[Soot-list] Exception Table

[Patrick Lam]

Silviu ANDRICA wrote:
> In the on-line version, 
> http://java.sun.com/docs/books/jvms/second_edition/html/Instructions2.doc.html, 
> 
> there is no mentioning about any exceptions that the instruction might 
> throw.

I don't know, then, if your problem actually causes any issues in 
practice. Nevertheless, I think that the following patch ought to fix 
the problem. When Soot adds the rN := @caughtexception it will now 
update its pointers so that the @caughtexception statement takes the 
place of the statement it got added just before.

This patch sort of seems to work at cross purposes with one of Michael 
Batchelder's commits, the one which changes the insertBefore into an 
insertBeforeNoRedirect. I'd be curious to see if he has any comments on 
this, if he can remember what happened. The relevant revision is 2513.

I've committed the patch.

pat

Index: src/soot/coffi/CFG.java
===================================================================
--- src/soot/coffi/CFG.java	(revision 3260)
+++ src/soot/coffi/CFG.java	(working copy)
@@ -1372,16 +1372,22 @@
  			
  			newTarget = Jimple.v().newIdentityStmt(local, 
Jimple.v().newCaughtExceptionRef());

-			// changed to account for catch blocks which are also part of normal 
control flow
-            //units.insertBefore(newTarget, firstTargetStmt);			
-            ((PatchingChain)units).insertBeforeNoRedirect(newTarget, 
firstTargetStmt);
+			((PatchingChain)units).insertBeforeNoRedirect(newTarget, 
firstTargetStmt);

  			targetToHandler.put(firstTargetStmt, newTarget);
-            if (units.getFirst()!=newTarget) {
-              Unit prev = (Unit)units.getPredOf(newTarget);
-              if (prev != null && prev.fallsThrough())
- 
units.insertAfter(Jimple.v().newGotoStmt(firstTargetStmt), prev);
-            }
+			if (units.getFirst()!=newTarget) {
+			    Unit prev = (Unit)units.getPredOf(newTarget);
+			    if (prev != null && prev.fallsThrough())
+				units.insertAfter(Jimple.v().newGotoStmt(firstTargetStmt), prev);
+			}
+
+			// Bug reported by Silviu Andrica:
+			// rN := @caughtexception gets ignored by future
+			// trap generation.
+			for (Map.Entry<Instruction,Stmt> e : 
instructionToFirstStmt.entrySet()) {
+			    if (e.getValue() == firstTargetStmt)
+				e.setValue(newTarget);
+			}
  		    }
  		}