Reuse registers better in the inner loop of a SELECT statement. (CVS 4719)

FossilOrigin-Name: 5ba4e5adf638c6812a2813961ea30a11a670409c

diff --git a/manifest b/manifest
index a599ffc1a0c0a087d1f789900cdfcea69de8541f..a47b52cc73faad424fcfdfd2a3a4fae6cb404283 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Registerification\sof\sthe\sVDBE\sis\scomplete.\s\sThe\soperand\sstack\shas\sbeen\nremoved\sfrom\sthe\scode.\s\sAll\sinstructions\soperate\sout\sof\sregisters\sonly.\s(CVS\s4718)
-D 2008-01-17T16:22:14
+C Reuse\sregisters\sbetter\sin\sthe\sinner\sloop\sof\sa\sSELECT\sstatement.\s(CVS\s4719)
+D 2008-01-17T17:15:56
 F Makefile.arm-wince-mingw32ce-gcc ac5f7b2cef0cd850d6f755ba6ee4ab961b1fadf7
 F Makefile.in 30789bf70614bad659351660d76b8e533f3340e9
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -92,7 +92,7 @@ F src/complete.c 4cf68fd75d60257524cbe74f87351b9848399131
 F src/date.c 49c5a6d2de6c12000905b4d36868b07d3011bbf6
 F src/delete.c 739ccbab8fa7478762bded5c9cc67f16a4d09dbe
 F src/experimental.c 1b2d1a6cd62ecc39610e97670332ca073c50792b
-F src/expr.c 217ba4f47ffc17b10c79b091d896535e28aaa033
+F src/expr.c f13ad688f64d93efe6c4f86c46e9d172d9166217
 F src/func.c 996071cf0af9d967e58b69fce1909555059ebc7d
 F src/hash.c 45a7005aac044b6c86bd7e49c44bc15d30006d6c
 F src/hash.h 031cd9f915aff27e12262cb9eb570ac1b8326b53
@@ -131,7 +131,7 @@ F src/pragma.c 155315ee3e6a861a0060ba4d184dfffd08ebbc03
 F src/prepare.c c31a879d6795f4765fd0b113675c6debbc96b7fd
 F src/printf.c eb27822ba2eec669161409ca31279a24c26ac910
 F src/random.c 02ef38b469237482f1ea14a78b2087cfbaec48bd
-F src/select.c fb2d6653954478c0a7f4ca64b5c4a6f024212296
+F src/select.c d9a394a2566849f9f7b03e2da3fd3ed4a91611eb
 F src/server.c 087b92a39d883e3fa113cae259d64e4c7438bc96
 F src/shell.c 0691a3d52dc37cf6ac2f74838e5ff8ae1055ac9b
 F src/sqlite.h.in 2a7e3776534bbe6ff2cdc058f3abebe91e7e429f
@@ -606,7 +606,7 @@ F www/tclsqlite.tcl 8be95ee6dba05eabcd27a9d91331c803f2ce2130
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
-P 5581160f43c60825d03de58e67aa66904d9d8964
-R 9b66d11764748ee0bf0a1a49c0663779
+P 706b41b70bd1e2030e6fa44358c38a26c5cf0985
+R 87052e903d0b7d48d785076f690c7979
 U drh
-Z a08c417a1e9cffb9cc564c4f53d0978f
+Z 0235b0e407d857e973632bb3bd532b62

diff --git a/manifest.uuid b/manifest.uuid
index c19098bb27f253a249cbdb2f575af97e1097feea..4701dc7a9db1bf864846429f618f4c5e7e148436 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-706b41b70bd1e2030e6fa44358c38a26c5cf0985
\ No newline at end of file
+5ba4e5adf638c6812a2813961ea30a11a670409c
\ No newline at end of file

diff --git a/src/expr.c b/src/expr.c
index 6693db4614d9605914d37f0dffd83fa5cb6aa466..cfae6450d10ebf2eb8e357ef78d188928312d924 100644 (file)
--- a/src/expr.c
+++ b/src/expr.c
@@ -12,7 +12,7 @@
 ** This file contains routines used for analyzing expressions and
 ** for generating VDBE code that evaluates expressions in SQLite.
 **
-** $Id: expr.c,v 1.347 2008/01/17 16:22:15 drh Exp $
+** $Id: expr.c,v 1.348 2008/01/17 17:15:56 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -2162,7 +2162,7 @@ static int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
         r1 = sqlite3GetTempRange(pParse, nExpr);
         sqlite3ExprCodeExprList(pParse, pList, r1);
       }else{
-        nExpr = 0;
+        nExpr = r1 = 0;
       }
 #ifndef SQLITE_OMIT_VIRTUALTABLE
       /* Possibly overload the function if the first argument is

diff --git a/src/select.c b/src/select.c
index 4c6b1f2b80f5010d3b1d1a1f13ff77aac69bf479..55334a08aae56a0c2c7892b222b9d372e5061b86 100644 (file)
--- a/src/select.c
+++ b/src/select.c
@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle SELECT statements in SQLite.
 **
-** $Id: select.c,v 1.404 2008/01/17 16:22:15 drh Exp $
+** $Id: select.c,v 1.405 2008/01/17 17:15:56 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -516,11 +516,13 @@ static int selectInnerLoop(
   char *aff               /* affinity string if eDest is SRT_Union */
 ){
   Vdbe *v = pParse->pVdbe;
-  int i, n;
+  int i;
   int hasDistinct;        /* True if the DISTINCT keyword is present */
-  int iMem;               /* Start of memory holding result set */
-  int eDest = pDest->eDest;
-  int iParm = pDest->iParm;
+  int regResult;              /* Start of memory holding result set */
+  int eDest = pDest->eDest;   /* How to dispose of results */
+  int iParm = pDest->iParm;   /* First argument to disposal method */
+  int nResultCol;             /* Number of result columns */
+  int nToFree;                /* Number of result columns to release */
 
   if( v==0 ) return 0;
   assert( pEList!=0 );
@@ -536,29 +538,30 @@ static int selectInnerLoop(
   /* Pull the requested columns.
   */
   if( nColumn>0 ){
-    n = nColumn;
+    nResultCol = nColumn;
   }else{
-    n = pEList->nExpr;
+    nResultCol = pEList->nExpr;
   }
   if( pDest->iMem>0 ){
-    iMem = pDest->iMem;
+    regResult = pDest->iMem;
+    nToFree = 0;
   }else{
-    pDest->iMem = iMem = pParse->nMem+1;
-    pParse->nMem += n;
+    pDest->iMem = regResult = sqlite3GetTempRange(pParse, nResultCol);
+    nToFree = nResultCol;
   }
   if( nColumn>0 ){
     for(i=0; i<nColumn; i++){
-      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, iMem+i);
+      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
     }
   }else if( eDest!=SRT_Exists ){
     /* If the destination is an EXISTS(...) expression, the actual
     ** values returned by the SELECT are not required.
     */
-    for(i=0; i<n; i++){
-      sqlite3ExprCode(pParse, pEList->a[i].pExpr, iMem+i);
+    for(i=0; i<nResultCol; i++){
+      sqlite3ExprCode(pParse, pEList->a[i].pExpr, regResult+i);
     }
   }
-  nColumn = n;
+  nColumn = nResultCol;
 
   /* If the DISTINCT keyword was present on the SELECT statement
   ** and this row has been seen before, then do not make this row
@@ -567,7 +570,7 @@ static int selectInnerLoop(
   if( hasDistinct ){
     assert( pEList!=0 );
     assert( pEList->nExpr==nColumn );
-    codeDistinct(pParse, distinct, iContinue, nColumn, iMem);
+    codeDistinct(pParse, distinct, iContinue, nColumn, regResult);
     if( pOrderBy==0 ){
       codeOffset(v, p, iContinue);
     }
@@ -585,7 +588,7 @@ static int selectInnerLoop(
     case SRT_Union: {
       int r1;
       r1 = sqlite3GetTempReg(pParse);
-      sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
       if( aff ){
         sqlite3VdbeChangeP4(v, -1, aff, P4_STATIC);
       }
@@ -601,7 +604,7 @@ static int selectInnerLoop(
     case SRT_Except: {
       int addr, r1;
       r1 = sqlite3GetTempReg(pParse);
-      addr = sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
+      addr = sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
       sqlite3VdbeChangeP4(v, -1, aff, P4_STATIC);
       sqlite3VdbeAddOp3(v, OP_NotFound, iParm, addr+3, r1);
       sqlite3VdbeAddOp1(v, OP_Delete, iParm);
@@ -615,7 +618,7 @@ static int selectInnerLoop(
     case SRT_Table:
     case SRT_EphemTab: {
       int r1 = sqlite3GetTempReg(pParse);
-      sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
+      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
       if( pOrderBy ){
         pushOntoSorter(pParse, pOrderBy, p, r1);
       }else{
@@ -638,17 +641,17 @@ static int selectInnerLoop(
       int addr2;
 
       assert( nColumn==1 );
-      addr2 = sqlite3VdbeAddOp2(v, OP_IsNull, iMem, 0);
+      addr2 = sqlite3VdbeAddOp1(v, OP_IsNull, regResult);
       p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affinity);
       if( pOrderBy ){
         /* At first glance you would think we could optimize out the
         ** ORDER BY in this case since the order of entries in the set
         ** does not matter.  But there might be a LIMIT clause, in which
         ** case the order does matter */
-        pushOntoSorter(pParse, pOrderBy, p, iMem);
+        pushOntoSorter(pParse, pOrderBy, p, regResult);
       }else{
         int r1 = sqlite3GetTempReg(pParse);
-        sqlite3VdbeAddOp4(v, OP_MakeRecord, iMem, 1, r1, &p->affinity, 1);
+        sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, 1, r1, &p->affinity, 1);
         sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
         sqlite3ReleaseTempReg(pParse, r1);
       }
@@ -671,9 +674,9 @@ static int selectInnerLoop(
     case SRT_Mem: {
       assert( nColumn==1 );
       if( pOrderBy ){
-        pushOntoSorter(pParse, pOrderBy, p, iMem);
+        pushOntoSorter(pParse, pOrderBy, p, regResult);
       }else{
-        sqlite3VdbeAddOp2(v, OP_Move, iMem, iParm);
+        sqlite3VdbeAddOp2(v, OP_Move, regResult, iParm);
         /* The LIMIT clause will jump out of the loop for us */
       }
       break;
@@ -688,13 +691,14 @@ static int selectInnerLoop(
     case SRT_Callback: {
       if( pOrderBy ){
         int r1 = sqlite3GetTempReg(pParse);
-        sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
+        sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
         pushOntoSorter(pParse, pOrderBy, p, r1);
         sqlite3ReleaseTempReg(pParse, r1);
       }else if( eDest==SRT_Subroutine ){
+        nToFree = 0;  /* Preserve registers. Subroutine will need them. */
         sqlite3VdbeAddOp2(v, OP_Gosub, 0, iParm);
       }else{
-        sqlite3VdbeAddOp2(v, OP_ResultRow, iMem, nColumn);
+        sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn);
       }
       break;
     }
@@ -718,6 +722,7 @@ static int selectInnerLoop(
     sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
     sqlite3VdbeAddOp2(v, OP_IfZero, p->iLimit, iBreak);
   }
+  sqlite3ReleaseTempRange(pParse, regResult, nToFree);
   return 0;
 }