/ Check-in [72d11133]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Omit an unnecessary OP_Null opcode from UPDATE.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 72d111336c5016e5b5092dfebcd01253266a7685
User & Date: drh 2013-12-19 02:56:01
Context
2013-12-19
14:34
Remove an unneeded column-cache flush in aggregate SELECT and an unreachable branch in the INSERT logic. check-in: ffa092e1 user: drh tags: trunk
02:56
Omit an unnecessary OP_Null opcode from UPDATE. check-in: 72d11133 user: drh tags: trunk
02:23
Omit one or more pointless instructions that occur in between OP_NoConflict and OP_Halt. check-in: 61e2f357 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/update.c.

492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515


516
517
518
519
520
521
522
  ** the database after the BEFORE triggers are fired anyway (as the trigger 
  ** may have modified them). So not loading those that are not going to
  ** be used eliminates some redundant opcodes.
  */
  newmask = sqlite3TriggerColmask(
      pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
  );
  sqlite3VdbeAddOp3(v, OP_Null, 0, regNew, regNew+pTab->nCol-1);
  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      /*sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);*/
    }else{
      j = aXRef[i];
      if( j>=0 ){
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask&(1<<i)) ){
        /* This branch loads the value of a column that will not be changed 
        ** into a register. This is done if there are no BEFORE triggers, or
        ** if there are one or more BEFORE triggers that use this value via
        ** a new.* reference in a trigger program.
        */
        testcase( i==31 );
        testcase( i==32 );
        sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, regNew+i);


      }
    }
  }

  /* Fire any BEFORE UPDATE triggers. This happens before constraints are
  ** verified. One could argue that this is wrong.
  */







|


|













>
>







492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
  ** the database after the BEFORE triggers are fired anyway (as the trigger 
  ** may have modified them). So not loading those that are not going to
  ** be used eliminates some redundant opcodes.
  */
  newmask = sqlite3TriggerColmask(
      pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
  );
  /*sqlite3VdbeAddOp3(v, OP_Null, 0, regNew, regNew+pTab->nCol-1);*/
  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
    }else{
      j = aXRef[i];
      if( j>=0 ){
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask&(1<<i)) ){
        /* This branch loads the value of a column that will not be changed 
        ** into a register. This is done if there are no BEFORE triggers, or
        ** if there are one or more BEFORE triggers that use this value via
        ** a new.* reference in a trigger program.
        */
        testcase( i==31 );
        testcase( i==32 );
        sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, i, regNew+i);
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
      }
    }
  }

  /* Fire any BEFORE UPDATE triggers. This happens before constraints are
  ** verified. One could argue that this is wrong.
  */