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Overview
Comment: | Be more aggressive in optimizing constant conditional expressions. |
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Downloads: | Tarball | ZIP archive | SQL archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
b7e39851a75b87ebca747b26a3998956 |
User & Date: | drh 2014-01-02 17:57:16 |
Context
2014-01-02
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19:35 | Avoid unnecessary affinity transformations when building indices using data from a table. (check-in: 10d85135 user: drh tags: trunk) | |
17:57 | Be more aggressive in optimizing constant conditional expressions. (check-in: b7e39851 user: drh tags: trunk) | |
2014-01-01
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15:18 | Try to detect process ID changes due to fork() calls in os_unix.c and reset the PRNG when a process ID change is detected. (check-in: e1eba1fb user: drh tags: trunk) | |
Changes
Changes to src/expr.c.
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519 520 521 522 523 524 525 | if( p ) { sqlite3ExprCheckHeight(pParse, p->nHeight); } return p; } /* | > > | > | | | | > > > > > > | 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 | if( p ) { sqlite3ExprCheckHeight(pParse, p->nHeight); } return p; } /* ** If the expression is always either TRUE or FALSE (respectively), ** then return 1. If one cannot determine the truth value of the ** expression at compile-time return 0. ** ** This is an optimization. If is OK to return 0 here even if ** the expression really is always false or false (a false negative). ** But it is a bug to return 1 if the expression might have different ** boolean values in different circumstances (a false positive.) ** ** Note that if the expression is part of conditional for a ** LEFT JOIN, then we cannot determine at compile-time whether or not ** is it true or false, so always return 0. */ static int exprAlwaysTrue(Expr *p){ int v = 0; if( ExprHasProperty(p, EP_FromJoin) ) return 0; if( !sqlite3ExprIsInteger(p, &v) ) return 0; return v!=0; } static int exprAlwaysFalse(Expr *p){ int v = 0; if( ExprHasProperty(p, EP_FromJoin) ) return 0; if( !sqlite3ExprIsInteger(p, &v) ) return 0; return v==0; } |
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3610 3611 3612 3613 3614 3615 3616 | sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull); sqlite3VdbeAddOp2(v, OP_Goto, 0, dest); sqlite3VdbeResolveLabel(v, destIfFalse); break; } #endif default: { | > > > > > | | | | > | 3619 3620 3621 3622 3623 3624 3625 3626 3627 3628 3629 3630 3631 3632 3633 3634 3635 3636 3637 3638 3639 3640 3641 3642 | sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull); sqlite3VdbeAddOp2(v, OP_Goto, 0, dest); sqlite3VdbeResolveLabel(v, destIfFalse); break; } #endif default: { if( exprAlwaysTrue(pExpr) ){ sqlite3VdbeAddOp2(v, OP_Goto, 0, dest); }else if( exprAlwaysFalse(pExpr) ){ /* No-op */ }else{ r1 = sqlite3ExprCodeTemp(pParse, pExpr, ®Free1); sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0); testcase( regFree1==0 ); testcase( jumpIfNull==0 ); } break; } } sqlite3ReleaseTempReg(pParse, regFree1); sqlite3ReleaseTempReg(pParse, regFree2); } |
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3755 3756 3757 3758 3759 3760 3761 | sqlite3ExprCodeIN(pParse, pExpr, dest, destIfNull); sqlite3VdbeResolveLabel(v, destIfNull); } break; } #endif default: { | > > > > > | | | | > | 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 3782 3783 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 | sqlite3ExprCodeIN(pParse, pExpr, dest, destIfNull); sqlite3VdbeResolveLabel(v, destIfNull); } break; } #endif default: { if( exprAlwaysFalse(pExpr) ){ sqlite3VdbeAddOp2(v, OP_Goto, 0, dest); }else if( exprAlwaysTrue(pExpr) ){ /* no-op */ }else{ r1 = sqlite3ExprCodeTemp(pParse, pExpr, ®Free1); sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0); testcase( regFree1==0 ); testcase( jumpIfNull==0 ); } break; } } sqlite3ReleaseTempReg(pParse, regFree1); sqlite3ReleaseTempReg(pParse, regFree2); } |
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