SQLite

        codeReal(v, z, negFlag, iMem);
      }
#endif
    }
  }
}

#if defined(SQLITE_DEBUG)
/*
** Verify the consistency of the column cache
*/
static int cacheIsValid(Parse *pParse){
  int i, n;
  for(i=n=0; i<SQLITE_N_COLCACHE; i++){
    if( pParse->aColCache[i].iReg>0 ) n++;
  }
  return n==pParse->nColCache;
}
#endif

/*
** Clear a cache entry.
*/
static void cacheEntryClear(Parse *pParse, struct yColCache *p){
  if( p->tempReg ){
    if( pParse->nTempReg<ArraySize(pParse->aTempReg) ){
      pParse->aTempReg[pParse->nTempReg++] = p->iReg;
    }
    p->tempReg = 0;
  }
  p->iReg = 0;
  pParse->nColCache--;
  assert( pParse->db->mallocFailed || cacheIsValid(pParse) );


}


/*
** Record in the column cache that a particular column from a
** particular table is stored in a particular register.
*/

  /* First replace any existing entry.
  **
  ** Actually, the way the column cache is currently used, we are guaranteed
  ** that the object will never already be in cache.  Verify this guarantee.
  */
#ifndef NDEBUG
  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
    assert( p->iReg==0 || p->iTable!=iTab || p->iColumn!=iCol );
  }
#endif

  /* Find an empty slot and replace it */
  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
    if( p->iReg==0 ){
      p->iLevel = pParse->iCacheLevel;
      p->iTable = iTab;
      p->iColumn = iCol;
      p->iReg = iReg;
      p->tempReg = 0;
      p->lru = pParse->iCacheCnt++;
      pParse->nColCache++;
      assert( pParse->db->mallocFailed || cacheIsValid(pParse) );
      return;
    }
  }

  /* Replace the last recently used */
  minLru = 0x7fffffff;
  idxLru = -1;
  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
    if( p->lru<minLru ){
      idxLru = i;
      minLru = p->lru;
    }
  }
  if( ALWAYS(idxLru>=0) ){

    p = &pParse->aColCache[idxLru];



    p->iLevel = pParse->iCacheLevel;
    p->iTable = iTab;
    p->iColumn = iCol;
    p->iReg = iReg;
    p->tempReg = 0;
    p->lru = pParse->iCacheCnt++;
    assert( cacheIsValid(pParse) );
    return;
  }
}

/*
** Indicate that registers between iReg..iReg+nReg-1 are being overwritten.
** Purge the range of registers from the column cache.
*/
void sqlite3ExprCacheRemove(Parse *pParse, int iReg, int nReg){
  struct yColCache *p;
  if( iReg<=0 || pParse->nColCache==0 ) return;
  p = &pParse->aColCache[SQLITE_N_COLCACHE-1];
  while(1){
    if( p->iReg >= iReg && p->iReg < iReg+nReg ) cacheEntryClear(pParse, p);
    if( p==pParse->aColCache ) break;
    p--;



  }
}

/*
** Remember the current column cache context.  Any new entries added
** added to the column cache after this call are removed when the
** corresponding pop occurs.

/*
** Remove from the column cache any entries that were added since the
** the previous sqlite3ExprCachePush operation.  In other words, restore
** the cache to the state it was in prior the most recent Push.
*/
void sqlite3ExprCachePop(Parse *pParse){
  int i;
  struct yColCache *p;
  assert( pParse->iCacheLevel>=1 );
  pParse->iCacheLevel--;
#ifdef SQLITE_DEBUG
  if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
    printf("POP  to %d\n", pParse->iCacheLevel);
  }
#endif
  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
    if( p->iReg && p->iLevel>pParse->iCacheLevel ){
      cacheEntryClear(pParse, p);


    }
  }
}

/*
** When a cached column is reused, make sure that its register is
** no longer available as a temp register.  ticket #3879:  that same
** register might be in the cache in multiple places, so be sure to
** get them all.
*/
static void sqlite3ExprCachePinRegister(Parse *pParse, int iReg){
  int i;
  struct yColCache *p;
  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
    if( p->iReg==iReg ){
      p->tempReg = 0;
    }
  }
}

/* Generate code that will load into register regOut a value that is

  int iReg,        /* Store results here */
  u8 p5            /* P5 value for OP_Column + FLAGS */
){
  Vdbe *v = pParse->pVdbe;
  int i;
  struct yColCache *p;

  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
    if( p->iReg>0 && p->iTable==iTable && p->iColumn==iColumn ){
      p->lru = pParse->iCacheCnt++;
      sqlite3ExprCachePinRegister(pParse, p->iReg);
      return p->iReg;
    }
  }  
  assert( v!=0 );

/*
** Clear all column cache entries.
*/
void sqlite3ExprCacheClear(Parse *pParse){
  int i;
  struct yColCache *p;

#if SQLITE_DEBUG
  if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
    printf("CLEAR\n");
  }
#endif

  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){

    if( p->iReg ){
      cacheEntryClear(pParse, p);
    }
  }

}

/*
** Record the fact that an affinity change has occurred on iCount
** registers starting with iStart.
*/
void sqlite3ExprCacheAffinityChange(Parse *pParse, int iStart, int iCount){

**
** This routine is used within assert() and testcase() macros only
** and does not appear in a normal build.
*/
static int usedAsColumnCache(Parse *pParse, int iFrom, int iTo){
  int i;
  struct yColCache *p;
  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
    int r = p->iReg;
    if( r>=iFrom && r<=iTo ) return 1;    /*NO_TEST*/
  }
  return 0;
}
#endif /* SQLITE_DEBUG || SQLITE_COVERAGE_TEST */

** the deallocation is deferred until the column cache line that uses
** the register becomes stale.
*/
void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
  if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
    int i;
    struct yColCache *p;
    for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
      if( p->iReg==iReg ){
        p->tempReg = 1;
        return;
      }
    }
    pParse->aTempReg[pParse->nTempReg++] = iReg;
  }

#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
  pOp->zComment = 0;
#endif
#ifdef SQLITE_DEBUG
  if( p->db->flags & SQLITE_VdbeAddopTrace ){
    int jj, kk;
    Parse *pParse = p->pParse;
    for(jj=kk=0; jj<SQLITE_N_COLCACHE; jj++){
      struct yColCache *x = pParse->aColCache + jj;
      if( x->iLevel>pParse->iCacheLevel || x->iReg==0 ) continue;
      printf(" r[%d]={%d:%d}", x->iReg, x->iTable, x->iColumn);
      kk++;
    }
    if( kk ) printf("\n");
    sqlite3VdbePrintOp(0, i, &p->aOp[i]);
    test_addop_breakpoint();
  }