Unify COFF and ELF data structures and procedures

include/swift/Reflection/ReflectionContext.h

@@ -320,10 +320,8 @@ class ReflectionContext
 
         // FIXME: This code needs to be cleaned up and updated
         // to make it work for 32 bit platforms.
-        if (SectionName != ".sw5cptr" && SectionName != ".sw5bltn") {
-          Begin = Begin.atByteOffset(8);
-          Size -= 16;
-        }
+        Begin = Begin.atByteOffset(8);
+        Size -= 16;
 
         return {Begin, Size};
       }

stdlib/public/SwiftShims/MetadataSections.h

@@ -29,15 +29,26 @@ namespace swift {
 extern "C" {
 #endif
 
+/// Specifies the address range corresponding to a section.
 typedef struct MetadataSectionRange {
   __swift_uintptr_t start;
   __swift_size_t length;
 } MetadataSectionRange;
 
+
+/// Identifies the address space ranges for the Swift metadata required by the Swift runtime.
 struct MetadataSections {
   __swift_uintptr_t version;
   __swift_uintptr_t reserved;
 
+  /// `next` and `prev` are used by the runtime to construct a
+  /// circularly doubly linked list to quickly iterate over the metadata
+  /// from each image loaded into the address space.  These are invasive
+  /// to enable the runtime registration, which occurs at image load time, to
+  /// be allocation-free as it is invoked from an image constructor function
+  /// context where the system may not yet be ready to perform allocations.
+  /// Additionally, avoiding the allocation enables a fast load operation, which
+  /// directly impacts application load time.
   struct MetadataSections *next;
   struct MetadataSections *prev;
 

stdlib/public/runtime/CMakeLists.txt

@@ -45,6 +45,7 @@ set(swift_runtime_sources
     Float16Support.cpp
     Heap.cpp
     HeapObject.cpp
+    ImageInspectionCommon.cpp
     ImageInspectionMachO.cpp
     ImageInspectionELF.cpp
     ImageInspectionCOFF.cpp

stdlib/public/runtime/ImageInspectionCOFF.cpp

@@ -13,7 +13,6 @@
 #if !defined(__ELF__) && !defined(__MACH__)
 
 #include "ImageInspection.h"
-#include "ImageInspectionCOFF.h"
 
 #if defined(__CYGWIN__)
 #include <dlfcn.h>
@@ -26,108 +25,6 @@
 
 using namespace swift;
 
-namespace {
-static const swift::MetadataSections *registered = nullptr;
-
-void record(const swift::MetadataSections *sections) {
-  if (registered == nullptr) {
-    registered = sections;
-    sections->next = sections->prev = sections;
-  } else {
-    registered->prev->next = sections;
-    sections->next = registered;
-    sections->prev = registered->prev;
-    registered->prev = sections;
-  }
-}
-}
-
-void swift::initializeProtocolLookup() {
-  const swift::MetadataSections *sections = registered;
-  while (true) {
-    const swift::MetadataSections::Range &protocols =
-      sections->swift5_protocols;
-    if (protocols.length)
-      addImageProtocolsBlockCallbackUnsafe(
-          reinterpret_cast<void *>(protocols.start), protocols.length);
-
-    if (sections->next == registered)
-      break;
-    sections = sections->next;
-  }
-}
-
-void swift::initializeProtocolConformanceLookup() {
-  const swift::MetadataSections *sections = registered;
-  while (true) {
-    const swift::MetadataSections::Range &conformances =
-        sections->swift5_protocol_conformances;
-    if (conformances.length)
-      addImageProtocolConformanceBlockCallbackUnsafe(
-          reinterpret_cast<void *>(conformances.start), conformances.length);
-
-    if (sections->next == registered)
-      break;
-    sections = sections->next;
-  }
-}
-
-void swift::initializeTypeMetadataRecordLookup() {
-  const swift::MetadataSections *sections = registered;
-  while (true) {
-    const swift::MetadataSections::Range &type_metadata =
-        sections->swift5_type_metadata;
-    if (type_metadata.length)
-      addImageTypeMetadataRecordBlockCallbackUnsafe(
-          reinterpret_cast<void *>(type_metadata.start), type_metadata.length);
-
-    if (sections->next == registered)
-      break;
-    sections = sections->next;
-  }
-}
-
-void swift::initializeDynamicReplacementLookup() {
-}
-
-SWIFT_RUNTIME_EXPORT
-void swift_addNewDSOImage(const void *addr) {
-  const swift::MetadataSections *sections =
-      static_cast<const swift::MetadataSections *>(addr);
-
-  record(sections);
-
-  const auto &protocols_section = sections->swift5_protocols;
-  const void *protocols =
-      reinterpret_cast<void *>(protocols_section.start);
-  if (protocols_section.length)
-    addImageProtocolsBlockCallback(protocols, protocols_section.length);
-
-  const auto &protocol_conformances = sections->swift5_protocol_conformances;
-  const void *conformances =
-      reinterpret_cast<void *>(protocol_conformances.start);
-  if (protocol_conformances.length)
-    addImageProtocolConformanceBlockCallback(conformances,
-                                             protocol_conformances.length);
-
-  const auto &type_metadata = sections->swift5_type_metadata;
-  const void *metadata = reinterpret_cast<void *>(type_metadata.start);
-  if (type_metadata.length)
-    addImageTypeMetadataRecordBlockCallback(metadata, type_metadata.length);
-
-  const auto &dynamic_replacements = sections->swift5_repl;
-  const auto *replacements =
-      reinterpret_cast<void *>(dynamic_replacements.start);
-  if (dynamic_replacements.length) {
-    const auto &dynamic_replacements_some = sections->swift5_reps;
-    const auto *replacements_some =
-      reinterpret_cast<void *>(dynamic_replacements_some.start);
-    addImageDynamicReplacementBlockCallback(
-        replacements, dynamic_replacements.length, replacements_some,
-        dynamic_replacements_some.length);
-  }
-}
-
 int swift::lookupSymbol(const void *address, SymbolInfo *info) {
 #if defined(__CYGWIN__)
   Dl_info dlinfo;
@@ -173,10 +70,4 @@ int swift::lookupSymbol(const void *address, SymbolInfo *info) {
 #endif // defined(__CYGWIN__) || defined(_WIN32)
 }
 
-// This is only used for backward deployment hooks, which we currently only support for
-// MachO. Add a stub here to make sure it still compiles.
-void *swift::lookupSection(const char *segment, const char *section, size_t *outSize) {
-  return nullptr;
-}
-
 #endif // !defined(__ELF__) && !defined(__MACH__)

stdlib/public/runtime/ImageInspectionCommon.cpp

@@ -0,0 +1,143 @@
+//===--- ImageInspectionCommon.cpp - Image inspection routines --*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+///
+/// This file unifies common ELF and COFF image inspection routines
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_RUNTIME_IMAGEINSPECTIONCOMMON_H
+#define SWIFT_RUNTIME_IMAGEINSPECTIONCOMMON_H
+
+#if !defined(__MACH__)
+
+#include "../SwiftShims/Visibility.h"
+#include "../SwiftShims/MetadataSections.h"
+#include "ImageInspection.h"
+
+
+namespace swift {
+
+static swift::MetadataSections *registered = nullptr;
+
+void record(swift::MetadataSections *sections) {
+  if (registered == nullptr) {
+    registered = sections;
+    sections->next = sections->prev = sections;
+  } else {
+    registered->prev->next = sections;
+    sections->next = registered;
+    sections->prev = registered->prev;
+    registered->prev = sections;
+  }
+}
+}
+
+SWIFT_RUNTIME_EXPORT
+void swift_addNewDSOImage(const void *addr) {
+  const swift::MetadataSections *sections =
+      static_cast<const swift::MetadataSections *>(addr);
+
+  // We cast off the const in order to update the linked list
+  // data structure. This is safe to do since we don't touch 
+  // any other fields.
+  auto casted_sections = const_cast<swift::MetadataSections *>(sections);
+  record(casted_sections);
+
+  const auto &protocols_section = sections->swift5_protocols;
+  const void *protocols = reinterpret_cast<void *>(protocols_section.start);
+  if (protocols_section.length)
+    swift::addImageProtocolsBlockCallback(protocols, protocols_section.length);
+
+  const auto &protocol_conformances = sections->swift5_protocol_conformances;
+  const void *conformances =
+      reinterpret_cast<void *>(protocol_conformances.start);
+  if (protocol_conformances.length)
+    swift::addImageProtocolConformanceBlockCallback(conformances,
+                                             protocol_conformances.length);
+
+  const auto &type_metadata = sections->swift5_type_metadata;
+  const void *metadata = reinterpret_cast<void *>(type_metadata.start);
+  if (type_metadata.length)
+    swift::addImageTypeMetadataRecordBlockCallback(metadata, type_metadata.length);
+
+  const auto &dynamic_replacements = sections->swift5_replace;
+  const auto *replacements =
+      reinterpret_cast<void *>(dynamic_replacements.start);
+  if (dynamic_replacements.length) {
+    const auto &dynamic_replacements_some = sections->swift5_replac2;
+    const auto *replacements_some =
+      reinterpret_cast<void *>(dynamic_replacements_some.start);
+    swift::addImageDynamicReplacementBlockCallback(
+        replacements, dynamic_replacements.length, replacements_some,
+        dynamic_replacements_some.length);
+  }
+}
+
+void swift::initializeProtocolLookup() {
+  const swift::MetadataSections *sections = registered;
+  while (true) {
+    const swift::MetadataSectionRange &protocols =
+      sections->swift5_protocols;
+    if (protocols.length)
+      addImageProtocolsBlockCallbackUnsafe(
+          reinterpret_cast<void *>(protocols.start), protocols.length);
+
+    if (sections->next == registered)
+      break;
+    sections = sections->next;
+  }
+}
+
+void swift::initializeProtocolConformanceLookup() {
+  const swift::MetadataSections *sections = registered;
+  while (true) {
+    const swift::MetadataSectionRange &conformances =
+        sections->swift5_protocol_conformances;
+    if (conformances.length)
+      addImageProtocolConformanceBlockCallbackUnsafe(
+          reinterpret_cast<void *>(conformances.start), conformances.length);
+
+    if (sections->next == registered)
+      break;
+    sections = sections->next;
+  }
+}
+
+void swift::initializeTypeMetadataRecordLookup() {
+  const swift::MetadataSections *sections = registered;
+  while (true) {
+    const swift::MetadataSectionRange &type_metadata =
+        sections->swift5_type_metadata;
+    if (type_metadata.length)
+      addImageTypeMetadataRecordBlockCallbackUnsafe(
+          reinterpret_cast<void *>(type_metadata.start), type_metadata.length);
+
+    if (sections->next == registered)
+      break;
+    sections = sections->next;
+  }
+}
+
+void swift::initializeDynamicReplacementLookup() {
+}
+
+// This is only used for backward deployment hooks, which we currently only support for
+// MachO. Add a stub here to make sure it still compiles.
+void *swift::lookupSection(const char *segment, const char *section, size_t *outSize) {
+  return nullptr;
+}
+
+#endif // !defined(__MACH__)
+
+#endif // SWIFT_RUNTIME_IMAGEINSPECTIONCOMMON_H