[C2] Backport JDK-8010500: Possible null pointer dereference at hotspot/src/share/vm/opto/loopnode.hpp

Summary:  Added NULL check for loopnode() in get_pre_loop_end()
Backport the fix for JDK-8010500 (https://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/4e7ee57b57bf) from OpenJDK.

Test Plan: none

Reviewed-by: kuaiwei, luchsh

Issue: https://github.com/alibaba/dragonwell8/issues/13

Summary: convert the assert into compilation check which will skip superword optimization
Reviewed-by: roland, thartmann

Summary: Emit CastII to make narrow ConvI2L dependent on the corresponding range check.
Reviewed-by: kvn, roland

Summary: Node::depends_only_on_test() should return false for Unsafe loads
Reviewed-by: kvn, adinn

Summary: Prevent vectorization of memory operations with different invariant offsets if unaligned memory accesses are not allowed.
Reviewed-by: kvn

Summary: C2 should not try to vectorize loops with loop variant vector base address.
Reviewed-by: kvn

Summary: check that offset % mem_oper_size == 0 when alignment is verified during vectorization.
Reviewed-by: iveresov

Summary: Emit CastII to make narrow ConvI2L dependent on the corresponding range check.
Reviewed-by: kvn, roland

Summary: Allow to execute vectorization and crc32 optimization on Atom. Enable UseFPUForSpilling by default on x86.
Reviewed-by: roland

Summary: add missing is_mem() check when we collect load nodes in SuperWord::co_locate_pack().
Reviewed-by: iveresov

Summary: Copyright year updated for files modified during 2013
Reviewed-by: twisti, iveresov

Summary: Added few checks and early bailout from Superword optimization to avoid such cases in a future.
Reviewed-by: roland, twisti

Summary: Added missed check that Load node is in processed loop block.
Reviewed-by: twisti

Summary: do vector right shift operation for small int types only after loads
Reviewed-by: jrose, dlong

Summary: Removed LoadUI2L node from Ideal nodes, use match rule in .ad files instead.
Reviewed-by: kvn

Summary: Add generation of vectors for scalar shift count.
Reviewed-by: roland, twisti, dlong

Summary: Deleted placement new operator of Node - node(size_t, Compile *, int).
Reviewed-by: kvn, twisti
Contributed-by: bharadwaj.yadavalli@oracle.com

Summary: Replaced is_vector_use() call with explicit check for vector shift's count.
Reviewed-by: twisti, roland, dlong, vlivanov

Summary: Fixed Pack node generation. Not vectorize shift instructions if count is not the same for all shifts and if count is vector.
Reviewed-by: twisti

Summary: Shifts with loop variant counts "a[i]=1<<b[i];" should not be vectorized since hw does not support it.
Reviewed-by: twisti

Summary: Added asm encoding and mach nodes for vector arithmetic instructions on x86.
Reviewed-by: roland

Summary: disable vectorization of a memory access with more elements per vector than one which is used for alignment on sparc
Reviewed-by: twisti

Summary: Increase vector size up to 256-bits for YMM AVX registers on x86.
Reviewed-by: never, twisti, roland

Summary: replace frequent C2 optimizer code patterns with new methods calls
Reviewed-by: kvn, twisti
Contributed-by: vladimir.x.ivanov@oracle.com

Summary: When constructing input vector use type of vector's operation which use it since element's sizes should match.
Reviewed-by: never, twisti

Summary: Fixed vectors alignment when several arrays are accessed in one loop.
Reviewed-by: roland, twisti

Summary: Save whole XMM/YMM registers in safepoint interrupt handler.
Reviewed-by: roland, twisti

Summary: Use cl->is_valid_counted_loop() check.
Reviewed-by: never

Summary: Remove flags which duplicate information in Node::NodeClasses.
Reviewed-by: never

Summary: Clone loop predicate for clonned loops
Reviewed-by: never

Summary: Replaced MakeDeps and the includeDB files with more standardized solutions.
Reviewed-by: coleenp, kvn, kamg

Summary: Use replace_node() method instead of subsume_node().
Reviewed-by: jrose, never

Reviewed-by: kvn

Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair

6852078: HSX 14/16 in jdk 5.0: api/javax_management api/org_omg jck tests crashes or make tnameserv crash
Summary: Disable SuperWord optimization for unsafe read/write
Reviewed-by: kvn, phh

Summary: filter out non-primitives before deciding whether two ops can be packed
Reviewed-by: kvn, never

6877254: Server vm crashes with no branches off of store slice" when run with CMS and UseSuperWord(default)
Summary: design StoreCMNode::Ideal to promote its oopStore input if the input is a MergeMem node
Reviewed-by: kvn, never

Summary: schedule the superword loads based on dependence constraints
Reviewed-by: kvn, never

Summary: Fixed SuperWord scheduling of memory operations.
Reviewed-by: kvn, never

Summary: Update copyright for files that have been modified in 2009, up to 03/09
Reviewed-by: katleman, tbell, ohair