Index: src/expr.c
==================================================================
--- src/expr.c
+++ src/expr.c
@@ -3190,10 +3190,14 @@
   Table *pTab,    /* The table containing the value */
   int iTabCur,    /* The table cursor.  Or the PK cursor for WITHOUT ROWID */
   int iCol,       /* Index of the column to extract */
   int regOut      /* Extract the value into this register */
 ){
+  if( pTab==0 ){
+    sqlite3VdbeAddOp3(v, OP_Column, iTabCur, iCol, regOut);
+    return;
+  }
   if( iCol<0 || iCol==pTab->iPKey ){
     sqlite3VdbeAddOp2(v, OP_Rowid, iTabCur, regOut);
   }else{
     int op = IsVirtual(pTab) ? OP_VColumn : OP_Column;
     int x = iCol;

Index: src/select.c
==================================================================
--- src/select.c
+++ src/select.c
@@ -3145,11 +3145,11 @@
 ** unchanged.)
 **
 ** This routine is part of the flattening procedure.  A subquery
 ** whose result set is defined by pEList appears as entry in the
 ** FROM clause of a SELECT such that the VDBE cursor assigned to that
-** FORM clause entry is iTable.  This routine make the necessary 
+** FORM clause entry is iTable.  This routine makes the necessary 
 ** changes to pExpr so that it refers directly to the source table
 ** of the subquery rather the result set of the subquery.
 */
 static Expr *substExpr(
   Parse *pParse,      /* Report errors here */

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -3322,10 +3322,11 @@
     SrcList *pSrcList;                         /* FROM clause */
     struct SrcCount *pSrcCount;                /* Counting column references */
     struct CCurHint *pCCurHint;                /* Used by codeCursorHint() */
     int *aiCol;                                /* array of column indexes */
     struct IdxCover *pIdxCover;                /* Check for index coverage */
+    struct IdxExprTrans *pIdxTrans;            /* Convert indexed expr to column */
   } u;
 };
 
 /* Forward declarations */
 int sqlite3WalkExpr(Walker*, Expr*);

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -4445,10 +4445,11 @@
     goto whereBeginError;
   }
   pWInfo->pParse = pParse;
   pWInfo->pTabList = pTabList;
   pWInfo->pOrderBy = pOrderBy;
+  pWInfo->pWhere = pWhere;
   pWInfo->pResultSet = pResultSet;
   pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1;
   pWInfo->nLevel = nTabList;
   pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(v);
   pWInfo->wctrlFlags = wctrlFlags;

Index: src/whereInt.h
==================================================================
--- src/whereInt.h
+++ src/whereInt.h
@@ -415,10 +415,11 @@
 struct WhereInfo {
   Parse *pParse;            /* Parsing and code generating context */
   SrcList *pTabList;        /* List of tables in the join */
   ExprList *pOrderBy;       /* The ORDER BY clause or NULL */
   ExprList *pResultSet;     /* Result set of the query */
+  Expr *pWhere;             /* The complete WHERE clause */
   LogEst iLimit;            /* LIMIT if wctrlFlags has WHERE_USE_LIMIT */
   int aiCurOnePass[2];      /* OP_OpenWrite cursors for the ONEPASS opt */
   int iContinue;            /* Jump here to continue with next record */
   int iBreak;               /* Jump here to break out of the loop */
   int savedNQueryLoop;      /* pParse->nQueryLoop outside the WHERE loop */

Index: src/wherecode.c
==================================================================
--- src/wherecode.c
+++ src/wherecode.c
@@ -1037,10 +1037,65 @@
     assert( nReg==1 );
     sqlite3ExprCode(pParse, p, iReg);
   }
 }
 
+#if 1 /* INDEXEXPRTRANS */
+typedef struct IdxExprTrans {
+  Expr *pIdxExpr;    /* The index expression */
+  int iTabCur;       /* The cursor of the corresponding table */
+  int iIdxCur;       /* The cursor for the index */
+  int iIdxCol;       /* The column for the index */
+} IdxExprTrans;
+
+static int whereIndexExprTransNode(Walker *p, Expr *pExpr){
+  IdxExprTrans *pX = p->u.pIdxTrans;
+  if( sqlite3ExprCompare(pExpr, pX->pIdxExpr, pX->iTabCur)==0 ){
+    pExpr->op = TK_COLUMN;
+    pExpr->iTable = pX->iIdxCur;
+    pExpr->iColumn = pX->iIdxCol;
+    pExpr->pTab = 0;
+    return WRC_Prune;
+  }else{
+    return WRC_Continue;
+  }
+}
+
+/*
+** For an indexes on expression X, locate every instance of expression X in pExpr
+** and change that subexpression into a reference to the appropriate column of
+** the index.
+*/
+static void whereIndexExprTrans(
+  Index *pIdx,      /* The Index */
+  int iTabCur,      /* Cursor of the table that is being indexed */
+  int iIdxCur,      /* Cursor of the index itself */
+  WhereInfo *pWInfo /* Transform expressions in this WHERE clause */
+){
+  int iIdxCol;               /* Column number of the index */
+  ExprList *aColExpr;        /* Expressions that are indexed */
+  Walker w;
+  IdxExprTrans x;
+  aColExpr = pIdx->aColExpr;
+  if( aColExpr==0 ) return;  /* Not an index on expressions */
+  memset(&w, 0, sizeof(w));
+  w.xExprCallback = whereIndexExprTransNode;
+  w.u.pIdxTrans = &x;
+  x.iTabCur = iTabCur;
+  x.iIdxCur = iIdxCur;
+  for(iIdxCol=0; iIdxCol<aColExpr->nExpr; iIdxCol++){
+    if( pIdx->aiColumn[iIdxCol]!=XN_EXPR ) continue;
+    assert( aColExpr->a[iIdxCol].pExpr!=0 );
+    x.iIdxCol = iIdxCol;
+    x.pIdxExpr = aColExpr->a[iIdxCol].pExpr;
+    sqlite3WalkExpr(&w, pWInfo->pWhere);
+    sqlite3WalkExprList(&w, pWInfo->pOrderBy);
+    sqlite3WalkExprList(&w, pWInfo->pResultSet);
+  }
+}
+#endif
+
 /*
 ** Generate code for the start of the iLevel-th loop in the WHERE clause
 ** implementation described by pWInfo.
 */
 Bitmask sqlite3WhereCodeOneLoopStart(
@@ -1617,10 +1672,14 @@
         sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, iRowidReg+j);
       }
       sqlite3VdbeAddOp4Int(v, OP_NotFound, iCur, addrCont,
                            iRowidReg, pPk->nKeyCol); VdbeCoverage(v);
     }
+
+#if 1  /* INDEXEXPRTANS */
+    whereIndexExprTrans(pIdx, iCur, iIdxCur, pWInfo);
+#endif
 
     /* Record the instruction used to terminate the loop. */
     if( pLoop->wsFlags & WHERE_ONEROW ){
       pLevel->op = OP_Noop;
     }else if( bRev ){

Index: tool/addopcodes.tcl
==================================================================
--- tool/addopcodes.tcl
+++ tool/addopcodes.tcl
@@ -30,10 +30,11 @@
   ISNOT
   END_OF_FILE
   UNCLOSED_STRING
   FUNCTION
   COLUMN
+  IDXCOLUMN
   AGG_FUNCTION
   AGG_COLUMN
   UMINUS
   UPLUS
   REGISTER