Index: src/vdbeaux.c ================================================================== --- src/vdbeaux.c +++ src/vdbeaux.c @@ -1719,45 +1719,47 @@ sqlite3IoTrace("SQL %s\n", z); } } #endif /* !SQLITE_OMIT_TRACE && SQLITE_ENABLE_IOTRACE */ -/* -** Allocate space from a fixed size buffer and return a pointer to -** that space. If insufficient space is available, return NULL. -** -** The pBuf parameter is the initial value of a pointer which will -** receive the new memory. pBuf is normally NULL. If pBuf is not -** NULL, it means that memory space has already been allocated and that -** this routine should not allocate any new memory. When pBuf is not -** NULL simply return pBuf. Only allocate new memory space when pBuf -** is NULL. -** -** nByte is the number of bytes of space needed. -** -** pFrom points to *pnFrom bytes of available space. New space is allocated -** from the end of the pFrom buffer and *pnFrom is decremented. -** -** *pnNeeded is a counter of the number of bytes of space that have failed -** to allocate. If there is insufficient space in pFrom to satisfy the -** request, then increment *pnNeeded by the amount of the request. +/* An instance of this object describes bulk memory available for use +** by subcomponents of a prepared statement. Space is allocated out +** of a ReusableSpace object by the allocSpace() routine below. +*/ +struct ReusableSpace { + u8 *pSpace; /* Available memory */ + int nFree; /* Bytes of available memory */ + int nNeeded; /* Total bytes that could not be allocated */ +}; + +/* Try to allocate nByte bytes of 8-byte aligned bulk memory for pBuf +** from the ReusableSpace object. Return a pointer to the allocated +** memory on success. If insufficient memory is available in the +** ReusableSpace object, increase the ReusableSpace.nNeeded +** value by the amount needed and return NULL. +** +** If pBuf is not initially NULL, that means that the memory has already +** been allocated by a prior call to this routine, so just return a copy +** of pBuf and leave ReusableSpace unchanged. +** +** This allocator is employed to repurpose unused slots at the end of the +** opcode array of prepared state for other memory needs of the prepared +** statement. */ static void *allocSpace( - void *pBuf, /* Where return pointer will be stored */ - int nByte, /* Number of bytes to allocate */ - u8 *pFrom, /* Memory available for allocation */ - int *pnFrom, /* IN/OUT: Space available at pFrom */ - int *pnNeeded /* If allocation cannot be made, increment *pnByte */ + struct ReusableSpace *p, /* Bulk memory available for allocation */ + void *pBuf, /* Pointer to a prior allocation */ + int nByte /* Bytes of memory needed */ ){ - assert( EIGHT_BYTE_ALIGNMENT(pFrom) ); + assert( EIGHT_BYTE_ALIGNMENT(p->pSpace) ); if( pBuf==0 ){ nByte = ROUND8(nByte); - if( nByte <= *pnFrom ){ - *pnFrom -= nByte; - pBuf = &pFrom[*pnFrom]; + if( nByte <= p->nFree ){ + p->nFree -= nByte; + pBuf = &p->pSpace[p->nFree]; }else{ - *pnNeeded += nByte; + p->nNeeded += nByte; } } assert( EIGHT_BYTE_ALIGNMENT(pBuf) ); return pBuf; } @@ -1829,13 +1831,11 @@ int nMem; /* Number of VM memory registers */ int nCursor; /* Number of cursors required */ int nArg; /* Number of arguments in subprograms */ int nOnce; /* Number of OP_Once instructions */ int n; /* Loop counter */ - int nFree; /* Available free space */ - u8 *zCsr; /* Memory available for allocation */ - int nByte; /* How much extra memory is needed */ + struct ReusableSpace x; /* Reusable bulk memory */ assert( p!=0 ); assert( p->nOp>0 ); assert( pParse!=0 ); assert( p->magic==VDBE_MAGIC_INIT ); @@ -1849,69 +1849,64 @@ nOnce = pParse->nOnce; if( nOnce==0 ) nOnce = 1; /* Ensure at least one byte in p->aOnceFlag[] */ /* For each cursor required, also allocate a memory cell. Memory ** cells (nMem+1-nCursor)..nMem, inclusive, will never be used by - ** the vdbe program. Instead they are used to allocate space for + ** the vdbe program. Instead they are used to allocate memory for ** VdbeCursor/BtCursor structures. The blob of memory associated with ** cursor 0 is stored in memory cell nMem. Memory cell (nMem-1) ** stores the blob of memory associated with cursor 1, etc. ** ** See also: allocateCursor(). */ nMem += nCursor; - /* zCsr will initially point to nFree bytes of unused space at the - ** end of the opcode array, p->aOp. The computation of nFree is - ** conservative - it might be smaller than the true number of free - ** bytes, but never larger. nFree must be a multiple of 8 - it is - ** rounded down if is not. + /* Figure out how much reusable memory is available at the end of the + ** opcode array. This extra memory will be reallocated for other elements + ** of the prepared statement. */ - n = ROUND8(sizeof(Op)*p->nOp); /* Bytes of opcode space used */ - zCsr = &((u8*)p->aOp)[n]; /* Unused opcode space */ - assert( EIGHT_BYTE_ALIGNMENT(zCsr) ); - nFree = ROUNDDOWN8(pParse->szOpAlloc - n); /* Bytes of unused space */ - assert( nFree>=0 ); - if( nFree>0 ){ - memset(zCsr, 0, nFree); - assert( EIGHT_BYTE_ALIGNMENT(&zCsr[nFree]) ); + n = ROUND8(sizeof(Op)*p->nOp); /* Bytes of opcode memory used */ + x.pSpace = &((u8*)p->aOp)[n]; /* Unused opcode memory */ + assert( EIGHT_BYTE_ALIGNMENT(x.pSpace) ); + x.nFree = ROUNDDOWN8(pParse->szOpAlloc - n); /* Bytes of unused memory */ + assert( x.nFree>=0 ); + if( x.nFree>0 ){ + memset(x.pSpace, 0, x.nFree); + assert( EIGHT_BYTE_ALIGNMENT(&x.pSpace[x.nFree]) ); } resolveP2Values(p, &nArg); p->usesStmtJournal = (u8)(pParse->isMultiWrite && pParse->mayAbort); if( pParse->explain && nMem<10 ){ nMem = 10; } p->expired = 0; - /* Memory for registers, parameters, cursor, etc, is allocated in two - ** passes. On the first pass, we try to reuse unused space at the + /* Memory for registers, parameters, cursor, etc, is allocated in one or two + ** passes. On the first pass, we try to reuse unused memory at the ** end of the opcode array. If we are unable to satisfy all memory ** requirements by reusing the opcode array tail, then the second - ** pass will fill in the rest using a fresh allocation. + ** pass will fill in the remainder using a fresh memory allocation. ** ** This two-pass approach that reuses as much memory as possible from - ** the leftover space at the end of the opcode array can significantly + ** the leftover memory at the end of the opcode array. This can significantly ** reduce the amount of memory held by a prepared statement. */ do { - nByte = 0; - p->aMem = allocSpace(p->aMem, nMem*sizeof(Mem), zCsr, &nFree, &nByte); - p->aVar = allocSpace(p->aVar, nVar*sizeof(Mem), zCsr, &nFree, &nByte); - p->apArg = allocSpace(p->apArg, nArg*sizeof(Mem*), zCsr, &nFree, &nByte); - p->apCsr = allocSpace(p->apCsr, nCursor*sizeof(VdbeCursor*), - zCsr, &nFree, &nByte); - p->aOnceFlag = allocSpace(p->aOnceFlag, nOnce, zCsr, &nFree, &nByte); + x.nNeeded = 0; + p->aMem = allocSpace(&x, p->aMem, nMem*sizeof(Mem)); + p->aVar = allocSpace(&x, p->aVar, nVar*sizeof(Mem)); + p->apArg = allocSpace(&x, p->apArg, nArg*sizeof(Mem*)); + p->apCsr = allocSpace(&x, p->apCsr, nCursor*sizeof(VdbeCursor*)); + p->aOnceFlag = allocSpace(&x, p->aOnceFlag, nOnce); #ifdef SQLITE_ENABLE_STMT_SCANSTATUS - p->anExec = allocSpace(p->anExec, p->nOp*sizeof(i64), zCsr, &nFree, &nByte); + p->anExec = allocSpace(&x, p->anExec, p->nOp*sizeof(i64)); #endif - if( nByte ){ - p->pFree = sqlite3DbMallocZero(db, nByte); - } - zCsr = p->pFree; - nFree = nByte; - }while( nByte && !db->mallocFailed ); + if( x.nNeeded==0 ) break; + x.pSpace = p->pFree = sqlite3DbMallocZero(db, x.nNeeded); + x.nFree = x.nNeeded; + }while( !db->mallocFailed ); p->nCursor = nCursor; p->nOnceFlag = nOnce; if( p->aVar ){ p->nVar = (ynVar)nVar;