[wasm] Add metadata registration SwiftRT-WASM.cpp

This patch adds the metadata registration for the wasm targets, and also
adds build support for it.

Author: kateinoigakukun

stdlib/public/runtime/CMakeLists.txt

@@ -88,6 +88,7 @@ set(swift_runtime_backtracing_sources
 set(LLVM_OPTIONAL_SOURCES
     SwiftRT-COFF.cpp
     SwiftRT-ELF.cpp
+    SwiftRT-WASM.cpp
     ${swift_runtime_sources}
     ${swift_runtime_objc_sources}
     ${swift_runtime_leaks_sources}
@@ -138,11 +139,14 @@ add_swift_target_library(swiftRuntime OBJECT_LIBRARY
 
 set(ELFISH_SDKS)
 set(COFF_SDKS)
+set(WASM_SDKS)
 foreach(sdk ${SWIFT_SDKS})
   if("${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "ELF")
     list(APPEND ELFISH_SDKS ${sdk})
   elseif("${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "COFF")
     list(APPEND COFF_SDKS ${sdk})
+  elseif("${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "WASM")
+    list(APPEND WASM_SDKS ${sdk})
   endif()
 endforeach()
 
@@ -169,13 +173,23 @@ add_swift_target_library(swiftImageRegistrationObjectCOFF
                   SWIFT_COMPILE_FLAGS ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
                   INSTALL_IN_COMPONENT none)
 
+add_swift_target_library(swiftImageRegistrationObjectWASM
+                  OBJECT_LIBRARY IS_STDLIB IS_STDLIB_CORE
+                  SwiftRT-WASM.cpp
+                  C_COMPILE_FLAGS ${SWIFT_RUNTIME_CORE_CXX_FLAGS}
+                  LINK_FLAGS ${SWIFT_RUNTIME_CORE_LINK_FLAGS}
+                  TARGET_SDKS ${WASM_SDKS}
+                  SWIFT_COMPILE_FLAGS ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+                  INSTALL_IN_COMPONENT none)
+
 foreach(sdk ${SWIFT_SDKS})
   foreach(arch ${SWIFT_SDK_${sdk}_ARCHITECTURES})
     set(arch_subdir "${SWIFT_SDK_${sdk}_LIB_SUBDIR}/${arch}")
     set(arch_suffix "${SWIFT_SDK_${sdk}_LIB_SUBDIR}-${arch}")
 
     if("${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "ELF" OR
-       "${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "COFF")
+       "${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "COFF" OR
+       "${SWIFT_SDK_${sdk}_OBJECT_FORMAT}" STREQUAL "WASM")
       # TODO(compnerd) switch to the generator expression when cmake is upgraded
       # to a version which supports it.
       # set(swiftrtObject "$<TARGET_OBJECTS:swiftImageRegistrationObject${SWIFT_SDK_${sdk}_OBJECT_FORMAT}-${arch_suffix}>")

stdlib/public/runtime/SwiftRT-WASM.cpp

@@ -0,0 +1,83 @@
+//===--- SwiftRT-WASM.cpp --------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "ImageInspectionCommon.h"
+#include "swift/shims/MetadataSections.h"
+
+#include <cstddef>
+#include <new>
+
+// Refer start/stop symbols weakly to link them if they aren't synthesized by the linker.
+#define DECLARE_SWIFT_SECTION(name)                                                             \
+  __attribute__((__visibility__("hidden"),__aligned__(1),weak)) extern const char __start_##name;    \
+  __attribute__((__visibility__("hidden"),__aligned__(1),weak)) extern const char __stop_##name;
+
+extern "C" {
+DECLARE_SWIFT_SECTION(swift5_protocols)
+DECLARE_SWIFT_SECTION(swift5_protocol_conformances)
+DECLARE_SWIFT_SECTION(swift5_type_metadata)
+
+DECLARE_SWIFT_SECTION(swift5_typeref)
+DECLARE_SWIFT_SECTION(swift5_reflstr)
+DECLARE_SWIFT_SECTION(swift5_fieldmd)
+DECLARE_SWIFT_SECTION(swift5_assocty)
+DECLARE_SWIFT_SECTION(swift5_replace)
+DECLARE_SWIFT_SECTION(swift5_replac2)
+DECLARE_SWIFT_SECTION(swift5_builtin)
+DECLARE_SWIFT_SECTION(swift5_capture)
+DECLARE_SWIFT_SECTION(swift5_mpenum)
+DECLARE_SWIFT_SECTION(swift5_accessible_functions)
+DECLARE_SWIFT_SECTION(swift5_runtime_attributes)
+}
+
+#undef DECLARE_SWIFT_SECTION
+
+namespace {
+static swift::MetadataSections sections{};
+}
+
+__attribute__((__constructor__))
+static void swift_image_constructor() {
+#define SWIFT_SECTION_RANGE(name)                                              \
+  { reinterpret_cast<uintptr_t>(&__start_##name),                              \
+    static_cast<uintptr_t>(&__stop_##name - &__start_##name) }
+
+  new (&sections) swift::MetadataSections {
+      swift::CurrentSectionMetadataVersion,
+      // NOTE: Multi images in a single process is not yet
+      // stabilized in WebAssembly toolchain outside of Emscripten.
+      { 0 },
+
+      nullptr,
+      nullptr,
+
+      SWIFT_SECTION_RANGE(swift5_protocols),
+      SWIFT_SECTION_RANGE(swift5_protocol_conformances),
+      SWIFT_SECTION_RANGE(swift5_type_metadata),
+
+      SWIFT_SECTION_RANGE(swift5_typeref),
+      SWIFT_SECTION_RANGE(swift5_reflstr),
+      SWIFT_SECTION_RANGE(swift5_fieldmd),
+      SWIFT_SECTION_RANGE(swift5_assocty),
+      SWIFT_SECTION_RANGE(swift5_replace),
+      SWIFT_SECTION_RANGE(swift5_replac2),
+      SWIFT_SECTION_RANGE(swift5_builtin),
+      SWIFT_SECTION_RANGE(swift5_capture),
+      SWIFT_SECTION_RANGE(swift5_mpenum),
+      SWIFT_SECTION_RANGE(swift5_accessible_functions),
+      SWIFT_SECTION_RANGE(swift5_runtime_attributes),
+  };
+
+#undef SWIFT_SECTION_RANGE
+
+  swift_addNewDSOImage(&sections);
+}