X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=blobdiff_plain;f=docs%2Fexceptions;h=d5ecaeead43a634984b2701a5c5bd5acaa8ff019;hb=8bd20198baba20aac184b89876a9aedc7445c40e;hp=e98202cf07b228750482d63e7df968d3cd6a4f2f;hpb=b6bb40164b894fc5a3cc6ee2aaa29a8ed925cb59;p=mono.git

diff --git a/docs/exceptions b/docs/exceptions
index e98202cf07b..d5ecaeead43 100644
--- a/docs/exceptions
+++ b/docs/exceptions
@@ -1,5 +1,6 @@
-Author: Dietmar Maurer (dietmar@ximian.com)
-(C) 2001 Ximian, Inc.
+	     Exception Implementation in the Mono Runtime
+		 Dietmar Maurer (dietmar@ximian.com)
+			(C) 2001 Ximian, Inc.
 
 Exception implementation (jit):
 ===============================
@@ -56,19 +57,20 @@ leave: is simply translated into a branch to the target. If the leave
 instruction is inside a finally block (but not inside another handler)
 we call the finally handler before we branch to the target.
 
-finally/endfinally: is translated into subroutine ending with a "return"
-statement. The subroutine does not save EBP/ESP, because we need access to the
-local variables of the enclosing method. We have to use a "call"
-instruction to execute such finally handlers. This makes it possible to
-execute them inside the stack unwinding code.
+finally/endfinally, filter/endfilter: is translated into subroutine ending with
+a "return" statement. The subroutine does not save EBP, because we need access
+to the local variables of the enclosing method. Its is possible that
+instructions inside those handlers modify the stack pointer, thus we save the
+stack pointer at the start of the handler, and restore it at the end. We have
+to use a "call" instruction to execute such finally handlers. This makes it
+also possible to execute them inside the stack unwinding code. The exception
+object for filters is passed in a local variable (cfg->exvar).
 
-throw: we first save all regs into a sigcontext struct (we pass the
-exception object in register ECX), and then call the stack unwinding
-code.
-
-catch handler: receives the exception object in ECX. They store that
-object into a local variable, so that rethrow can access the object.
+throw: we first save all regs into a sigcontext struct and then call the stack
+unwinding code.
 
+catch handler: catch hanlders are always called from the stack unwinding
+code. The exception object is passed in a local variable (cfg->exvar).
 
 gcc support for Exceptions
 ==========================