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Remove the column-cache from the code generator. The column-cache has been

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a persistent source of bugs for years and with recent improvements
in the performance of OP_Column, it no longer provides a benefit.  After
the column cache is removed, the binary is almost 2KB smaller and the
speed-check.sh performance test is over 3 million cycles faster.

FossilOrigin-Name: cdff3af7bedc5ebea04bd9b5e2112d3db451a475c18c9a9ebd45f6f3a89a43cb
This commit is contained in:
drh
2018-08-04 20:30:55 +00:00
parent bb9c45b49a cfdeeeb966
commit dda7e66d7d
19 changed files with 51 additions and 472 deletions
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276
src/expr.c
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@@ -581,7 +581,6 @@ static void codeVectorCompare(
Expr *pL, *pR;
int r1, r2;
assert( i>=0 && i<nLeft );
if( i>0 ) sqlite3ExprCachePush(pParse);
r1 = exprVectorRegister(pParse, pLeft, i, regLeft, &pL, &regFree1);
r2 = exprVectorRegister(pParse, pRight, i, regRight, &pR, &regFree2);
codeCompare(pParse, pL, pR, opx, r1, r2, dest, p5);
@@ -593,7 +592,6 @@ static void codeVectorCompare(
testcase(op==OP_Ne); VdbeCoverageIf(v,op==OP_Ne);
sqlite3ReleaseTempReg(pParse, regFree1);
sqlite3ReleaseTempReg(pParse, regFree2);
if( i>0 ) sqlite3ExprCachePop(pParse);
if( i==nLeft-1 ){
break;
}
@@ -2627,7 +2625,6 @@ int sqlite3CodeSubselect(
int rReg = 0; /* Register storing resulting */
Vdbe *v = sqlite3GetVdbe(pParse);
if( NEVER(v==0) ) return 0;
sqlite3ExprCachePush(pParse);
/* The evaluation of the IN/EXISTS/SELECT must be repeated every time it
** is encountered if any of the following is true:
@@ -2763,7 +2760,6 @@ int sqlite3CodeSubselect(
sqlite3VdbeAddOp3(v, OP_Insert, pExpr->iTable, r2, r3);
}else{
sqlite3VdbeAddOp4(v, OP_MakeRecord, r3, 1, r2, &affinity, 1);
sqlite3ExprCacheAffinityChange(pParse, r3, 1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, pExpr->iTable, r2, r3, 1);
}
}
@@ -2844,7 +2840,6 @@ int sqlite3CodeSubselect(
if( jmpIfDynamic>=0 ){
sqlite3VdbeJumpHere(v, jmpIfDynamic);
}
sqlite3ExprCachePop(pParse);
return rReg;
}
@@ -2963,7 +2958,6 @@ static void sqlite3ExprCodeIN(
** aiMap[] array contains a mapping from the original LHS field order to
** the field order that matches the RHS index.
*/
sqlite3ExprCachePush(pParse);
rLhsOrig = exprCodeVector(pParse, pLeft, &iDummy);
for(i=0; i<nVector && aiMap[i]==i; i++){} /* Are LHS fields reordered? */
if( i==nVector ){
@@ -3122,7 +3116,6 @@ static void sqlite3ExprCodeIN(
sqlite3ExprCodeIN_finished:
if( rLhs!=rLhsOrig ) sqlite3ReleaseTempReg(pParse, rLhs);
sqlite3ExprCachePop(pParse);
VdbeComment((v, "end IN expr"));
sqlite3ExprCodeIN_oom_error:
sqlite3DbFree(pParse->db, aiMap);
@@ -3190,152 +3183,6 @@ static void codeInteger(Parse *pParse, Expr *pExpr, int negFlag, int iMem){
}
}
/*
** Erase column-cache entry number i
*/
static void cacheEntryClear(Parse *pParse, int i){
if( pParse->aColCache[i].tempReg ){
if( pParse->nTempReg<ArraySize(pParse->aTempReg) ){
pParse->aTempReg[pParse->nTempReg++] = pParse->aColCache[i].iReg;
}
}
pParse->nColCache--;
if( i<pParse->nColCache ){
pParse->aColCache[i] = pParse->aColCache[pParse->nColCache];
}
}
/*
** Record in the column cache that a particular column from a
** particular table is stored in a particular register.
*/
void sqlite3ExprCacheStore(Parse *pParse, int iTab, int iCol, int iReg){
int i;
int minLru;
int idxLru;
struct yColCache *p;
/* Unless an error has occurred, register numbers are always positive. */
assert( iReg>0 || pParse->nErr || pParse->db->mallocFailed );
assert( iCol>=-1 && iCol<32768 ); /* Finite column numbers */
/* The SQLITE_ColumnCache flag disables the column cache. This is used
** for testing only - to verify that SQLite always gets the same answer
** with and without the column cache.
*/
if( OptimizationDisabled(pParse->db, SQLITE_ColumnCache) ) return;
/* First replace any existing entry.
**
** Actually, the way the column cache is currently used, we are guaranteed
** that the object will never already be in cache. Verify this guarantee.
*/
#ifndef NDEBUG
for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
assert( p->iTable!=iTab || p->iColumn!=iCol );
}
#endif
#ifdef SQLITE_DEBUG_COLUMNCACHE
/* Add a SetTabCol opcode for run-time verification that the column
** cache is working correctly.
*/
sqlite3VdbeAddOp3(pParse->pVdbe, OP_SetTabCol, iTab, iCol, iReg);
#endif
/* If the cache is already full, delete the least recently used entry */
if( pParse->nColCache>=SQLITE_N_COLCACHE ){
minLru = 0x7fffffff;
idxLru = -1;
for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
if( p->lru<minLru ){
idxLru = i;
minLru = p->lru;
}
}
p = &pParse->aColCache[idxLru];
}else{
p = &pParse->aColCache[pParse->nColCache++];
}
/* Add the new entry to the end of the cache */
p->iLevel = pParse->iCacheLevel;
p->iTable = iTab;
p->iColumn = iCol;
p->iReg = iReg;
p->tempReg = 0;
p->lru = pParse->iCacheCnt++;
}
/*
** Indicate that registers between iReg..iReg+nReg-1 are being overwritten.
** Purge the range of registers from the column cache.
*/
void sqlite3ExprCacheRemove(Parse *pParse, int iReg, int nReg){
int i = 0;
while( i<pParse->nColCache ){
struct yColCache *p = &pParse->aColCache[i];
if( p->iReg >= iReg && p->iReg < iReg+nReg ){
cacheEntryClear(pParse, i);
}else{
i++;
}
}
}
/*
** Remember the current column cache context. Any new entries added
** added to the column cache after this call are removed when the
** corresponding pop occurs.
*/
void sqlite3ExprCachePush(Parse *pParse){
pParse->iCacheLevel++;
#ifdef SQLITE_DEBUG
if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
printf("PUSH to %d\n", pParse->iCacheLevel);
}
#endif
}
/*
** Remove from the column cache any entries that were added since the
** the previous sqlite3ExprCachePush operation. In other words, restore
** the cache to the state it was in prior the most recent Push.
*/
void sqlite3ExprCachePop(Parse *pParse){
int i = 0;
assert( pParse->iCacheLevel>=1 );
pParse->iCacheLevel--;
#ifdef SQLITE_DEBUG
if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
printf("POP to %d\n", pParse->iCacheLevel);
}
#endif
while( i<pParse->nColCache ){
if( pParse->aColCache[i].iLevel>pParse->iCacheLevel ){
cacheEntryClear(pParse, i);
}else{
i++;
}
}
}
/*
** When a cached column is reused, make sure that its register is
** no longer available as a temp register. ticket #3879: that same
** register might be in the cache in multiple places, so be sure to
** get them all.
*/
static void sqlite3ExprCachePinRegister(Parse *pParse, int iReg){
int i;
struct yColCache *p;
for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
if( p->iReg==iReg ){
p->tempReg = 0;
}
}
}
/* Generate code that will load into register regOut a value that is
** appropriate for the iIdxCol-th column of index pIdx.
@@ -3391,12 +3238,7 @@ void sqlite3ExprCodeGetColumnOfTable(
/*
** Generate code that will extract the iColumn-th column from
** table pTab and store the column value in a register.
**
** An effort is made to store the column value in register iReg. This
** is not garanteeed for GetColumn() - the result can be stored in
** any register. But the result is guaranteed to land in register iReg
** for GetColumnToReg().
** table pTab and store the column value in register iReg.
**
** There must be an open cursor to pTab in iTable when this routine
** is called. If iColumn<0 then code is generated that extracts the rowid.
@@ -3410,99 +3252,23 @@ int sqlite3ExprCodeGetColumn(
u8 p5 /* P5 value for OP_Column + FLAGS */
){
Vdbe *v = pParse->pVdbe;
int i;
struct yColCache *p;
for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
if( p->iTable==iTable && p->iColumn==iColumn ){
p->lru = pParse->iCacheCnt++;
sqlite3ExprCachePinRegister(pParse, p->iReg);
#ifdef SQLITE_DEBUG_COLUMNCACHE
sqlite3VdbeAddOp3(v, OP_VerifyTabCol, iTable, iColumn, p->iReg);
#endif
return p->iReg;
}
}
assert( v!=0 );
sqlite3ExprCodeGetColumnOfTable(v, pTab, iTable, iColumn, iReg);
if( p5 ){
sqlite3VdbeChangeP5(v, p5);
}else{
sqlite3ExprCacheStore(pParse, iTable, iColumn, iReg);
}
return iReg;
}
void sqlite3ExprCodeGetColumnToReg(
Parse *pParse, /* Parsing and code generating context */
Table *pTab, /* Description of the table we are reading from */
int iColumn, /* Index of the table column */
int iTable, /* The cursor pointing to the table */
int iReg /* Store results here */
){
int r1 = sqlite3ExprCodeGetColumn(pParse, pTab, iColumn, iTable, iReg, 0);
if( r1!=iReg ) sqlite3VdbeAddOp2(pParse->pVdbe, OP_SCopy, r1, iReg);
}
/*
** Clear all column cache entries.
*/
void sqlite3ExprCacheClear(Parse *pParse){
int i;
#ifdef SQLITE_DEBUG
if( pParse->db->flags & SQLITE_VdbeAddopTrace ){
printf("CLEAR\n");
}
#endif
for(i=0; i<pParse->nColCache; i++){
if( pParse->aColCache[i].tempReg
&& pParse->nTempReg<ArraySize(pParse->aTempReg)
){
pParse->aTempReg[pParse->nTempReg++] = pParse->aColCache[i].iReg;
}
}
pParse->nColCache = 0;
}
/*
** Record the fact that an affinity change has occurred on iCount
** registers starting with iStart.
*/
void sqlite3ExprCacheAffinityChange(Parse *pParse, int iStart, int iCount){
sqlite3ExprCacheRemove(pParse, iStart, iCount);
}
/*
** Generate code to move content from registers iFrom...iFrom+nReg-1
** over to iTo..iTo+nReg-1. Keep the column cache up-to-date.
** over to iTo..iTo+nReg-1.
*/
void sqlite3ExprCodeMove(Parse *pParse, int iFrom, int iTo, int nReg){
assert( iFrom>=iTo+nReg || iFrom+nReg<=iTo );
sqlite3VdbeAddOp3(pParse->pVdbe, OP_Move, iFrom, iTo, nReg);
sqlite3ExprCacheRemove(pParse, iFrom, nReg);
}
#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
/*
** Return true if any register in the range iFrom..iTo (inclusive)
** is used as part of the column cache.
**
** This routine is used within assert() and testcase() macros only
** and does not appear in a normal build.
*/
static int usedAsColumnCache(Parse *pParse, int iFrom, int iTo){
int i;
struct yColCache *p;
for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
int r = p->iReg;
if( r>=iFrom && r<=iTo ) return 1; /*NO_TEST*/
}
return 0;
}
#endif /* SQLITE_DEBUG || SQLITE_COVERAGE_TEST */
/*
** Convert a scalar expression node to a TK_REGISTER referencing
** register iReg. The caller must ensure that iReg already contains
@@ -3683,8 +3449,6 @@ expr_code_doover:
}
sqlite3VdbeAddOp2(v, OP_Cast, target,
sqlite3AffinityType(pExpr->u.zToken, 0));
testcase( usedAsColumnCache(pParse, inReg, inReg) );
sqlite3ExprCacheAffinityChange(pParse, inReg, 1);
return inReg;
}
#endif /* SQLITE_OMIT_CAST */
@@ -3870,10 +3634,7 @@ expr_code_doover:
for(i=1; i<nFarg; i++){
sqlite3VdbeAddOp2(v, OP_NotNull, target, endCoalesce);
VdbeCoverage(v);
sqlite3ExprCacheRemove(pParse, target, 1);
sqlite3ExprCachePush(pParse);
sqlite3ExprCode(pParse, pFarg->a[i].pExpr, target);
sqlite3ExprCachePop(pParse);
}
sqlite3VdbeResolveLabel(v, endCoalesce);
break;
@@ -3939,10 +3700,8 @@ expr_code_doover:
}
}
sqlite3ExprCachePush(pParse); /* Ticket 2ea2425d34be */
sqlite3ExprCodeExprList(pParse, pFarg, r1, 0,
SQLITE_ECEL_DUP|SQLITE_ECEL_FACTOR);
sqlite3ExprCachePop(pParse); /* Ticket 2ea2425d34be */
}else{
r1 = 0;
}
@@ -4115,9 +3874,7 @@ expr_code_doover:
case TK_IF_NULL_ROW: {
int addrINR;
addrINR = sqlite3VdbeAddOp1(v, OP_IfNullRow, pExpr->iTable);
sqlite3ExprCachePush(pParse);
inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
sqlite3ExprCachePop(pParse);
sqlite3VdbeJumpHere(v, addrINR);
sqlite3VdbeChangeP3(v, addrINR, inReg);
break;
@@ -4154,7 +3911,6 @@ expr_code_doover:
Expr opCompare; /* The X==Ei expression */
Expr *pX; /* The X expression */
Expr *pTest = 0; /* X==Ei (form A) or just Ei (form B) */
VVA_ONLY( int iCacheLevel = pParse->iCacheLevel; )
assert( !ExprHasProperty(pExpr, EP_xIsSelect) && pExpr->x.pList );
assert(pExpr->x.pList->nExpr > 0);
@@ -4178,7 +3934,6 @@ expr_code_doover:
regFree1 = 0;
}
for(i=0; i<nExpr-1; i=i+2){
sqlite3ExprCachePush(pParse);
if( pX ){
assert( pTest!=0 );
opCompare.pRight = aListelem[i].pExpr;
@@ -4191,18 +3946,13 @@ expr_code_doover:
testcase( aListelem[i+1].pExpr->op==TK_COLUMN );
sqlite3ExprCode(pParse, aListelem[i+1].pExpr, target);
sqlite3VdbeGoto(v, endLabel);
sqlite3ExprCachePop(pParse);
sqlite3VdbeResolveLabel(v, nextCase);
}
if( (nExpr&1)!=0 ){
sqlite3ExprCachePush(pParse);
sqlite3ExprCode(pParse, pEList->a[nExpr-1].pExpr, target);
sqlite3ExprCachePop(pParse);
}else{
sqlite3VdbeAddOp2(v, OP_Null, 0, target);
}
assert( pParse->db->mallocFailed || pParse->nErr>0
|| pParse->iCacheLevel==iCacheLevel );
sqlite3VdbeResolveLabel(v, endLabel);
break;
}
@@ -4562,18 +4312,14 @@ void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
int d2 = sqlite3VdbeMakeLabel(v);
testcase( jumpIfNull==0 );
sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,jumpIfNull^SQLITE_JUMPIFNULL);
sqlite3ExprCachePush(pParse);
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3VdbeResolveLabel(v, d2);
sqlite3ExprCachePop(pParse);
break;
}
case TK_OR: {
testcase( jumpIfNull==0 );
sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
sqlite3ExprCachePush(pParse);
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3ExprCachePop(pParse);
break;
}
case TK_NOT: {
@@ -4732,19 +4478,15 @@ void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
case TK_AND: {
testcase( jumpIfNull==0 );
sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
sqlite3ExprCachePush(pParse);
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3ExprCachePop(pParse);
break;
}
case TK_OR: {
int d2 = sqlite3VdbeMakeLabel(v);
testcase( jumpIfNull==0 );
sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, jumpIfNull^SQLITE_JUMPIFNULL);
sqlite3ExprCachePush(pParse);
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3VdbeResolveLabel(v, d2);
sqlite3ExprCachePop(pParse);
break;
}
case TK_NOT: {
@@ -5512,21 +5254,9 @@ int sqlite3GetTempReg(Parse *pParse){
/*
** Deallocate a register, making available for reuse for some other
** purpose.
**
** If a register is currently being used by the column cache, then
** the deallocation is deferred until the column cache line that uses
** the register becomes stale.
*/
void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
int i;
struct yColCache *p;
for(i=0, p=pParse->aColCache; i<pParse->nColCache; i++, p++){
if( p->iReg==iReg ){
p->tempReg = 1;
return;
}
}
pParse->aTempReg[pParse->nTempReg++] = iReg;
}
}
@@ -5540,7 +5270,6 @@ int sqlite3GetTempRange(Parse *pParse, int nReg){
i = pParse->iRangeReg;
n = pParse->nRangeReg;
if( nReg<=n ){
assert( !usedAsColumnCache(pParse, i, i+n-1) );
pParse->iRangeReg += nReg;
pParse->nRangeReg -= nReg;
}else{
@@ -5554,7 +5283,6 @@ void sqlite3ReleaseTempRange(Parse *pParse, int iReg, int nReg){
sqlite3ReleaseTempReg(pParse, iReg);
return;
}
sqlite3ExprCacheRemove(pParse, iReg, nReg);
if( nReg>pParse->nRangeReg ){
pParse->nRangeReg = nReg;
pParse->iRangeReg = iReg;