Explicitly lower value pack and parameter expansion types in SIL

Introduce a new SILPackType which captures whether the element types
are stored inline in the pack array.  Add ParameterConventions and
SILArgumentConventions for passing packs.  Make a bunch of changes,
some of which might be correct.

Author: rjmccall

docs/ABI/Mangling.rst

@@ -665,6 +665,7 @@ Types
   
   type ::= pattern-type count-type 'Qp'      // pack expansion type
   type ::= pack-element-list 'QP'            // pack type
+  type ::= pack-element-list 'QS' DIRECTNESS // SIL pack type
 
   pack-element-list ::= type '_' type*
   pack-element-list ::= empty-list
@@ -746,6 +747,9 @@ mangled in to disambiguate.
   PARAM-CONVENTION ::= 'y'                   // direct unowned
   PARAM-CONVENTION ::= 'g'                   // direct guaranteed
   PARAM-CONVENTION ::= 'e'                   // direct deallocating
+  PARAM-CONVENTION ::= 'v'                   // pack owned
+  PARAM-CONVENTION ::= 'p'                   // pack guaranteed
+  PARAM-CONVENTION ::= 'm'                   // pack inout
 
   PARAM-DIFFERENTIABILITY ::= 'w'            // @noDerivative
 
@@ -757,6 +761,9 @@ mangled in to disambiguate.
 
   RESULT-DIFFERENTIABILITY ::= 'w'            // @noDerivative
 
+  DIRECTNESS ::= 'i'                         // indirect
+  DIRECTNESS ::= 'd'                         // direct
+
 For the most part, manglings follow the structure of formal language
 types.  However, in some cases it is more useful to encode the exact
 implementation details of a function type.

include/swift/AST/Attr.def.gyb

@@ -66,11 +66,15 @@ TYPE_ATTR(dynamic_self)
 #include "swift/AST/ReferenceStorage.def"
 TYPE_ATTR(error)
 TYPE_ATTR(out)
+TYPE_ATTR(direct)
 TYPE_ATTR(in)
 TYPE_ATTR(inout)
 TYPE_ATTR(inout_aliasable)
 TYPE_ATTR(in_guaranteed)
 TYPE_ATTR(in_constant)
+TYPE_ATTR(pack_owned)
+TYPE_ATTR(pack_guaranteed)
+TYPE_ATTR(pack_inout)
 TYPE_ATTR(owned)
 TYPE_ATTR(unowned_inner_pointer)
 TYPE_ATTR(guaranteed)

include/swift/AST/TypeDifferenceVisitor.h

@@ -136,6 +136,14 @@ class CanTypeDifferenceVisitor : public CanTypePairVisitor<Impl, bool> {
                                type2->getElementTypes());
   }
 
+  bool visitSILPackType(CanSILPackType type1, CanSILPackType type2) {
+    if (type1->isElementAddress() != type2->isElementAddress())
+      return asImpl().visitDifferentTypeStructure(type1, type2);
+    return visitComponentArray(type1, type2,
+                               type1->getElementTypes(),
+                               type2->getElementTypes());
+  }
+
   bool visitPackExpansionType(CanPackExpansionType type1,
                               CanPackExpansionType type2) {
     return asImpl().visit(type1.getPatternType(), type2.getPatternType());

include/swift/AST/TypeMatcher.h

@@ -143,6 +143,29 @@ class TypeMatcher {
       return mismatch(firstTuple.getPointer(), secondType, sugaredFirstType);
     }
 
+    bool visitSILPackType(CanSILPackType firstPack, Type secondType,
+                          Type sugaredFirstType) {
+      if (auto secondPack = secondType->getAs<SILPackType>()) {
+        if (firstPack->getNumElements() != secondPack->getNumElements())
+          return mismatch(firstPack.getPointer(), secondPack,
+                          sugaredFirstType);
+
+        for (unsigned i = 0, n = firstPack->getNumElements(); i != n; ++i) {
+          // Recurse on the pack elements.  There's no need to preserve
+          // sugar for SIL types.
+          if (!this->visit(firstPack->getElementType(i),
+                           secondPack->getElementType(i),
+                           firstPack->getElementType(i)))
+            return false;
+        }
+
+        return true;
+      }
+
+      // Pack/non-pack mismatch.
+      return mismatch(firstPack.getPointer(), secondType, sugaredFirstType);
+    }
+
     bool visitPackType(CanPackType firstTuple, Type secondType,
                        Type sugaredFirstType) {
       if (auto secondTuple = secondType->getAs<PackType>()) {

include/swift/AST/TypeNodes.def

@@ -53,6 +53,17 @@
 ///   This is only expanded if SINGLETON_TYPE is defined, and in this
 ///   case no other macros are expanded.
 
+#ifndef ALWAYS_CANONICAL_ARTIFICIAL_TYPE
+#ifdef ALWAYS_CANONICAL_TYPE
+#ifdef ARTIFICIAL_TYPE
+#error must define ALWAYS_CANONICAL_ARTIFICIAL_TYPE if also defining both ALWAYS_CANONICAL_TYPE and ARTIFICIAL_TYPE
+#endif
+#define ALWAYS_CANONICAL_ARTIFICIAL_TYPE(id, parent) ALWAYS_CANONICAL_TYPE(id, parent)
+#else
+#define ALWAYS_CANONICAL_ARTIFICIAL_TYPE(id, parent) ARTIFICIAL_TYPE(id, parent)
+#endif
+#endif
+
 #ifndef ALWAYS_CANONICAL_TYPE
 #define ALWAYS_CANONICAL_TYPE(id, parent) TYPE(id, parent)
 #endif
@@ -165,6 +176,7 @@ ARTIFICIAL_TYPE(SILFunction, Type)
 ARTIFICIAL_TYPE(SILBlockStorage, Type)
 ARTIFICIAL_TYPE(SILBox, Type)
 ARTIFICIAL_TYPE(SILMoveOnlyWrapped, Type)
+ALWAYS_CANONICAL_ARTIFICIAL_TYPE(SILPack, Type)
 ARTIFICIAL_TYPE(SILToken, Type)
 TYPE(ProtocolComposition, Type)
 TYPE(ParameterizedProtocol, Type)
@@ -213,5 +225,6 @@ SINGLETON_TYPE(SILToken, SILToken)
 #undef SUGARED_TYPE
 #undef BUILTIN_TYPE
 #undef ALWAYS_CANONICAL_TYPE
+#undef ALWAYS_CANONICAL_ARTIFICIAL_TYPE
 #undef TYPE
 #undef LAST_TYPE

include/swift/AST/Types.h

@@ -407,10 +407,10 @@ class alignas(1 << TypeAlignInBits) TypeBase
     ID : 32
   );
 
-  SWIFT_INLINE_BITFIELD(SILFunctionType, TypeBase, NumSILExtInfoBits+1+3+1+2+1+1,
+  SWIFT_INLINE_BITFIELD(SILFunctionType, TypeBase, NumSILExtInfoBits+1+4+1+2+1+1,
     ExtInfoBits : NumSILExtInfoBits,
     HasClangTypeInfo : 1,
-    CalleeConvention : 3,
+    CalleeConvention : 4,
     HasErrorResult : 1,
     CoroutineKind : 2,
     HasInvocationSubs : 1,
@@ -451,7 +451,17 @@ class alignas(1 << TypeAlignInBits) TypeBase
   SWIFT_INLINE_BITFIELD_FULL(PackType, TypeBase, 32,
     : NumPadBits,
 
-    /// The number of elements of the tuple.
+    /// The number of elements of the pack.
+    Count : 32
+  );
+
+  SWIFT_INLINE_BITFIELD_FULL(SILPackType, TypeBase, 1+32,
+    /// Whether elements of the pack are addresses.
+    ElementIsAddress : 1,
+
+    : NumPadBits,
+
+    /// The number of elements of the pack
     Count : 32
   );
 
@@ -3777,9 +3787,24 @@ enum class ParameterConvention : uint8_t {
   /// This argument is passed directly.  Its type is non-trivial, and the caller
   /// guarantees its validity for the entirety of the call.
   Direct_Guaranteed,
+
+  /// This argument is a value pack of mutable references to storage,
+  /// which the function is being given exclusive access to.  The elements
+  /// must be passed indirectly.
+  Pack_Inout,
+
+  /// This argument is a value pack, and ownership of the elements is being
+  /// transferred into this function.  Whether the elements are passed
+  /// indirectly is recorded in the pack type.
+  Pack_Owned,
+
+  /// This argument is a value pack, and ownership of the elements is not
+  /// being transferred into this function.  Whether the elements are passed
+  /// indirectly is recorded in the pack type.
+  Pack_Guaranteed,
 };
 // Check that the enum values fit inside Bits.SILFunctionType.
-static_assert(unsigned(ParameterConvention::Direct_Guaranteed) < (1<<3),
+static_assert(unsigned(ParameterConvention::Pack_Guaranteed) < (1<<4),
               "fits in Bits.SILFunctionType");
 
 // Does this parameter convention require indirect storage? This reflects a
@@ -3796,6 +3821,9 @@ inline bool isIndirectFormalParameter(ParameterConvention conv) {
   case ParameterConvention::Direct_Unowned:
   case ParameterConvention::Direct_Guaranteed:
   case ParameterConvention::Direct_Owned:
+  case ParameterConvention::Pack_Inout:
+  case ParameterConvention::Pack_Owned:
+  case ParameterConvention::Pack_Guaranteed:
     return false;
   }
   llvm_unreachable("covered switch isn't covered?!");
@@ -3804,13 +3832,16 @@ inline bool isConsumedParameter(ParameterConvention conv) {
   switch (conv) {
   case ParameterConvention::Indirect_In:
   case ParameterConvention::Direct_Owned:
+  case ParameterConvention::Pack_Owned:
     return true;
 
   case ParameterConvention::Indirect_Inout:
   case ParameterConvention::Indirect_InoutAliasable:
   case ParameterConvention::Direct_Unowned:
   case ParameterConvention::Direct_Guaranteed:
   case ParameterConvention::Indirect_In_Guaranteed:
+  case ParameterConvention::Pack_Inout:
+  case ParameterConvention::Pack_Guaranteed:
     return false;
   }
   llvm_unreachable("bad convention kind");
@@ -3823,13 +3854,16 @@ inline bool isGuaranteedParameter(ParameterConvention conv) {
   switch (conv) {
   case ParameterConvention::Direct_Guaranteed:
   case ParameterConvention::Indirect_In_Guaranteed:
+  case ParameterConvention::Pack_Guaranteed:
     return true;
 
   case ParameterConvention::Indirect_Inout:
   case ParameterConvention::Indirect_InoutAliasable:
   case ParameterConvention::Indirect_In:
   case ParameterConvention::Direct_Unowned:
   case ParameterConvention::Direct_Owned:
+  case ParameterConvention::Pack_Inout:
+  case ParameterConvention::Pack_Owned:
     return false;
   }
   llvm_unreachable("bad convention kind");
@@ -5138,6 +5172,97 @@ class SILTokenType final : public TypeBase {
 };
 DEFINE_EMPTY_CAN_TYPE_WRAPPER(SILTokenType, Type)
 
+/// A lowered pack type which structurally carries lowered information
+/// about the pack elements.
+///
+/// A value pack is basically treated as a unique-ownership, unmovable
+/// reference-semantics aggregate in SIL: ownership of the pack as a whole
+/// is communicated with normal borrows of the pack, and packs can only
+/// be created locally and forwarded as arguments rather than being moved
+/// in any more complex way.
+class SILPackType final : public TypeBase, public llvm::FoldingSetNode,
+    private llvm::TrailingObjects<SILPackType, CanType> {
+public:
+  /// Type structure not reflected in the pack element type list.
+  ///
+  /// In the design of this, we considered storing ownership here,
+  /// but ended up just with the one bit.
+  struct ExtInfo {
+    bool ElementIsAddress;
+
+    ExtInfo(bool elementIsAddress) : ElementIsAddress(elementIsAddress) {}
+  };
+
+private:
+  friend TrailingObjects;
+  friend class ASTContext;
+  SILPackType(const ASTContext &ctx, RecursiveTypeProperties properties,
+              ExtInfo info, ArrayRef<CanType> elements)
+      : TypeBase(TypeKind::SILPack, &ctx, properties) {
+    Bits.SILPackType.Count = elements.size();
+    Bits.SILPackType.ElementIsAddress = info.ElementIsAddress;
+    memcpy(getTrailingObjects<CanType>(), elements.data(),
+           elements.size() * sizeof(CanType));
+  }
+
+public:
+  static CanTypeWrapper<SILPackType> get(const ASTContext &ctx,
+                                         ExtInfo info,
+                                         ArrayRef<CanType> elements);
+
+  ExtInfo getExtInfo() const {
+    return { isElementAddress() };
+  }
+
+  bool isElementAddress() const {
+    return Bits.SILPackType.ElementIsAddress;
+  }
+
+  /// Retrieves the number of elements in this pack.
+  unsigned getNumElements() const { return Bits.SILPackType.Count; }
+
+  /// Retrieves the type of the elements in the pack.
+  ArrayRef<CanType> getElementTypes() const {
+    return {getTrailingObjects<CanType>(), getNumElements()};
+  }
+
+  /// Returns the type of the element at the given \p index.
+  /// This is a lowered SIL type.
+  CanType getElementType(unsigned index) const {
+    return getTrailingObjects<CanType>()[index];
+  }
+
+  SILType getSILElementType(unsigned index) const; // in SILType.h
+
+  /// Return the reduced shape of this pack.  For consistency with
+  /// general shape-handling routines, we produce an AST pack type
+  /// as the shape, not a SIL pack type.
+  CanTypeWrapper<PackType> getReducedShape() const;
+
+  bool containsPackExpansionType() const;
+
+  void Profile(llvm::FoldingSetNodeID &ID) const {
+    Profile(ID, getExtInfo(), getElementTypes());
+  }
+  static void Profile(llvm::FoldingSetNodeID &ID,
+                      ExtInfo info,
+                      ArrayRef<CanType> elements);
+
+  // Implement isa/cast/dyncast/etc.
+  static bool classof(const TypeBase *T) {
+    return T->getKind() == TypeKind::SILPack;
+  }
+};
+BEGIN_CAN_TYPE_WRAPPER(SILPackType, Type)
+  CanType getElementType(unsigned elementNo) const {
+    return getPointer()->getElementType(elementNo);
+  }
+
+  ArrayRef<CanType> getElementTypes() const {
+    return getPointer()->getElementTypes();
+  }
+END_CAN_TYPE_WRAPPER(SILPackType, Type)
+
 /// A type with a special syntax that is always sugar for a library type. The
 /// library type may have multiple base types. For unary syntax sugar, see
 /// UnarySyntaxSugarType.
@@ -6654,6 +6779,8 @@ class PackExpansionType : public TypeBase, public llvm::FoldingSetNode {
                     const ASTContext *ctx);
 };
 BEGIN_CAN_TYPE_WRAPPER(PackExpansionType, Type)
+  static CanPackExpansionType get(CanType pattern, CanType countType);
+
   CanType getPatternType() const {
     return CanType(getPointer()->getPatternType());
   }

include/swift/SIL/ApplySite.h

@@ -379,6 +379,7 @@ class ApplySite {
     switch (conv) {
     case SILArgumentConvention::Indirect_Inout:
     case SILArgumentConvention::Indirect_InoutAliasable:
+    case SILArgumentConvention::Pack_Inout:
       return conv;
     case SILArgumentConvention::Direct_Owned:
     case SILArgumentConvention::Direct_Unowned:
@@ -389,7 +390,12 @@ class ApplySite {
     case SILArgumentConvention::Indirect_In_Guaranteed:
       return pai->isOnStack() ? SILArgumentConvention::Indirect_In_Guaranteed
                               : SILArgumentConvention::Indirect_In;
+    case SILArgumentConvention::Pack_Guaranteed:
+    case SILArgumentConvention::Pack_Owned:
+      return pai->isOnStack() ? SILArgumentConvention::Pack_Guaranteed
+                              : SILArgumentConvention::Pack_Owned;
     case SILArgumentConvention::Indirect_Out:
+    case SILArgumentConvention::Pack_Out:
       llvm_unreachable("partial_apply cannot have an @out operand");
     }
     llvm_unreachable("covered switch");