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Clean up the IN operator code generation logic to make it easier to reason

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about.  In the process, improve code generation to omit some unused OP_Null
operations.

FossilOrigin-Name: 7c6fbcfe6ed5739e8e4639b7b123fbf9828cbfc0
This commit is contained in:
drh
2014-08-01 15:51:36 +00:00
parent cefc87fca5 e80c9b9ad5
commit 5c3e9cf9de
5 changed files with 55 additions and 42 deletions
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manifest
+9 -8
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@@ -1,5 +1,5 @@
C Enhance\sthe\sPRAGMA\sintegrity_check\scommand\sto\sdetect\sUNIQUE\sand\sNOT\sNULL\nconstraint\sviolations.
D 2014-08-01T01:40:33.869
C Clean\sup\sthe\sIN\soperator\scode\sgeneration\slogic\sto\smake\sit\seasier\sto\sreason\nabout.\s\sIn\sthe\sprocess,\simprove\scode\sgeneration\sto\somit\ssome\sunused\sOP_Null\noperations.
D 2014-08-01T15:51:36.528
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in 5eb79e334a5de69c87740edd56af6527dd219308
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -176,7 +176,7 @@ F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
F src/ctime.c 0231df905e2c4abba4483ee18ffc05adc321df2a
F src/date.c 593c744b2623971e45affd0bde347631bdfa4625
F src/delete.c bcf8f72126cea80fc3d5bc5494cf19b3f8935aaf
F src/expr.c 3be0e9f90bb1c475a99a821a11eecde53ecefc1d
F src/expr.c 1f7fa7ddbdffd89898a3ce5ff1e57d137ec87aa5
F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
F src/fkey.c 8545f3b36da47473e10800ea4fb0810fd4062514
F src/func.c 3bc223ea36cd29a91c481485343d0ee4257ab8dc
@@ -227,7 +227,7 @@ F src/shell.c 191129c3f7a9cf241aea90ff6a6be3e74d3767f0
F src/sqlite.h.in 9bbc5815c73b0e77e68b5275481a5e3e7814a804
F src/sqlite3.rc 11094cc6a157a028b301a9f06b3d03089ea37c3e
F src/sqlite3ext.h 886f5a34de171002ad46fae8c36a7d8051c190fc
F src/sqliteInt.h 3b17ba74eec22781f51e7b3e4c73d2cbd458f89b
F src/sqliteInt.h 5cee19f34f6efe6e6f7733d55a5c59e3a35a378a
F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
F src/status.c 7ac05a5c7017d0b9f0b4bcd701228b784f987158
F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@@ -296,7 +296,7 @@ F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
F src/wal.c 264df50a1b33124130b23180ded2e2c5663c652a
F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
F src/walker.c 11edb74d587bc87b33ca96a5173e3ec1b8389e45
F src/where.c a7d0434de56d6a4b60cc98ec661969d521201d39
F src/where.c ce1b9a3a2573033cd15e0882719db7f211f21cdd
F src/whereInt.h 929c1349b5355fd44f22cee5c14d72b3329c58a6
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@@ -1185,7 +1185,8 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
P e75b26ee357bb3d3c1a539b05d633ebf314726d7
R 50d518176c08d9fef67243df4085599b
P 9abcf2698c09f4f6a44a68e74f9f6b538f3253d6 e13175d3579e1045165bab091b3b28951d691704
R b49330a02feffafe84f051ae1dbb9076
T +closed e13175d3579e1045165bab091b3b28951d691704
U drh
Z ae546b77e53655a859301e9ce422b440
Z e21436d3fd2e7daacda65f50d724cf15
manifest.uuid
+1 -1
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@@ -1 +1 @@
9abcf2698c09f4f6a44a68e74f9f6b538f3253d6
7c6fbcfe6ed5739e8e4639b7b123fbf9828cbfc0
src/expr.c
+30 -26
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@@ -1484,7 +1484,7 @@ int sqlite3CodeOnce(Parse *pParse){
** be used either to test for membership in the RHS set or to iterate through
** all members of the RHS set, skipping duplicates.
**
** A cursor is opened on the b-tree object that the RHS of the IN operator
** A cursor is opened on the b-tree object that is the RHS of the IN operator
** and pX->iTable is set to the index of that cursor.
**
** The returned value of this function indicates the b-tree type, as follows:
@@ -1505,21 +1505,28 @@ int sqlite3CodeOnce(Parse *pParse){
** pX->iTable made to point to the ephermeral table instead of an
** existing table.
**
** If the prNotFound parameter is 0, then the b-tree will be used to iterate
** through the set members, skipping any duplicates. In this case an
** epheremal table must be used unless the selected <column> is guaranteed
** The inFlags parameter must contain exactly one of the bits
** IN_INDEX_MEMBERSHIP or IN_INDEX_LOOP. If inFlags contains
** IN_INDEX_MEMBERSHIP, then the generated table will be used for a
** fast membership test. When the IN_INDEX_LOOP bit is set, the
** IN index will be used to loop over all values of the RHS of the
** IN operator.
**
** When IN_INDEX_LOOP is used (and the b-tree will be used to iterate
** through the set members) then the b-tree must not contain duplicates.
** An epheremal table must be used unless the selected <column> is guaranteed
** to be unique - either because it is an INTEGER PRIMARY KEY or it
** has a UNIQUE constraint or UNIQUE index.
**
** If the prNotFound parameter is not 0, then the b-tree will be used
** for fast set membership tests. In this case an epheremal table must
** When IN_INDEX_MEMBERSHIP is used (and the b-tree will be used
** for fast set membership tests) then an epheremal table must
** be used unless <column> is an INTEGER PRIMARY KEY or an index can
** be found with <column> as its left-most column.
**
** When the b-tree is being used for membership tests, the calling function
** needs to know whether or not the structure contains an SQL NULL
** value in order to correctly evaluate expressions like "X IN (Y, Z)".
** If there is any chance that the (...) might contain a NULL value at
** might need to know whether or not the RHS side of the IN operator
** contains a NULL. If prNotFound is not NULL and
** if there is any chance that the (...) might contain a NULL value at
** runtime, then a register is allocated and the register number written
** to *prNotFound. If there is no chance that the (...) contains a
** NULL value, then *prNotFound is left unchanged.
@@ -1540,14 +1547,15 @@ int sqlite3CodeOnce(Parse *pParse){
** test more often than is necessary.
*/
#ifndef SQLITE_OMIT_SUBQUERY
int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
int sqlite3FindInIndex(Parse *pParse, Expr *pX, u32 inFlags, int *prNotFound){
Select *p; /* SELECT to the right of IN operator */
int eType = 0; /* Type of RHS table. IN_INDEX_* */
int iTab = pParse->nTab++; /* Cursor of the RHS table */
int mustBeUnique = (prNotFound==0); /* True if RHS must be unique */
int mustBeUnique; /* True if RHS must be unique */
Vdbe *v = sqlite3GetVdbe(pParse); /* Virtual machine being coded */
assert( pX->op==TK_IN );
mustBeUnique = (inFlags & IN_INDEX_LOOP)!=0;
/* Check to see if an existing table or index can be used to
** satisfy the query. This is preferable to generating a new
@@ -1630,14 +1638,14 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
u32 savedNQueryLoop = pParse->nQueryLoop;
int rMayHaveNull = 0;
eType = IN_INDEX_EPH;
if( prNotFound ){
*prNotFound = rMayHaveNull = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Null, 0, *prNotFound);
}else{
if( inFlags & IN_INDEX_LOOP ){
pParse->nQueryLoop = 0;
if( pX->pLeft->iColumn<0 && !ExprHasProperty(pX, EP_xIsSelect) ){
eType = IN_INDEX_ROWID;
}
}else if( prNotFound ){
*prNotFound = rMayHaveNull = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Null, 0, rMayHaveNull);
}
sqlite3CodeSubselect(pParse, pX, rMayHaveNull, eType==IN_INDEX_ROWID);
pParse->nQueryLoop = savedNQueryLoop;
@@ -1668,15 +1676,9 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
**
** If rMayHaveNull is non-zero, that means that the operation is an IN
** (not a SELECT or EXISTS) and that the RHS might contains NULLs.
** Furthermore, the IN is in a WHERE clause and that we really want
** to iterate over the RHS of the IN operator in order to quickly locate
** all corresponding LHS elements. All this routine does is initialize
** the register given by rMayHaveNull to NULL. Calling routines will take
** care of changing this register value to non-NULL if the RHS is NULL-free.
**
** If rMayHaveNull is zero, that means that the subquery is being used
** for membership testing only. There is no need to initialize any
** registers to indicate the presence or absence of NULLs on the RHS.
** All this routine does is initialize the register given by rMayHaveNull
** to NULL. Calling routines will take care of changing this register
** value to non-NULL if the RHS is NULL-free.
**
** For a SELECT or EXISTS operator, return the register that holds the
** result. For IN operators or if an error occurs, the return value is 0.
@@ -1928,7 +1930,8 @@ static void sqlite3ExprCodeIN(
v = pParse->pVdbe;
assert( v!=0 ); /* OOM detected prior to this routine */
VdbeNoopComment((v, "begin IN expr"));
eType = sqlite3FindInIndex(pParse, pExpr, &rRhsHasNull);
eType = sqlite3FindInIndex(pParse, pExpr, IN_INDEX_MEMBERSHIP,
destIfFalse==destIfNull ? 0 : &rRhsHasNull);
/* Figure out the affinity to use to create a key from the results
** of the expression. affinityStr stores a static string suitable for
@@ -1974,7 +1977,8 @@ static void sqlite3ExprCodeIN(
** contains one or more NULL values, then the result of the
** expression is also NULL.
*/
if( rRhsHasNull==0 || destIfFalse==destIfNull ){
assert( destIfFalse!=destIfNull || rRhsHasNull==0 );
if( rRhsHasNull==0 ){
/* This branch runs if it is known at compile time that the RHS
** cannot contain NULL values. This happens as the result
** of a "NOT NULL" constraint in the database schema.
src/sqliteInt.h
+13 -5
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@@ -3591,11 +3591,19 @@ const char *sqlite3JournalModename(int);
#define sqlite3EndBenignMalloc()
#endif
#define IN_INDEX_ROWID 1
#define IN_INDEX_EPH 2
#define IN_INDEX_INDEX_ASC 3
#define IN_INDEX_INDEX_DESC 4
int sqlite3FindInIndex(Parse *, Expr *, int*);
/*
** Allowed return values from sqlite3FindInIndex()
*/
#define IN_INDEX_ROWID 1 /* Search the rowid of the table */
#define IN_INDEX_EPH 2 /* Search an ephemeral b-tree */
#define IN_INDEX_INDEX_ASC 3 /* Existing index ASCENDING */
#define IN_INDEX_INDEX_DESC 4 /* Existing index DESCENDING */
/*
** Allowed flags for the 3rd parameter to sqlite3FindInIndex().
*/
#define IN_INDEX_MEMBERSHIP 0x0001 /* IN operator used for membership test */
#define IN_INDEX_LOOP 0x0002 /* IN operator used as a loop */
int sqlite3FindInIndex(Parse *, Expr *, u32, int*);
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
src/where.c
+1 -1
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@@ -2522,7 +2522,7 @@ static int codeEqualityTerm(
}
assert( pX->op==TK_IN );
iReg = iTarget;
eType = sqlite3FindInIndex(pParse, pX, 0);
eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0);
if( eType==IN_INDEX_INDEX_DESC ){
testcase( bRev );
bRev = !bRev;