[embedded] Build the _Builtin_float overlay in embedded Swift mode

Add embedded targets for the _Builtin_float overlay.

rdar://123951443

Author: ian-twilightcoder

stdlib/public/ClangOverlays/CMakeLists.txt

@@ -1,4 +1,12 @@
 if(NOT DEFINED SWIFT_BUILD_CLANG_OVERLAYS_SKIP_BUILTIN_FLOAT OR NOT SWIFT_BUILD_CLANG_OVERLAYS_SKIP_BUILTIN_FLOAT)
+  set(BUILTIN_FLOAT_SOURCES
+    linker-support/magic-symbols-for-install-name.c
+  )
+
+  set(BUILTIN_FLOAT_GYB_SOURCES
+    float.swift.gyb
+  )
+
   if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     set(BUILTIN_FLOAT_SWIFT_FLAGS -Xfrontend -module-abi-name -Xfrontend Darwin)
   else()
@@ -9,10 +17,10 @@ if(NOT DEFINED SWIFT_BUILD_CLANG_OVERLAYS_SKIP_BUILTIN_FLOAT OR NOT SWIFT_BUILD_
       ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES}
       IS_SDK_OVERLAY
 
-      linker-support/magic-symbols-for-install-name.c
+      ${BUILTIN_FLOAT_SOURCES}
 
       GYB_SOURCES
-        float.swift.gyb
+        ${BUILTIN_FLOAT_GYB_SOURCES}
 
       SWIFT_COMPILE_FLAGS
         ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS}
@@ -25,3 +33,46 @@ if(NOT DEFINED SWIFT_BUILD_CLANG_OVERLAYS_SKIP_BUILTIN_FLOAT OR NOT SWIFT_BUILD_
       INSTALL_IN_COMPONENT stdlib
       MACCATALYST_BUILD_FLAVOR zippered)
 endif()
+
+# Embedded clang overlays - embedded libraries are built as .swiftmodule only,
+# i.e. there is no .o or .a file produced (no binary code is actually produced)
+# and only users of a library are going to actually compile any needed code.
+if(SWIFT_SHOULD_BUILD_EMBEDDED_STDLIB)
+  add_custom_target(embedded-builtin_float)
+  add_dependencies(embedded-libraries embedded-builtin_float)
+
+  foreach(entry ${EMBEDDED_STDLIB_TARGET_TRIPLES})
+    string(REGEX REPLACE "[ \t]+" ";" list "${entry}")
+    list(GET list 0 arch)
+    list(GET list 1 mod)
+    list(GET list 2 triple)
+
+    set(SWIFT_SDK_embedded_ARCH_${arch}_MODULE "${mod}")
+    set(SWIFT_SDK_embedded_LIB_SUBDIR "embedded")
+    set(SWIFT_SDK_embedded_ARCH_${arch}_TRIPLE "${triple}")
+    set(SWIFT_SDK_embedded_PATH ${SWIFT_SDK_OSX_PATH})
+    set(SWIFT_SDK_embedded_ARCH_${arch}_PATH ${SWIFT_SDK_OSX_PATH})
+    set(SWIFT_SDK_embedded_USE_ISYSROOT TRUE)
+    add_swift_target_library_single(
+      embedded-builtin_float-${mod}
+      swift_Builtin_float
+      ONLY_SWIFTMODULE
+      IS_FRAGILE
+      
+      ${BUILTIN_FLOAT_SOURCES}
+      GYB_SOURCES
+        ${BUILTIN_FLOAT_GYB_SOURCES}
+
+      SWIFT_COMPILE_FLAGS
+        ${BUILTIN_FLOAT_SWIFT_FLAGS}
+        -Xcc -ffreestanding -enable-experimental-feature Embedded
+
+      MODULE_DIR "${CMAKE_BINARY_DIR}/lib/swift/embedded"
+      SDK "embedded"
+      ARCHITECTURE "${arch}"
+      DEPENDS embedded-stdlib-${mod}
+      INSTALL_IN_COMPONENT stdlib
+      )
+    add_dependencies(embedded-builtin_float embedded-builtin_float-${mod})
+  endforeach()
+endif()

stdlib/public/ClangOverlays/float.swift.gyb

@@ -18,7 +18,7 @@ public let FLT_RADIX = Double.radix
 
 %for type, prefix in [('Float', 'FLT'), ('Double', 'DBL'), ('Float80', 'LDBL')]:
 % if type == "Float80":
-#if !os(Android) && !os(WASI) && !os(Windows) && (arch(i386) || arch(x86_64))
+#if !os(Android) && !os(WASI) && !os(Windows) && !$Embedded && (arch(i386) || arch(x86_64))
 % end
 //  Where does the 1 come from? C counts the usually-implicit leading
 //  significand bit, but Swift does not. Neither is really right or wrong.