Merge pull request #7 from aschackmull/java/shared-ssa-fixes

Some fixes to #16900

Author: hvitved

java/ql/lib/semmle/code/java/dataflow/SSA.qll

@@ -228,9 +228,10 @@ class SsaImplicitUpdate extends SsaUpdate {
   }
 
   private predicate hasExplicitQualifierUpdate() {
-    exists(SsaExplicitUpdate qdef, BasicBlock bb, int i |
+    exists(SsaUpdate qdef, BasicBlock bb, int i |
       qdef.definesAt(this.getSourceVariable().getQualifier(), bb, i) and
-      this.definesAt(_, bb, i)
+      this.definesAt(_, bb, i) and
+      not qdef instanceof SsaUncertainImplicitUpdate
     )
   }
 

java/ql/lib/semmle/code/java/dataflow/internal/SsaImpl.qll

@@ -44,7 +44,7 @@ private module TrackedVariablesImpl {
   }
 
   /** Holds if `f` is accessed more than once or inside a loop. */
-  predicate multiAccessed(SsaSourceField f) { loopAccessed(f) or 1 < numberOfAccesses(f) }
+  private predicate multiAccessed(SsaSourceField f) { loopAccessed(f) or 1 < numberOfAccesses(f) }
 
   /**
    * Holds if `f` is a field that is interesting as a basis for SSA.
@@ -619,13 +619,12 @@ private module Cached {
         useReaches(use, mid, sameVarMid) and
         DataFlowIntegration::localFlowStep(_, mid, node, _)
       |
-        // flow into phi input node
-        mid instanceof DataFlowIntegration::SsaInputNode and
-        sameVar = false
-        or
-        // flow into definition
         exists(Impl::DefinitionExt def |
+          // flow into definition
           def = mid.(DataFlowIntegration::SsaDefinitionExtNode).getDefinitionExt()
+          or
+          // flow into phi input node
+          def = mid.(DataFlowIntegration::SsaInputNode).getDefinitionExt()
         |
           if def instanceof Impl::PhiReadNode then sameVar = sameVarMid else sameVar = false
         )