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Simplification of the WHERE loop code generator for NULLS LAST saves a

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few CPU cycles and about a hundred bytes of code space.

FossilOrigin-Name: e3ed2f496f51234a8f81d90d47ba603b06dbed38b8bd8f1934294379cde74d3a
This commit is contained in:
drh
2019-08-23 16:12:20 +00:00
parent ec3dda5b11
commit 0086e07865
3 changed files with 21 additions and 31 deletions
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38
src/wherecode.c
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@@ -1671,10 +1671,10 @@ Bitmask sqlite3WhereCodeOneLoopStart(
}
bSeekPastNull = 0;
}else if( bSeekPastNull ){
sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
nConstraint++;
startEq = 0;
sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
start_constraints = 1;
nConstraint++;
}else if( regBignull ){
sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
start_constraints = 1;
@@ -1705,30 +1705,20 @@ Bitmask sqlite3WhereCodeOneLoopStart(
VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE );
VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT );
assert( bSeekPastNull==0 || bStopAtNull==0 );
if( regBignull ){
assert( bSeekPastNull==1 || bStopAtNull==1 );
assert( bStopAtNull==startEq );
sqlite3VdbeAddOp2(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+2);
if( bStopAtNull ){
start_constraints = (nConstraint>1);
op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint-1);
VdbeCoverage(v);
VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind );
VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last );
VdbeCoverageIf(v, op==OP_SeekGT); testcase( op==OP_SeekGT );
VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE );
VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE );
VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT );
}else{
op = aStartOp[(start_constraints<<2) + ((!startEq)<<1) + bRev];
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
VdbeCoverage(v);
VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind );
VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last );
VdbeCoverageIf(v, op==OP_SeekGT); testcase( op==OP_SeekGT );
VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE );
VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE );
VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT );
}
op = aStartOp[(nConstraint>1)*4 + 2 + bRev];
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase,
nConstraint-startEq);
VdbeCoverage(v);
VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind );
VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last );
VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE );
VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE );
assert( op==OP_Rewind || op==OP_Last || op==OP_SeekGE || op==OP_SeekLE);
}
}