Request reviews (L): 6895383: JCK test throws NPE for method compiled with Escape Analysis

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6895383/webrev.04

Fixed 6895383: JCK test throws NPE for method compiled with Escape Analysis

Problem:
EA misses checks for MemBar nodes when looking for following
MergeMem nodes. As result it did not add memory slice for
the volatile store (followed by several MemBar nodes)
in MergeMem of uncommon trap.
So when the method deoptimized and eliminated object reallocated
the NULL is stored to the corresponding field.

Solution:
Collect all MergeMem nodes at the beginning of EA when it walks
through Ideal graph instead of searching MergeMem nodes by going
down trough memory during memory splitting for non escaping objects.
Also check for general MemBar nodes instead of only Initialize nodes
during memory splitting.

I also did next optimizations/fixes:

1. Check for SafePointScalarObject nodes to avoid printing empty lines
    in PrintOptoAssembly output since they don't have corresponding mach nodes.

2. Eliminate volatile MemBars nodes for stores into a scalar replaced objects.
    I noticed that we still generate membars even if the object is eliminated.
    For that I added the Precedent edge to corresponding Store node.

3. The check for ClearArray node is missing when searching for
    a better memory edge during EA, memory optimization and an object
    scalar replacement. We can't bypass it since it is the part of object
    initialization (zeroing). I will try to factor it into separate function
    before push.

4. Add missing checks for string intrinsic nodes to adjust the escape state
    (non scalar replaceable) of char[] arrays they use.

5. Move code for searching objects which are not scalar replaceable to separate
    method verify_escape_state() since the code became too large. Add a simple
    control flow check to find initializing store for oop fields.

Reviewed by:

Fix verified (y/n): y, test

Other testing:
JPRT, CTW (32 and 64bit)