Thread Safety Analysis: Compare values of literals

The typical case for literals is an array of mutexes, where we want to
distinguish `mutex[0]` from `mutex[1]` and so on. Currently they're
treated as the same expression, in fact all literals are treated as the
same expression.

The infrastructure for literals is already there, although it required
some changes, and some simplifications seemed opportune:
* The `ValueType` had fields for size and signedness. But only integer
  have signedness, and the size is irrelevant if we don't want to emit
  machine code. For the abstract semantics that we're interested in,
  only the number matters.
* We remove the `BT_Void`: `void` literals don't exist in C++.
* We remove `BT_Float` and `BT_ValueRef`: floating-point numbers and
  complex numbers are probably not used in lock expressions.
* We replace `BT_Pointer` with `BT_NullPointer`. There are no pointer
  literals, only null pointer literals.

It seems to me that `ValueType` was intended to assign types to any node
in the TIL, but it is currently only used for literals. I was trying to
come up with reasons to assign types everywhere, but we're not trying to
type check anything, and we don't support overloading. The comparison of
expressions surely doesn't need it. But maybe this should be clarified
at some point. (Including the fact that it is called Typed Intermediate
Language.)

We turn `Literal` into a pure base class, as it seems to have been
intended, and only create `LiteralT` instances of the correct type.
Assertions on `as` ensure we're not mixing up types.

We print to `llvm::raw_ostream` instead of `std::ostream` because that's
required for `CharacterLiteral::print`.

Fixes #58535.

Author: aaronpuchert

clang/include/clang/Analysis/Analyses/ThreadSafetyCommon.h

@@ -35,7 +35,7 @@
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Casting.h"
-#include <sstream>
+#include "llvm/Support/raw_ostream.h"
 #include <string>
 #include <utility>
 #include <vector>
@@ -90,9 +90,10 @@ inline bool partiallyMatches(const til::SExpr *E1, const til::SExpr *E2) {
 }
 
 inline std::string toString(const til::SExpr *E) {
-  std::stringstream ss;
+  std::string s;
+  llvm::raw_string_ostream ss(s);
   til::StdPrinter::print(E, ss);
-  return ss.str();
+  return s;
 }
 
 }  // namespace sx

clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h

@@ -148,129 +148,54 @@ StringRef getBinaryOpcodeString(TIL_BinaryOpcode Op);
 /// All variables and expressions must have a value type.
 /// Pointer types are further subdivided into the various heap-allocated
 /// types, such as functions, records, etc.
-/// Structured types that are passed by value (e.g. complex numbers)
-/// require special handling; they use BT_ValueRef, and size ST_0.
 struct ValueType {
   enum BaseType : unsigned char {
-    BT_Void = 0,
     BT_Bool,
-    BT_Int,
-    BT_Float,
-    BT_String,    // String literals
-    BT_Pointer,
-    BT_ValueRef
+    BT_Char,
+    BT_SInt,
+    BT_UInt,
+    BT_String, // String literals
+    BT_NullPointer,
   };
 
-  enum SizeType : unsigned char {
-    ST_0 = 0,
-    ST_1,
-    ST_8,
-    ST_16,
-    ST_32,
-    ST_64,
-    ST_128
-  };
-
-  ValueType(BaseType B, SizeType Sz, bool S, unsigned char VS)
-      : Base(B), Size(Sz), Signed(S), VectSize(VS) {}
-
-  inline static SizeType getSizeType(unsigned nbytes);
+  ValueType(BaseType B) : Base(B) {}
 
   template <class T>
   inline static ValueType getValueType();
 
   BaseType Base;
-  SizeType Size;
-  bool Signed;
-
-  // 0 for scalar, otherwise num elements in vector
-  unsigned char VectSize;
 };
 
-inline ValueType::SizeType ValueType::getSizeType(unsigned nbytes) {
-  switch (nbytes) {
-    case 1: return ST_8;
-    case 2: return ST_16;
-    case 4: return ST_32;
-    case 8: return ST_64;
-    case 16: return ST_128;
-    default: return ST_0;
-  }
-}
-
-template<>
-inline ValueType ValueType::getValueType<void>() {
-  return ValueType(BT_Void, ST_0, false, 0);
+inline bool operator==(const ValueType &a, const ValueType &b) {
+  return a.Base == b.Base;
 }
 
 template<>
 inline ValueType ValueType::getValueType<bool>() {
-  return ValueType(BT_Bool, ST_1, false, 0);
+  return ValueType(BT_Bool);
 }
 
-template<>
-inline ValueType ValueType::getValueType<int8_t>() {
-  return ValueType(BT_Int, ST_8, true, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<uint8_t>() {
-  return ValueType(BT_Int, ST_8, false, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<int16_t>() {
-  return ValueType(BT_Int, ST_16, true, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<uint16_t>() {
-  return ValueType(BT_Int, ST_16, false, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<int32_t>() {
-  return ValueType(BT_Int, ST_32, true, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<uint32_t>() {
-  return ValueType(BT_Int, ST_32, false, 0);
+template <> inline ValueType ValueType::getValueType<char32_t>() {
+  return ValueType(BT_Char);
 }
 
 template<>
 inline ValueType ValueType::getValueType<int64_t>() {
-  return ValueType(BT_Int, ST_64, true, 0);
+  return ValueType(BT_SInt);
 }
 
 template<>
 inline ValueType ValueType::getValueType<uint64_t>() {
-  return ValueType(BT_Int, ST_64, false, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<float>() {
-  return ValueType(BT_Float, ST_32, true, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<double>() {
-  return ValueType(BT_Float, ST_64, true, 0);
-}
-
-template<>
-inline ValueType ValueType::getValueType<long double>() {
-  return ValueType(BT_Float, ST_128, true, 0);
+  return ValueType(BT_UInt);
 }
 
 template<>
 inline ValueType ValueType::getValueType<StringRef>() {
-  return ValueType(BT_String, getSizeType(sizeof(StringRef)), false, 0);
+  return ValueType(BT_String);
 }
 
-template<>
-inline ValueType ValueType::getValueType<void*>() {
-  return ValueType(BT_Pointer, getSizeType(sizeof(void*)), false, 0);
+template <> inline ValueType ValueType::getValueType<std::nullptr_t>() {
+  return ValueType(BT_NullPointer);
 }
 
 /// Base class for AST nodes in the typed intermediate language.
@@ -532,37 +457,29 @@ template <class T> class LiteralT;
 
 // Base class for literal values.
 class Literal : public SExpr {
-public:
-  Literal(const Expr *C)
-     : SExpr(COP_Literal), ValType(ValueType::getValueType<void>()), Cexpr(C) {}
+protected:
   Literal(ValueType VT) : SExpr(COP_Literal), ValType(VT) {}
-  Literal(const Literal &) = default;
 
+public:
   static bool classof(const SExpr *E) { return E->opcode() == COP_Literal; }
 
-  // The clang expression for this literal.
-  const Expr *clangExpr() const { return Cexpr; }
-
   ValueType valueType() const { return ValType; }
 
   template<class T> const LiteralT<T>& as() const {
+    assert(ValType == ValueType::getValueType<T>());
     return *static_cast<const LiteralT<T>*>(this);
   }
   template<class T> LiteralT<T>& as() {
+    assert(ValType == ValueType::getValueType<T>());
     return *static_cast<LiteralT<T>*>(this);
   }
 
   template <class V> typename V::R_SExpr traverse(V &Vs, typename V::R_Ctx Ctx);
 
-  template <class C>
-  typename C::CType compare(const Literal* E, C& Cmp) const {
-    // TODO: defer actual comparison to LiteralT
-    return Cmp.trueResult();
-  }
+  template <class C> typename C::CType compare(const Literal *E, C &Cmp) const;
 
 private:
   const ValueType ValType;
-  const Expr *Cexpr = nullptr;
 };
 
 // Derived class for literal values, which stores the actual value.
@@ -583,60 +500,50 @@ class LiteralT : public Literal {
   T Val;
 };
 
+template <class T> LiteralT(T) -> LiteralT<T>;
+
 template <class V>
 typename V::R_SExpr Literal::traverse(V &Vs, typename V::R_Ctx Ctx) {
-  if (Cexpr)
-    return Vs.reduceLiteral(*this);
-
   switch (ValType.Base) {
-  case ValueType::BT_Void:
-    break;
   case ValueType::BT_Bool:
     return Vs.reduceLiteralT(as<bool>());
-  case ValueType::BT_Int: {
-    switch (ValType.Size) {
-    case ValueType::ST_8:
-      if (ValType.Signed)
-        return Vs.reduceLiteralT(as<int8_t>());
-      else
-        return Vs.reduceLiteralT(as<uint8_t>());
-    case ValueType::ST_16:
-      if (ValType.Signed)
-        return Vs.reduceLiteralT(as<int16_t>());
-      else
-        return Vs.reduceLiteralT(as<uint16_t>());
-    case ValueType::ST_32:
-      if (ValType.Signed)
-        return Vs.reduceLiteralT(as<int32_t>());
-      else
-        return Vs.reduceLiteralT(as<uint32_t>());
-    case ValueType::ST_64:
-      if (ValType.Signed)
-        return Vs.reduceLiteralT(as<int64_t>());
-      else
-        return Vs.reduceLiteralT(as<uint64_t>());
-    default:
-      break;
-    }
-  }
-  case ValueType::BT_Float: {
-    switch (ValType.Size) {
-    case ValueType::ST_32:
-      return Vs.reduceLiteralT(as<float>());
-    case ValueType::ST_64:
-      return Vs.reduceLiteralT(as<double>());
-    default:
-      break;
-    }
-  }
+  case ValueType::BT_Char:
+    return Vs.reduceLiteralT(as<char32_t>());
+  case ValueType::BT_SInt:
+    return Vs.reduceLiteralT(as<int64_t>());
+  case ValueType::BT_UInt:
+    return Vs.reduceLiteralT(as<uint64_t>());
   case ValueType::BT_String:
     return Vs.reduceLiteralT(as<StringRef>());
-  case ValueType::BT_Pointer:
-    return Vs.reduceLiteralT(as<void*>());
-  case ValueType::BT_ValueRef:
-    break;
+  case ValueType::BT_NullPointer:
+    return Vs.reduceLiteralT(as<std::nullptr_t>());
+  }
+  llvm_unreachable("Invalid BaseType");
+}
+
+template <class C>
+typename C::CType Literal::compare(const Literal *E, C &Cmp) const {
+  typename C::CType Ct = Cmp.compareIntegers(ValType.Base, E->ValType.Base);
+  if (Cmp.notTrue(Ct))
+    return Ct;
+  switch (ValType.Base) {
+  case ValueType::BT_Bool:
+    return Cmp.compareIntegers(as<bool>().value(), E->as<bool>().value());
+  case ValueType::BT_Char:
+    return Cmp.compareIntegers(as<char32_t>().value(),
+                               E->as<char32_t>().value());
+  case ValueType::BT_SInt:
+    return Cmp.compareIntegers(as<int64_t>().value(), E->as<int64_t>().value());
+  case ValueType::BT_UInt:
+    return Cmp.compareIntegers(as<uint64_t>().value(),
+                               E->as<uint64_t>().value());
+  case ValueType::BT_String:
+    return Cmp.compareStrings(as<StringRef>().value(),
+                              E->as<StringRef>().value());
+  case ValueType::BT_NullPointer:
+    return Cmp.trueResult();
   }
-  return Vs.reduceLiteral(*this);
+  llvm_unreachable("Invalid BaseType");
 }
 
 /// A Literal pointer to an object allocated in memory.