1 files changed, 59 insertions, 22 deletions

diff --git a/src/expr.c b/src/expr.c
index 0484f3b45..874a044d7 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1808,6 +1808,33 @@ int sqlite3ExprTruthValue(const Expr *pExpr){
   return pExpr->u.zToken[4]==0;
 }
 
+/*
+** If pExpr is an AND or OR expression, try to simplify it by eliminating
+** terms that are always true or false.  Return the simplified expression.
+** Or return the original expression if no simplification is possible.
+**
+** Examples:
+**
+**     (x<10) AND true                =>   (x<10)
+**     (x<10) AND false               =>   false
+**     (x<10) AND (y=22 OR false)     =>   (x<10) AND (y=22)
+**     (x<10) AND (y=22 OR true)      =>   (x<10)
+**     (y=22) OR true                 =>   true
+*/
+Expr *sqlite3ExprSimplifiedAndOr(Expr *pExpr){
+  assert( pExpr!=0 );
+  if( pExpr->op==TK_AND || pExpr->op==TK_OR ){
+    Expr *pRight = sqlite3ExprSimplifiedAndOr(pExpr->pRight);
+    Expr *pLeft = sqlite3ExprSimplifiedAndOr(pExpr->pLeft);
+    if( ExprAlwaysTrue(pLeft) || ExprAlwaysFalse(pRight) ){
+      pExpr = pExpr->op==TK_AND ? pRight : pLeft;
+    }else if( ExprAlwaysTrue(pRight) || ExprAlwaysFalse(pLeft) ){
+      pExpr = pExpr->op==TK_AND ? pLeft : pRight;
+    }
+  }
+  return pExpr;
+}
+
 
 /*
 ** These routines are Walker callbacks used to check expressions to
@@ -4399,18 +4426,23 @@ void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
   if( NEVER(pExpr==0) ) return;  /* No way this can happen */
   op = pExpr->op;
   switch( op ){
-    case TK_AND: {
-      int d2 = sqlite3VdbeMakeLabel(pParse);
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,jumpIfNull^SQLITE_JUMPIFNULL);
-      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
-      sqlite3VdbeResolveLabel(v, d2);
-      break;
-    }
+    case TK_AND:
     case TK_OR: {
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
-      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
+      Expr *pAlt = sqlite3ExprSimplifiedAndOr(pExpr);
+      if( pAlt!=pExpr ){
+        sqlite3ExprIfTrue(pParse, pAlt, dest, jumpIfNull);
+      }else if( op==TK_AND ){
+        int d2 = sqlite3VdbeMakeLabel(pParse);
+        testcase( jumpIfNull==0 );
+        sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,
+                           jumpIfNull^SQLITE_JUMPIFNULL);
+        sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
+        sqlite3VdbeResolveLabel(v, d2);
+      }else{
+        testcase( jumpIfNull==0 );
+        sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
+        sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
+      }
       break;
     }
     case TK_NOT: {
@@ -4566,18 +4598,23 @@ void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
   assert( pExpr->op!=TK_GE || op==OP_Lt );
 
   switch( pExpr->op ){
-    case TK_AND: {
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
-      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
-      break;
-    }
+    case TK_AND:
     case TK_OR: {
-      int d2 = sqlite3VdbeMakeLabel(pParse);
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, jumpIfNull^SQLITE_JUMPIFNULL);
-      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
-      sqlite3VdbeResolveLabel(v, d2);
+      Expr *pAlt = sqlite3ExprSimplifiedAndOr(pExpr);
+      if( pAlt!=pExpr ){
+        sqlite3ExprIfFalse(pParse, pAlt, dest, jumpIfNull);
+      }else if( pExpr->op==TK_AND ){
+        testcase( jumpIfNull==0 );
+        sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
+        sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
+      }else{
+        int d2 = sqlite3VdbeMakeLabel(pParse);
+        testcase( jumpIfNull==0 );
+        sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2,
+                          jumpIfNull^SQLITE_JUMPIFNULL);
+        sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
+        sqlite3VdbeResolveLabel(v, d2);
+      }
       break;
     }
     case TK_NOT: {