[Mono-bugs] [Bug 53871][Nor] Changed - Invalid IL code on simple IL

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Changed by vargaz@freemail.hu.

http://bugzilla.ximian.com/show_bug.cgi?id=53871

--- shadow/53871	2004-02-04 11:10:53.000000000 -0500
+++ shadow/53871.tmp.16567	2004-02-04 16:19:39.000000000 -0500
@@ -1,14 +1,14 @@
 Bug#: 53871
 Product: Mono/Runtime
 Version: unspecified
-OS: 
+OS: unknown
 OS Details: 
-Status: NEW   
-Resolution: 
-Severity: 
+Status: RESOLVED   
+Resolution: INVALID
+Severity: Unknown
 Priority: Normal
 Component: misc
 AssignedTo: mono-bugs@ximian.com                            
 ReportedBy: equim@planetquake.com               
 QAContact: mono-bugs@ximian.com
 TargetMilestone: ---
@@ -46,6 +46,25 @@
     br      L3
 L1: br      L2
 
 L3: ret
   }
 }
+
+------- Additional Comments From vargaz@freemail.hu  2004-02-04 16:19 -------
+The example program is not valid IL, since the stack at L2 is not
+empty. The fact that the MS runtime and PEVerify accept this program
+is a bug in the MS implementation.
+
+According to the ECMA spac, Partition III, section 1.7.5:
+
+It must be possible, with a single forward-pass through the CIL
+instruction stream for any method, to infer the exact state of the
+evaluation stack at every instruction (where by “state” we mean the
+number and type of each item on the evaluation stack).
+In particular, if that single-pass analysis arrives at an instruction,
+call it location X, that immediately follows an unconditional branch,
+and where X is not the target of an earlier branch instruction, then
+the state of the evaluation stack at X, clearly, cannot be derived
+from existing information. In this case, the CLI demands that the
+evaluation stack at X be empty.
+