG_MUTEX</dt>
 ** <dd>This option takes a single argument which is a pointer to an
@@ -1150,9 +1158,9 @@ struct sqlite3_mem_methods {
 ** <dd>This option takes three additional arguments that determine the 
 ** [lookaside memory allocator] configuration for the [database connection].
 ** The first argument (the third parameter to [sqlite3_db_config()] is a
-** pointer to a memory buffer to use for lookaside memory.  The first
-** argument may be NULL in which case SQLite will allocate the lookaside
-** buffer itself using [sqlite3_malloc()].  The second argument is the
+** pointer to an 8-byte aligned memory buffer to use for lookaside memory.
+** The first argument may be NULL in which case SQLite will allocate the
+** lookaside buffer itself using [sqlite3_malloc()].  The second argument is the
 ** size of each lookaside buffer slot and the third argument is the number of
 ** slots.  The size of the buffer in the first argument must be greater than
 ** or equal to the product of the second and third arguments.</dd>