Index: src/expr.c
==================================================================
--- src/expr.c
+++ src/expr.c
@@ -771,11 +771,11 @@
     memset(pNew, 0, sizeof(Expr));
     pNew->op = (u8)op;
     pNew->iAgg = -1;
     if( pToken ){
       if( nExtra==0 ){
-        pNew->flags |= EP_IntValue|EP_Leaf;
+        pNew->flags |= EP_IntValue|EP_Leaf|(iValue?EP_IsTrue:EP_IsFalse);
         pNew->u.iValue = iValue;
       }else{
         pNew->u.zToken = (char*)&pNew[1];
         assert( pToken->z!=0 || pToken->n==0 );
         if( pToken->n ) memcpy(pNew->u.zToken, pToken->z, pToken->n);
@@ -878,37 +878,10 @@
     sqlite3SelectDelete(pParse->db, pSelect);
   }
 }
 
 
-/*
-** If the expression is always either TRUE or FALSE (respectively),
-** then return 1.  If one cannot determine the truth value of the
-** expression at compile-time return 0.
-**
-** This is an optimization.  If is OK to return 0 here even if
-** the expression really is always false or false (a false negative).
-** But it is a bug to return 1 if the expression might have different
-** boolean values in different circumstances (a false positive.)
-**
-** Note that if the expression is part of conditional for a
-** LEFT JOIN, then we cannot determine at compile-time whether or not
-** is it true or false, so always return 0.
-*/
-static int exprAlwaysTrue(Expr *p){
-  int v = 0;
-  if( ExprHasProperty(p, EP_FromJoin) ) return 0;
-  if( !sqlite3ExprIsInteger(p, &v) ) return 0;
-  return v!=0;
-}
-static int exprAlwaysFalse(Expr *p){
-  int v = 0;
-  if( ExprHasProperty(p, EP_FromJoin) ) return 0;
-  if( !sqlite3ExprIsInteger(p, &v) ) return 0;
-  return v==0;
-}
-
 /*
 ** Join two expressions using an AND operator.  If either expression is
 ** NULL, then just return the other expression.
 **
 ** If one side or the other of the AND is known to be false, then instead
@@ -921,11 +894,11 @@
     return pRight;
   }else if( pRight==0 ){
     return pLeft;
   }else if( pParse->nErr || IN_RENAME_OBJECT ){
     return sqlite3PExpr(pParse, TK_AND, pLeft, pRight);
-  }else if( exprAlwaysFalse(pLeft) || exprAlwaysFalse(pRight) ){
+  }else if( ExprAlwaysFalse(pLeft) || ExprAlwaysFalse(pRight) ){
     sqlite3ExprDelete(db, pLeft);
     sqlite3ExprDelete(db, pRight);
     return sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0);
   }else{
     return sqlite3PExpr(pParse, TK_AND, pLeft, pRight);
@@ -1816,10 +1789,11 @@
   if( !ExprHasProperty(pExpr, EP_Quoted)
    && (sqlite3StrICmp(pExpr->u.zToken, "true")==0
        || sqlite3StrICmp(pExpr->u.zToken, "false")==0)
   ){
     pExpr->op = TK_TRUEFALSE;
+    ExprSetProperty(pExpr, pExpr->u.zToken[4]==0 ? EP_IsTrue : EP_IsFalse);
     return 1;
   }
   return 0;
 }
 
@@ -4520,13 +4494,13 @@
       break;
     }
 #endif
     default: {
     default_expr:
-      if( exprAlwaysTrue(pExpr) ){
+      if( ExprAlwaysTrue(pExpr) ){
         sqlite3VdbeGoto(v, dest);
-      }else if( exprAlwaysFalse(pExpr) ){
+      }else if( ExprAlwaysFalse(pExpr) ){
         /* No-op */
       }else{
         r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
         sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0);
         VdbeCoverage(v);
@@ -4690,13 +4664,13 @@
       break;
     }
 #endif
     default: {
     default_expr: 
-      if( exprAlwaysFalse(pExpr) ){
+      if( ExprAlwaysFalse(pExpr) ){
         sqlite3VdbeGoto(v, dest);
-      }else if( exprAlwaysTrue(pExpr) ){
+      }else if( ExprAlwaysTrue(pExpr) ){
         /* no-op */
       }else{
         r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
         sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0);
         VdbeCoverage(v);

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -2528,10 +2528,12 @@
 #define EP_Leaf      0x800000 /* Expr.pLeft, .pRight, .u.pSelect all NULL */
 #define EP_WinFunc  0x1000000 /* TK_FUNCTION with Expr.y.pWin set */
 #define EP_Subrtn   0x2000000 /* Uses Expr.y.sub. TK_IN, _SELECT, or _EXISTS */
 #define EP_Quoted   0x4000000 /* TK_ID was originally quoted */
 #define EP_Static   0x8000000 /* Held in memory not obtained from malloc() */
+#define EP_IsTrue  0x10000000 /* Always has boolean value of TRUE */
+#define EP_IsFalse 0x20000000 /* Always has boolean value of FALSE */
 
 /*
 ** The EP_Propagate mask is a set of properties that automatically propagate
 ** upwards into parent nodes.
 */
@@ -2543,10 +2545,12 @@
 */
 #define ExprHasProperty(E,P)     (((E)->flags&(P))!=0)
 #define ExprHasAllProperty(E,P)  (((E)->flags&(P))==(P))
 #define ExprSetProperty(E,P)     (E)->flags|=(P)
 #define ExprClearProperty(E,P)   (E)->flags&=~(P)
+#define ExprAlwaysTrue(E)   (((E)->flags&(EP_FromJoin|EP_IsTrue))==EP_IsTrue)
+#define ExprAlwaysFalse(E)  (((E)->flags&(EP_FromJoin|EP_IsFalse))==EP_IsFalse)
 
 /* The ExprSetVVAProperty() macro is used for Verification, Validation,
 ** and Accreditation only.  It works like ExprSetProperty() during VVA
 ** processes but is a no-op for delivery.
 */