* Throughout, use __try/__except/__endtry blocks, rather than myfault

handler.
	* cygtls.cc (_cygtls::remove): Accommodate the fact that pathbufs
	has been moved from _local_storage to _cygtls.
	* cygtls.h (class tls_pathbuf): Add comment to hint to gendef usage
	of counters.  Change type of counters to uint32_t for clarity.
	Remove _cygtls as friend class.
	(struct _local_storage): Move pathbufs from here...
	(struct _cygtls): ...to here, allowing to access it from _sigbe.
	(class san): Only define on 32 bit.  Remove errno, _c_cnt and _w_cnt
	members.
	(san::setup): Drop parameter.  Don't initialize removed members.
	(san::leave): Don't set removed members.
	(class myfault): Only define on 32 bit.
	(myfault::faulted): Only keep implementation not taking any parameter.
	Drop argument in call to sebastian.setup.
	(__try/__leave/__except/__endtry): Implement to support real SEH.  For
	now stick to SJLJ on 32 bit.
	* dcrt0.cc (dll_crt0_0): Drop 64 bit call to
	exception::install_myfault_handler.
	* exception.h (exception_handler): Define with EXCEPTION_DISPOSITION
	as return type.
	(PDISPATCHER_CONTEXT): Define as void * on 32 bit.  Define as pointer
	to _DISPATCHER_CONTEXT on 64 bit.
	(class exception): Define separately for 32 and 64 bit.
	(exception::myfault): Add handler for myfault SEH handling on 64 bit.
	(exception::exception): Fix mangled method name to account for change
	in type of last parameter.
	(exception::install_myfault_handler): Remove.
	* exceptions.cc (exception::myfault_handle): Remove.
	(exception::myfault): New SEH handler for 64 bit.
	* gendef (_sigbe): Set tls_pathbuf counters to 0 explicitely when
	returning to the caller.
	* ntdll.h: Move a comment to a better place.
	(struct _SCOPE_TABLE): Define on 64 bit.
	* thread.cc (verifyable_object_isvalid): Remove gcc 4.7 workaround.
	* tls_pbuf.cc (tls_pbuf): Fix to accommodate new place of pathbufs.
	(tls_pathbuf::destroy): Change type of loop variables to uint32_t.
	* tls_pbuf.h (class tmp_pathbuf): Change type of buffer counters to
	uint32_t.  Accommodate new place of pathbufs.
	* tlsoffsets.h: Regenerate.
	* tlsoffsets64.h: Regenerate.

winsup/cygwin/exception.h

@@ -94,8 +94,10 @@ to install your own exception filter. This one is documented.
    a teensy bit of detail of the innards of exception handling (i.e. what we
    have to do).  */
 
-typedef int (exception_handler) (EXCEPTION_RECORD *, struct _exception_list *,
-				 CONTEXT *, void *);
+typedef EXCEPTION_DISPOSITION (exception_handler) (EXCEPTION_RECORD *,
+						   struct _exception_list *,
+						   CONTEXT *,
+						   void *);
 
 typedef struct _exception_list
 {
@@ -104,70 +106,53 @@ typedef struct _exception_list
 } exception_list;
 
 extern exception_list *_except_list asm ("%fs:0");
-#else
-typedef void exception_list;
-#endif /* !__x86_64 */
+typedef void *PDISPATCHER_CONTEXT;
 
 class exception
 {
-#ifdef __x86_64__
-  static LONG myfault_handle (LPEXCEPTION_POINTERS ep);
-#else
   exception_list el;
   exception_list *save;
-#endif /* __x86_64__ */
-  static int handle (EXCEPTION_RECORD *, exception_list *, CONTEXT *, void *);
+  static EXCEPTION_DISPOSITION handle (EXCEPTION_RECORD *, exception_list *,
+				       CONTEXT *, PDISPATCHER_CONTEXT);
 public:
   exception () __attribute__ ((always_inline))
   {
     /* Install SEH handler. */
+    save = _except_list;
+    el.handler = handle;
+    el.prev = _except_list;
+    _except_list = ⪙
+  };
+  ~exception () __attribute__ ((always_inline)) { _except_list = save; }
+};
+
+#else
+
+#define exception_list void
+typedef struct _DISPATCHER_CONTEXT *PDISPATCHER_CONTEXT;
+
+class exception
+{
 #ifdef __x86_64__
+  static EXCEPTION_DISPOSITION myfault (EXCEPTION_RECORD *, exception_list *,
+					CONTEXT *, PDISPATCHER_CONTEXT);
+#endif
+  static EXCEPTION_DISPOSITION handle (EXCEPTION_RECORD *, exception_list *,
+				       CONTEXT *, PDISPATCHER_CONTEXT);
+public:
+  exception () __attribute__ ((always_inline))
+  {
+    /* Install SEH handler. */
     asm volatile ("\n\
     1:									\n\
       .seh_handler							  \
-	_ZN9exception6handleEP17_EXCEPTION_RECORDPvP8_CONTEXTS2_,	  \
+	_ZN9exception6handleEP17_EXCEPTION_RECORDPvP8_CONTEXTP19_DISPATCHER_CONTEXT,	  \
 	@except								\n\
       .seh_handlerdata							\n\
       .long 1								\n\
       .rva 1b, 2f, 2f, 2f						\n\
       .seh_code								\n");
-#else
-    save = _except_list;
-    el.handler = handle;
-    el.prev = _except_list;
-    _except_list = ⪙
-#endif /* __x86_64__ */
   };
-#ifdef __x86_64__
-  static void install_myfault_handler () __attribute__ ((always_inline))
-  {
-    /* Install myfault exception handler as VEH.  Here's what happens:
-       Some Windows DLLs (advapi32, for instance) are using SEH to catch
-       exceptions inside its own functions.  If we install a VEH handler
-       to catch all exceptions, our Cygwin VEH handler would illegitimatly
-       handle exceptions inside of Windows DLLs which are usually handled
-       by its own SEH handler.  So, for standard exceptions we use an SEH
-       handler as installed in the constructor above so as not to override
-       the SEH handlers in Windows DLLs.
-       But we have a special case, myfault handling.  The myfault handling
-       catches exceptions inside of the Cygwin DLL, some of them entirely
-       expected as in verifyable_object_isvalid.  The ultimately right thing
-       to do would be to install SEH handlers for each of these cases.
-       But there are two problems with that:
-
-       1. It would be a massive and, partially unreliable change in the
-          calling functions due to the incomplete SEH support in GCC.
-
-       2. It doesn't always work.  Certain DLLs appear to call Cygwin
-	  functions during DLL initialization while the SEH handler is
-	  not installed in the active call frame.  For these cases we
-	  need a more generic approach.
-       
-       So, what we do here is to install a myfault VEH handler.  This
-       function is called from dll_crt0_0, so the myfault handler is
-       available very early. */
-    AddVectoredExceptionHandler (1, myfault_handle);
-  }
   ~exception () __attribute__ ((always_inline))
   {
     asm volatile ("\n\
@@ -175,11 +160,10 @@ public:
     2:									\n\
       nop								\n");
   }
-#else
-  ~exception () __attribute__ ((always_inline)) { _except_list = save; }
-#endif /* !__x86_64__ */
 };
 
+#endif /* !__x86_64 */
+
 class cygwin_exception
 {
   PUINT_PTR framep;