Fix x64 cross build on arm64 macOS (dotnet#75677)

* Fix x64 cross build on arm64 macOS

There were couple of minor issues that prevented successful building of x64 macOS
runtime on arm64 macOS device.
This change fixes them.

* Remove cross architecture combination check

* Reflect PR feedback

* Fix #endif comment

Author: janvorli

eng/native/configureplatform.cmake

@@ -443,13 +443,7 @@ else()
 endif(CLR_CMAKE_TARGET_UNIX)
 
 # check if host & target os/arch combination are valid
-if (CLR_CMAKE_TARGET_OS STREQUAL CLR_CMAKE_HOST_OS)
-    if(NOT(CLR_CMAKE_TARGET_ARCH STREQUAL CLR_CMAKE_HOST_ARCH))
-        if(NOT((CLR_CMAKE_HOST_ARCH_AMD64 AND CLR_CMAKE_TARGET_ARCH_ARM64) OR (CLR_CMAKE_HOST_ARCH_I386 AND CLR_CMAKE_TARGET_ARCH_ARM) OR (CLR_CMAKE_HOST_ARCH_AMD64 AND CLR_CMAKE_TARGET_ARCH_ARM) OR (CLR_CMAKE_HOST_ARCH_AMD64 AND CLR_CMAKE_TARGET_ARCH_I386)))
-            message(FATAL_ERROR "Invalid platform and target arch combination TARGET_ARCH=${CLR_CMAKE_TARGET_ARCH} HOST_ARCH=${CLR_CMAKE_HOST_ARCH}")
-        endif()
-    endif()
-else()
+if (NOT (CLR_CMAKE_TARGET_OS STREQUAL CLR_CMAKE_HOST_OS))
     if(NOT (CLR_CMAKE_HOST_OS STREQUAL windows))
         message(FATAL_ERROR "Invalid host and target os/arch combination. Host OS: ${CLR_CMAKE_HOST_OS}")
     endif()

src/coreclr/pal/inc/pal.h

@@ -2674,7 +2674,7 @@ PALIMPORT BOOL PALAPI PAL_GetUnwindInfoSize(SIZE_T baseAddress, ULONG64 ehFrameH
 
 #if defined(__APPLE__) && defined(__i386__)
 #define PAL_CS_NATIVE_DATA_SIZE 76
-#elif defined(__APPLE__) && defined(__x86_64__)
+#elif defined(__APPLE__) && defined(HOST_AMD64)
 #define PAL_CS_NATIVE_DATA_SIZE 120
 #elif defined(__APPLE__) && defined(HOST_ARM64)
 #define PAL_CS_NATIVE_DATA_SIZE 120
@@ -4581,12 +4581,14 @@ void _mm_setcsr(unsigned int i);
 
 #ifdef  __cplusplus
 
+#if defined(HOST_ARM64) && defined(TARGET_ARM64)
 class CORJIT_FLAGS;
 
 PALIMPORT
 VOID
 PALAPI
 PAL_GetJitCpuCapabilityFlags(CORJIT_FLAGS *flags);
+#endif // HOST_ARM64 && TARGET_ARM64
 
 #endif
 

src/coreclr/pal/src/exception/seh-unwind.cpp

@@ -54,7 +54,7 @@ Module Name:
 
 #endif // HOST_UNIX
 
-#if defined(TARGET_OSX) && defined(TARGET_ARM64)
+#if defined(TARGET_OSX) && defined(HOST_ARM64)
 // MacOS uses ARM64 instead of AARCH64 to describe these registers
 // Create aliases to reuse more code
 enum
@@ -96,7 +96,7 @@ enum
     UNW_AARCH64_V30 = UNW_ARM64_D30,
     UNW_AARCH64_V31 = UNW_ARM64_D31
 };
-#endif // defined(TARGET_OSX) && defined(TARGET_ARM64)
+#endif // defined(TARGET_OSX) && defined(HOST_ARM64)
 
 
 //----------------------------------------------------------------------

src/coreclr/pal/src/misc/jitsupport.cpp

@@ -148,14 +148,14 @@ static unsigned long GetCpuCapabilityFlagsFromCpuInfo()
 }
 #endif // defined(HOST_ARM64) && defined(__linux__)
 
+#if defined(HOST_ARM64) && defined(TARGET_ARM64)
 PALIMPORT
 VOID
 PALAPI
 PAL_GetJitCpuCapabilityFlags(CORJIT_FLAGS *flags)
 {
     _ASSERTE(flags);
 
-#if defined(HOST_ARM64)
 #if HAVE_AUXV_HWCAP_H
     unsigned long hwCap = getauxval(AT_HWCAP);
 
@@ -294,10 +294,5 @@ PAL_GetJitCpuCapabilityFlags(CORJIT_FLAGS *flags)
     flags->Set(InstructionSet_AdvSimd);
     //    flags->Set(CORJIT_FLAGS::CORJIT_FLAG_HAS_ARM64_FP);
 #endif // HAVE_AUXV_HWCAP_H
-#elif defined(TARGET_ARM64)
-    // Enable ARM64 based flags by default so we always crossgen
-    // ARM64 intrinsics for Linux
-    flags->Set(InstructionSet_ArmBase);
-    flags->Set(InstructionSet_AdvSimd);
-#endif // defined(HOST_ARM64)
 }
+#endif // HOST_ARM64 && TARGET_ARM64