Simplification of the logic in the constant-propagation optimization.

FossilOrigin-Name: 1c3e5c20a9e6f501befa2bf6241a1b5190872bd83b765dac67065d252d04ea4f

1 files changed, 25 insertions, 20 deletions

diff --git a/src/select.c b/src/select.c
index 4826d65f4..2ec131b3a 100644
--- a/src/select.c
+++ b/src/select.c
@@ -4146,15 +4146,28 @@ struct WhereConst {
 
 /*
 ** Add a new entry to the pConst object.  Except, do not add duplicate
-** pColumn entires.
+** pColumn entires.  Also, do not add if doing so would not be appropriate.
+**
+** The caller guarantees the pColumn is a column and pValue is a constant.
+** This routine has to do some additional checks before completing the
+** insert.
 */
 static void constInsert(
-  WhereConst *pConst,      /* The WhereConst into which we are inserting */
-  Expr *pColumn,           /* The COLUMN part of the constraint */
-  Expr *pValue             /* The VALUE part of the constraint */
+  WhereConst *pConst,  /* The WhereConst into which we are inserting */
+  Expr *pColumn,       /* The COLUMN part of the constraint */
+  Expr *pValue,        /* The VALUE part of the constraint */
+  Expr *pExpr          /* Overall expression: COLUMN=VALUE or VALUE=COLUMN */
 ){
   int i;
   assert( pColumn->op==TK_COLUMN );
+  assert( sqlite3ExprIsConstant(pValue) );
+
+  if( !ExprHasProperty(pValue, EP_FixedCol) && sqlite3ExprAffinity(pValue)!=0 ){
+    return;
+  }
+  if( !sqlite3IsBinary(sqlite3ExprCompareCollSeq(pConst->pParse,pExpr)) ){
+    return;
+  }
 
   /* 2018-10-25 ticket [cf5ed20f]
   ** Make sure the same pColumn is not inserted more than once */
@@ -4174,7 +4187,9 @@ static void constInsert(
   if( pConst->apExpr==0 ){
     pConst->nConst = 0;
   }else{
-    if( ExprHasProperty(pValue, EP_FixedCol) ) pValue = pValue->pLeft;
+    if( ExprHasProperty(pValue, EP_FixedCol) ){
+      pValue = pValue->pLeft;
+    }
     pConst->apExpr[pConst->nConst*2-2] = pColumn;
     pConst->apExpr[pConst->nConst*2-1] = pValue;
   }
@@ -4200,21 +4215,11 @@ static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
   pLeft = pExpr->pLeft;
   assert( pRight!=0 );
   assert( pLeft!=0 );
-  if( pRight->op==TK_COLUMN
-   && !ExprHasProperty(pRight, EP_FixedCol)
-   && sqlite3ExprIsConstant(pLeft)
-   && sqlite3ExprAffinity(pLeft)==0
-   && sqlite3IsBinary(sqlite3ExprCompareCollSeq(pConst->pParse,pExpr))
-  ){
-    constInsert(pConst, pRight, pLeft);
-  }else
-  if( pLeft->op==TK_COLUMN
-   && !ExprHasProperty(pLeft, EP_FixedCol)
-   && sqlite3ExprIsConstant(pRight)
-   && sqlite3ExprAffinity(pRight)==0
-   && sqlite3IsBinary(sqlite3ExprCompareCollSeq(pConst->pParse,pExpr))
-  ){
-    constInsert(pConst, pLeft, pRight);
+  if( pRight->op==TK_COLUMN && sqlite3ExprIsConstant(pLeft) ){
+    constInsert(pConst,pRight,pLeft,pExpr);
+  }
+  if( pLeft->op==TK_COLUMN && sqlite3ExprIsConstant(pRight) ){
+    constInsert(pConst,pLeft,pRight,pExpr);
   }
 }