Prune writes to constant instances in the Python ModRef analysis (#104)

Fixes #103.
wala · Nov 7, 2023 · f7bf0f4 · f7bf0f4
1 parent 3c81c94
commit f7bf0f4
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Showing 3 changed files with 48 additions and 5 deletions.
diff --git a/com.ibm.wala.cast.python.test/data/kw_args.py b/com.ibm.wala.cast.python.test/data/kw_args.py
@@ -0,0 +1,9 @@
+def g(p1, p2):
+    assert p1 == 5 and p2 == 2
+
+
+def f():
+    g(5, p2=2)
+
+
+f()
diff --git a/....wala.cast.python.test/source/com/ibm/wala/cast/python/test/TestPythonModRefAnalysis.java b/....wala.cast.python.test/source/com/ibm/wala/cast/python/test/TestPythonModRefAnalysis.java
@@ -24,15 +24,14 @@
 
 public class TestPythonModRefAnalysis extends TestPythonCallGraphShape {
 
-  @Test
-  public void testComputeModCallGraphPointerAnalysisOfT()
-      throws ClassHierarchyException, IllegalArgumentException, CancelException, IOException {
-    PythonAnalysisEngine<?> engine = makeEngine("globals.py");
+  private OrdinalSet<PointerKey> getModSet(String filename)
+      throws ClassHierarchyException, CancelException, IOException {
+    PythonAnalysisEngine<?> engine = makeEngine(filename);
     SSAPropagationCallGraphBuilder builder =
         (SSAPropagationCallGraphBuilder) engine.defaultCallGraphBuilder();
     CallGraph CG = builder.makeCallGraph(builder.getOptions());
 
-    Collection<CGNode> nodes = getNodes(CG, "script globals.py/f");
+    Collection<CGNode> nodes = getNodes(CG, "script " + filename + "/f");
     assertEquals(1, nodes.size());
 
     assertTrue(nodes.iterator().hasNext());
@@ -43,6 +42,13 @@ public void testComputeModCallGraphPointerAnalysisOfT()
 
     // what heap locations does f() (transitively) modify?
     OrdinalSet<PointerKey> modSet = mod.get(fNode);
+    return modSet;
+  }
+
+  @Test
+  public void testGlobalMods()
+      throws ClassHierarchyException, IllegalArgumentException, CancelException, IOException {
+    OrdinalSet<PointerKey> modSet = getModSet("globals.py");
 
     // should only modify the global.
     assertEquals(1, modSet.size());
@@ -57,4 +63,11 @@ public void testComputeModCallGraphPointerAnalysisOfT()
     Atom name = field.getName();
     assertEquals(Atom.findOrCreateAsciiAtom("global a"), name);
   }
+
+  @Test
+  public void testKeywordArgs()
+      throws ClassHierarchyException, IllegalArgumentException, CancelException, IOException {
+    OrdinalSet<PointerKey> modSet = getModSet("kw_args.py");
+    assertEquals("Should be no modifications to heap locations in this file.", 0, modSet.size());
+  }
 }
diff --git a/com.ibm.wala.cast.python/source/com/ibm/wala/cast/python/modref/PythonModRef.java b/com.ibm.wala.cast.python/source/com/ibm/wala/cast/python/modref/PythonModRef.java
@@ -3,16 +3,20 @@
 import com.ibm.wala.cast.ipa.callgraph.AstHeapModel;
 import com.ibm.wala.cast.ipa.modref.AstModRef;
 import com.ibm.wala.cast.ir.ssa.AstGlobalWrite;
+import com.ibm.wala.cast.ir.ssa.AstPropertyWrite;
 import com.ibm.wala.cast.python.ssa.PythonInstructionVisitor;
 import com.ibm.wala.classLoader.IField;
 import com.ibm.wala.core.util.strings.Atom;
 import com.ibm.wala.ipa.callgraph.CGNode;
+import com.ibm.wala.ipa.callgraph.propagation.ConstantKey;
+import com.ibm.wala.ipa.callgraph.propagation.InstanceFieldPointerKey;
 import com.ibm.wala.ipa.callgraph.propagation.InstanceKey;
 import com.ibm.wala.ipa.callgraph.propagation.PointerAnalysis;
 import com.ibm.wala.ipa.callgraph.propagation.PointerKey;
 import com.ibm.wala.ipa.callgraph.propagation.StaticFieldKey;
 import com.ibm.wala.ipa.modref.ExtendedHeapModel;
 import java.util.Collection;
+import java.util.Iterator;
 
 public class PythonModRef extends AstModRef<InstanceKey> {
 
@@ -62,6 +66,23 @@ public void visitAstGlobalWrite(AstGlobalWrite instruction) {
         }
       }
     }
+
+    @Override
+    public void visitPropertyWrite(AstPropertyWrite instruction) {
+      super.visitPropertyWrite(instruction);
+
+      // prune "writes" to ConstantKeys. See https://github.com/wala/ML/issues/103.
+      for (Iterator<PointerKey> it = this.result.iterator(); it.hasNext(); ) {
+        PointerKey pointerKey = it.next();
+
+        if (pointerKey instanceof InstanceFieldPointerKey) {
+          InstanceFieldPointerKey instanceFieldPointerKey = (InstanceFieldPointerKey) pointerKey;
+          InstanceKey instanceKey = instanceFieldPointerKey.getInstanceKey();
+
+          if (instanceKey instanceof ConstantKey) it.remove();
+        }
+      }
+    }
   }
 
   @Override