Apply suggestions from code review

yoff · RasmusWL · web-flow · commit 3a19b1e7fd7d · 2020-09-10T15:06:06.000+02:00
Co-authored-by: Rasmus Wriedt Larsen &lt;rasmuswriedtlarsen@gmail.com&gt;
diff --git a/python/ql/src/experimental/dataflow/internal/DataFlowPrivate.qll b/python/ql/src/experimental/dataflow/internal/DataFlowPrivate.qll
@@ -156,8 +156,7 @@ predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) {
 }
 
 /**
- * If a node `n` has a post-update node `pun(n)`, we want forward flow to go from
- * `pun(n)` as well as from `n`.
+ * Holds if `result` is either `node`, or the post-update node for `node`.
  */
 private Node update(Node node) {
   exists(PostUpdateNode pun |
diff --git a/python/ql/src/semmle/python/essa/SsaCompute.qll b/python/ql/src/semmle/python/essa/SsaCompute.qll
@@ -391,7 +391,9 @@ private module SsaComputeImpl {
      * between `b1` and `b2`.
      */
     private predicate varBlockReaches(SsaSourceVariable v, BasicBlock b1, BasicBlock b2) {
-      varOccursInBlock(v, b1) and b2 = b1.getASuccessor()
+      varOccursInBlock(v, b1) and 
+      b2 = b1.getASuccessor() and
+      blockPrecedesVar(v, b2)
       or
       exists(BasicBlock mid |
         varBlockReaches(v, b1, mid) and

Original file line number	Diff line number	Diff line change
`@@ -156,8 +156,7 @@ predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) {`
`156`	`156`	`}`
`157`	`157`
`158`	`158`	`/**`
`159`		- * If a node `n` has a post-update node `pun(n)`, we want forward flow to go from
`160`		- * `pun(n)` as well as from `n`.
	`159`	+ * Holds if `result` is either `node`, or the post-update node for `node`.
`161`	`160`	`*/`
`162`	`161`	`private Node update(Node node) {`
`163`	`162`	`exists(PostUpdateNode pun \|`