Python: Split up (small)step into intra/interprocedural predicates

Author: hvitved

python/ql/src/experimental/typetracking/TypeTracker.qll

@@ -55,31 +55,32 @@ class StepSummary extends TStepSummary {
 
 /** Provides predicates for updating step summaries (`StepSummary`s). */
 module StepSummary {
+  cached
+  private predicate stepNoCall(LocalSourceNode nodeFrom, LocalSourceNode nodeTo, StepSummary summary) {
+    exists(Node mid | nodeFrom.flowsTo(mid) and smallstepNoCall(mid, nodeTo, summary))
+  }
+
+  cached
+  private predicate stepCall(LocalSourceNode nodeFrom, LocalSourceNode nodeTo, StepSummary summary) {
+    exists(Node mid | nodeFrom.flowsTo(mid) and smallstepCall(mid, nodeTo, summary))
+  }
+
   /**
    * Gets the summary that corresponds to having taken a forwards
    * heap and/or inter-procedural step from `nodeFrom` to `nodeTo`.
    */
-  cached
+  pragma[inline]
   predicate step(LocalSourceNode nodeFrom, LocalSourceNode nodeTo, StepSummary summary) {
-    exists(Node mid | nodeFrom.flowsTo(mid) and smallstep(mid, nodeTo, summary))
+    stepNoCall(nodeFrom, nodeTo, summary)
+    or
+    stepCall(nodeFrom, nodeTo, summary)
   }
 
-  /**
-   * Gets the summary that corresponds to having taken a forwards
-   * local, heap and/or inter-procedural step from `nodeFrom` to `nodeTo`.
-   *
-   * Unlike `StepSummary::step`, this predicate does not compress
-   * type-preserving steps.
-   */
-  predicate smallstep(Node nodeFrom, LocalSourceNode nodeTo, StepSummary summary) {
+  pragma[noinline]
+  private predicate smallstepNoCall(Node nodeFrom, LocalSourceNode nodeTo, StepSummary summary) {
     jumpStep(nodeFrom, nodeTo) and
     summary = LevelStep()
     or
-    callStep(nodeFrom, nodeTo) and summary = CallStep()
-    or
-    returnStep(nodeFrom, nodeTo) and
-    summary = ReturnStep()
-    or
     exists(string content |
       localSourceStoreStep(nodeFrom, nodeTo, content) and
       summary = StoreStep(content)
@@ -88,6 +89,28 @@ module StepSummary {
     )
   }
 
+  pragma[noinline]
+  private predicate smallstepCall(Node nodeFrom, LocalSourceNode nodeTo, StepSummary summary) {
+    callStep(nodeFrom, nodeTo) and summary = CallStep()
+    or
+    returnStep(nodeFrom, nodeTo) and
+    summary = ReturnStep()
+  }
+
+  /**
+   * Gets the summary that corresponds to having taken a forwards
+   * local, heap and/or inter-procedural step from `nodeFrom` to `nodeTo`.
+   *
+   * Unlike `StepSummary::step`, this predicate does not compress
+   * type-preserving steps.
+   */
+  pragma[inline]
+  predicate smallstep(Node nodeFrom, LocalSourceNode nodeTo, StepSummary summary) {
+    smallstepNoCall(nodeFrom, nodeTo, summary)
+    or
+    smallstepCall(nodeFrom, nodeTo, summary)
+  }
+
   /**
    * Holds if `nodeFrom` is being written to the `content` content of the object in `nodeTo`.
    *