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Overview
Comment:Reuse space left-over opcode space at the end of the VDBE opcode array to store memory cells, VDBE cursors, and other content needed by the VDBE. This reduces the memory required by a prepared statement. (CVS 6307)
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SHA1: 58a1809257ccfb7d9112a35f79ca2f82b3daa878
User & Date: drh 2009-02-20 01:28:59
Context
2009-02-20
03:02
Add the OP_HaltIfNull opcode and use it to simplify prepared statements for INSERTs and UPDATEs of tables with NOT NULL columns. (CVS 6308) check-in: feccad8d user: drh tags: trunk
01:28
Reuse space left-over opcode space at the end of the VDBE opcode array to store memory cells, VDBE cursors, and other content needed by the VDBE. This reduces the memory required by a prepared statement. (CVS 6307) check-in: 58a18092 user: drh tags: trunk
2009-02-19
20:50
Remove code in malloc.c that was already commented out using #if 0. (CVS 6306) check-in: e1ad757e user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/vdbeInt.h.

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*************************************************************************
** This is the header file for information that is private to the
** VDBE.  This information used to all be at the top of the single
** source code file "vdbe.c".  When that file became too big (over
** 6000 lines long) it was split up into several smaller files and
** this header information was factored out.
**
** $Id: vdbeInt.h,v 1.163 2009/02/19 14:39:25 danielk1977 Exp $
*/
#ifndef _VDBEINT_H_
#define _VDBEINT_H_

/*
** intToKey() and keyToInt() used to transform the rowid.  But with
** the latest versions of the design they are no-ops.
................................................................................
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  i64 startTime;          /* Time when query started - used for profiling */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */
  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
  int aCounter[2];        /* Counters used by sqlite3_stmt_status() */
  char *zSql;           /* Text of the SQL statement that generated this */

#ifdef SQLITE_DEBUG
  FILE *trace;          /* Write an execution trace here, if not NULL */
#endif
  int openedStatement;  /* True if this VM has opened a statement journal */
#ifdef SQLITE_SSE
  int fetchId;          /* Statement number used by sqlite3_fetch_statement */
  int lru;              /* Counter used for LRU cache replacement */







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*************************************************************************
** This is the header file for information that is private to the
** VDBE.  This information used to all be at the top of the single
** source code file "vdbe.c".  When that file became too big (over
** 6000 lines long) it was split up into several smaller files and
** this header information was factored out.
**
** $Id: vdbeInt.h,v 1.164 2009/02/20 01:28:59 drh Exp $
*/
#ifndef _VDBEINT_H_
#define _VDBEINT_H_

/*
** intToKey() and keyToInt() used to transform the rowid.  But with
** the latest versions of the design they are no-ops.
................................................................................
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  i64 startTime;          /* Time when query started - used for profiling */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */
  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
  int aCounter[2];        /* Counters used by sqlite3_stmt_status() */
  char *zSql;           /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */
#ifdef SQLITE_DEBUG
  FILE *trace;          /* Write an execution trace here, if not NULL */
#endif
  int openedStatement;  /* True if this VM has opened a statement journal */
#ifdef SQLITE_SSE
  int fetchId;          /* Statement number used by sqlite3_fetch_statement */
  int lru;              /* Counter used for LRU cache replacement */

Changes to src/vdbeaux.c.

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**
*************************************************************************
** This file contains code used for creating, destroying, and populating
** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.)  Prior
** to version 2.8.7, all this code was combined into the vdbe.c source file.
** But that file was getting too big so this subroutines were split out.
**
** $Id: vdbeaux.c,v 1.436 2009/02/19 14:39:25 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"



/*
................................................................................
** correctly deallocated along with the rest of the Vdbe).
*/
static int growOpArray(Vdbe *p){
  VdbeOp *pNew;
  int nNew = (p->nOpAlloc ? p->nOpAlloc*2 : (int)(1024/sizeof(Op)));
  pNew = sqlite3DbRealloc(p->db, p->aOp, nNew*sizeof(Op));
  if( pNew ){
    p->nOpAlloc = nNew;
    p->aOp = pNew;
  }
  return (pNew ? SQLITE_OK : SQLITE_NOMEM);
}

/*
** Add a new instruction to the list of instructions current in the
................................................................................
    }
    z[j] = 0;
    sqlite3IoTrace("SQL %s\n", z);
  }
}
#endif /* !SQLITE_OMIT_TRACE && SQLITE_ENABLE_IOTRACE */



































/*
** Prepare a virtual machine for execution.  This involves things such
** as allocating stack space and initializing the program counter.
** After the VDBE has be prepped, it can be executed by one or more
** calls to sqlite3VdbeExec().  
**
................................................................................
  nMem += nCursor;

  /* Allocate space for memory registers, SQL variables, VDBE cursors and 
  ** an array to marshal SQL function arguments in. This is only done the
  ** first time this function is called for a given VDBE, not when it is
  ** being called from sqlite3_reset() to reset the virtual machine.
  */
  if( nVar>=0 ){


    int nByte;
    int nArg;       /* Maximum number of args passed to a user function. */
    resolveP2Values(p, &nArg);
    if( isExplain && nMem<10 ){
      nMem = 10;
    }
    nByte = nMem*sizeof(Mem)               /* aMem */
          + nVar*sizeof(Mem)               /* aVar */
          + nArg*sizeof(Mem*)              /* apArg */
          + nVar*sizeof(char*)             /* azVar */
          + nCursor*sizeof(VdbeCursor*);   /* apCsr */
    if( nByte ){
      p->aMem = sqlite3DbMallocZero(db, nByte);
    }
    if( !db->mallocFailed ){
      p->aMem--;             /* aMem[] goes from 1..nMem */
      p->nMem = nMem;        /*       not from 0..nMem-1 */
      p->aVar = &p->aMem[nMem+1];
      p->nVar = nVar;
      p->okVar = 0;
      p->apArg = (Mem**)&p->aVar[nVar];
      p->azVar = (char**)&p->apArg[nArg];
      p->apCsr = (VdbeCursor**)&p->azVar[nVar];
      p->nCursor = nCursor;



      for(n=0; n<nVar; n++){
        p->aVar[n].flags = MEM_Null;
        p->aVar[n].db = db;
      }




      for(n=1; n<=nMem; n++){
        p->aMem[n].flags = MEM_Null;
        p->aMem[n].db = db;
      }
    }
  }
#ifdef SQLITE_DEBUG
................................................................................
    Op *pOp = p->aOp;
    for(i=0; i<p->nOp; i++, pOp++){
      freeP4(db, pOp->p4type, pOp->p4.p);
#ifdef SQLITE_DEBUG
      sqlite3DbFree(db, pOp->zComment);
#endif     
    }
    sqlite3DbFree(db, p->aOp);
  }
  releaseMemArray(p->aVar, p->nVar);
  sqlite3DbFree(db, p->aLabel);
  if( p->aMem ){
    sqlite3DbFree(db, &p->aMem[1]);
  }
  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
  sqlite3DbFree(db, p->aColName);
  sqlite3DbFree(db, p->zSql);
  p->magic = VDBE_MAGIC_DEAD;


  sqlite3DbFree(db, p);
}

/*
** If a MoveTo operation is pending on the given cursor, then do that
** MoveTo now.  Return an error code.  If no MoveTo is pending, this
** routine does nothing and returns SQLITE_OK.







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**
*************************************************************************
** This file contains code used for creating, destroying, and populating
** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.)  Prior
** to version 2.8.7, all this code was combined into the vdbe.c source file.
** But that file was getting too big so this subroutines were split out.
**
** $Id: vdbeaux.c,v 1.437 2009/02/20 01:28:59 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"



/*
................................................................................
** correctly deallocated along with the rest of the Vdbe).
*/
static int growOpArray(Vdbe *p){
  VdbeOp *pNew;
  int nNew = (p->nOpAlloc ? p->nOpAlloc*2 : (int)(1024/sizeof(Op)));
  pNew = sqlite3DbRealloc(p->db, p->aOp, nNew*sizeof(Op));
  if( pNew ){
    p->nOpAlloc = sqlite3MallocSize(pNew)/sizeof(Op);
    p->aOp = pNew;
  }
  return (pNew ? SQLITE_OK : SQLITE_NOMEM);
}

/*
** Add a new instruction to the list of instructions current in the
................................................................................
    }
    z[j] = 0;
    sqlite3IoTrace("SQL %s\n", z);
  }
}
#endif /* !SQLITE_OMIT_TRACE && SQLITE_ENABLE_IOTRACE */

/*
** Allocate space from a fixed size buffer.  Make *pp point to the
** allocated space.  (Note:  pp is a char* rather than a void** to
** work around the pointer aliasing rules of C.)  *pp should initially
** be zero.  If *pp is not zero, that means that the space has already
** been allocated and this routine is a noop.
**
** nByte is the number of bytes of space needed.
**
** *ppFrom point to available space and pEnd points to the end of the
** available space.
**
** *pnByte is a counter of the number of bytes of space that have failed
** to allocate.  If there is insufficient space in *ppFrom to satisfy the
** request, then increate *pnByte by the amount of the request.
*/
static void allocSpace(
  char *pp,            /* IN/OUT: Set *pp to point to allocated buffer */
  int nByte,           /* Number of bytes to allocate */
  u8 **ppFrom,         /* IN/OUT: Allocate from *ppFrom */
  u8 *pEnd,            /* Pointer to 1 byte passed end of *ppFrom buffer */
  int *pnByte          /* If allocation cannot be made, increment *pnByte */
){
  if( (*(void**)pp)==0 ){
    nByte = (nByte+7)&~7;
    if( (pEnd - *ppFrom)>=nByte ){
      *(void**)pp = (void *)*ppFrom;
      *ppFrom += nByte;
    }else{
      *pnByte += nByte;
    }
  }
}

/*
** Prepare a virtual machine for execution.  This involves things such
** as allocating stack space and initializing the program counter.
** After the VDBE has be prepped, it can be executed by one or more
** calls to sqlite3VdbeExec().  
**
................................................................................
  nMem += nCursor;

  /* Allocate space for memory registers, SQL variables, VDBE cursors and 
  ** an array to marshal SQL function arguments in. This is only done the
  ** first time this function is called for a given VDBE, not when it is
  ** being called from sqlite3_reset() to reset the virtual machine.
  */
  if( nVar>=0 && !db->mallocFailed ){
    u8 *zCsr = (u8 *)&p->aOp[p->nOp];
    u8 *zEnd = (u8 *)&p->aOp[p->nOpAlloc];
    int nByte;
    int nArg;       /* Maximum number of args passed to a user function. */
    resolveP2Values(p, &nArg);
    if( isExplain && nMem<10 ){
      nMem = 10;
    }

    do {
      memset(zCsr, 0, zEnd-zCsr);
      nByte = 0;
      allocSpace((char*)&p->aMem, nMem*sizeof(Mem), &zCsr, zEnd, &nByte);
      allocSpace((char*)&p->aVar, nVar*sizeof(Mem), &zCsr, zEnd, &nByte);
      allocSpace((char*)&p->apArg, nArg*sizeof(Mem*), &zCsr, zEnd, &nByte);
      allocSpace((char*)&p->azVar, nVar*sizeof(char*), &zCsr, zEnd, &nByte);
      allocSpace((char*)&p->apCsr, 
                 nCursor*sizeof(VdbeCursor*), &zCsr, zEnd, &nByte
      );
      if( nByte ){
        p->pFree = sqlite3DbMallocRaw(db, nByte);
      }
      zCsr = p->pFree;
      zEnd = &zCsr[nByte];
    }while( nByte && !db->mallocFailed );

    p->nCursor = nCursor;
    if( p->aVar ){
      p->nVar = nVar;
      for(n=0; n<nVar; n++){
        p->aVar[n].flags = MEM_Null;
        p->aVar[n].db = db;
      }
    }
    if( p->aMem ){
      p->aMem--;                      /* aMem[] goes from 1..nMem */
      p->nMem = nMem;                 /*       not from 0..nMem-1 */
      for(n=1; n<=nMem; n++){
        p->aMem[n].flags = MEM_Null;
        p->aMem[n].db = db;
      }
    }
  }
#ifdef SQLITE_DEBUG
................................................................................
    Op *pOp = p->aOp;
    for(i=0; i<p->nOp; i++, pOp++){
      freeP4(db, pOp->p4type, pOp->p4.p);
#ifdef SQLITE_DEBUG
      sqlite3DbFree(db, pOp->zComment);
#endif     
    }

  }
  releaseMemArray(p->aVar, p->nVar);
  sqlite3DbFree(db, p->aLabel);



  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
  sqlite3DbFree(db, p->aColName);
  sqlite3DbFree(db, p->zSql);
  p->magic = VDBE_MAGIC_DEAD;
  sqlite3DbFree(db, p->aOp);
  sqlite3DbFree(db, p->pFree);
  sqlite3DbFree(db, p);
}

/*
** If a MoveTo operation is pending on the given cursor, then do that
** MoveTo now.  Return an error code.  If no MoveTo is pending, this
** routine does nothing and returns SQLITE_OK.