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Optimization to the comparison opcodes in the byte-code engine.

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FossilOrigin-Name: 654935c7737f1a9e08fde9b220c543e86ff6e05910e2f08973a2f93ab2b3e028
This commit is contained in:
drh
2017-08-03 00:29:23 +00:00
parent a485ad191f
commit 5859636fb1
3 changed files with 24 additions and 15 deletions
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25
src/vdbe.c
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@@ -1955,13 +1955,23 @@ case OP_Ge: { /* same as TK_GE, jump, in1, in3 */
res = sqlite3MemCompare(pIn3, pIn1, pOp->p4.pColl);
}
compare_op:
switch( pOp->opcode ){
case OP_Eq: res2 = res==0; break;
case OP_Ne: res2 = res; break;
case OP_Lt: res2 = res<0; break;
case OP_Le: res2 = res<=0; break;
case OP_Gt: res2 = res>0; break;
default: res2 = res>=0; break;
/* At this point, res is negative, zero, or positive if reg[P1] is
** less than, equal to, or greater than reg[P3], respectively. Compute
** the answer to this operator in res2, depending on what the comparison
** operator actually is. The next block of code depends on the fact
** that the 6 comparison operators are consecutive integers in this
** order: NE, EQ, GT, LE, LT, GE */
assert( OP_Eq==OP_Ne+1 ); assert( OP_Gt==OP_Ne+2 ); assert( OP_Le==OP_Ne+3 );
assert( OP_Lt==OP_Ne+4 ); assert( OP_Ge==OP_Ne+5 );
if( res<0 ){ /* ne, eq, gt, le, lt, ge */
static const unsigned char aLTb[] = { 1, 0, 0, 1, 1, 0 };
res2 = aLTb[pOp->opcode - OP_Ne];
}else if( res==0 ){
static const unsigned char aEQb[] = { 0, 1, 0, 1, 0, 1 };
res2 = aEQb[pOp->opcode - OP_Ne];
}else{
static const unsigned char aGTb[] = { 1, 0, 1, 0, 0, 1 };
res2 = aGTb[pOp->opcode - OP_Ne];
}
/* Undo any changes made by applyAffinity() to the input registers. */
@@ -1973,7 +1983,6 @@ compare_op:
if( pOp->p5 & SQLITE_STOREP2 ){
pOut = &aMem[pOp->p2];
iCompare = res;
res2 = res2!=0; /* For this path res2 must be exactly 0 or 1 */
if( (pOp->p5 & SQLITE_KEEPNULL)!=0 ){
/* The KEEPNULL flag prevents OP_Eq from overwriting a NULL with 1
** and prevents OP_Ne from overwriting NULL with 0. This flag