[Runtime] Rename the segment for protocol conformance records.

The format of protocol conformance records will be changing in Swift 5, so
rename the segment (from, e.g., __swift2_proto to __swift5_proto) to allow
Swift < 5 and Swift 5+ runtimes to coexist.

Author: DougGregor

lib/IRGen/GenDecl.cpp

@@ -2385,13 +2385,13 @@ llvm::Constant *IRGenModule::emitProtocolConformances() {
   StringRef sectionName;
   switch (TargetInfo.OutputObjectFormat) {
   case llvm::Triple::MachO:
-    sectionName = "__TEXT, __swift2_proto, regular, no_dead_strip";
+    sectionName = "__TEXT, __swift5_proto, regular, no_dead_strip";
     break;
   case llvm::Triple::ELF:
-    sectionName = "swift2_protocol_conformances";
+    sectionName = "swift5_protocol_conformances";
     break;
   case llvm::Triple::COFF:
-    sectionName = ".sw2prtc$B";
+    sectionName = ".sw5prtc$B";
     break;
   default:
     llvm_unreachable("Don't know how to emit protocol conformances for "

stdlib/public/runtime/ImageInspectionCOFF.cpp

@@ -41,7 +41,7 @@ void swift::initializeProtocolConformanceLookup() {
   const swift::MetadataSections *sections = registered;
   while (true) {
     const swift::MetadataSections::Range &conformances =
-        sections->swift2_protocol_conformances;
+        sections->swift5_protocol_conformances;
     if (conformances.length)
       addImageProtocolConformanceBlockCallback(reinterpret_cast<void *>(conformances.start),
                                                conformances.length);
@@ -74,7 +74,7 @@ void swift_addNewDSOImage(const void *addr) {
 
   record(sections);
 
-  const auto &protocol_conformances = sections->swift2_protocol_conformances;
+  const auto &protocol_conformances = sections->swift5_protocol_conformances;
   const void *conformances =
       reinterpret_cast<void *>(protocol_conformances.start);
   if (protocol_conformances.length)

stdlib/public/runtime/ImageInspectionCOFF.h

@@ -45,7 +45,7 @@ struct MetadataSections {
     size_t length;
   };
 
-  Range swift2_protocol_conformances;
+  Range swift5_protocol_conformances;
   Range swift2_type_metadata;
   Range swift3_typeref;
   Range swift3_reflstr;

stdlib/public/runtime/ImageInspectionELF.cpp

@@ -46,7 +46,7 @@ void swift::initializeProtocolConformanceLookup() {
   const swift::MetadataSections *sections = registered;
   while (true) {
     const swift::MetadataSections::Range &conformances =
-        sections->swift2_protocol_conformances;
+        sections->swift5_protocol_conformances;
     if (conformances.length)
       addImageProtocolConformanceBlockCallback(reinterpret_cast<void *>(conformances.start),
                                                conformances.length);
@@ -83,7 +83,7 @@ void swift_addNewDSOImage(const void *addr) {
 
   record(sections);
 
-  const auto &protocol_conformances = sections->swift2_protocol_conformances;
+  const auto &protocol_conformances = sections->swift5_protocol_conformances;
   const void *conformances =
       reinterpret_cast<void *>(protocol_conformances.start);
   if (protocol_conformances.length)

stdlib/public/runtime/ImageInspectionELF.h

@@ -45,7 +45,7 @@ struct MetadataSections {
     size_t length;
   };
 
-  Range swift2_protocol_conformances;
+  Range swift5_protocol_conformances;
   Range swift2_type_metadata;
   Range swift3_typeref;
   Range swift3_reflstr;

stdlib/public/runtime/ImageInspectionMachO.cpp

@@ -31,7 +31,7 @@ using namespace swift;
 namespace {
 /// The Mach-O section name for the section containing protocol conformances.
 /// This lives within SEG_TEXT.
-constexpr const char ProtocolConformancesSection[] = "__swift2_proto";
+constexpr const char ProtocolConformancesSection[] = "__swift5_proto";
 /// The Mach-O section name for the section containing type references.
 /// This lives within SEG_TEXT.
 constexpr const char TypeMetadataRecordSection[] = "__swift2_types";
@@ -46,7 +46,7 @@ void addImageCallback(const mach_header *mh, intptr_t vmaddr_slide) {
   using mach_header_platform = mach_header;
 #endif
 
-  // Look for a __swift2_proto section.
+  // Look for a __swift5_proto section.
   unsigned long size;
   const uint8_t *section =
   getsectiondata(reinterpret_cast<const mach_header_platform *>(mh),

stdlib/public/runtime/SwiftRT-ELF.cpp

@@ -24,7 +24,7 @@
   __attribute__((__visibility__("hidden"))) extern const char __stop_##name;
 
 extern "C" {
-DECLARE_SWIFT_SECTION(swift2_protocol_conformances)
+DECLARE_SWIFT_SECTION(swift5_protocol_conformances)
 DECLARE_SWIFT_SECTION(swift2_type_metadata)
 
 DECLARE_SWIFT_SECTION(swift3_typeref)
@@ -52,7 +52,7 @@ static void swift_image_constructor() {
       nullptr,
       nullptr,
 
-      SWIFT_SECTION_RANGE(swift2_protocol_conformances),
+      SWIFT_SECTION_RANGE(swift5_protocol_conformances),
       SWIFT_SECTION_RANGE(swift2_type_metadata),
 
       SWIFT_SECTION_RANGE(swift3_typeref),