[clang] Thread Safety Analysis: Support reentrant capabilities (PR #137133)

[Marco Elver via cfe-commits]

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@@ -271,26 +272,34 @@ class CFGWalker {
 // translateAttrExpr needs it, but that should be moved too.
 class CapabilityExpr {
 private:
-  /// The capability expression and whether it's negated.
-  llvm::PointerIntPair<const til::SExpr *, 1, bool> CapExpr;
+  static constexpr unsigned FlagNegative = 1u << 0;
+  static constexpr unsigned FlagReentrant = 1u << 1;
+
+  /// The capability expression and flags.
+  llvm::PointerIntPair<const til::SExpr *, 2, unsigned> CapExpr;
 
   /// The kind of capability as specified by @ref CapabilityAttr::getName.
   StringRef CapKind;
 
 public:
-  CapabilityExpr() : CapExpr(nullptr, false) {}
-  CapabilityExpr(const til::SExpr *E, StringRef Kind, bool Neg)
-      : CapExpr(E, Neg), CapKind(Kind) {}
+  CapabilityExpr() : CapExpr(nullptr, 0) {}
+  CapabilityExpr(const til::SExpr *E, StringRef Kind, bool Neg, bool Reentrant)
+      : CapExpr(E, (Neg ? FlagNegative : 0) | (Reentrant ? FlagReentrant : 0)),
+        CapKind(Kind) {}
+  CapabilityExpr(const til::SExpr *E, QualType QT, bool Neg);
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melver wrote:

It's a bit of a maze, but I felt this is a decent trade-off. Less/simpler code traded off against (minimal) loss of abstraction.

https://github.com/llvm/llvm-project/pull/137133