RFR (S): 8014972: Crash with specific values for -XX:InitialCodeCacheSize=500K -XX:ReservedCodeCacheSize=500k

[Albert Noll]

Hi,

thanks for reviewing this small patch.

Albert

jbs: https://jbs.oracle.com/bugs/browse/JDK-8014972
webrev: http://cr.openjdk.java.net/~anoll/8014972/webrev.00/ 
<http://cr.openjdk.java.net/%7Eanoll/8014972/webrev.00/>


Problem:
If -XX:ReservedCodeCacheSize is set too small, the VM crashes when 
starting up.

Solution:
Introduce a minimum code cache size (ReservedCodeCacheSize) that 
guarantees that the VM can startup. The minimum code cache size is 
defined by a new parameter (MinimumInitialCodeCacheSize) that cannot be 
changed in product build. My reasoning for this is that smaller values 
make the JVM crash at startup. However, in a development build, the 
parameter can be changed.

The current patch sets MinimumInitialCodeCacheSize to 400k for all 
platforms. On Solaris, MinimumInitialCodeCacheSize could be set to 300k 
and the VM still starts up. However, I am not sure if it makes sense to 
make MinimumInitialCodeCacheSize platform-dependent so that we can 
potentially save 100k on Solaris. If there is a reason, please let me know.

Also note that the InitialCodeCacheSize must be > 0. The reason is that 
otherwise the following  assertion fails:

Internal Error 
(/tmp/workspace/2-build-solaris-i586/jdk8/4767/hotspot/src/share/vm/memory/heap.cpp:50), 
pid=27190, tid=2
#  assert(0 <= beg && beg < _number_of_committed_segments) failed: 
interval begin out of bounds


Testing:
With the current value of MinimumInitialCodeCacheSize, the VM starts up 
on all Windows, Linux, and Solaris.

Note that we can still get exceptions (and the JVM cannot continue to 
execute) if the value for CodeCacheMinimumFreeSpace is to small (in that 
case, here is not enough space for adapters) .
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