Merge pull request #64138 from al45tair/eng/PR-106284325

[Backtracing] Disable assembly language on ARM Windows.

Author: al45tair

CMakeLists.txt

@@ -49,16 +49,24 @@ enable_language(CXX)
 # On Windows, use MASM or MARMASM
 set(SWIFT_ASM_DIALECT ASM)
 set(SWIFT_ASM_EXT S)
+set(SWIFT_ASM_AVAILABLE YES)
 if(CMAKE_SYSTEM_NAME STREQUAL Windows)
   if(CMAKE_SYSTEM_PROCESSOR MATCHES "ARM64")
-    set(SWIFT_ASM_DIALECT ASM_MARMASM)
+    if(CMAKE_VERSION VERSION_LESS "3.26")
+      message(warning "We can't build assembly language for ARM64 until CMake 3.26")
+      set(SWIFT_ASM_AVAILABLE NO)
+    else()
+      set(SWIFT_ASM_DIALECT ASM_MARMASM)
+    endif()
   else()
     set(SWIFT_ASM_DIALECT ASM_MASM)
   endif()
   set(SWIFT_ASM_EXT asm)
 endif()
 
-enable_language(${SWIFT_ASM_DIALECT})
+if(SWIFT_ASM_AVAILABLE)
+  enable_language(${SWIFT_ASM_DIALECT})
+endif()
 
 # Use C++14.
 set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to conform to")

stdlib/public/Backtracing/CMakeLists.txt

@@ -28,6 +28,15 @@ set(BACKTRACING_SOURCES
   get-cpu-context.${SWIFT_ASM_EXT}
 )
 
+set(BACKTRACING_COMPILE_FLAGS)
+
+if(SWIFT_ASM_AVAILABLE)
+  list(APPEND BACKTRACING_SOURCES get-cpu-context.${SWIFT_ASM_EXT})
+  list(APPEND BACKTRACING_COMPILE_FLAGS "-DSWIFT_ASM_AVAILABLE")
+else()
+  message(warning "Assembly language not available on this platform; backtracing will fail.")
+endif()
+
 set(LLVM_OPTIONAL_SOURCES
   get-cpu-context.S
   get-cpu-context.asm
@@ -48,6 +57,7 @@ add_swift_target_library(swift_Backtracing ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
 
   SWIFT_COMPILE_FLAGS
     ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+    ${BACKTRACING_COMPILE_FLAGS}
     -parse-stdlib
 
   LINK_FLAGS

stdlib/public/Backtracing/Context.swift

@@ -268,10 +268,10 @@ extension arm_gprs {
   }
   #endif
 
-  #if os(Windows)
-  struct NotYetImplemented: Error {}
+  #if os(Windows) || !SWIFT_ASM_AVAILABLE
+  struct NotImplemented: Error {}
   public static func withCurrentContext<T>(fn: (X86_64Context) throws -> T) throws -> T {
-    throw NotYetImplemented()
+    throw NotImplemented()
   }
   #elseif arch(x86_64)
   @_silgen_name("_swift_get_cpu_context")
@@ -423,10 +423,10 @@ extension arm_gprs {
 
   public static var registerCount: Int { return 50 }
 
-  #if os(Windows)
-  struct NotYetImplemented: Error {}
+  #if os(Windows) || !SWIFT_ASM_AVAILABLE
+  struct NotImplemented: Error {}
   public static func withCurrentContext<T>(fn: (I386Context) throws -> T) throws -> T {
-    throw NotYetImplemented()
+    throw NotImplemented()
   }
   #elseif arch(i386)
   @_silgen_name("_swift_get_cpu_context")
@@ -624,10 +624,10 @@ extension arm_gprs {
   }
 #endif
 
-  #if os(Windows)
-  struct NotYetImplemented: Error {}
+  #if os(Windows) || !SWIFT_ASM_AVAILABLE
+  struct NotImplemented: Error {}
   public static func withCurrentContext<T>(fn: (ARM64Context) throws -> T) throws -> T {
-    throw NotYetImplemented()
+    throw NotImplemented()
   }
   #elseif arch(arm64) || arch(arm64_32)
   @_silgen_name("_swift_get_cpu_context")
@@ -763,10 +763,10 @@ extension arm_gprs {
 
   public static var registerCount: Int { return 16 }
 
-  #if os(Windows)
-  struct NotYetImplemented: Error {}
+  #if os(Windows) || !SWIFT_ASM_AVAILABLE
+  struct NotImplemented: Error {}
   public static func withCurrentContext<T>(fn: (ARMContext) throws -> T) throws -> T {
-    throw NotYetImplemented()
+    throw NotImplemented()
   }
   #elseif arch(arm)
   @_silgen_name("_swift_get_cpu_context")