Re-add dependency on libatomic for 32-bit Linux platforms (swiftlang#36659)

Author: drexin

cmake/modules/AddSwift.cmake

@@ -301,6 +301,9 @@ function(_add_host_variant_link_flags target)
     target_link_libraries(${target} PRIVATE
       pthread
       dl)
+    if("${SWIFT_HOST_VARIANT_ARCH}" MATCHES "armv6|armv7|i686")
+      target_link_libraries(${target} PRIVATE atomic)
+    endif()
   elseif(SWIFT_HOST_VARIANT_SDK STREQUAL FREEBSD)
     target_link_libraries(${target} PRIVATE
       pthread)

cmake/modules/AddSwiftUnittests.cmake

@@ -56,6 +56,9 @@ function(add_swift_unittest test_dirname)
     if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64")
       target_compile_options(${test_dirname} PRIVATE
         -march=core2)
+    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "armv6|armv7|i686")
+      set_property(TARGET "${test_dirname}" APPEND PROPERTY LINK_LIBRARIES
+        "atomic")
     endif()
   elseif("${SWIFT_HOST_VARIANT}" STREQUAL "windows")
     target_compile_definitions("${test_dirname}" PRIVATE

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -358,6 +358,9 @@ function(_add_target_variant_link_flags)
     MACCATALYST_BUILD_FLAVOR  "${LFLAGS_MACCATALYST_BUILD_FLAVOR}")
   if("${LFLAGS_SDK}" STREQUAL "LINUX")
     list(APPEND link_libraries "pthread" "dl")
+    if("${SWIFT_HOST_VARIANT_ARCH}" MATCHES "armv6|armv7|i686")
+      list(APPEND link_libraries PRIVATE "atomic")
+    endif()
   elseif("${LFLAGS_SDK}" STREQUAL "FREEBSD")
     list(APPEND link_libraries "pthread")
   elseif("${LFLAGS_SDK}" STREQUAL "OPENBSD")

unittests/runtime/CMakeLists.txt

@@ -52,6 +52,11 @@ if(("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "${SWIFT_PRIMARY_VARIANT_SDK}") AND
       ${FOUNDATION_LIBRARY}
       swiftStdlibUnittest${SWIFT_PRIMARY_VARIANT_SUFFIX}
       )
+  elseif(SWIFT_HOST_VARIANT STREQUAL "Linux")
+    if(SWIFT_HOST_VARIANT_ARCH MATCHES "armv6|armv7|i686")
+      list(APPEND PLATFORM_TARGET_LINK_LIBRARIES
+        "atomic")
+    endif()
   elseif(SWIFT_HOST_VARIANT STREQUAL "freebsd")
     find_library(EXECINFO_LIBRARY execinfo)
     list(APPEND PLATFORM_TARGET_LINK_LIBRARIES

unittests/runtime/LongTests/CMakeLists.txt

@@ -19,6 +19,12 @@ if(("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "${SWIFT_PRIMARY_VARIANT_SDK}") AND
 
     # Link the Objective-C runtime.
     list(APPEND PLATFORM_TARGET_LINK_LIBRARIES "objc")
+  elseif(SWIFT_HOST_VARIANT STREQUAL "linux")
+    if(SWIFT_HOST_VARIANT_ARCH MATCHES "armv6|armv7|i686")
+      list(APPEND PLATFORM_TARGET_LINK_LIBRARIES
+        "atomic"
+        )
+    endif()
   elseif(SWIFT_HOST_VARIANT STREQUAL "freebsd")
     find_library(EXECINFO_LIBRARY execinfo)
     list(APPEND PLATFORM_TARGET_LINK_LIBRARIES