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From: Chris Faylor <cgf AT cygnus DOT com>
Date: Wed, 9 Jun 1999 17:47:33 -0400
To: John R Hanson <JRSON AT NetZero DOT Net>
Cc: cygwin-developers AT sourceware DOT cygnus DOT com
Subject: Re: JIT debugging with gdb
Message-ID: <19990609174733.A23582@cygnus.com>
References: <375ec652 DOT 10516371 AT smtp DOT netzero DOT net>
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In-Reply-To: <375ec652.10516371@smtp.netzero.net>; from John R Hanson on Wed, Jun 09, 1999 at 08:07:20PM +0000

I'm not sure why you'd want to use gdb in this fashion since it can't
currently use symbol information from VC++ programs.

Also, I *really* don't want to have discussions in cygwin-developers
that are cross-pollinated from cygwin so I've removed
cygwin AT sourceware DOT cygnus DOT com from the To:.

cgf

On Wed, Jun 09, 1999 at 08:07:20PM +0000, John R Hanson wrote:
>Following is a patch to add basic support to the cvs gdb
>for JIT debugging on win95 and NT 4.
>
>Currently only works for vc++ and mingw32 .exe's cause
>cygwin doesn't let the system handle exceptions.
>(easy fix is just to return 1 in .../winsup/exceptions.cc->handel_exceptions()
> instead of printing out those oh so useful *.core files :)
>
>TODO (for someone else ;) get executable name from pid and load it.
>WORKAROUND use 
>add-symbol-file filename.exe 0x401000
>at the (gdb) prompt.
>
>Could someone please check if this works for
>98 and 2000?
>
>REGEDIT4
>
>[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\aedebug]
>"Auto"="0"
>"Debugger"="d:/usr/H-i586~1/bin/gdb -c %#x -Event-HANDLE %ld"
>
>
>
>--- ./win32-nat.c	1999/05/30 10:17:24	1.2
>+++ ./win32-nat.c	1999/06/04 11:22:14
>@@ -119,6 +119,8 @@
> static int debug_memory = 0;		/* show target memory accesses */
> static int debug_exceptions = 0;	/* show target exceptions */
> 
>+HANDLE notify_attach = 0; /* JIT event handle from command line to notify kernel we are attached */
>+
> /* This vector maps GDB's idea of a register's number into an address
>    in the win32 exception context vector.
> 
>@@ -639,6 +641,8 @@
>     case EXCEPTION_BREAKPOINT:
>       DEBUG_EXCEPT (("gdb: Target exception BREAKPOINT at 0x%08x\n",
> 		     current_event.u.Exception.ExceptionRecord.ExceptionAddress));
>+      if (current_event.u.Exception.dwFirstChance && notify_attach){ th->context.Eip = (DWORD)current_event.u.Exception.ExceptionRecord.ExceptionAddress + 1; SetThreadContext(th->h, &th->context); }
>+      if (notify_attach && (exception_count == 1) && !(GetVersion() < 0x80000000) && !SetEvent(notify_attach)) DEBUG_EXCEPT (("gdb: could not notify windows of attach\n"));
>       ourstatus->value.sig = TARGET_SIGNAL_TRAP;
>       break;
>     case DBG_CONTROL_C:
>@@ -712,6 +716,7 @@
>       char *p;
>       thread_info *th;
>       int sig;
>+      int except_result;
> 
>       if (debug_event)
> 	{
>@@ -738,6 +743,8 @@
> 			     current_event.dwProcessId, current_event.dwThreadId,
> 			     "EXIT_THREAD_DEBUG_EVENT"));
> 	      child_delete_thread (current_event.dwThreadId);
>+              if (notify_attach && (GetVersion() < 0x80000000) && SetEvent(notify_attach)) notify_attach = 0;
>+              else if (notify_attach && (GetVersion() < 0x80000000)) {DEBUG_EVENTS (("gdb: could not notify NT of attach event. HANDLE=%\n", notify_attach)); notify_attach = 0;}
> 	      break;
> 
> 	    case CREATE_PROCESS_DEBUG_EVENT:
>@@ -780,8 +787,11 @@
> 	      DEBUG_EVENTS (("gdb: kernel event for pid=%d tid=%d code=%s)\n",
> 			     current_event.dwProcessId, current_event.dwThreadId,
> 			     "EXCEPTION_DEBUG_EVENT"));
>-	      if (handle_exception (ourstatus))
>-		return current_event.dwThreadId;
>+              if ((except_result = handle_exception (ourstatus)) && ((ourstatus->value.sig != TARGET_SIGNAL_TRAP) || !notify_attach))
>+                return current_event.dwThreadId; /* not a trap or we are not JIT attaching */
>+#define DBG_EXCEPTION_HANDLED ((DWORD)0x00010001L)
>+              else if (except_result && (GetVersion() < 0x80000000)) { continue_status = DBG_EXCEPTION_HANDLED; break; /* attaching NT */ } 
>+              else if (except_result && (exception_count == 2)){notify_attach = 0;break; /* 9x fall through for the 1st one */}
> 	      continue_status = DBG_EXCEPTION_NOT_HANDLED;
> 	      break;
> 
>--- ./config/i386/xm-cygwin.h	1999/05/31 14:41:24	1.1
>+++ ./config/i386/xm-cygwin.h	1999/06/04 11:09:58
>@@ -33,3 +33,7 @@
> 
> #define HAVE_SIGSETMASK 0
> 
>+extern void *notify_attach; /* kernel supplied event handle to notify it of JIT attach */
>+#define	ADDITIONAL_OPTIONS         {"Event-HANDLE", required_argument, 0, 1004},
>+#define	ADDITIONAL_OPTION_CASES	case 1004:  notify_attach = (HANDLE)atoi(optarg);  break;
>+#define	ADDITIONAL_OPTION_HELP 	"  -Event-HANDLE HANDLE   handle to signal the kernel we have attached for JIT.\n"