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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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12
manifest
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@ -1,5 +1,5 @@
C Invert\sthe\smeaning\sof\sthe\sregBignull\sflag\sso\sthat\sit\sis\s1\swhen\sdoing\sthe\nnormal\sscan\sand\s1\swhen\sscanning\snulls.\s\sThis\senables\sthe\sre-do\sjump\sat\sthe\nbottom\sof\sthe\sloop\sto\sbe\scoded\swith\sa\ssingle\sOP_IfNotZero\sopcode,\srather\nthan\sa\ssequence\sof\sOP_If,\sOP_Integer,\sOP_Goto.
D 2019-08-23T13:32:03.306
C Simplification\sof\sthe\sWHERE\sloop\scode\sgenerator\sfor\sNULLS\sLAST\ssaves\sa\nfew\sCPU\scycles\sand\sabout\sa\shundred\sbytes\sof\scode\sspace.
D 2019-08-23T16:12:20.533
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@ -611,7 +611,7 @@ F src/wal.h 606292549f5a7be50b6227bd685fa76e3a4affad71bb8ac5ce4cb5c79f6a176a
F src/walker.c d5a94907dcac990e31976be9dc769d17f6a806782593d6aec9d760ee01ec22cd
F src/where.c 10e21ac338582a4f87b2d09f09dd812c9bda0a0c4c456f54daeeee355afae733
F src/whereInt.h 4a296fd4fa79fdcbc2b5e8c1b898901617655811223e1082b899c23ecb092217
F src/wherecode.c c02ff23ea48b8980d003817bd412e3ce7ce4982159a090566a24cb6101688a9d
F src/wherecode.c f8ba85888b8a6843bce84e7e21f61d6c043c21c888871ad84fb911f45671e95d
F src/whereexpr.c 2757afbd5cfdbb420f9d0392e1bd5f5c0e33dee50a8c692befc7e502308e449f
F src/window.c 3ea716bb0dd5ffc8cdbaa48baffc525958b51bc61b2afd73a56baccfcd7ceb2f
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
@ -1837,7 +1837,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P 649b08ead50f10a9ec0357a5e1ed020195d9f93be61ef703ea036a8e53f07a34
R c7fec8ea82d2ec3c4ef608bd58d88fd0
P bf875e1a259a4167694e06349458452dc36c1d38aa6843518d9ae46ce74e5559
R f34508d6bf0c4c450df67caf81b0a3ce
U drh
Z 0dcd16d55adeefa06ece8236ed711d36
Z 77866c600215002b5dd6dd0eeafd861f

2
manifest.uuid
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@ -1 +1 @@
bf875e1a259a4167694e06349458452dc36c1d38aa6843518d9ae46ce74e5559
e3ed2f496f51234a8f81d90d47ba603b06dbed38b8bd8f1934294379cde74d3a

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);
}
}