Restore -static-executable on Linux.

- Add back StaticBinaryELF.cpp which provides swift::lookupSymbol()
  for statically linked ELF binaries.

- Build libswiftImageInspectionStatic.a from StaticBinaryELF.cpp

- Update static-executable-args.lnk and replace
  libswiftImageInspectionShared with libswiftImageInspectionStatic.

- Fix linkage to pthreads to avoid weak linkage issues in a static
  executable.

- Add driver test for '-static-executable' on Linux to validate
  that output binary is statically linked.

Author: spevans

lib/Driver/UnixToolChains.cpp

@@ -189,11 +189,6 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
     Arguments.push_back(context.Args.MakeArgString(A->getValue()));
   }
 
-  if (getTriple().getOS() == llvm::Triple::Linux &&
-      job.getKind() == LinkKind::Executable) {
-    Arguments.push_back("-pie");
-  }
-
   bool staticExecutable = false;
   bool staticStdlib = false;
 
@@ -205,6 +200,11 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
     staticStdlib = true;
   }
 
+  if (getTriple().getOS() == llvm::Triple::Linux &&
+      job.getKind() == LinkKind::Executable && !staticExecutable) {
+    Arguments.push_back("-pie");
+  }
+
   SmallVector<std::string, 4> RuntimeLibPaths;
   getRuntimeLibraryPaths(RuntimeLibPaths, context.Args, context.OI.SDKPath,
                          /*Shared=*/!(staticExecutable || staticStdlib));

stdlib/public/runtime/CMakeLists.txt

@@ -78,6 +78,7 @@ endif(LLVM_ENABLE_ASSERTIONS)
 
 # Acknowledge that the following sources are known.
 set(LLVM_OPTIONAL_SOURCES
+    StaticBinaryELF.cpp
     SwiftRT-COFF.cpp
     SwiftRT-ELF.cpp
     ${swift_runtime_sources}
@@ -102,35 +103,43 @@ if(SWIFT_BUILD_STATIC_STDLIB AND "${sdk}" STREQUAL "LINUX")
     SWIFT_COMPILE_FLAGS ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
     INSTALL_IN_COMPONENT stdlib)
 
-  foreach(arch IN LISTS SWIFT_SDK_${sdk}_ARCHITECTURES)
-    set(FragileSupportLibrary swiftImageInspectionShared-${SWIFT_SDK_${sdk}_LIB_SUBDIR}-${arch})
-    set(LibraryLocation ${SWIFTSTATICLIB_DIR}/${lowercase_sdk}/${arch})
-    add_custom_command_target(swift_image_inspection_${arch}_static
-      COMMAND
-        "${CMAKE_COMMAND}" -E copy $<TARGET_FILE:${FragileSupportLibrary}> ${LibraryLocation}
-      OUTPUT
-        "${LibraryLocation}/${CMAKE_STATIC_LIBRARY_PREFIX}swiftImageInspectionShared${CMAKE_STATIC_LIBRARY_SUFFIX}"
-      DEPENDS
-         ${FragileSupportLibrary})
-    add_dependencies(stdlib ${FragileSupportLibrary})
-    swift_install_in_component(FILES $<TARGET_FILE:${FragileSupportLibrary}>
-                               DESTINATION "lib/swift_static/${lowercase_sdk}/${arch}"
-                               COMPONENT stdlib)
-  endforeach()
+  add_swift_target_library(swiftImageInspectionStatic TARGET_LIBRARY STATIC
+    StaticBinaryELF.cpp ImageInspectionELF.cpp
+    C_COMPILE_FLAGS ${swift_runtime_library_compile_flags} -DELF_STATIC_LIB
+    LINK_FLAGS ${swift_runtime_linker_flags}
+	  INSTALL_IN_COMPONENT stdlib)
 
-  set(FragileSupportLibraryPrimary swiftImageInspectionShared-${SWIFT_SDK_${sdk}_LIB_SUBDIR}-${SWIFT_PRIMARY_VARIANT_ARCH})
-  set(LibraryLocationPrimary ${SWIFTSTATICLIB_DIR}/${lowercase_sdk})
-  add_custom_command_target(swift_image_inspection_static_primary_arch
-      COMMAND
-         "${CMAKE_COMMAND}" -E copy $<TARGET_FILE:${FragileSupportLibraryPrimary}> ${LibraryLocationPrimary}
-      OUTPUT
-      "${LibraryLocationPrimary}/${CMAKE_STATIC_LIBRARY_PREFIX}swiftImageInspectionShared${CMAKE_STATIC_LIBRARY_SUFFIX}"
-      DEPENDS
-         ${FragileSupportLibraryPrimary})
-    add_dependencies(stdlib ${FragileSupportLibraryPrimary})
-    swift_install_in_component(FILES $<TARGET_FILE:${FragileSupportLibraryPrimary}>
-                               DESTINATION "lib/swift_static/${lowercase_sdk}"
-                               COMPONENT stdlib)
+  foreach(linktype Shared Static)
+    foreach(arch IN LISTS SWIFT_SDK_${sdk}_ARCHITECTURES)
+      set(FragileSupportLibrary swiftImageInspection${linktype}-${SWIFT_SDK_${sdk}_LIB_SUBDIR}-${arch})
+      set(LibraryLocation ${SWIFTSTATICLIB_DIR}/${lowercase_sdk}/${arch})
+      add_custom_command_target(swift_image_inspection_${linktype}_${arch}_static
+        COMMAND
+          "${CMAKE_COMMAND}" -E copy $<TARGET_FILE:${FragileSupportLibrary}> ${LibraryLocation}
+        OUTPUT
+          "${LibraryLocation}/${CMAKE_STATIC_LIBRARY_PREFIX}swiftImageInspection${linktype}${CMAKE_STATIC_LIBRARY_SUFFIX}"
+        DEPENDS
+           ${FragileSupportLibrary})
+      add_dependencies(stdlib ${FragileSupportLibrary})
+      swift_install_in_component(FILES $<TARGET_FILE:${FragileSupportLibrary}>
+                                 DESTINATION "lib/swift_static/${lowercase_sdk}/${arch}"
+                                 COMPONENT stdlib)
+    endforeach()
+
+    set(FragileSupportLibraryPrimary swiftImageInspection${linktype}-${SWIFT_SDK_${sdk}_LIB_SUBDIR}-${SWIFT_PRIMARY_VARIANT_ARCH})
+    set(LibraryLocationPrimary ${SWIFTSTATICLIB_DIR}/${lowercase_sdk})
+    add_custom_command_target(swift_image_inspection_${linktype}_primary_arch
+        COMMAND
+           "${CMAKE_COMMAND}" -E copy $<TARGET_FILE:${FragileSupportLibraryPrimary}> ${LibraryLocationPrimary}
+        OUTPUT
+          "${LibraryLocationPrimary}/${CMAKE_STATIC_LIBRARY_PREFIX}swiftImageInspection${linktype}${CMAKE_STATIC_LIBRARY_SUFFIX}"
+        DEPENDS
+           ${FragileSupportLibraryPrimary})
+      add_dependencies(stdlib ${FragileSupportLibraryPrimary})
+      swift_install_in_component(FILES $<TARGET_FILE:${FragileSupportLibraryPrimary}>
+                                 DESTINATION "lib/swift_static/${lowercase_sdk}"
+                                 COMPONENT stdlib)
+  endforeach()
 
   # Generate the static-executable-args.lnk file used for ELF systems (eg linux)
   set(linkfile "${lowercase_sdk}/static-executable-args.lnk")
@@ -149,10 +158,12 @@ if(SWIFT_BUILD_STATIC_STDLIB AND "${sdk}" STREQUAL "LINUX")
                              DESTINATION "lib/swift_static/${lowercase_sdk}"
                              COMPONENT stdlib)
   add_custom_target(static_binary_magic ALL DEPENDS ${static_binary_lnk_file_list})
-  foreach(arch IN LISTS SWIFT_SDK_LINUX_ARCHITECTURES)
-    add_dependencies(static_binary_magic ${swift_image_inspection_${arch}_static})
+  foreach(linktype Shared Static)
+    foreach(arch IN LISTS SWIFT_SDK_LINUX_ARCHITECTURES)
+      add_dependencies(static_binary_magic ${swift_image_inspection_${linktype}_${arch}_static})
+    endforeach()
+    add_dependencies(static_binary_magic ${swift_image_inspection_${linktype}_primary_arch})
   endforeach()
-  add_dependencies(static_binary_magic ${swift_image_inspection_static_primary_arch})
   add_dependencies(stdlib static_binary_magic)
 
   add_swift_target_library(swiftImageInspectionSharedObject OBJECT_LIBRARY

stdlib/public/runtime/ImageInspectionELF.cpp

@@ -22,7 +22,10 @@
 
 #include "ImageInspection.h"
 #include "ImageInspectionELF.h"
+
+#ifndef ELF_STATIC_LIB
 #include <dlfcn.h>
+#endif
 
 using namespace swift;
 
@@ -56,6 +59,7 @@ void swift::initializeProtocolLookup() {
     sections = sections->next;
   }
 }
+
 void swift::initializeProtocolConformanceLookup() {
   const swift::MetadataSections *sections = registered;
   while (true) {
@@ -89,10 +93,8 @@ void swift::initializeTypeMetadataRecordLookup() {
 void swift::initializeDynamicReplacementLookup() {
 }
 
-// As ELF images are loaded, ImageInspectionInit:sectionDataInit() will call
-// addNewDSOImage() with an address in the image that can later be used via
-// dladdr() to dlopen() the image after the appropriate initialize*Lookup()
-// function has been called.
+// As ELF images are loaded, SwiftRT-ELF:swift_image_constructor() will call
+// addNewDSOImage() with a pointer to the MetadataSections in the image.
 SWIFT_RUNTIME_EXPORT
 void swift_addNewDSOImage(const void *addr) {
   const swift::MetadataSections *sections =
@@ -131,6 +133,12 @@ void swift_addNewDSOImage(const void *addr) {
   }
 }
 
+#ifndef ELF_STATIC_LIB
+
+// For shared executables only, static executables use the version defined in
+// StaticBinaryELF.cpp.
+// libswiftImageInspectionShared.a contains the below function and
+// libswiftImageInspectionStatic.a contains the version in StaticBinaryELF.cpp
 int swift::lookupSymbol(const void *address, SymbolInfo *info) {
   Dl_info dlinfo;
   if (dladdr(address, &dlinfo) == 0) {
@@ -144,6 +152,8 @@ int swift::lookupSymbol(const void *address, SymbolInfo *info) {
   return 1;
 }
 
+#endif
+
 // 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) {