[9] RFR (S): 8157181: Compilers accept modification of final fields outside initializer methods

[Zoltán Majó]

Hi,


please review the patch for 8157181.

https://bugs.openjdk.java.net/browse/JDK-8157181

Problem: According to the Java VM Specification, the putstatic bytecode 
is allowed to modify a final field only
- (1) if the field is declared in the current class (the class that 
declares the current method) and
- (2) if the putstatic instruction appears in the class or interface 
initializer method <clinit> of the current class.

If any of the conditions above does not hold, an IllegalAccessError must 
be thrown. Similar conditions apply for putfield bytecodes targeting 
final fields.

Currently, HotSpot checks only condition (1) but not (2) [1]. Methods 
that do not satisfy condition (2) violate the assumptions of the 
compilers (e.g., at [2]). Compiling such methods results in different 
behavior of compiled and interpreted code. The bug report describes such 
a case in detail.

Solution: Bail out compilation of methods that do not satisfy condition (2).

Webrev:
http://cr.openjdk.java.net/~zmajo/8157181/webrev.00/

Testing:
- JPRT
- local testing with reproducer.

It seems to me that the interpeter is affected by a related problem 
(i.e., the interpreter does not throw an IllegalAccessError if (2) does 
not hold). I'd prefer to file a separate bug for that problem.

Thank you!

Best regards,


Zoltan

[1]: 
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/file/07a5eceac654/src/share/vm/interpreter/linkResolver.cpp#l910
[2]: 
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/file/07a5eceac654/src/share/vm/opto/parse3.cpp#l303