Ensure local variables are initialized at declaration

While investigating a crash in eclipse-openj9/openj9#5988, I had to look at the AVL code and there were cases where it wasn't clear all the variables had been initialized before they were read. This patch makes initialization explicit and ensures variables are initialized at their declaration site. This patch is code cleanup to make it easier to reason about the AVL code. Signed-off-by: Dan Heidinga <[email protected]>
DanHeidinga · Jun 4, 2019 · 8068563 · 8068563
1 parent 575dfa1
commit 8068563
Showing 1 changed file with 21 additions and 24 deletions.
diff --git a/util/avl/avlsup.c b/util/avl/avlsup.c
@@ -43,7 +43,7 @@ static J9AVLTreeNode *insertNode(J9AVLTree *tree, J9AVLTreeNode **walkPtr, J9WSR
 J9AVLTreeNode *
 avl_insert(J9AVLTree *tree, J9AVLTreeNode *nodeToInsert)
 {
-	intptr_t heightChange;
+	intptr_t heightChange = 0;
 
 	return insertNode(tree, &tree->rootNode, NULL, nodeToInsert, &heightChange);
 }
@@ -59,7 +59,7 @@ avl_insert(J9AVLTree *tree, J9AVLTreeNode *nodeToInsert)
 J9AVLTreeNode *
 avl_delete(J9AVLTree *tree, J9AVLTreeNode *nodeToDelete)
 {
-	intptr_t heightChange;
+	intptr_t heightChange = 0;
 
 	return deleteNode(tree, &tree->rootNode, NULL, nodeToDelete, &heightChange);
 }
@@ -90,7 +90,7 @@ avl_search(J9AVLTree *tree, uintptr_t searchValue)
 static J9AVLTreeNode *
 findRightMostLeaf(J9AVLTree *tree, J9WSRP *walkSRPPtr, intptr_t *heightChange)
 {
-	J9AVLTreeNode *find;
+	J9AVLTreeNode *find = NULL;
 	J9AVLTreeNode *walk = NULL;
 
 	Trc_AVL_findRightMostLeaf_Entry(tree, walkSRPPtr, heightChange);
@@ -134,9 +134,9 @@ findRightMostLeaf(J9AVLTree *tree, J9WSRP *walkSRPPtr, intptr_t *heightChange)
 static J9AVLTreeNode *
 rotate(J9AVLTree *tree, J9AVLTreeNode *walk, intptr_t direction, intptr_t *heightChange)
 {
-	J9WSRP *heavyNodePtr;
-	J9WSRP *graftNodePtr;
-	J9AVLTreeNode *heavyNode;
+	J9WSRP *heavyNodePtr = NULL;
+	J9WSRP *graftNodePtr = NULL;
+	J9AVLTreeNode *heavyNode = NULL;
 
 	Trc_AVL_rotate_Entry(tree, walk, direction, heightChange);
 
@@ -199,12 +199,12 @@ rotate(J9AVLTree *tree, J9AVLTreeNode *walk, intptr_t direction, intptr_t *heigh
 static J9AVLTreeNode *
 doubleRotate(J9AVLTree *tree, J9AVLTreeNode *walk, intptr_t direction, intptr_t *heightChange)
 {
-	J9WSRP *heavyNodePtr;
-	J9WSRP *graft1NodePtr;
-	J9WSRP *graft2NodePtr;
-	J9WSRP *newrootNodePtr;
-	J9AVLTreeNode *heavyNode;
-	J9AVLTreeNode *newrootNode;
+	J9WSRP *heavyNodePtr = NULL;
+	J9WSRP *graft1NodePtr = NULL;
+	J9WSRP *graft2NodePtr = NULL;
+	J9WSRP *newrootNodePtr = NULL;
+	J9AVLTreeNode *heavyNode = NULL;
+	J9AVLTreeNode *newrootNode = NULL;
 
 	Trc_AVL_doubleRotate_Entry(tree, walk, direction, heightChange);
 
@@ -283,7 +283,7 @@ static void
 rebalance(J9AVLTree *tree, J9AVLTreeNode **walkPtr, J9WSRP *walkSRPPtr, intptr_t direction, intptr_t *heightChange)
 {
 	J9AVLTreeNode *walk = NULL;
-	uintptr_t walkBalance;
+	uintptr_t walkBalance = 0;
 
 	if (!(*heightChange)) {
 		return;
@@ -363,8 +363,8 @@ static J9AVLTreeNode *
 insertNode(J9AVLTree *tree, J9AVLTreeNode **walkPtr, J9WSRP *walkSRPPtr, J9AVLTreeNode *node, intptr_t *heightChange)
 {
 	J9AVLTreeNode *find = NULL;
-	J9AVLTreeNode *walk;
-	intptr_t dir;
+	J9AVLTreeNode *walk = NULL;
+	intptr_t dir = 0;
 
 	Trc_AVL_insertNode_Entry(tree, walkPtr, walkSRPPtr, node, heightChange);
 
@@ -431,13 +431,12 @@ _done :
 static J9AVLTreeNode *
 findNode(J9AVLTree *tree, J9AVLTreeNode *node, uintptr_t search)
 {
-	intptr_t dir;
 	J9AVLTreeNode *walk = node;
 
 	Trc_AVL_findNode_Entry(tree, walk, search);
 
 	while (walk) {
-		dir = tree->searchComparator(tree, search, walk);
+		intptr_t dir = tree->searchComparator(tree, search, walk);
 		if (dir == 0) {
 			break;
 		}
@@ -469,9 +468,9 @@ findNode(J9AVLTree *tree, J9AVLTreeNode *node, uintptr_t search)
 static J9AVLTreeNode *
 deleteNode(J9AVLTree *tree, J9AVLTreeNode **walkPtr, J9WSRP *walkSRPPtr, J9AVLTreeNode *node, intptr_t *heightChange)
 {
-	J9AVLTreeNode *find;
-	J9AVLTreeNode *walk;
-	intptr_t dir;
+	J9AVLTreeNode *find = NULL;
+	J9AVLTreeNode *walk = NULL;
+	intptr_t dir = 0;
 
 	Trc_AVL_deleteNode_Entry(tree, walkPtr, walkSRPPtr, node, heightChange);
 
@@ -491,10 +490,8 @@ deleteNode(J9AVLTree *tree, J9AVLTreeNode **walkPtr, J9WSRP *walkSRPPtr, J9AVLTr
 
 	dir = tree->insertionComparator(tree, node, walk);
 	if (!dir) {
-		J9AVLTreeNode *walkLeftChild, *walkRightChild;
-
-		walkLeftChild = AVL_SRP_GETNODE(walk->leftChild);
-		walkRightChild = AVL_SRP_GETNODE(walk->rightChild);
+		J9AVLTreeNode *walkLeftChild = AVL_SRP_GETNODE(walk->leftChild);
+		J9AVLTreeNode *walkRightChild = AVL_SRP_GETNODE(walk->rightChild);
 
 		if (!walkLeftChild) {
 			if (!walkSRPPtr) {