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Overview
Comment:Get rid of the OP_Undef and OP_IsUndef opcodes in favor of higher-level OP_InitCoroutine and OP_EndCoroutine.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | coroutine-refactor
Files: files | file ages | folders
SHA1: 1ec0e9dd4b26d9f597adc8e062317d4866c5a6a6
User & Date: drh 2014-02-07 18:27:53.008
Context
2014-02-07
19:18
Change the OP_InitCoroutine instruction to jump over the co-routine implementation. (Closed-Leaf check-in: a522f364a6 user: drh tags: coroutine-refactor)
18:27
Get rid of the OP_Undef and OP_IsUndef opcodes in favor of higher-level OP_InitCoroutine and OP_EndCoroutine. (check-in: 1ec0e9dd4b user: drh tags: coroutine-refactor)
13:20
Add the OP_Undef and OP_IsUndef opcodes. With these, use the first register in the result register range as the flag to indicate EOF on an INSERT from a SELECT, rather than allocating a separate boolean register for that task. (check-in: 6fb7448550 user: drh tags: coroutine-refactor)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/insert.c.
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**         goto B
**      A: setup for the SELECT
**         loop rows in the SELECT
**           load results into registers R..S
**           yield X
**         end loop
**         cleanup after the SELECT
**         R <- undefined (signals EOF)
**         yield X
**         halt-error
**      B:
**
** To use this subroutine, the caller generates code as follows:
**
**         [ Co-routine generated by this subroutine, shown above ]
**      S: yield X
**         if R==undefined goto E
**         if skip this row, goto C
**         if terminate loop, goto E
**         deal with this row
**      C: goto S
**      E:
*/
int sqlite3CodeCoroutine(Parse *pParse, Select *pSelect, SelectDest *pDest){
  int regYield;       /* Register holding co-routine entry-point */
  int addrTop;        /* Top of the co-routine */
  int j1;             /* Jump instruction */
  int rc;             /* Result code */
  Vdbe *v;            /* VDBE under construction */

  regYield = ++pParse->nMem;
  v = sqlite3GetVdbe(pParse);
  addrTop = sqlite3VdbeCurrentAddr(v);
  sqlite3VdbeAddOp2(v, OP_Integer, addrTop+1, regYield); /* X <- A */
  VdbeComment((v, "Co-routine entry point"));
  sqlite3SelectDestInit(pDest, SRT_Coroutine, regYield);
  j1 = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0);
  rc = sqlite3Select(pParse, pSelect, pDest);
  assert( pParse->nErr==0 || rc );
  if( pParse->db->mallocFailed && rc==SQLITE_OK ) rc = SQLITE_NOMEM;
  if( rc ) return rc;
  sqlite3VdbeAddOp1(v, OP_Undef, pDest->iSdst);     /* Signal EOF */
  sqlite3VdbeAddOp1(v, OP_Yield, regYield);         /* yield X */
  sqlite3VdbeAddOp2(v, OP_Halt, SQLITE_INTERNAL, OE_Abort);
  VdbeComment((v, "End of coroutine"));
  sqlite3VdbeJumpHere(v, j1);                             /* label B: */
  return rc;
}



/* Forward declaration */







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**         goto B
**      A: setup for the SELECT
**         loop rows in the SELECT
**           load results into registers R..S
**           yield X
**         end loop
**         cleanup after the SELECT

**         end co-routine R

**      B:
**
** To use this subroutine, the caller generates code as follows:
**
**         [ Co-routine generated by this subroutine, shown above ]
**      S: yield X, at EOF goto E

**         if skip this row, goto C
**         if terminate loop, goto E
**         deal with this row
**      C: goto S
**      E:
*/
int sqlite3CodeCoroutine(Parse *pParse, Select *pSelect, SelectDest *pDest){
  int regYield;       /* Register holding co-routine entry-point */
  int addrTop;        /* Top of the co-routine */
  int j1;             /* Jump instruction */
  int rc;             /* Result code */
  Vdbe *v;            /* VDBE under construction */

  regYield = ++pParse->nMem;
  v = sqlite3GetVdbe(pParse);
  addrTop = sqlite3VdbeCurrentAddr(v);
  sqlite3VdbeAddOp2(v, OP_InitCoroutine, regYield, addrTop+2);

  sqlite3SelectDestInit(pDest, SRT_Coroutine, regYield);
  j1 = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0);
  rc = sqlite3Select(pParse, pSelect, pDest);
  assert( pParse->nErr==0 || rc );
  if( pParse->db->mallocFailed && rc==SQLITE_OK ) rc = SQLITE_NOMEM;
  if( rc ) return rc;

  sqlite3VdbeAddOp1(v, OP_EndCoroutine, regYield);


  sqlite3VdbeJumpHere(v, j1);                             /* label B: */
  return rc;
}



/* Forward declaration */
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**         goto B
**      A: setup for the SELECT
**         loop over the rows in the SELECT
**           load values into registers R..R+n
**           yield X
**         end loop
**         cleanup after the SELECT
**         R <- undefined (signals EOF)
**         yield X
**         goto A
**      B: open write cursor to <table> and its indices
**      C: yield X
**         if R=undefined goto D
**         insert the select result into <table> from R..R+n
**         goto C
**      D: cleanup
**
** The 4th template is used if the insert statement takes its
** values from a SELECT but the data is being inserted into a table
** that is also read as part of the SELECT.  In the third form,
** we have to use a intermediate table to store the results of
** the select.  The template is like this:
**
**         X <- A
**         goto B
**      A: setup for the SELECT
**         loop over the tables in the SELECT
**           load value into register R..R+n
**           yield X
**         end loop
**         cleanup after the SELECT
**         R <- undefined (signals EOF)
**         yield X
**         halt-error
**      B: open temp table
**      L: yield X
**         if R=undefined goto M
**         insert row from R..R+n into temp table
**         goto L
**      M: open write cursor to <table> and its indices
**         rewind temp table
**      C: loop over rows of intermediate table
**           transfer values form intermediate table into <table>
**         end loop







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**         goto B
**      A: setup for the SELECT
**         loop over the rows in the SELECT
**           load values into registers R..R+n
**           yield X
**         end loop
**         cleanup after the SELECT


**         end-coroutine X
**      B: open write cursor to <table> and its indices
**      C: yield X, at EOF goto D

**         insert the select result into <table> from R..R+n
**         goto C
**      D: cleanup
**
** The 4th template is used if the insert statement takes its
** values from a SELECT but the data is being inserted into a table
** that is also read as part of the SELECT.  In the third form,
** we have to use a intermediate table to store the results of
** the select.  The template is like this:
**
**         X <- A
**         goto B
**      A: setup for the SELECT
**         loop over the tables in the SELECT
**           load value into register R..R+n
**           yield X
**         end loop
**         cleanup after the SELECT

**         end co-routine R

**      B: open temp table
**      L: yield X, at EOF goto M

**         insert row from R..R+n into temp table
**         goto L
**      M: open write cursor to <table> and its indices
**         rewind temp table
**      C: loop over rows of intermediate table
**           transfer values form intermediate table into <table>
**         end loop
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    if( useTempTable ){
      /* Invoke the coroutine to extract information from the SELECT
      ** and add it to a transient table srcTab.  The code generated
      ** here is from the 4th template:
      **
      **      B: open temp table
      **      L: yield X
      **         if R=undefined goto M
      **         insert row from R..R+n into temp table
      **         goto L
      **      M: ...
      */
      int regRec;          /* Register to hold packed record */
      int regTempRowid;    /* Register to hold temp table ROWID */
      int addrTop;         /* Label "L" */
      int addrIf;          /* Address of jump to M */

      srcTab = pParse->nTab++;
      regRec = sqlite3GetTempReg(pParse);
      regTempRowid = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp2(v, OP_OpenEphemeral, srcTab, nColumn);
      addrTop = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm);
      addrIf = sqlite3VdbeAddOp1(v, OP_IsUndef, regFromSelect);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regFromSelect, nColumn, regRec);
      sqlite3VdbeAddOp2(v, OP_NewRowid, srcTab, regTempRowid);
      sqlite3VdbeAddOp3(v, OP_Insert, srcTab, regRec, regTempRowid);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, addrTop);
      sqlite3VdbeJumpHere(v, addrIf);
      sqlite3ReleaseTempReg(pParse, regRec);
      sqlite3ReleaseTempReg(pParse, regTempRowid);
    }
  }else{
    /* This is the case if the data for the INSERT is coming from a VALUES
    ** clause
    */







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    if( useTempTable ){
      /* Invoke the coroutine to extract information from the SELECT
      ** and add it to a transient table srcTab.  The code generated
      ** here is from the 4th template:
      **
      **      B: open temp table
      **      L: yield X, goto M at EOF

      **         insert row from R..R+n into temp table
      **         goto L
      **      M: ...
      */
      int regRec;          /* Register to hold packed record */
      int regTempRowid;    /* Register to hold temp table ROWID */
      int addrTop;         /* Label "L" */


      srcTab = pParse->nTab++;
      regRec = sqlite3GetTempReg(pParse);
      regTempRowid = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp2(v, OP_OpenEphemeral, srcTab, nColumn);
      addrTop = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm);

      sqlite3VdbeAddOp3(v, OP_MakeRecord, regFromSelect, nColumn, regRec);
      sqlite3VdbeAddOp2(v, OP_NewRowid, srcTab, regTempRowid);
      sqlite3VdbeAddOp3(v, OP_Insert, srcTab, regRec, regTempRowid);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, addrTop);
      sqlite3VdbeJumpHere(v, addrTop);
      sqlite3ReleaseTempReg(pParse, regRec);
      sqlite3ReleaseTempReg(pParse, regTempRowid);
    }
  }else{
    /* This is the case if the data for the INSERT is coming from a VALUES
    ** clause
    */
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  }

  /* This is the top of the main insertion loop */
  if( useTempTable ){
    /* This block codes the top of loop only.  The complete loop is the
    ** following pseudocode (template 4):
    **
    **         rewind temp table
    **      C: loop over rows of intermediate table
    **           transfer values form intermediate table into <table>
    **         end loop
    **      D: ...
    */
    addrInsTop = sqlite3VdbeAddOp1(v, OP_Rewind, srcTab);
    addrCont = sqlite3VdbeCurrentAddr(v);
  }else if( pSelect ){
    /* This block codes the top of loop only.  The complete loop is the
    ** following pseudocode (template 3):
    **
    **      C: yield X
    **         if R=undefined goto D
    **         insert the select result into <table> from R..R+n
    **         goto C
    **      D: ...
    */
    addrCont = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm);
    addrInsTop = sqlite3VdbeAddOp1(v, OP_IsUndef, dest.iSdst);
  }

  /* Allocate registers for holding the rowid of the new row,
  ** the content of the new row, and the assemblied row record.
  */
  regRowid = regIns = pParse->nMem+1;
  pParse->nMem += pTab->nCol + 1;







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  }

  /* This is the top of the main insertion loop */
  if( useTempTable ){
    /* This block codes the top of loop only.  The complete loop is the
    ** following pseudocode (template 4):
    **
    **         rewind temp table, if empty goto D
    **      C: loop over rows of intermediate table
    **           transfer values form intermediate table into <table>
    **         end loop
    **      D: ...
    */
    addrInsTop = sqlite3VdbeAddOp1(v, OP_Rewind, srcTab);
    addrCont = sqlite3VdbeCurrentAddr(v);
  }else if( pSelect ){
    /* This block codes the top of loop only.  The complete loop is the
    ** following pseudocode (template 3):
    **
    **      C: yield X, at EOF goto D

    **         insert the select result into <table> from R..R+n
    **         goto C
    **      D: ...
    */
    addrInsTop = addrCont = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm);

  }

  /* Allocate registers for holding the rowid of the new row,
  ** the content of the new row, and the assemblied row record.
  */
  regRowid = regIns = pParse->nMem+1;
  pParse->nMem += pTab->nCol + 1;
Changes to src/select.c.
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        sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
        /* The LIMIT clause will jump out of the loop for us */
      }
      break;
    }
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */

    /* Send the data to the callback function or to a subroutine.  In the
    ** case of a subroutine, the subroutine itself is responsible for
    ** popping the data from the stack.
    */
    case SRT_Coroutine:
    case SRT_Output: {
      testcase( eDest==SRT_Coroutine );
      testcase( eDest==SRT_Output );
      if( pOrderBy ){
        int r1 = sqlite3GetTempReg(pParse);
        sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
        pushOntoSorter(pParse, pOrderBy, p, r1);
        sqlite3ReleaseTempReg(pParse, r1);







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        sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
        /* The LIMIT clause will jump out of the loop for us */
      }
      break;
    }
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */





    case SRT_Coroutine:       /* Send data to a co-routine */
    case SRT_Output: {        /* Return the results */
      testcase( eDest==SRT_Coroutine );
      testcase( eDest==SRT_Output );
      if( pOrderBy ){
        int r1 = sqlite3GetTempReg(pParse);
        sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
        pushOntoSorter(pParse, pOrderBy, p, r1);
        sqlite3ReleaseTempReg(pParse, r1);
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){
  int i, j;             /* Loop counters */
  Select *pPrior;       /* Another SELECT immediately to our left */
  Vdbe *v;              /* Generate code to this VDBE */
  SelectDest destA;     /* Destination for coroutine A */
  SelectDest destB;     /* Destination for coroutine B */
  int regAddrA;         /* Address register for select-A coroutine */
  int regEofA;          /* Flag to indicate when select-A is complete */
  int regAddrB;         /* Address register for select-B coroutine */
  int regEofB;          /* Flag to indicate when select-B is complete */
  int addrSelectA;      /* Address of the select-A coroutine */
  int addrSelectB;      /* Address of the select-B coroutine */
  int regOutA;          /* Address register for the output-A subroutine */
  int regOutB;          /* Address register for the output-B subroutine */
  int addrOutA;         /* Address of the output-A subroutine */
  int addrOutB = 0;     /* Address of the output-B subroutine */
  int addrEofA;         /* Address of the select-A-exhausted subroutine */

  int addrEofB;         /* Address of the select-B-exhausted subroutine */
  int addrAltB;         /* Address of the A<B subroutine */
  int addrAeqB;         /* Address of the A==B subroutine */
  int addrAgtB;         /* Address of the A>B subroutine */
  int regLimitA;        /* Limit register for select-A */
  int regLimitB;        /* Limit register for select-A */
  int regPrev;          /* A range of registers to hold previous output */







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){
  int i, j;             /* Loop counters */
  Select *pPrior;       /* Another SELECT immediately to our left */
  Vdbe *v;              /* Generate code to this VDBE */
  SelectDest destA;     /* Destination for coroutine A */
  SelectDest destB;     /* Destination for coroutine B */
  int regAddrA;         /* Address register for select-A coroutine */

  int regAddrB;         /* Address register for select-B coroutine */

  int addrSelectA;      /* Address of the select-A coroutine */
  int addrSelectB;      /* Address of the select-B coroutine */
  int regOutA;          /* Address register for the output-A subroutine */
  int regOutB;          /* Address register for the output-B subroutine */
  int addrOutA;         /* Address of the output-A subroutine */
  int addrOutB = 0;     /* Address of the output-B subroutine */
  int addrEofA;         /* Address of the select-A-exhausted subroutine */
  int addrEofA_noB;     /* Alternate addrEofA if B is uninitialized */
  int addrEofB;         /* Address of the select-B-exhausted subroutine */
  int addrAltB;         /* Address of the A<B subroutine */
  int addrAeqB;         /* Address of the A==B subroutine */
  int addrAgtB;         /* Address of the A>B subroutine */
  int regLimitA;        /* Limit register for select-A */
  int regLimitB;        /* Limit register for select-A */
  int regPrev;          /* A range of registers to hold previous output */
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  }
  sqlite3ExprDelete(db, p->pLimit);
  p->pLimit = 0;
  sqlite3ExprDelete(db, p->pOffset);
  p->pOffset = 0;

  regAddrA = ++pParse->nMem;
  regEofA = ++pParse->nMem;
  regAddrB = ++pParse->nMem;
  regEofB = ++pParse->nMem;
  regOutA = ++pParse->nMem;
  regOutB = ++pParse->nMem;
  sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
  sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);

  /* Jump past the various subroutines and coroutines to the main
  ** merge loop
  */
  j1 = sqlite3VdbeAddOp0(v, OP_Goto);
  addrSelectA = sqlite3VdbeCurrentAddr(v);


  /* Generate a coroutine to evaluate the SELECT statement to the
  ** left of the compound operator - the "A" select.
  */
  VdbeNoopComment((v, "Begin coroutine for left SELECT"));

  pPrior->iLimit = regLimitA;
  explainSetInteger(iSub1, pParse->iNextSelectId);
  sqlite3Select(pParse, pPrior, &destA);
  sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofA);
  sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
  VdbeNoopComment((v, "End coroutine for left SELECT"));

  /* Generate a coroutine to evaluate the SELECT statement on 
  ** the right - the "B" select
  */

  addrSelectB = sqlite3VdbeCurrentAddr(v);
  VdbeNoopComment((v, "Begin coroutine for right SELECT"));
  savedLimit = p->iLimit;
  savedOffset = p->iOffset;
  p->iLimit = regLimitB;
  p->iOffset = 0;  
  explainSetInteger(iSub2, pParse->iNextSelectId);
  sqlite3Select(pParse, p, &destB);
  p->iLimit = savedLimit;
  p->iOffset = savedOffset;
  sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofB);
  sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
  VdbeNoopComment((v, "End coroutine for right SELECT"));

  /* Generate a subroutine that outputs the current row of the A
  ** select as the next output row of the compound select.
  */
  VdbeNoopComment((v, "Output routine for A"));
  addrOutA = generateOutputSubroutine(pParse,
                 p, &destA, pDest, regOutA,







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2740
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2742

2743
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2746
2747
2748
2749
2750

2751

2752
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2754
2755
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2757
2758
  }
  sqlite3ExprDelete(db, p->pLimit);
  p->pLimit = 0;
  sqlite3ExprDelete(db, p->pOffset);
  p->pOffset = 0;

  regAddrA = ++pParse->nMem;

  regAddrB = ++pParse->nMem;

  regOutA = ++pParse->nMem;
  regOutB = ++pParse->nMem;
  sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
  sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);

  /* Jump past the various subroutines and coroutines to the main
  ** merge loop
  */
  j1 = sqlite3VdbeAddOp0(v, OP_Goto);



  /* Generate a coroutine to evaluate the SELECT statement to the
  ** left of the compound operator - the "A" select.
  */
  VdbeNoopComment((v, "coroutine for left SELECT"));
  addrSelectA = sqlite3VdbeCurrentAddr(v);
  pPrior->iLimit = regLimitA;
  explainSetInteger(iSub1, pParse->iNextSelectId);
  sqlite3Select(pParse, pPrior, &destA);

  sqlite3VdbeAddOp1(v, OP_EndCoroutine, regAddrA);


  /* Generate a coroutine to evaluate the SELECT statement on 
  ** the right - the "B" select
  */
  VdbeNoopComment((v, "coroutine for right SELECT"));
  addrSelectB = sqlite3VdbeCurrentAddr(v);

  savedLimit = p->iLimit;
  savedOffset = p->iOffset;
  p->iLimit = regLimitB;
  p->iOffset = 0;  
  explainSetInteger(iSub2, pParse->iNextSelectId);
  sqlite3Select(pParse, p, &destB);
  p->iLimit = savedLimit;
  p->iOffset = savedOffset;

  sqlite3VdbeAddOp1(v, OP_EndCoroutine, regAddrB);


  /* Generate a subroutine that outputs the current row of the A
  ** select as the next output row of the compound select.
  */
  VdbeNoopComment((v, "Output routine for A"));
  addrOutA = generateOutputSubroutine(pParse,
                 p, &destA, pDest, regOutA,
2779
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2783
2784
2785
2786
2787
2788
2789
2790

2791
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2793
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2802
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2822
2823
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2860
                 regPrev, pKeyDup, labelEnd);
  }
  sqlite3KeyInfoUnref(pKeyDup);

  /* Generate a subroutine to run when the results from select A
  ** are exhausted and only data in select B remains.
  */
  VdbeNoopComment((v, "eof-A subroutine"));
  if( op==TK_EXCEPT || op==TK_INTERSECT ){
    addrEofA = sqlite3VdbeAddOp2(v, OP_Goto, 0, labelEnd);
  }else{  
    addrEofA = sqlite3VdbeAddOp2(v, OP_If, regEofB, labelEnd);

    sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
    sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA);
    p->nSelectRow += pPrior->nSelectRow;
  }

  /* Generate a subroutine to run when the results from select B
  ** are exhausted and only data in select A remains.
  */
  if( op==TK_INTERSECT ){
    addrEofB = addrEofA;
    if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
  }else{  
    VdbeNoopComment((v, "eof-B subroutine"));
    addrEofB = sqlite3VdbeAddOp2(v, OP_If, regEofA, labelEnd);
    sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
    sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofB);
  }

  /* Generate code to handle the case of A<B
  */
  VdbeNoopComment((v, "A-lt-B subroutine"));
  addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
  sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
  sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
  sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);

  /* Generate code to handle the case of A==B
  */
  if( op==TK_ALL ){
    addrAeqB = addrAltB;
  }else if( op==TK_INTERSECT ){
    addrAeqB = addrAltB;
    addrAltB++;
  }else{
    VdbeNoopComment((v, "A-eq-B subroutine"));
    addrAeqB =
    sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
    sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
  }

  /* Generate code to handle the case of A>B
  */
  VdbeNoopComment((v, "A-gt-B subroutine"));
  addrAgtB = sqlite3VdbeCurrentAddr(v);
  if( op==TK_ALL || op==TK_UNION ){
    sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
  }
  sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
  sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);
  sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);

  /* This code runs once to initialize everything.
  */
  sqlite3VdbeJumpHere(v, j1);
  sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofA);
  sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofB);
  sqlite3VdbeAddOp2(v, OP_Gosub, regAddrA, addrSelectA);
  sqlite3VdbeAddOp2(v, OP_Gosub, regAddrB, addrSelectB);
  sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
  sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);

  /* Implement the main merge loop
  */
  sqlite3VdbeResolveLabel(v, labelCmpr);
  sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
  sqlite3VdbeAddOp4(v, OP_Compare, destA.iSdst, destB.iSdst, nOrderBy,
                         (char*)pKeyMerge, P4_KEYINFO);







<

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<
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<
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<
|





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|
<
<
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2768
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2775
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2777

2778
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2826
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2833


2834
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2840
2841
2842
                 regPrev, pKeyDup, labelEnd);
  }
  sqlite3KeyInfoUnref(pKeyDup);

  /* Generate a subroutine to run when the results from select A
  ** are exhausted and only data in select B remains.
  */

  if( op==TK_EXCEPT || op==TK_INTERSECT ){
    addrEofA_noB = addrEofA = labelEnd;
  }else{  

    VdbeNoopComment((v, "eof-A subroutine"));
    addrEofA = sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
    addrEofA_noB = sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, labelEnd);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA);
    p->nSelectRow += pPrior->nSelectRow;
  }

  /* Generate a subroutine to run when the results from select B
  ** are exhausted and only data in select A remains.
  */
  if( op==TK_INTERSECT ){
    addrEofB = addrEofA;
    if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
  }else{  
    VdbeNoopComment((v, "eof-B subroutine"));

    addrEofB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
    sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, labelEnd);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofB);
  }

  /* Generate code to handle the case of A<B
  */
  VdbeNoopComment((v, "A-lt-B subroutine"));
  addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);

  sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA);
  sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);

  /* Generate code to handle the case of A==B
  */
  if( op==TK_ALL ){
    addrAeqB = addrAltB;
  }else if( op==TK_INTERSECT ){
    addrAeqB = addrAltB;
    addrAltB++;
  }else{
    VdbeNoopComment((v, "A-eq-B subroutine"));
    addrAeqB =

    sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
  }

  /* Generate code to handle the case of A>B
  */
  VdbeNoopComment((v, "A-gt-B subroutine"));
  addrAgtB = sqlite3VdbeCurrentAddr(v);
  if( op==TK_ALL || op==TK_UNION ){
    sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
  }

  sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB);
  sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);

  /* This code runs once to initialize everything.
  */
  sqlite3VdbeJumpHere(v, j1);
  sqlite3VdbeAddOp2(v, OP_InitCoroutine, regAddrA, addrSelectA);
  sqlite3VdbeAddOp2(v, OP_InitCoroutine, regAddrB, addrSelectB);


  sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA_noB);
  sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB);

  /* Implement the main merge loop
  */
  sqlite3VdbeResolveLabel(v, labelCmpr);
  sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
  sqlite3VdbeAddOp4(v, OP_Compare, destA.iSdst, destB.iSdst, nOrderBy,
                         (char*)pKeyMerge, P4_KEYINFO);
4555
4556
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4558
4559
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4597
    }else if( pTabList->nSrc==1
           && OptimizationEnabled(db, SQLITE_SubqCoroutine)
    ){
      /* Implement a co-routine that will return a single row of the result
      ** set on each invocation.
      */
      int addrTop;
      int addrEof;
      pItem->regReturn = ++pParse->nMem;
      addrEof = ++pParse->nMem;
      /* Before coding the OP_Goto to jump to the start of the main routine,
      ** ensure that the jump to the verify-schema routine has already
      ** been coded. Otherwise, the verify-schema would likely be coded as 
      ** part of the co-routine. If the main routine then accessed the 
      ** database before invoking the co-routine for the first time (for 
      ** example to initialize a LIMIT register from a sub-select), it would 
      ** be doing so without having verified the schema version and obtained 
      ** the required db locks. See ticket d6b36be38.  */
      sqlite3CodeVerifySchema(pParse, -1);
      sqlite3VdbeAddOp0(v, OP_Goto);
      addrTop = sqlite3VdbeAddOp1(v, OP_OpenPseudo, pItem->iCursor);
      sqlite3VdbeChangeP5(v, 1);
      VdbeComment((v, "coroutine for %s", pItem->pTab->zName));
      pItem->addrFillSub = addrTop;
      sqlite3VdbeAddOp2(v, OP_Integer, 0, addrEof);
      sqlite3VdbeChangeP5(v, 1);
      sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
      explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
      sqlite3Select(pParse, pSub, &dest);
      pItem->pTab->nRowEst = (unsigned)pSub->nSelectRow;
      pItem->viaCoroutine = 1;
      sqlite3VdbeChangeP2(v, addrTop, dest.iSdst);
      sqlite3VdbeChangeP3(v, addrTop, dest.nSdst);
      sqlite3VdbeAddOp2(v, OP_Integer, 1, addrEof);
      sqlite3VdbeAddOp1(v, OP_Yield, pItem->regReturn);
      VdbeComment((v, "end %s", pItem->pTab->zName));
      sqlite3VdbeJumpHere(v, addrTop-1);
      sqlite3ClearTempRegCache(pParse);
    }else{
      /* Generate a subroutine that will fill an ephemeral table with
      ** the content of this subquery.  pItem->addrFillSub will point
      ** to the address of the generated subroutine.  pItem->regReturn
      ** is a register allocated to hold the subroutine return address







<

<












|

<
<







<
|
<







4537
4538
4539
4540
4541
4542
4543

4544

4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558


4559
4560
4561
4562
4563
4564
4565

4566

4567
4568
4569
4570
4571
4572
4573
    }else if( pTabList->nSrc==1
           && OptimizationEnabled(db, SQLITE_SubqCoroutine)
    ){
      /* Implement a co-routine that will return a single row of the result
      ** set on each invocation.
      */
      int addrTop;

      pItem->regReturn = ++pParse->nMem;

      /* Before coding the OP_Goto to jump to the start of the main routine,
      ** ensure that the jump to the verify-schema routine has already
      ** been coded. Otherwise, the verify-schema would likely be coded as 
      ** part of the co-routine. If the main routine then accessed the 
      ** database before invoking the co-routine for the first time (for 
      ** example to initialize a LIMIT register from a sub-select), it would 
      ** be doing so without having verified the schema version and obtained 
      ** the required db locks. See ticket d6b36be38.  */
      sqlite3CodeVerifySchema(pParse, -1);
      sqlite3VdbeAddOp0(v, OP_Goto);
      addrTop = sqlite3VdbeAddOp1(v, OP_OpenPseudo, pItem->iCursor);
      sqlite3VdbeChangeP5(v, 1);
      VdbeComment((v, "coroutine %s", pItem->pTab->zName));
      pItem->addrFillSub = addrTop;


      sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
      explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
      sqlite3Select(pParse, pSub, &dest);
      pItem->pTab->nRowEst = (unsigned)pSub->nSelectRow;
      pItem->viaCoroutine = 1;
      sqlite3VdbeChangeP2(v, addrTop, dest.iSdst);
      sqlite3VdbeChangeP3(v, addrTop, dest.nSdst);

      sqlite3VdbeAddOp1(v, OP_EndCoroutine, pItem->regReturn);

      sqlite3VdbeJumpHere(v, addrTop-1);
      sqlite3ClearTempRegCache(pParse);
    }else{
      /* Generate a subroutine that will fill an ephemeral table with
      ** the content of this subquery.  pItem->addrFillSub will point
      ** to the address of the generated subroutine.  pItem->regReturn
      ** is a register allocated to hold the subroutine return address
Changes to src/vdbe.c.
716
717
718
719
720
721
722
723

724
725
726
727
728

729
730
731




































732
733
734




735
736
737
738
739
740
741
742
743
  REGISTER_TRACE(pOp->p1, pIn1);
  pc = pOp->p2 - 1;
  break;
}

/* Opcode:  Return P1 * * * *
**
** Jump to the next instruction after the address in register P1.

*/
case OP_Return: {           /* in1 */
  pIn1 = &aMem[pOp->p1];
  assert( pIn1->flags & MEM_Int );
  pc = (int)pIn1->u.i;

  break;
}





































/* Opcode:  Yield P1 * * * *
**
** Swap the program counter with the value in register P1.




*/
case OP_Yield: {            /* in1 */
  int pcDest;
  pIn1 = &aMem[pOp->p1];
  assert( (pIn1->flags & MEM_Dyn)==0 );
  pIn1->flags = MEM_Int;
  pcDest = (int)pIn1->u.i;
  pIn1->u.i = pc;
  REGISTER_TRACE(pOp->p1, pIn1);







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>



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>



>
>
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>
>
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>
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>
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>
>
>
>

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716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
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732
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734
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739
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741
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766
767
768
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771
772
773
774
775
776
777
778
779
780
781
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783
784
785
  REGISTER_TRACE(pOp->p1, pIn1);
  pc = pOp->p2 - 1;
  break;
}

/* Opcode:  Return P1 * * * *
**
** Jump to the next instruction after the address in register P1.  After
** the jump, register P1 becomes undefined.
*/
case OP_Return: {           /* in1 */
  pIn1 = &aMem[pOp->p1];
  assert( pIn1->flags==MEM_Int );
  pc = (int)pIn1->u.i;
  pIn1->flags = MEM_Undefined;
  break;
}

/* Opcode: InitCoroutine P1 P2 * * *
**
** Identify the co-routine at address P2 using the register P1
** as its return address.  Run this opcode prior to the first 
** OP_Yield to invoke the co-routine.
*/
case OP_InitCoroutine: {     /* jump */
  assert( pOp->p1>0 );
  assert( pOp->p1<=(p->nMem-p->nCursor) );
  pOut = &aMem[pOp->p1];
  memAboutToChange(p, pOut);
  VdbeMemRelease(pOut);
  pOut->u.i = pOp->p2 - 1;
  pOut->flags = MEM_Int;
  break;
}

/* Opcode:  EndCoroutine P1 * * * *
**
** The instruction at the address in register P1 is an OP_Yield.
** Jump to the P2 parameter of that OP_Yield.
** After the jump, register P1 becomes undefined.
*/
case OP_EndCoroutine: {           /* in1 */
  VdbeOp *pCaller;
  pIn1 = &aMem[pOp->p1];
  assert( pIn1->flags==MEM_Int );
  assert( pIn1->u.i>=0 && pIn1->u.i<p->nOp );
  pCaller = &aOp[pIn1->u.i];
  assert( pCaller->opcode==OP_Yield );
  assert( pCaller->p2>=0 && pCaller->p2<p->nOp );
  pc = pCaller->p2 - 1;
  pIn1->flags = MEM_Undefined;
  break;
}

/* Opcode:  Yield P1 P2 * * *
**
** Swap the program counter with the value in register P1.
**
** If the co-routine ends with OP_Yield or OP_Return then continue
** to the next instruction.  But if the co-routine ends with
** OP_EndCoroutine, jump immediately to P2.
*/
case OP_Yield: {            /* in1, jump */
  int pcDest;
  pIn1 = &aMem[pOp->p1];
  assert( (pIn1->flags & MEM_Dyn)==0 );
  pIn1->flags = MEM_Int;
  pcDest = (int)pIn1->u.i;
  pIn1->u.i = pc;
  REGISTER_TRACE(pOp->p1, pIn1);
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990
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993
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997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
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1009
  assert( pOp->p1 <= SQLITE_MAX_LENGTH );
  sqlite3VdbeMemSetStr(pOut, pOp->p4.z, pOp->p1, 0, 0);
  pOut->enc = encoding;
  UPDATE_MAX_BLOBSIZE(pOut);
  break;
}

/* Opcode: Undef P1 * * * *
** Synopsis: r[P1]=undef
**
** Mark register P1 as undefined.
*/
case OP_Undef: {
  assert( pOp->p1>0 );
  assert( pOp->p1<=(p->nMem-p->nCursor) );
  pOut = &aMem[pOp->p1];
  memAboutToChange(p, pOut);
  VdbeMemRelease(pOut);
  pOut->flags = MEM_Undefined;
  break;
}

/* Opcode: Variable P1 P2 * P4 *
** Synopsis: r[P2]=parameter(P1,P4)
**
** Transfer the values of bound parameter P1 into register P2
**
** If the parameter is named, then its name appears in P4.
** The P4 value is used by sqlite3_bind_parameter_name().







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<
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<
<
<
<
<
<
<







1023
1024
1025
1026
1027
1028
1029















1030
1031
1032
1033
1034
1035
1036
  assert( pOp->p1 <= SQLITE_MAX_LENGTH );
  sqlite3VdbeMemSetStr(pOut, pOp->p4.z, pOp->p1, 0, 0);
  pOut->enc = encoding;
  UPDATE_MAX_BLOBSIZE(pOut);
  break;
}
















/* Opcode: Variable P1 P2 * P4 *
** Synopsis: r[P2]=parameter(P1,P4)
**
** Transfer the values of bound parameter P1 into register P2
**
** If the parameter is named, then its name appears in P4.
** The P4 value is used by sqlite3_bind_parameter_name().
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2149
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2151
2152
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    c = sqlite3VdbeRealValue(pIn1)!=0.0;
#endif
    if( pOp->opcode==OP_IfNot ) c = !c;
  }
  if( c ){
    pc = pOp->p2-1;
  }
  break;
}

/* Opcode: IsUndef P1 P2 * * *
** Synopsis:  if r[P1]==undefined goto P2
**
** Jump to P2 if the value in register P1 is undefined
*/
case OP_IsUndef: {            /* jump */
  pIn1 = &aMem[pOp->p1];
  if( (pIn1->flags & MEM_Undefined)!=0 ){
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: IsNull P1 P2 * * *
** Synopsis:  if r[P1]==NULL goto P2
**
** Jump to P2 if the value in register P1 is NULL.







<
<
<
<
<
<
<
<
<
<
<
<
<







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    c = sqlite3VdbeRealValue(pIn1)!=0.0;
#endif
    if( pOp->opcode==OP_IfNot ) c = !c;
  }
  if( c ){
    pc = pOp->p2-1;
  }













  break;
}

/* Opcode: IsNull P1 P2 * * *
** Synopsis:  if r[P1]==NULL goto P2
**
** Jump to P2 if the value in register P1 is NULL.
Changes to src/where.c.
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    sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
    VdbeComment((v, "init LEFT JOIN no-match flag"));
  }

  /* Special case of a FROM clause subquery implemented as a co-routine */
  if( pTabItem->viaCoroutine ){
    int regYield = pTabItem->regReturn;
    sqlite3VdbeAddOp2(v, OP_Integer, pTabItem->addrFillSub-1, regYield);
    pLevel->p2 =  sqlite3VdbeAddOp1(v, OP_Yield, regYield);
    VdbeComment((v, "next row of co-routine %s", pTabItem->pTab->zName));
    sqlite3VdbeAddOp2(v, OP_If, regYield+1, addrBrk);
    pLevel->op = OP_Goto;
  }else

#ifndef SQLITE_OMIT_VIRTUALTABLE
  if(  (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
    /* Case 1:  The table is a virtual-table.  Use the VFilter and VNext
    **          to access the data.







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|

<







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    sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
    VdbeComment((v, "init LEFT JOIN no-match flag"));
  }

  /* Special case of a FROM clause subquery implemented as a co-routine */
  if( pTabItem->viaCoroutine ){
    int regYield = pTabItem->regReturn;
    sqlite3VdbeAddOp2(v, OP_InitCoroutine, regYield, pTabItem->addrFillSub);
    pLevel->p2 =  sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
    VdbeComment((v, "next row of co-routine %s", pTabItem->pTab->zName));

    pLevel->op = OP_Goto;
  }else

#ifndef SQLITE_OMIT_VIRTUALTABLE
  if(  (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
    /* Case 1:  The table is a virtual-table.  Use the VFilter and VNext
    **          to access the data.