commit ad31727fc68e47612edcc1566ef88174da75f258
author drh <drh@noemail.net> Fri Apr 19 16:21:51 2019 +0000
committer drh <drh@noemail.net> Fri Apr 19 16:21:51 2019 +0000
tree 96b7bc0055715c1c1bf301de92648276dc0712e6
parent d5c851c1cbcb96d541fa7e6e20342c2a437434e9

Use macros to determine if an expression is always true or always false.

FossilOrigin-Name: 6de980a09c3a7adf71f2c9a63a242673b5e1f246e8ee071b26844275f0dad0fc

src/expr.c

diff --git a/src/expr.c b/src/expr.c
index c9f917c..0484f3b 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -773,7 +773,7 @@
     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];
@@ -881,33 +881,6 @@
 
 
 /*
-** 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.
 **
@@ -923,7 +896,7 @@
     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);
@@ -1818,6 +1791,7 @@
        || 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;
@@ -4522,9 +4496,9 @@
 #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);
@@ -4692,9 +4666,9 @@
 #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);