[PATCH] D128056: [clang][dataflow] Singleton pointer values for null pointers.

[Gábor Horváth via Phabricator via cfe-commits]

xazax.hun added a comment.

I am wondering about the future plans regarding how pointers are represented.
What will be the expected behavior when the analysis discovers that the pointer has a null value? E.g.:

  if (p == nullptr)
  {
    ....
  }

Would we expect `p` in this case to have the same singleton value in the then block of the if statement?



================
Comment at: clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h:146
+  ///  `PointeeType`.
+  void setNullPointerVal(QualType PointeeType, PointerValue &Val) {
+    assert(NullPointerVals.find(PointeeType.getAsString()) ==
----------------
Since you always want this function to create a null pointer value, I think it would be less error prone to ask for the location instead of an arbitrary value. Currently, a confused caller could put a non-null value into a table. 


================
Comment at: clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h:149
+           NullPointerVals.end());
+    NullPointerVals[PointeeType.getAsString()] = &Val;
+  }
----------------
I think `getAsString` is considered expensive. Could you use `QualType` directly as the key?


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