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Improvement to the OP_Permutation opcode to prevent it from using CPU cycles

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for initialization in prepared statements that do not use that opcode.

FossilOrigin-Name: b4a98f65564a0d9fba2fef95ebd00a39b3e1e572
This commit is contained in:
drh
2017-01-26 18:00:00 +00:00
parent fae58d51ce
commit b7dab70a92
3 changed files with 21 additions and 13 deletions
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20
src/vdbe.c
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@@ -583,7 +583,6 @@ int sqlite3VdbeExec(
Mem *pIn2 = 0; /* 2nd input operand */
Mem *pIn3 = 0; /* 3rd input operand */
Mem *pOut = 0; /* Output operand */
int *aPermute = 0; /* Permutation of columns for OP_Compare */
#ifdef VDBE_PROFILE
u64 start; /* CPU clock count at start of opcode */
#endif
@@ -2136,8 +2135,8 @@ case OP_ElseNotEq: { /* same as TK_ESCAPE, jump */
/* Opcode: Permutation * * * P4 *
**
** Set the permutation used by the OP_Compare operator to be the array
** of integers in P4.
** Set the permutation used by the OP_Compare operator in the next
** instruction. The permutation is stored in the P4 operand.
**
** The permutation is only valid until the next OP_Compare that has
** the OPFLAG_PERMUTE bit set in P5. Typically the OP_Permutation should
@@ -2149,7 +2148,8 @@ case OP_ElseNotEq: { /* same as TK_ESCAPE, jump */
case OP_Permutation: {
assert( pOp->p4type==P4_INTARRAY );
assert( pOp->p4.ai );
aPermute = pOp->p4.ai + 1;
assert( pOp[1].opcode==OP_Compare );
assert( pOp[1].p5 & OPFLAG_PERMUTE );
break;
}
@@ -2182,8 +2182,17 @@ case OP_Compare: {
int idx;
CollSeq *pColl; /* Collating sequence to use on this term */
int bRev; /* True for DESCENDING sort order */
int *aPermute; /* The permutation */
if( (pOp->p5 & OPFLAG_PERMUTE)==0 ) aPermute = 0;
if( (pOp->p5 & OPFLAG_PERMUTE)==0 ){
aPermute = 0;
}else{
assert( pOp>aOp );
assert( pOp[-1].opcode==OP_Permutation );
assert( pOp[-1].p4type==P4_INTARRAY );
aPermute = pOp[-1].p4.ai + 1;
assert( aPermute!=0 );
}
n = pOp->p3;
pKeyInfo = pOp->p4.pKeyInfo;
assert( n>0 );
@@ -2216,7 +2225,6 @@ case OP_Compare: {
break;
}
}
aPermute = 0;
break;
}