runtime: use VEH, not SEH, for windows/386 exception handling

Structured Exception Handling (SEH) was the first way to handle
exceptions (memory faults, divides by zero) on Windows.
The S might as well stand for "stack-based": the implementation
interprets stack addresses in a few different ways, and it gets
subtly confused by Go's management of stacks. It's also something
that requires active maintenance during cgo switches, and we've
had bugs in that maintenance in the past.

We have recently come to believe that SEH cannot work with
Go's stack usage. See http://golang.org/issue/7325 for details.

Vectored Exception Handling (VEH) is more like a Unix signal
handler: you set it once for the whole process and forget about it.

This CL drops all the SEH code and replaces it with VEH code.
Many special cases and 7 #ifdefs disappear.

VEH was introduced in Windows XP, so Go on windows/386 will
now require Windows XP or later. The previous requirement was
Windows 2000 or later. Windows 2000 immediately preceded
Windows XP, so Windows 2000 is the only affected version.
Microsoft stopped supporting Windows 2000 in 2010.
See http://golang.org/s/win2000-golang-nuts for details.

Fixes #7325.

LGTM=alex.brainman, r
R=golang-codereviews, alex.brainman, stephen.gutekanst, dave
CC=golang-codereviews, iant, r
https://golang.org/cl/74790043

1 files changed, 0 insertions, 35 deletions

diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index baa751cd72..9cb6960c62 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -83,8 +83,6 @@ typedef	struct	Hchan		Hchan;
 typedef	struct	Complex64	Complex64;
 typedef	struct	Complex128	Complex128;
 typedef	struct	LibCall		LibCall;
-typedef	struct	SEH		SEH;
-typedef	struct	SEHUnwind		SEHUnwind;
 typedef	struct	WinCallbackContext	WinCallbackContext;
 typedef	struct	Timers		Timers;
 typedef	struct	Timer		Timer;
@@ -241,18 +239,6 @@ struct	LibCall
 	uintptr	err;	// error number
 };
 
-struct	SEH
-{
-	void*	prev;
-	void*	handler;
-};
-
-struct	SEHUnwind
-{
-	SEHUnwind*	link;
-	SEH*	seh;
-};
-
 // describes how to handle callback
 struct	WinCallbackContext
 {
@@ -303,15 +289,6 @@ struct	G
 	uintptr	end[];
 };
 
-// Define a symbol for windows/386 because that is the only
-// system with SEH handling, and we end up checking that
-// repeatedly.
-#ifdef GOOS_windows
-#ifdef GOARCH_386
-#define GOOSARCH_windows_386
-#endif
-#endif
-
 struct	M
 {
 	G*	g0;		// goroutine with scheduling stack
@@ -394,8 +371,6 @@ struct	M
 	int8*	notesig;
 	byte*	errstr;
 #endif
-	SEH*	seh;
-	SEHUnwind*	sehunwind;
 	uintptr	end[];
 };
 
@@ -975,16 +950,6 @@ void*	runtime·funcdata(Func*, int32);
 int32	runtime·setmaxthreads(int32);
 G*	runtime·timejump(void);
 
-// On Windows 386, we have functions for saving and restoring
-// the SEH values; elsewhere #define them away.
-#ifdef GOOSARCH_windows_386
-SEH*	runtime·getseh(void);
-void	runtime·setseh(SEH*);
-#else
-#define runtime·getseh() nil
-#define runtime·setseh(x) do{}while(0)
-#endif
-
 #pragma	varargck	argpos	runtime·printf	1
 #pragma	varargck	type	"c"	int32
 #pragma	varargck	type	"d"	int32