[all-commits] [llvm/llvm-project] b61137: [clang][dataflow] Singleton pointer values for nul...

[weiyi via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b611376e7eb5ea8bd0b32c2911e039b29828b9a8
      https://github.com/llvm/llvm-project/commit/b611376e7eb5ea8bd0b32c2911e039b29828b9a8
  Author: Wei Yi Tee <wyt at google.com>
  Date:   2022-06-27 (Mon, 27 Jun 2022)

  Changed paths:
    M clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h
    M clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h
    M clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp
    M clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
    M clang/lib/Analysis/FlowSensitive/Transfer.cpp
    M clang/unittests/Analysis/FlowSensitive/TransferTest.cpp

  Log Message:
  -----------
  [clang][dataflow] Singleton pointer values for null pointers.

When a `nullptr` is assigned to a pointer variable, it is wrapped in a `ImplicitCastExpr` with cast kind `CK_NullTo(Member)Pointer`. This patch assigns singleton pointer values representing null to these expressions.

For each pointee type, a singleton null `PointerValue` is created and stored in the `NullPointerVals` map of the `DataflowAnalysisContext` class. The pointee type is retrieved from the implicit cast expression, and used to initialise the `PointeeLoc` field of the `PointerValue`. The `PointeeLoc` created is not mapped to any `Value`, reflecting the absence of value indicated by null pointers.

Reviewed By: gribozavr2, sgatev, xazax.hun

Differential Revision: https://reviews.llvm.org/D128056