Summary: Add executable parameters to reserve_memory and commit_memory to reduce executable memory to only the Code Heap.
Reviewed-by: xlu, kvn, acorn

Summary: Use zero based compressed oops if java heap is below 32gb and unscaled compressed oops if java heap is below 4gb.
Reviewed-by: never, twisti, jcoomes, coleenp

Summary: Update for files that have been modified starting July 2008
Reviewed-by: ohair, tbell

Summary: allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check
Reviewed-by: kvn, jmasa, phh, jcoomes