Claw back most of the performance lost in the previous commit.

FossilOrigin-Name: df8ce2675b070fcdc338918e7652a26ffc90439fe399ceac206fadf8a93a681f

2 files changed, 18 insertions, 8 deletions

diff --git a/src/update.c b/src/update.c
index 04648149c..f8cb2afed 100644
--- a/src/update.c
+++ b/src/update.c
@@ -652,8 +652,7 @@ void sqlite3Update(
   if( nChangeFrom==0 && HasRowid(pTab) ){
     sqlite3VdbeAddOp3(v, OP_Null, 0, regRowSet, regOldRowid);
     iEph = pParse->nTab++;
-    addrOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEph, 0);
-    sqlite3VdbeLoadString(v, regRowSet, "");
+    addrOpen = sqlite3VdbeAddOp3(v, OP_OpenEphemeral, iEph, 0, regRowSet);
   }else{
     assert( pPk!=0 || HasRowid(pTab) );
     nPk = pPk ? pPk->nKeyCol : 0;
@@ -748,7 +747,7 @@ void sqlite3Update(
         aRegIdx[nAllIdx] = ++pParse->nMem;
         sqlite3VdbeAddOp3(v, OP_Insert, iEph, regRowSet, regOldRowid);
       }else{
-        if( addrOpen ) sqlite3VdbeChangeToNoop(v, addrOpen);
+        if( ALWAYS(addrOpen) ) sqlite3VdbeChangeToNoop(v, addrOpen);
       }
     }else{
       /* Read the PK of the current row into an array of registers. In
@@ -1088,11 +1087,9 @@ void sqlite3Update(
   }else if( eOnePass==ONEPASS_MULTI ){
     sqlite3VdbeResolveLabel(v, labelContinue);
     sqlite3WhereEnd(pWInfo);
-  }else /*if( pPk || nChangeFrom )*/{
+  }else{
     sqlite3VdbeResolveLabel(v, labelContinue);
     sqlite3VdbeAddOp2(v, OP_Next, iEph, addrTop); VdbeCoverage(v);
-//  }else{
-//    sqlite3VdbeGoto(v, labelContinue);
   }
   sqlite3VdbeResolveLabel(v, labelBreak);
 
diff --git a/src/vdbe.c b/src/vdbe.c
index 5823ebd92..b9b6b398a 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3901,7 +3901,7 @@ case OP_OpenDup: {
 }
 
 
-/* Opcode: OpenEphemeral P1 P2 * P4 P5
+/* Opcode: OpenEphemeral P1 P2 P3 P4 P5
 ** Synopsis: nColumn=P2
 **
 ** Open a new cursor P1 to a transient table.
@@ -3921,6 +3921,10 @@ case OP_OpenDup: {
 ** in btree.h.  These flags control aspects of the operation of
 ** the btree.  The BTREE_OMIT_JOURNAL and BTREE_SINGLE flags are
 ** added automatically.
+**
+** If P3 is positive, then reg[P3] is modified slightly so that it
+** can be used as zero-length data for OP_Insert.  This is an optimization
+** that avoids an extra OP_Blob opcode to initialize that register.
 */
 /* Opcode: OpenAutoindex P1 P2 * P4 *
 ** Synopsis: nColumn=P2
@@ -3943,6 +3947,15 @@ case OP_OpenEphemeral: {
       SQLITE_OPEN_TRANSIENT_DB;
   assert( pOp->p1>=0 );
   assert( pOp->p2>=0 );
+  if( pOp->p3>0 ){
+    /* Make register reg[P3] into a value that can be used as the data
+    ** form sqlite3BtreeInsert() where the length of the data is zero. */
+    assert( pOp->p2==0 ); /* Only used when number of columns is zero */
+    assert( pOp->opcode==OP_OpenEphemeral );
+    assert( aMem[pOp->p3].flags & MEM_Null );
+    aMem[pOp->p3].n = 0;
+    aMem[pOp->p3].z = "";
+  }
   pCx = p->apCsr[pOp->p1];
   if( pCx && pCx->pBtx ){
     /* If the ephermeral table is already open, erase all existing content
@@ -5102,7 +5115,7 @@ case OP_Insert: {
 
   if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
   if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = x.nKey;
-  assert( pData->flags & (MEM_Blob|MEM_Str) );
+  assert( (pData->flags & (MEM_Blob|MEM_Str))!=0 || pData->n==0 );
   x.pData = pData->z;
   x.nData = pData->n;
   seekResult = ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0);