Cygwin: restore '#ifdef __x86_64__' for CPU-specific code

Commit e1ce752a1d, "Cygwin: remove miscellaneous 32-bit code", removed
most occurrences of '#ifdef __x86_64__'.  Restore those occurrences
that guarded code specific to the AMD64 processor, and #error out if
the processor is different.  This will make it easier to find
AMD64-specific code if we ever want to add support for a different
64-bit processor (e.g., ARM64).

winsup/cygwin/autoload.cc

@@ -66,6 +66,7 @@ bool NO_COPY wsock_started;
 /* LoadDLLprime is used to prime the DLL info information, providing an
    additional initialization routine to call prior to calling the first
    function.  */
+#ifdef __x86_64__
 #define LoadDLLprime(dllname, init_also, no_resolve_on_fork) __asm__ ("	\n\
 .ifndef " #dllname "_primed				\n\
   .section	.data_cygwin_nocopy,\"w\"		\n\
@@ -81,6 +82,9 @@ bool NO_COPY wsock_started;
   .set		" #dllname "_primed, 1			\n\
 .endif							\n\
 ");
+#else
+#error unimplemented for this target
+#endif
 
 /* Standard DLL load macro.  May invoke a fatal error if the function isn't
    found. */
@@ -92,6 +96,7 @@ bool NO_COPY wsock_started;
   LoadDLLfuncEx3(name, n, dllname, notimp, err, 0)
 
 /* Main DLL setup stuff. */
+#ifdef __x86_64__
 #define LoadDLLfuncEx3(name, n, dllname, notimp, err, no_resolve_on_fork) \
   LoadDLLprime (dllname, dll_func_load, no_resolve_on_fork) \
   __asm__ ("						\n\
@@ -116,6 +121,9 @@ _win32_" #name ":					\n\
   .asciz	\"" #name "\"				\n\
   .text							\n\
 ");
+#else
+#error unimplemented for this target
+#endif
 
 /* DLL loader helper functions used during initialization. */
 
@@ -131,6 +139,7 @@ extern "C" void dll_chain () __asm__ ("dll_chain");
 
 extern "C" {
 
+#ifdef __x86_64__
 __asm__ ("								\n\
 	 .section .rdata,\"r\"							\n\
 msg1:									\n\
@@ -192,6 +201,9 @@ dll_chain:								\n\
 	push	%rax		# Restore 'return address'		\n\
 	jmp	*%rdx		# Jump to next init function		\n\
 ");
+#else
+#error unimplemented for this target
+#endif
 
 /* C representations of the two info blocks described above.
    FIXME: These structures confuse gdb for some reason.  GDB can print
@@ -246,6 +258,7 @@ dll_load (HANDLE& handle, PWCHAR name)
 #define RETRY_COUNT 10
 
 /* The standard DLL initialization routine. */
+#ifdef __x86_64__
 
 /* On x86_64, we need assembler wrappers for std_dll_init and wsock_init.
    In the x86_64 ABI it's no safe bet that frame[1] (aka 8(%rbp)) contains
@@ -285,6 +298,10 @@ _" #func ":								\n\
 
 INIT_WRAPPER (std_dll_init)
 
+#else
+#error unimplemented for this target
+#endif
+
 __attribute__ ((used, noinline)) static two_addr_t
 std_dll_init (struct func_info *func)
 {
@@ -341,8 +358,12 @@ std_dll_init (struct func_info *func)
 
 /* Initialization function for winsock stuff. */
 
+#ifdef __x86_64__
 /* See above comment preceeding std_dll_init. */
 INIT_WRAPPER (wsock_init)
+#else
+#error unimplemented for this target
+#endif
 
 __attribute__ ((used, noinline)) static two_addr_t
 wsock_init (struct func_info *func)

winsup/cygwin/cpuid.h

@@ -18,6 +18,7 @@ cpuid (uint32_t *a, uint32_t *b, uint32_t *c, uint32_t *d, uint32_t ain,
 		: "a" (ain), "c" (cin));
 }
 
+#ifdef __x86_64__
 static inline bool __attribute ((always_inline))
 can_set_flag (uint32_t long flag)
 {
@@ -38,5 +39,8 @@ can_set_flag (uint32_t long flag)
   );
   return ((r1 ^ r2) & flag) != 0;
 }
+#else
+#error unimplemented for this target
+#endif
 
 #endif // !CPUID_H

winsup/cygwin/fork.cc

@@ -626,7 +626,11 @@ dofork (void **proc, bool *with_forkables)
     ischild = !!setjmp (grouped.ch.jmp);
 
     volatile char * volatile stackp;
+#ifdef __x86_64__
     __asm__ volatile ("movq %%rsp,%0": "=r" (stackp));
+#else
+#error unimplemented for this target
+#endif
 
     if (!ischild)
       res = grouped.parent (stackp);

winsup/cygwin/include/cygwin/config.h

@@ -36,7 +36,11 @@ __attribute__((__gnu_inline__))
 extern inline struct _reent *__getreent (void)
 {
   register char *ret;
+#ifdef __x86_64__
   __asm __volatile__ ("movq %%gs:8,%0" : "=r" (ret));
+#else
+#error unimplemented for this target
+#endif
   return (struct _reent *) (ret - __CYGTLS_PADSIZE__);
 }
 #endif /* _LIBC || __INSIDE_CYGWIN__ */

winsup/cygwin/include/cygwin/signal.h

@@ -19,6 +19,7 @@ extern "C" {
   Define a struct __mcontext, which should be identical in layout to the Win32
   API type CONTEXT with the addition of oldmask and cr2 fields at the end.
 */
+#ifdef __x86_64__
 
 struct _uc_fpxreg {
   __uint16_t significand[4];
@@ -97,6 +98,10 @@ struct __attribute__ ((__aligned__ (16))) __mcontext
   __uint64_t cr2;
 };
 
+#else
+#error unimplemented for this target
+#endif
+
 /* Needed for GDB.  It only compiles in the context copy code if this macro is
    defined.  This is not sizeof(CONTEXT) due to historical accidents. */
 #define __COPY_CONTEXT_SIZE 816

winsup/cygwin/miscfuncs.cc

@@ -413,6 +413,7 @@ pthread_wrapper (PVOID arg)
   /* Initialize new _cygtls. */
   _my_tls.init_thread (wrapper_arg.stackbase - __CYGTLS_PADSIZE__,
 		       (DWORD (*)(void*, void*)) wrapper_arg.func);
+#ifdef __x86_64__
   __asm__ ("\n\
 	   leaq  %[WRAPPER_ARG], %%rbx	# Load &wrapper_arg into rbx	\n\
 	   movq  (%%rbx), %%r12		# Load thread func into r12	\n\
@@ -436,6 +437,9 @@ pthread_wrapper (PVOID arg)
 	   call  *%%r12			# Call thread func		\n"
 	   : : [WRAPPER_ARG] "o" (wrapper_arg),
 	       [CYGTLS] "i" (__CYGTLS_PADSIZE__));
+#else
+#error unimplemented for this target
+#endif
   /* pthread::thread_init_wrapper calls pthread::exit, which
      in turn calls ExitThread, so we should never arrive here. */
   api_fatal ("Dumb thinko in pthread handling.  Whip the developer.");
@@ -698,6 +702,7 @@ err:
   return thread;
 }
 
+#ifdef __x86_64__
 /* These functions are almost verbatim FreeBSD code (even if the header of
    one file mentiones NetBSD), just wrapped in the minimum required code to
    make them work with the MS AMD64 ABI.
@@ -900,6 +905,10 @@ wmempcpy:								\n\
 	.seh_endproc							\n\
 ");
 
+#else
+#error unimplemented for this target
+#endif
+
 /* Signal the thread name to any attached debugger
 
    (See "How to: Set a Thread Name in Native Code"