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Overview
Comment:Enhance the sqlite3VdbeMemAboutToChange() shallow-copy validation mechanism by adding the new OP_ReleaseReg opcode to tell MemAboutToChange() that a range of registers is no longer needed so that the source register can be freely changed. This is a change to debugging and test builds only and does not impact release builds. Fix for ticket [c62c5e58524b204d] and [5ad2aa6921faa1ee]. The previous fix to ticket [5ad2aa6921faa1ee] is backed out by this change since this change is a better fix.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: 36fdeb4f0a66970a35de688b617f90899c89cfdfab659f864df99aa7ebf854ea
User & Date: drh 2019-12-23 02:18:49
References
2019-12-23
13:24
Fix a shift-overflow problem in yesterday's check-in [36fdeb4f0a66970a] that OSSFuzz helpfully discovered overnight. Thanks Google. (check-in: bff38e2b user: drh tags: trunk)
Context
2019-12-23
02:43
Change the assert() back into a testcase(). See also check-ins [9ab985a9c8160b90] and [ddb17d92df194337] and other check-ins that those reference. Fix for ticket [9d708e474201c001] (check-in: 2c44c734 user: drh tags: trunk)
02:18
Enhance the sqlite3VdbeMemAboutToChange() shallow-copy validation mechanism by adding the new OP_ReleaseReg opcode to tell MemAboutToChange() that a range of registers is no longer needed so that the source register can be freely changed. This is a change to debugging and test builds only and does not impact release builds. Fix for ticket [c62c5e58524b204d] and [5ad2aa6921faa1ee]. The previous fix to ticket [5ad2aa6921faa1ee] is backed out by this change since this change is a better fix. (check-in: 36fdeb4f user: drh tags: trunk)
2019-12-22
23:48
Change the code generator for the IN operator so that it avoids creating OP_Eq and OP_Ne opcode with the same P1 and P3 arguments. This enables us to back out check-in [ddb17d92df194337] and also fix ticket [188f912b51cd802]. (check-in: 9ab985a9 user: drh tags: trunk)
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/expr.c.

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              sqlite3ExprCodeGeneratedColumn(pParse, pCol, iSrc);
            }
            pCol->colFlags &= ~(COLFLAG_BUSY|COLFLAG_NOTAVAIL);
            return iSrc;
          }else
#endif /* SQLITE_OMIT_GENERATED_COLUMNS */
          if( pCol->affinity==SQLITE_AFF_REAL ){
            sqlite3VdbeAddOp2(v, OP_Copy, iSrc, target);
            sqlite3VdbeAddOp1(v, OP_RealAffinity, target);
            return target;
          }else{
            return iSrc;
          }
        }else{
          /* Coding an expression that is part of an index where column names
................................................................................
        }
      }else
#endif
      {
        sqlite3VdbeAddFunctionCall(pParse, constMask, r1, target, nFarg,
                                   pDef, pExpr->op2);
      }

      if( nFarg && constMask==0 ){
        sqlite3ReleaseTempRange(pParse, r1, nFarg);



      }
      return target;
    }
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_EXISTS:
    case TK_SELECT: {
      int nCol;
................................................................................
}

/*
** Deallocate a register, making available for reuse for some other
** purpose.
*/
void sqlite3ReleaseTempReg(Parse *pParse, int iReg){


  if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
    pParse->aTempReg[pParse->nTempReg++] = iReg;

  }
}

/*
** Allocate or deallocate a block of nReg consecutive registers.
*/
int sqlite3GetTempRange(Parse *pParse, int nReg){
................................................................................
  return i;
}
void sqlite3ReleaseTempRange(Parse *pParse, int iReg, int nReg){
  if( nReg==1 ){
    sqlite3ReleaseTempReg(pParse, iReg);
    return;
  }

  if( nReg>pParse->nRangeReg ){
    pParse->nRangeReg = nReg;
    pParse->iRangeReg = iReg;
  }
}

/*







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              sqlite3ExprCodeGeneratedColumn(pParse, pCol, iSrc);
            }
            pCol->colFlags &= ~(COLFLAG_BUSY|COLFLAG_NOTAVAIL);
            return iSrc;
          }else
#endif /* SQLITE_OMIT_GENERATED_COLUMNS */
          if( pCol->affinity==SQLITE_AFF_REAL ){
            sqlite3VdbeAddOp2(v, OP_SCopy, iSrc, target);
            sqlite3VdbeAddOp1(v, OP_RealAffinity, target);
            return target;
          }else{
            return iSrc;
          }
        }else{
          /* Coding an expression that is part of an index where column names
................................................................................
        }
      }else
#endif
      {
        sqlite3VdbeAddFunctionCall(pParse, constMask, r1, target, nFarg,
                                   pDef, pExpr->op2);
      }
      if( nFarg ){
        if( constMask==0 ){
          sqlite3ReleaseTempRange(pParse, r1, nFarg);
        }else{
          sqlite3VdbeReleaseRegisters(pParse, r1, nFarg, constMask);
        }
      }
      return target;
    }
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_EXISTS:
    case TK_SELECT: {
      int nCol;
................................................................................
}

/*
** Deallocate a register, making available for reuse for some other
** purpose.
*/
void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
  if( iReg ){
    sqlite3VdbeReleaseRegisters(pParse, iReg, 1, 0);
    if( pParse->nTempReg<ArraySize(pParse->aTempReg) ){
      pParse->aTempReg[pParse->nTempReg++] = iReg;
    }
  }
}

/*
** Allocate or deallocate a block of nReg consecutive registers.
*/
int sqlite3GetTempRange(Parse *pParse, int nReg){
................................................................................
  return i;
}
void sqlite3ReleaseTempRange(Parse *pParse, int iReg, int nReg){
  if( nReg==1 ){
    sqlite3ReleaseTempReg(pParse, iReg);
    return;
  }
  sqlite3VdbeReleaseRegisters(pParse, iReg, nReg, 0);
  if( nReg>pParse->nRangeReg ){
    pParse->nRangeReg = nReg;
    pParse->iRangeReg = iReg;
  }
}

/*

Changes to src/vdbe.c.

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    }
  }
  break;
}

/* Opcode: ElseNotEq * P2 * * *
**
** This opcode must immediately follow an OP_Lt or OP_Gt comparison operator.





** If result of an OP_Eq comparison on the same two operands
** would have be NULL or false (0), then then jump to P2. 
** If the result of an OP_Eq comparison on the two previous operands
** would have been true (1), then fall through.
*/
case OP_ElseNotEq: {       /* same as TK_ESCAPE, jump */
  assert( pOp>aOp );
  assert( pOp[-1].opcode==OP_Lt || pOp[-1].opcode==OP_Gt );









  assert( pOp[-1].p5 & SQLITE_STOREP2 );



  VdbeBranchTaken(iCompare!=0, 2);
  if( iCompare!=0 ) goto jump_to_p2;
  break;
}


/* Opcode: Permutation * * * P4 *
................................................................................
** an active statement journal.
*/
case OP_Abortable: {
  sqlite3VdbeAssertAbortable(p);
  break;
}
#endif
















































/* Opcode: Noop * * * * *
**
** Do nothing.  This instruction is often useful as a jump
** destination.
*/
/*







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    }
  }
  break;
}

/* Opcode: ElseNotEq * P2 * * *
**
** This opcode must follow an OP_Lt or OP_Gt comparison operator.  There
** can be zero or more OP_ReleaseReg opcodes intervening, but no other
** opcodes are allowed to occur between this instruction and the previous
** OP_Lt or OP_Gt.  Furthermore, the prior OP_Lt or OP_Gt must have the
** SQLITE_STOREP2 bit set in the P5 field.
**
** If result of an OP_Eq comparison on the same two operands as the
** prior OP_Lt or OP_Gt would have been NULL or false (0), then then
** jump to P2.  If the result of an OP_Eq comparison on the two previous
** operands would have been true (1), then fall through.
*/
case OP_ElseNotEq: {       /* same as TK_ESCAPE, jump */



#ifdef SQLITE_DEBUG
  /* Verify the preconditions of this opcode - that it follows an OP_Lt or
  ** OP_Gt with the SQLITE_STOREP2 flag set, with zero or more intervening
  ** OP_ReleaseReg opcodes */
  int iAddr;
  for(iAddr = (int)(pOp - aOp) - 1; ALWAYS(iAddr>=0); iAddr--){
    if( aOp[iAddr].opcode==OP_ReleaseReg ) continue;
    assert( aOp[iAddr].opcode==OP_Lt || aOp[iAddr].opcode==OP_Gt );
    assert( aOp[iAddr].p5 & SQLITE_STOREP2 );
    break;
  }
#endif /* SQLITE_DEBUG */
  VdbeBranchTaken(iCompare!=0, 2);
  if( iCompare!=0 ) goto jump_to_p2;
  break;
}


/* Opcode: Permutation * * * P4 *
................................................................................
** an active statement journal.
*/
case OP_Abortable: {
  sqlite3VdbeAssertAbortable(p);
  break;
}
#endif

#ifdef SQLITE_DEBUG
/* Opcode:  ReleaseReg   P1 P2 P3 * *
** Synopsis: release r[P1@P2] mask P3
**
** Release registers from service.  Any content that was in the
** the registers is unreliable after this opcode completes.
**
** The registers released will be the P2 registers starting at P1,
** except if bit ii of P3 set, then do not release register P1+ii.
** In other words, P3 is a mask of registers to preserve.
**
** Releasing a register clears the Mem.pScopyFrom pointer.  That means
** that if the content of the released register was set using OP_SCopy,
** a change to the value of the source register for the OP_SCopy will no longer
** generate an assertion fault in sqlite3VdbeMemAboutToChange().
**
** TODO: Released registers ought to also have their datatype set to
** MEM_Undefined so that any subsequent attempt to read the released
** register (before it is reinitialized) will generate an assertion fault.
** However, there are places in the code generator which release registers
** before their are used, under the (valid) assumption that the registers
** will not be reallocated for some other purpose before they are used and
** hence are safe to release.
**
** This opcode is only available in testing and debugging builds.  It is
** not generated for release builds.  The purpose of this opcode is to help
** validate the generated bytecode.  This opcode does not actually contribute
** to computing an answer.
*/
case OP_ReleaseReg: {
  Mem *pMem;
  int i;
  u32 constMask;
  assert( pOp->p1>0 );
  assert( pOp->p1+pOp->p2<=(p->nMem+1 - p->nCursor)+1 );
  pMem = &aMem[pOp->p1];
  constMask = pOp->p3;
  for(i=0; i<pOp->p2; i++, pMem++){
    if( (constMask & MASKBIT32(i))==0 ){
      pMem->pScopyFrom = 0;
      /* MemSetTypeFlag(pMem, MEM_Undefined); // See the TODO */
    }
  }
  break;
}
#endif

/* Opcode: Noop * * * * *
**
** Do nothing.  This instruction is often useful as a jump
** destination.
*/
/*

Changes to src/vdbe.h.

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void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
void sqlite3VdbeJumpHere(Vdbe*, int addr);
int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);





void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
void sqlite3VdbeAppendP4(Vdbe*, void *pP4, int p4type);
void sqlite3VdbeSetP4KeyInfo(Parse*, Index*);
void sqlite3VdbeUsesBtree(Vdbe*, int);
VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
int sqlite3VdbeMakeLabel(Parse*);
void sqlite3VdbeRunOnlyOnce(Vdbe*);







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void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
void sqlite3VdbeJumpHere(Vdbe*, int addr);
int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);
#ifdef SQLITE_DEBUG
  void sqlite3VdbeReleaseRegisters(Parse*,int addr, int n, u32 mask);
#else
# define sqlite3VdbeReleaseRegisters(P,A,N,M)
#endif
void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
void sqlite3VdbeAppendP4(Vdbe*, void *pP4, int p4type);
void sqlite3VdbeSetP4KeyInfo(Parse*, Index*);
void sqlite3VdbeUsesBtree(Vdbe*, int);
VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
int sqlite3VdbeMakeLabel(Parse*);
void sqlite3VdbeRunOnlyOnce(Vdbe*);

Changes to src/vdbeaux.c.

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int sqlite3VdbeDeletePriorOpcode(Vdbe *p, u8 op){
  if( p->nOp>0 && p->aOp[p->nOp-1].opcode==op ){
    return sqlite3VdbeChangeToNoop(p, p->nOp-1);
  }else{
    return 0;
  }
}
























/*
** Change the value of the P4 operand for a specific instruction.
** This routine is useful when a large program is loaded from a
** static array using sqlite3VdbeAddOpList but we want to make a
** few minor changes to the program.
**







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int sqlite3VdbeDeletePriorOpcode(Vdbe *p, u8 op){
  if( p->nOp>0 && p->aOp[p->nOp-1].opcode==op ){
    return sqlite3VdbeChangeToNoop(p, p->nOp-1);
  }else{
    return 0;
  }
}

#ifdef SQLITE_DEBUG
/*
** Generate an OP_ReleaseReg opcode to indicate that a range of
** registers, except any identified by mask, are no longer in use.
*/
void sqlite3VdbeReleaseRegisters(Parse *pParse, int iFirst, int N, u32 mask){
  assert( pParse->pVdbe );
  while( N>0 && (mask&1)!=0 ){
    mask >>= 1;
    iFirst++;
    N--;
  }
  while( N>0 && N<=32 && (mask & MASKBIT32(N-1))!=0 ){
    mask &= ~MASKBIT32(N-1);
    N--;
  }
  if( N>0 ){
    sqlite3VdbeAddOp3(pParse->pVdbe, OP_ReleaseReg, iFirst, N, *(int*)&mask);
  }
}
#endif /* SQLITE_DEBUG */


/*
** Change the value of the P4 operand for a specific instruction.
** This routine is useful when a large program is loaded from a
** static array using sqlite3VdbeAddOpList but we want to make a
** few minor changes to the program.
**

Changes to test/update.test.

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  CREATE TABLE t0(c0 REAL, c1);
  INSERT INTO t0(c0,c1) VALUES('xyz',11),('uvw',22);
  CREATE INDEX i0 ON t0(c1) WHERE c0 GLOB 3;
  CREATE INDEX i1 ON t0(c0,c1) WHERE typeof(c0)='text' AND typeof(c1)='integer';
  UPDATE t0 SET c1=345;
  SELECT * FROM t0;
} {xyz 345 uvw 345}













finish_test








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  CREATE TABLE t0(c0 REAL, c1);
  INSERT INTO t0(c0,c1) VALUES('xyz',11),('uvw',22);
  CREATE INDEX i0 ON t0(c1) WHERE c0 GLOB 3;
  CREATE INDEX i1 ON t0(c0,c1) WHERE typeof(c0)='text' AND typeof(c1)='integer';
  UPDATE t0 SET c1=345;
  SELECT * FROM t0;
} {xyz 345 uvw 345}

# 2019-12-22 ticket c62c5e58524b204d
# This is really the same underlying problem as 5ad2aa6921faa1ee
#
reset_db
do_execsql_test update-18.20 {
  PRAGMA encoding = 'utf16';
  CREATE TABLE t0(c0 TEXT);
  CREATE INDEX i0 ON t0(0 LIKE COALESCE(c0, 0));
  INSERT INTO t0(c0) VALUES (0), (0);
  SELECT * FROM t0;
} {0 0}

finish_test