================
@@ -4639,6 +4645,303 @@ class FunctionNoProtoType : public FunctionType, public
llvm::FoldingSetNode {
}
};
+//
------------------------------------------------------------------------------
+
+/// Represents an abstract function effect, using just an enumeration
describing
+/// its kind.
+class FunctionEffect {
+public:
+ /// Identifies the particular effect.
+ enum class Kind : uint8_t {
+ None = 0,
+ NonBlocking = 1,
+ NonAllocating = 2,
+ Blocking = 3,
+ Allocating = 4
+ };
+
+ /// Flags describing some behaviors of the effect.
+ using Flags = unsigned;
+ enum FlagBit : Flags {
+ // Can verification inspect callees' implementations? (e.g. nonblocking:
+ // yes, tcb+types: no). This also implies the need for 2nd-pass
+ // verification.
+ FE_InferrableOnCallees = 0x1,
+
+ // Language constructs which effects can diagnose as disallowed.
+ FE_ExcludeThrow = 0x2,
+ FE_ExcludeCatch = 0x4,
+ FE_ExcludeObjCMessageSend = 0x8,
+ FE_ExcludeStaticLocalVars = 0x10,
+ FE_ExcludeThreadLocalVars = 0x20
+ };
+
+private:
+ LLVM_PREFERRED_TYPE(Kind)
+ unsigned FKind : 3;
+
+ // Expansion: for hypothetical TCB+types, there could be one Kind for TCB,
+ // then ~16(?) bits "SubKind" to map to a specific named TCB. SubKind would
+ // be considered for uniqueness.
+
+public:
+ FunctionEffect() : FKind(unsigned(Kind::None)) {}
+
+ explicit FunctionEffect(Kind K) : FKind(unsigned(K)) {}
+
+ /// The kind of the effect.
+ Kind kind() const { return Kind(FKind); }
+
+ /// Return the opposite kind, for effects which have opposites.
+ Kind oppositeKind() const;
+
+ /// For serialization.
+ uint32_t toOpaqueInt32() const { return FKind; }
+ static FunctionEffect fromOpaqueInt32(uint32_t Value) {
+ return FunctionEffect(Kind(Value));
+ }
+
+ /// Flags describing some behaviors of the effect.
+ Flags flags() const {
+ switch (kind()) {
+ case Kind::NonBlocking:
+ return FE_InferrableOnCallees | FE_ExcludeThrow | FE_ExcludeCatch |
+ FE_ExcludeObjCMessageSend | FE_ExcludeStaticLocalVars |
+ FE_ExcludeThreadLocalVars;
+ case Kind::NonAllocating:
+ // Same as NonBlocking, except without FE_ExcludeStaticLocalVars
+ return FE_InferrableOnCallees | FE_ExcludeThrow | FE_ExcludeCatch |
+ FE_ExcludeObjCMessageSend | FE_ExcludeThreadLocalVars;
+ case Kind::Blocking:
+ case Kind::Allocating:
+ return 0;
+ case Kind::None:
+ break;
+ }
+ llvm_unreachable("unknown effect kind");
+ }
+
+ /// The description printed in diagnostics, e.g. 'nonblocking'.
+ StringRef name() const;
+
+ /// Return true if the effect is allowed to be inferred on the callee,
+ /// which is either a FunctionDecl or BlockDecl.
+ /// This is only used if the effect has FE_InferrableOnCallees flag set.
+ /// Example: This allows nonblocking(false) to prevent inference for the
+ /// function.
+ bool canInferOnFunction(const Decl &Callee) const;
+
+ // Return false for success. When true is returned for a direct call, then
the
+ // FE_InferrableOnCallees flag may trigger inference rather than an immediate
+ // diagnostic. Caller should be assumed to have the effect (it may not have
it
+ // explicitly when inferring).
+ bool shouldDiagnoseFunctionCall(bool Direct,
+ ArrayRef<FunctionEffect> CalleeFX) const;
+
+ friend bool operator==(const FunctionEffect &LHS, const FunctionEffect &RHS)
{
+ return LHS.FKind == RHS.FKind;
+ }
+ friend bool operator!=(const FunctionEffect &LHS, const FunctionEffect &RHS)
{
+ return !(LHS == RHS);
+ }
+ friend bool operator<(const FunctionEffect &LHS, const FunctionEffect &RHS) {
+ return LHS.FKind < RHS.FKind;
+ }
+};
+
+/// Wrap a function effect's condition expression in another struct so
+/// that FunctionProtoType's TrailingObjects can treat it separately.
+class FunctionEffectCondition {
+ Expr *Cond = nullptr; // if null, unconditional
+
+public:
+ FunctionEffectCondition() = default;
+ FunctionEffectCondition(Expr *E) : Cond(E) {} // implicit OK
+
+ Expr *expr() const { return Cond; }
+
+ bool operator==(const FunctionEffectCondition &RHS) const {
+ return Cond == RHS.Cond;
+ }
+};
+
+/// A FunctionEffect plus a potential boolean expression determining whether
+/// the effect is declared (e.g. nonblocking(expr)). Generally the condition
+/// expression when present, is dependent.
+struct FunctionEffectWithCondition {
+ FunctionEffect Effect;
+ FunctionEffectCondition Cond;
+
+ FunctionEffectWithCondition() = default;
+ FunctionEffectWithCondition(const FunctionEffect &E,
+ const FunctionEffectCondition &C)
+ : Effect(E), Cond(C) {}
+
+ /// Return a textual description of the effect, and its condition, if any.
+ std::string description() const;
+
+ friend bool operator<(const FunctionEffectWithCondition &LHS,
+ const FunctionEffectWithCondition &RHS) {
+ if (LHS.Effect < RHS.Effect)
+ return true;
+ if (RHS.Effect < LHS.Effect)
+ return false;
+ return LHS.Cond.expr() < RHS.Cond.expr();
+ }
+};
+
+/// Support iteration in parallel through a pair of FunctionEffect and
+/// FunctionEffectCondition containers.
+template <typename Container> class FunctionEffectIterator {
+ const Container &Outer;
+ size_t Idx;
+
+public:
+ FunctionEffectIterator(const Container &O, size_t I) : Outer(O), Idx(I) {}
+ bool operator==(const FunctionEffectIterator &Other) const {
+ return Idx == Other.Idx;
+ }
+ bool operator!=(const FunctionEffectIterator &Other) const {
+ return Idx != Other.Idx;
+ }
+
+ // prefix increment
+ FunctionEffectIterator operator++() {
+ ++Idx;
+ return *this;
+ }
+
+ FunctionEffectWithCondition operator*() const {
+ const bool HasConds = !Outer.Conditions.empty();
+ return FunctionEffectWithCondition{Outer.Effects[Idx],
+ HasConds ? Outer.Conditions[Idx]
+ : FunctionEffectCondition()};
+ }
+};
+
+/// An immutable set of FunctionEffects and possibly conditions attached to
+/// them. The effects and conditions reside in memory not managed by this
object
+/// (typically, trailing objects in FunctionProtoType, or borrowed references
+/// from a FunctionEffectSet).
+///
+/// Invariants:
+/// - there is never more than one instance of any given effect.
+/// - the array of conditions is either empty or has the same size as the
+/// array of effects.
+/// - some conditions may be null expressions; each condition pertains to
+/// the effect at the same array index.
+///
+/// Also, if there are any conditions, at least one of those expressions will
be
+/// dependent, but this is only asserted in the constructor of
+/// FunctionProtoType.
+///
+/// See also FunctionEffectSet, in Sema, which provides a mutable set.
+class FunctionEffectsRef {
+ // Restrict classes which can call the private constructor -- these friends
+ // all maintain the required invariants. FunctionEffectSet is generally the
+ // only way in which the arrays are created; FunctionProtoType will not
+ // reorder them.
+ friend FunctionProtoType;
+ friend FunctionEffectSet;
+
+ ArrayRef<FunctionEffect> Effects;
+ ArrayRef<FunctionEffectCondition> Conditions;
+
+ // The arrays are expected to have been sorted by the caller, with the
+ // effects in order. The conditions array must be empty or the same size
+ // as the effects array, since the conditions are associated with the effects
+ // at the same array indices.
+ FunctionEffectsRef(ArrayRef<FunctionEffect> FX,
+ ArrayRef<FunctionEffectCondition> Conds)
+ : Effects(FX), Conditions(Conds) {}
+
+public:
+ /// Extract the effects from a Type if it is a function, block, or member
+ /// function pointer, or a reference or pointer to one.
+ static FunctionEffectsRef get(QualType QT);
+
+ /// Asserts invariants.
+ static FunctionEffectsRef create(ArrayRef<FunctionEffect> FX,
+ ArrayRef<FunctionEffectCondition> Conds);
+
+ FunctionEffectsRef() = default;
+
+ bool empty() const { return Effects.empty(); }
+ size_t size() const { return Effects.size(); }
+
+ ArrayRef<FunctionEffect> effects() const { return Effects; }
+ ArrayRef<FunctionEffectCondition> conditions() const { return Conditions; }
+
+ using iterator = FunctionEffectIterator<FunctionEffectsRef>;
+ friend iterator;
+ iterator begin() const { return iterator(*this, 0); }
+ iterator end() const { return iterator(*this, size()); }
+
+ friend bool operator==(const FunctionEffectsRef &LHS,
+ const FunctionEffectsRef &RHS) {
+ return LHS.Effects == RHS.Effects && LHS.Conditions == RHS.Conditions;
+ }
+ friend bool operator!=(const FunctionEffectsRef &LHS,
+ const FunctionEffectsRef &RHS) {
+ return !(LHS == RHS);
+ }
+
+ void Profile(llvm::FoldingSetNodeID &ID) const;
+ void dump(llvm::raw_ostream &OS) const;
+};
+
+/// A mutable set of FunctionEffects and possibly conditions attached to them.
+/// Used to compare and merge effects on declarations.
+///
+/// Has the same invariants as FunctionEffectsRef.
+class FunctionEffectSet {
+ SmallVector<FunctionEffect> Effects;
+ SmallVector<FunctionEffectCondition> Conditions;
+
+public:
+ FunctionEffectSet() = default;
+
+ explicit FunctionEffectSet(const FunctionEffectsRef &FX)
+ : Effects(FX.effects()), Conditions(FX.conditions()) {}
+
+ bool empty() const { return Effects.empty(); }
+ size_t size() const { return Effects.size(); }
+
+ using iterator = FunctionEffectIterator<FunctionEffectSet>;
+ friend iterator;
+ iterator begin() const { return iterator(*this, 0); }
+ iterator end() const { return iterator(*this, size()); }
+
+ operator FunctionEffectsRef() const { return {Effects, Conditions}; }
+
+ void dump(llvm::raw_ostream &OS) const;
+
+ // Mutators
+
+ // On insertion, a conflict occurs when attempting to insert an
+ // effect which is opposite an effect already in the set, or attempting
+ // to insert an effect which is already in the set but with a condition
+ // which is not identical.
+ struct Conflict {
+ FunctionEffectWithCondition Kept;
+ FunctionEffectWithCondition Rejected;
+ };
+ using Conflicts = SmallVector<Conflict>;
+
+ void insert(const FunctionEffectWithCondition &NewEC, Conflicts &Errs);
+ void insert(const FunctionEffectsRef &Set, Conflicts &Errs);
+ void insertIgnoringConditions(const FunctionEffectsRef &Set, Conflicts
&Errs);
+
+ void replaceItem(unsigned Idx, const FunctionEffectWithCondition &Item);
+ void erase(unsigned Idx);
----------------
dougsonos wrote:
As it happens, `erase` isn't currently used; will remove.
The only caller of `replaceItem` is in TreeTransform, where it's making a
mutated copy of a `FunctionProtoType` and needs to deal with the effect and
condition arrays separately, by index. Pretty much everywhere else the class
serves to "zip" the two arrays together to avoid the ugliness of dual iteration
and the possibility of there being no conditions at all.
I could add a subscript operator with the caveat that it's a read-only "view"
-- enforced by making the returned struct `const`. The iterator's `operator*()`
needs to do that too.
https://github.com/llvm/llvm-project/pull/84983
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