8373145: [BACKOUT] Remove ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch

Reviewed-by: mdoerr, kvn

src/hotspot/cpu/ppc/ppc.ad

@@ -6335,8 +6335,36 @@ instruct loadConD_Ex(regD dst, immD src) %{
 // Prefetch instructions.
 // Must be safe to execute with invalid address (cannot fault).
 
+// Special prefetch versions which use the dcbz instruction.
+instruct prefetch_alloc_zero(indirectMemory mem, iRegLsrc src) %{
+  match(PrefetchAllocation (AddP mem src));
+  predicate(AllocatePrefetchStyle == 3);
+  ins_cost(MEMORY_REF_COST);
+
+  format %{ "PREFETCH $mem, 2, $src \t// Prefetch write-many with zero" %}
+  size(4);
+  ins_encode %{
+    __ dcbz($src$$Register, $mem$$base$$Register);
+  %}
+  ins_pipe(pipe_class_memory);
+%}
+
+instruct prefetch_alloc_zero_no_offset(indirectMemory mem) %{
+  match(PrefetchAllocation mem);
+  predicate(AllocatePrefetchStyle == 3);
+  ins_cost(MEMORY_REF_COST);
+
+  format %{ "PREFETCH $mem, 2 \t// Prefetch write-many with zero" %}
+  size(4);
+  ins_encode %{
+    __ dcbz($mem$$base$$Register);
+  %}
+  ins_pipe(pipe_class_memory);
+%}
+
 instruct prefetch_alloc(indirectMemory mem, iRegLsrc src) %{
   match(PrefetchAllocation (AddP mem src));
+  predicate(AllocatePrefetchStyle != 3);
   ins_cost(MEMORY_REF_COST);
 
   format %{ "PREFETCH $mem, 2, $src \t// Prefetch write-many" %}
@@ -6349,6 +6377,7 @@ instruct prefetch_alloc(indirectMemory mem, iRegLsrc src) %{
 
 instruct prefetch_alloc_no_offset(indirectMemory mem) %{
   match(PrefetchAllocation mem);
+  predicate(AllocatePrefetchStyle != 3);
   ins_cost(MEMORY_REF_COST);
 
   format %{ "PREFETCH $mem, 2 \t// Prefetch write-many" %}

src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp

@@ -37,6 +37,7 @@
 #include "utilities/copy.hpp"
 
 size_t       ThreadLocalAllocBuffer::_max_size = 0;
+int          ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch = 0;
 unsigned int ThreadLocalAllocBuffer::_target_refills = 0;
 
 ThreadLocalAllocBuffer::ThreadLocalAllocBuffer() :
@@ -224,6 +225,30 @@ void ThreadLocalAllocBuffer::startup_initialization() {
   // abort during VM initialization.
   _target_refills = MAX2(_target_refills, 2U);
 
+#ifdef COMPILER2
+  // If the C2 compiler is present, extra space is needed at the end of
+  // TLABs, otherwise prefetching instructions generated by the C2
+  // compiler will fault (due to accessing memory outside of heap).
+  // The amount of space is the max of the number of lines to
+  // prefetch for array and for instance allocations. (Extra space must be
+  // reserved to accommodate both types of allocations.)
+  //
+  // Only SPARC-specific BIS instructions are known to fault. (Those
+  // instructions are generated if AllocatePrefetchStyle==3 and
+  // AllocatePrefetchInstr==1). To be on the safe side, however,
+  // extra space is reserved for all combinations of
+  // AllocatePrefetchStyle and AllocatePrefetchInstr.
+  //
+  // If the C2 compiler is not present, no space is reserved.
+
+  // +1 for rounding up to next cache line, +1 to be safe
+  if (CompilerConfig::is_c2_or_jvmci_compiler_enabled()) {
+    int lines =  MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2;
+    _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) /
+                                       (int)HeapWordSize;
+  }
+#endif
+
   // During jvm startup, the main thread is initialized
   // before the heap is initialized.  So reinitialize it now.
   guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
@@ -429,7 +454,8 @@ void ThreadLocalAllocStats::publish() {
 }
 
 size_t ThreadLocalAllocBuffer::end_reserve() {
-  return CollectedHeap::lab_alignment_reserve();
+  size_t reserve_size = CollectedHeap::lab_alignment_reserve();
+  return MAX2(reserve_size, (size_t)_reserve_for_allocation_prefetch);
 }
 
 const HeapWord* ThreadLocalAllocBuffer::start_relaxed() const {

src/hotspot/share/gc/shared/threadLocalAllocBuffer.hpp

@@ -58,6 +58,7 @@ private:
   size_t    _allocated_before_last_gc;           // total bytes allocated up until the last gc
 
   static size_t   _max_size;                          // maximum size of any TLAB
+  static int      _reserve_for_allocation_prefetch;   // Reserve at the end of the TLAB
   static unsigned _target_refills;                    // expected number of refills between GCs
 
   unsigned  _number_of_refills;

src/hotspot/share/opto/macro.cpp

@@ -1914,7 +1914,8 @@ Node* PhaseMacroExpand::prefetch_allocation(Node* i_o, Node*& needgc_false,
       transform_later(cache_adr);
       cache_adr = new CastP2XNode(needgc_false, cache_adr);
       transform_later(cache_adr);
-      // Address is aligned to execute prefetch to the beginning of cache line size.
+      // Address is aligned to execute prefetch to the beginning of cache line size
+      // (it is important when BIS instruction is used on SPARC as prefetch).
       Node* mask = _igvn.MakeConX(~(intptr_t)(step_size-1));
       cache_adr = new AndXNode(cache_adr, mask);
       transform_later(cache_adr);

src/hotspot/share/runtime/vmStructs.cpp

@@ -353,6 +353,7 @@
   nonstatic_field(ThreadLocalAllocBuffer,      _pf_top,                                       HeapWord*)                             \
   nonstatic_field(ThreadLocalAllocBuffer,      _desired_size,                                 size_t)                                \
   nonstatic_field(ThreadLocalAllocBuffer,      _refill_waste_limit,                           size_t)                                \
+     static_field(ThreadLocalAllocBuffer,      _reserve_for_allocation_prefetch,              int)                                   \
      static_field(ThreadLocalAllocBuffer,      _target_refills,                               unsigned)                              \
   nonstatic_field(ThreadLocalAllocBuffer,      _number_of_refills,                            unsigned)                              \
   nonstatic_field(ThreadLocalAllocBuffer,      _refill_waste,                                 unsigned)                              \

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/ThreadLocalAllocBuffer.java

@@ -76,9 +76,10 @@ public class ThreadLocalAllocBuffer extends VMObject {
 
   private long endReserve() {
     long labAlignmentReserve = VM.getVM().getLabAlignmentReserve();
+    long reserveForAllocationPrefetch = VM.getVM().getReserveForAllocationPrefetch();
     long heapWordSize = VM.getVM().getHeapWordSize();
 
-    return labAlignmentReserve * heapWordSize;
+    return Math.max(labAlignmentReserve, reserveForAllocationPrefetch) * heapWordSize;
   }
 
   /** Support for iteration over heap -- not sure how this will

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/VM.java

@@ -123,6 +123,7 @@ public class VM {
   private int          invocationEntryBCI;
   private ReversePtrs  revPtrs;
   private VMRegImpl    vmregImpl;
+  private int          reserveForAllocationPrefetch;
   private int          labAlignmentReserve;
 
   // System.getProperties from debuggee VM
@@ -446,6 +447,8 @@ public class VM {
     boolType = (CIntegerType) db.lookupType("bool");
 
     Type threadLocalAllocBuffer = db.lookupType("ThreadLocalAllocBuffer");
+    CIntegerField reserveForAllocationPrefetchField = threadLocalAllocBuffer.getCIntegerField("_reserve_for_allocation_prefetch");
+    reserveForAllocationPrefetch = (int)reserveForAllocationPrefetchField.getCInteger(intType);
 
     Type collectedHeap = db.lookupType("CollectedHeap");
     CIntegerField labAlignmentReserveField = collectedHeap.getCIntegerField("_lab_alignment_reserve");
@@ -912,6 +915,10 @@ public class VM {
     return vmInternalInfo;
   }
 
+  public int getReserveForAllocationPrefetch() {
+    return reserveForAllocationPrefetch;
+  }
+
   public int getLabAlignmentReserve() {
     return labAlignmentReserve;
   }