Reflection: Traffic in RemoteRefs.

Instead of passing around raw local pointers and references, and spreading
tricky offset arithmetic around with the Local/RemoteAddress fields in
ReflectionInfo, have the TypeRefBuilder code use RemoteRefs everywhere,
which keep the remote/local mapping together in one unit and provide
centralized API for this logic.

This doesn't yet change how code uses the RemoteRef address data to
follow pointers across objects, for things like reading type refs, but
that should be much easier to do after this lands.

Author: jckarter

include/swift/Reflection/Records.h

@@ -70,10 +70,11 @@ class FieldRecordFlags {
 
 class FieldRecord {
   const FieldRecordFlags Flags;
+
+public:
   const RelativeDirectPointer<const char> MangledTypeName;
   const RelativeDirectPointer<const char> FieldName;
 
-public:
   FieldRecord() = delete;
 
   bool hasMangledTypeName() const {
@@ -84,11 +85,8 @@ class FieldRecord {
     return Demangle::makeSymbolicMangledNameStringRef(MangledTypeName.get());
   }
 
-  StringRef getFieldName(uintptr_t Low, uintptr_t High) const {
-    uintptr_t nameAddr = (uintptr_t)FieldName.get();
-    if (nameAddr < Low || nameAddr > High)
-      return "";
-    return (const char *)nameAddr;
+  StringRef getFieldName() const {
+    return FieldName.get();
   }
 
   bool isIndirectCase() const {
@@ -162,10 +160,10 @@ class FieldDescriptor {
     return reinterpret_cast<const FieldRecord *>(this + 1);
   }
 
+public:
   const RelativeDirectPointer<const char> MangledTypeName;
   const RelativeDirectPointer<const char> Superclass;
 
-public:
   FieldDescriptor() = delete;
 
   const FieldDescriptorKind Kind;
@@ -227,46 +225,13 @@ class FieldDescriptor {
   }
 };
 
-class FieldDescriptorIterator
-  : public std::iterator<std::forward_iterator_tag, FieldDescriptor> {
-public:
-  const void *Cur;
-  const void * const End;
-  FieldDescriptorIterator(const void *Cur, const void * const End)
-    : Cur(Cur), End(End) {}
-
-  const FieldDescriptor &operator*() const {
-    return *reinterpret_cast<const FieldDescriptor *>(Cur);
-  }
-
-  const FieldDescriptor *operator->() const {
-    return reinterpret_cast<const FieldDescriptor *>(Cur);
-  }
-
-  FieldDescriptorIterator &operator++() {
-    const auto &FR = this->operator*();
-    const void *Next = reinterpret_cast<const char *>(Cur)
-      + sizeof(FieldDescriptor) + FR.NumFields * FR.FieldRecordSize;
-    Cur = Next;
-    return *this;
-  }
-
-  bool operator==(FieldDescriptorIterator const &other) const {
-    return Cur == other.Cur && End == other.End;
-  }
-
-  bool operator!=(FieldDescriptorIterator const &other) const {
-    return !(*this == other);
-  }
-};
-
 // Associated type records describe the mapping from an associated
 // type to the type witness of a conformance.
 class AssociatedTypeRecord {
+public:
   const RelativeDirectPointer<const char> Name;
   const RelativeDirectPointer<const char> SubstitutedTypeName;
 
-public:
   StringRef getName() const {
     return Name.get();
   }
@@ -322,10 +287,9 @@ struct AssociatedTypeRecordIterator {
 // An associated type descriptor contains a collection of associated
 // type records for a conformance.
 struct AssociatedTypeDescriptor {
-private:
+public:
   const RelativeDirectPointer<const char> ConformingTypeName;
   const RelativeDirectPointer<const char> ProtocolTypeName;
-public:
 
   uint32_t NumAssociatedTypes;
   uint32_t AssociatedTypeRecordSize;
@@ -357,46 +321,12 @@ struct AssociatedTypeDescriptor {
   }
 };
 
-class AssociatedTypeIterator
-  : public std::iterator<std::forward_iterator_tag, AssociatedTypeDescriptor> {
-public:
-  const void *Cur;
-  const void * const End;
-  AssociatedTypeIterator(const void *Cur, const void * const End)
-    : Cur(Cur), End(End) {}
-
-  const AssociatedTypeDescriptor &operator*() const {
-    return *reinterpret_cast<const AssociatedTypeDescriptor *>(Cur);
-  }
-
-  const AssociatedTypeDescriptor *operator->() const {
-    return reinterpret_cast<const AssociatedTypeDescriptor *>(Cur);
-  }
-
-  AssociatedTypeIterator &operator++() {
-    const auto &ATR = this->operator*();
-    size_t Size = sizeof(AssociatedTypeDescriptor) +
-      ATR.NumAssociatedTypes * ATR.AssociatedTypeRecordSize;
-    const void *Next = reinterpret_cast<const char *>(Cur) + Size;
-    Cur = Next;
-    return *this;
-  }
-
-  bool operator==(AssociatedTypeIterator const &other) const {
-    return Cur == other.Cur && End == other.End;
-  }
-
-  bool operator!=(AssociatedTypeIterator const &other) const {
-    return !(*this == other);
-  }
-};
-
 // Builtin type records describe basic layout information about
 // any builtin types referenced from the other sections.
 class BuiltinTypeDescriptor {
+public:
   const RelativeDirectPointer<const char> TypeName;
 
-public:
   uint32_t Size;
 
   // - Least significant 16 bits are the alignment.
@@ -424,42 +354,10 @@ class BuiltinTypeDescriptor {
   }
 };
 
-class BuiltinTypeDescriptorIterator
-  : public std::iterator<std::forward_iterator_tag, BuiltinTypeDescriptor> {
-public:
-  const void *Cur;
-  const void * const End;
-  BuiltinTypeDescriptorIterator(const void *Cur, const void * const End)
-    : Cur(Cur), End(End) {}
-
-  const BuiltinTypeDescriptor &operator*() const {
-    return *reinterpret_cast<const BuiltinTypeDescriptor *>(Cur);
-  }
-
-  const BuiltinTypeDescriptor *operator->() const {
-    return reinterpret_cast<const BuiltinTypeDescriptor *>(Cur);;
-  }
-
-  BuiltinTypeDescriptorIterator &operator++() {
-    const void *Next = reinterpret_cast<const char *>(Cur)
-      + sizeof(BuiltinTypeDescriptor);
-    Cur = Next;
-    return *this;
-  }
-
-  bool operator==(BuiltinTypeDescriptorIterator const &other) const {
-    return Cur == other.Cur && End == other.End;
-  }
-
-  bool operator!=(BuiltinTypeDescriptorIterator const &other) const {
-    return !(*this == other);
-  }
-};
-
 class CaptureTypeRecord {
+public:
   const RelativeDirectPointer<const char> MangledTypeName;
 
-public:
   CaptureTypeRecord() = delete;
 
   bool hasMangledTypeName() const {
@@ -502,10 +400,10 @@ struct CaptureTypeRecordIterator {
 };
 
 class MetadataSourceRecord {
+public:
   const RelativeDirectPointer<const char> MangledTypeName;
   const RelativeDirectPointer<const char> MangledMetadataSource;
 
-public:
   MetadataSourceRecord() = delete;
 
   bool hasMangledTypeName() const {
@@ -608,41 +506,6 @@ class CaptureDescriptor {
   }
 };
 
-class CaptureDescriptorIterator
-  : public std::iterator<std::forward_iterator_tag, CaptureDescriptor> {
-public:
-  const void *Cur;
-  const void * const End;
-  CaptureDescriptorIterator(const void *Cur, const void * const End)
-    : Cur(Cur), End(End) {}
-
-  const CaptureDescriptor &operator*() const {
-    return *reinterpret_cast<const CaptureDescriptor *>(Cur);
-  }
-
-  const CaptureDescriptor *operator->() const {
-    return reinterpret_cast<const CaptureDescriptor *>(Cur);
-  }
-
-  CaptureDescriptorIterator &operator++() {
-    const auto &CR = this->operator*();
-    const void *Next = reinterpret_cast<const char *>(Cur)
-      + sizeof(CaptureDescriptor)
-      + CR.NumCaptureTypes * sizeof(CaptureTypeRecord)
-      + CR.NumMetadataSources * sizeof(MetadataSourceRecord);
-    Cur = Next;
-    return *this;
-  }
-
-  bool operator==(CaptureDescriptorIterator const &other) const {
-    return Cur == other.Cur && End == other.End;
-  }
-
-  bool operator!=(CaptureDescriptorIterator const &other) const {
-    return !(*this == other);
-  }
-};
-
 } // end namespace reflection
 } // end namespace swift
 

include/swift/Reflection/ReflectionContext.h

@@ -206,7 +206,7 @@ class ReflectionContext
                                                RangeEnd - RangeStart);
 
     auto findMachOSectionByName = [&](std::string Name)
-        -> std::pair<const char *, const char *> {
+        -> std::pair<RemoteRef<void>, uint64_t> {
       for (unsigned I = 0; I < NumSect; ++I) {
         auto S = reinterpret_cast<typename T::Section *>(
             SectionsBuf + (I * sizeof(typename T::Section)));
@@ -216,10 +216,11 @@ class ReflectionContext
         auto SectBufData = reinterpret_cast<const char *>(SectBuf.get());
         auto LocalSectStart =
             reinterpret_cast<const char *>(SectBufData + RemoteSecStart - RangeStart);
-        auto LocalSectEnd = reinterpret_cast<const char *>(LocalSectStart + S->size);
-        return {LocalSectStart, LocalSectEnd};
+        
+        auto StartRef = RemoteRef<void>(RemoteSecStart, LocalSectStart);
+        return {StartRef, S->size};
       }
-      return {nullptr, nullptr};
+      return {nullptr, 0};
     };
 
     auto FieldMdSec = findMachOSectionByName("__swift5_fieldmd");
@@ -298,7 +299,7 @@ class ReflectionContext
         sizeof(llvm::object::coff_section) * COFFFileHdr->NumberOfSections);
 
     auto findCOFFSectionByName = [&](llvm::StringRef Name)
-        -> std::pair<const char *, const char *> {
+        -> std::pair<RemoteRef<void>, uint64_t> {
       for (size_t i = 0; i < COFFFileHdr->NumberOfSections; ++i) {
         const llvm::object::coff_section *COFFSec =
             reinterpret_cast<const llvm::object::coff_section *>(
@@ -313,34 +314,30 @@ class ReflectionContext
         auto Addr = ImageStart.getAddressData() + COFFSec->VirtualAddress;
         auto Buf = this->getReader().readBytes(RemoteAddress(Addr),
                                                COFFSec->VirtualSize);
-        const char *Begin = reinterpret_cast<const char *>(Buf.get());
-        const char *End = Begin + COFFSec->VirtualSize;
+        auto BufStart = Buf.get();
         savedBuffers.push_back(std::move(Buf));
 
+        auto Begin = RemoteRef<void>(Addr, BufStart);
+        auto Size = COFFSec->VirtualSize;
+        
         // FIXME: This code needs to be cleaned up and updated
         // to make it work for 32 bit platforms.
         if (SectionName != ".sw5cptr" && SectionName != ".sw5bltn") {
-          Begin += 8;
-          End -= 8;
+          Begin = Begin.atByteOffset(8);
+          Size -= 16;
         }
 
-        return {Begin, End};
+        return {Begin, Size};
       }
-      return {nullptr, nullptr};
+      return {nullptr, 0};
     };
 
-    std::pair<const char *, const char *> CaptureSec =
-        findCOFFSectionByName(".sw5cptr");
-    std::pair<const char *, const char *> TypeRefMdSec =
-        findCOFFSectionByName(".sw5tyrf");
-    std::pair<const char *, const char *> FieldMdSec =
-        findCOFFSectionByName(".sw5flmd");
-    std::pair<const char *, const char *> AssocTySec =
-        findCOFFSectionByName(".sw5asty");
-    std::pair<const char *, const char *> BuiltinTySec =
-        findCOFFSectionByName(".sw5bltn");
-    std::pair<const char *, const char *> ReflStrMdSec =
-        findCOFFSectionByName(".sw5rfst");
+    auto CaptureSec = findCOFFSectionByName(".sw5cptr");
+    auto TypeRefMdSec = findCOFFSectionByName(".sw5tyrf");
+    auto FieldMdSec = findCOFFSectionByName(".sw5flmd");
+    auto AssocTySec = findCOFFSectionByName(".sw5asty");
+    auto BuiltinTySec = findCOFFSectionByName(".sw5bltn");
+    auto ReflStrMdSec = findCOFFSectionByName(".sw5rfst");
 
     if (FieldMdSec.first == nullptr &&
         AssocTySec.first == nullptr &&
@@ -434,7 +431,7 @@ class ReflectionContext
     auto StrTab = reinterpret_cast<const char *>(StrTabBuf.get());
 
     auto findELFSectionByName = [&](std::string Name)
-        -> std::pair<const char *, const char *> {
+        -> std::pair<RemoteRef<void>, uint64_t> {
       // Now for all the sections, find their name.
       for (const typename T::Section *Hdr : SecHdrVec) {
         uint32_t Offset = Hdr->sh_name;
@@ -445,10 +442,12 @@ class ReflectionContext
             RemoteAddress(ImageStart.getAddressData() + Hdr->sh_addr);
         auto SecSize = Hdr->sh_size;
         auto SecBuf = this->getReader().readBytes(SecStart, SecSize);
-        auto SecContents = reinterpret_cast<const char *>(SecBuf.get());
-        return {SecContents, SecContents + SecSize};
+        auto SecContents = RemoteRef<void>(SecStart.getAddressData(),
+                                           SecBuf.get());
+        savedBuffers.push_back(std::move(SecBuf));
+        return {SecContents, SecSize};
       }
-      return {nullptr, nullptr};
+      return {nullptr, 0};
     };
 
     auto FieldMdSec = findELFSectionByName("swift5_fieldmd");
@@ -634,11 +633,11 @@ class ReflectionContext
       //
       // Non-generic SIL boxes share metadata among types with compatible
       // layout, but we need some way to get an outgoing pointer map for them.
-      auto *CD = getBuilder().getCaptureDescriptor(*CDAddr);
+      auto CD = getBuilder().getCaptureDescriptor(*CDAddr);
       if (CD == nullptr)
         return nullptr;
 
-      auto Info = getBuilder().getClosureContextInfo(*CD);
+      auto Info = getBuilder().getClosureContextInfo(CD);
 
       return getClosureContextInfo(ObjectAddress, Info);
     }