Index: src/select.c
==================================================================
--- src/select.c
+++ src/select.c
@@ -5938,13 +5938,15 @@
 
       sqlite3WindowCodeStep(pParse, p, pWInfo, regGosub, addrGosub);
 
       sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak);
       sqlite3VdbeResolveLabel(v, addrGosub);
+      VdbeNoopComment((v, "SELECT inner-loop subroutine"));
       selectInnerLoop(pParse, p, -1, &sSort, &sDistinct, pDest, iCont, iBreak);
       sqlite3VdbeResolveLabel(v, iCont);
       sqlite3VdbeAddOp1(v, OP_Return, regGosub);
+      VdbeComment((v, "end inner-loop subroutine"));
       sqlite3VdbeResolveLabel(v, iBreak);
     }else
 #endif /* SQLITE_OMIT_WINDOWFUNC */
     {
       /* Use the standard inner loop. */

Index: src/window.c
==================================================================
--- src/window.c
+++ src/window.c
@@ -1032,13 +1032,17 @@
   Vdbe *v = sqlite3GetVdbe(pParse);
   int regZero = sqlite3GetTempReg(pParse);
   assert( eCond==0 || eCond==1 || eCond==2 );
   sqlite3VdbeAddOp2(v, OP_Integer, 0, regZero);
   sqlite3VdbeAddOp2(v, OP_MustBeInt, reg, sqlite3VdbeCurrentAddr(v)+2);
-  VdbeCoverage(v);
+  VdbeCoverageIf(v, eCond==0);
+  VdbeCoverageIf(v, eCond==1);
+  VdbeCoverageIf(v, eCond==2);
   sqlite3VdbeAddOp3(v, aOp[eCond], regZero, sqlite3VdbeCurrentAddr(v)+2, reg);
-  VdbeCoverage(v);
+  VdbeCoverageIf(v, eCond==0);
+  VdbeCoverageIf(v, eCond==1);
+  VdbeCoverageIf(v, eCond==2);
   sqlite3VdbeAddOp2(v, OP_Halt, SQLITE_ERROR, OE_Abort);
   sqlite3VdbeAppendP4(v, (void*)azErr[eCond], P4_STATIC);
   sqlite3ReleaseTempReg(pParse, regZero);
 }
 
@@ -1248,10 +1252,11 @@
     sqlite3VdbeAppendP4(v, (void*)pKeyInfo, P4_KEYINFO);
     sqlite3VdbeAddOp3(v, OP_Jump, addr+2, addr+4, addr+2);
     VdbeCoverage(v);
     sqlite3VdbeAddOp3(v, OP_Copy, regNewPart, pMWin->regPart, nPart-1);
     sqlite3VdbeAddOp2(v, OP_Gosub, regFlushPart, lblFlushPart);
+    VdbeComment((v, "call flush_partition"));
   }
 
   /* Buffer the current row in the ephemeral table. */
   sqlite3VdbeAddOp2(v, OP_NewRowid, pMWin->iEphCsr, regRowid);
   sqlite3VdbeAddOp3(v, OP_Insert, pMWin->iEphCsr, regRecord, regRowid);
@@ -1259,10 +1264,11 @@
   /* End of the input loop */
   sqlite3WhereEnd(pWInfo);
 
   /* Invoke "flush_partition" to deal with the final (or only) partition */
   sqlite3VdbeAddOp2(v, OP_Gosub, regFlushPart, lblFlushPart);
+  VdbeComment((v, "call flush_partition"));
 }
 
 /*
 ** Invoke the sub-routine at regGosub (generated by code in select.c) to
 ** return the current row of Window.iEphCsr. If all window functions are
@@ -1586,10 +1592,11 @@
 
   /* Start of "flush_partition" */
   sqlite3VdbeResolveLabel(v, lblFlushPart);
   sqlite3VdbeAddOp2(v, OP_Once, 0, sqlite3VdbeCurrentAddr(v)+3);
   VdbeCoverage(v);
+  VdbeComment((v, "Flush_partition subroutine"));
   sqlite3VdbeAddOp2(v, OP_OpenDup, csrStart, pMWin->iEphCsr);
   sqlite3VdbeAddOp2(v, OP_OpenDup, csrEnd, pMWin->iEphCsr);
 
   /* If either regStart or regEnd are not non-negative integers, throw 
   ** an exception.  */
@@ -1707,10 +1714,11 @@
 
   /* flush_partition_done: */
   sqlite3VdbeResolveLabel(v, lblFlushDone);
   sqlite3VdbeAddOp1(v, OP_ResetSorter, pMWin->iEphCsr);
   sqlite3VdbeAddOp1(v, OP_Return, regFlushPart);
+  VdbeComment((v, "end flush_partition subroutine"));
 
   /* Jump to here to skip over flush_partition */
   sqlite3VdbeJumpHere(v, addrGoto);
 }