[Mono-bugs] [Bug 27311][Nor] Changed - checked{} does not always use .ovf opcodes

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Changed by lupus@ximian.com.

http://bugzilla.ximian.com/show_bug.cgi?id=27311

--- shadow/27311	Mon Jul  1 17:33:18 2002
+++ shadow/27311.tmp.6109	Tue Jul  2 03:43:23 2002
@@ -1,23 +1,23 @@
 Bug#: 27311
-Product: Mono/Runtime
+Product: Mono/MCS
 Version: unspecified
-OS: 
+OS: unknown
 OS Details: LFS
-Status: NEW   
+Status: ASSIGNED   
 Resolution: 
-Severity: 
-Priority: Wishlist
-Component: misc
+Severity: Unknown
+Priority: Normal
+Component: Misc
 AssignedTo: mono-bugs@ximian.com                            
 ReportedBy: mwh@sysrq.dk               
 QAContact: mono-bugs@ximian.com
 TargetMilestone: ---
 URL: 
 Cc: 
-Summary: checked{} does not generate any exception
+Summary: checked{} does not always use .ovf opcodes
 
 Description of Problem:
 
 The language construct checked seems to have no effect. No exception is
 throwned.
 
@@ -50,6 +50,26 @@
 An OverflowException
 
 How often does this happen? 
 Everytime
 
 Additional Information:
+
+------- Additional Comments From lupus@ximian.com  2002-07-02 03:43 -------
+Thanks for the test. This turns out to be a compiler issue:
+mcs uses the correct .ovf variants when doing the computations, but
+not when converting the value back to byte (the eval stack uses 32 bit
+ints).
+Example code produced by csc:
+	IL_0014: ldloc.0 
+	IL_0015: ldloc.1 
+	IL_0016: sub.ovf 
+	IL_0017: conv.ovf.u1 
+	IL_0018: stloc.2 
+The same code produced by mcs:
+	IL_0014: ldloc.0 
+	IL_0015: ldloc.1 
+	IL_0016: sub.ovf 
+	IL_0017: conv.u1 
+	IL_0018: stloc.2 
+(note the conv opcode).
+The csc compiled program works fine in both mono and mint.