[PATCH] Don't reference main() in stacktrace.cc on MinGW

[PATCH] Don't reference main() in stacktrace.cc on MinGW

[Aaron W. LaFramboise]

The generic i386 fall-back unwinder has logic to stop early at main(). 
However, on Windows, main() isn't always available, primarily when we're 
in a shared library (DLL).  Also, when libgcj is linked as a DLL (patch 
coming soon), the 'main' symbol doesn't have the proper dynamic linkage 
to get the one we want, so things won't work.

This patch fixes this issue by removing this stopping condition on Windows.

I tested this by building a static libjava on i386-pc-mingw32.

OK to commit?

Re: [PATCH] Don't reference main() in stacktrace.cc on MinGW

[Aaron W. LaFramboise]

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Aaron W. LaFramboise wrote:
> The generic i386 fall-back unwinder has logic to stop early at main(). 
> However, on Windows, main() isn't always available, primarily when we're 
> in a shared library (DLL).  Also, when libgcj is linked as a DLL (patch 
> coming soon), the 'main' symbol doesn't have the proper dynamic linkage 
> to get the one we want, so things won't work.
> 
> This patch fixes this issue by removing this stopping condition on Windows.
> 
> I tested this by building a static libjava on i386-pc-mingw32.
> 
> OK to commit?

Patch attached.


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2008-08-21  Aaron W. LaFramboise  <aaronavay62@aaronwl.com>

	* sysdep/i386/backtrace.h (DONT_REFERENCE_MAIN) [_WIN32]: New.
	(fallback_backtrace) [DONT_REFERENCE_MAIN]: Don't generate references to main().

Index: sysdep/i386/backtrace.h
===================================================================
--- sysdep/i386/backtrace.h	(revision 139186)
+++ sysdep/i386/backtrace.h	(working copy)
@@ -13,7 +13,13 @@ details.  */
 
 #include <java-stack.h>
 
+#ifdef _WIN32
+#define DONT_REFERENCE_MAIN
+#endif
+
+#ifndef DONT_REFERENCE_MAIN
 extern int main (int, char **);
+#endif
 
 /* The context used to keep track of our position while unwinding through
    the call stack.  */
@@ -104,7 +110,10 @@ fallback_backtrace (_Unwind_Trace_Fn tra
                             const char **, bool))_Jv_RunMain;
       if (ctx.meth_addr == (_Jv_uintptr_t)jv_runmain
           || ctx.meth_addr == (_Jv_uintptr_t)_Jv_ThreadStart
-          || (ctx.meth_addr - (_Jv_uintptr_t)main) < 16)
+#ifndef DONT_REFERENCE_MAIN
+          || (ctx.meth_addr - (_Jv_uintptr_t)main) < 16
+#endif
+          )
         break;
     }