8253180: ZGC: Implementation of JEP 376: ZGC: Concurrent Thread-Stack Processing

Reviewed-by: stefank, pliden, rehn, neliasso, coleenp, smonteith

Author: fisk

src/hotspot/cpu/aarch64/aarch64.ad

@@ -1966,9 +1966,10 @@ void MachEpilogNode::format(PhaseRegAlloc *ra_, outputStream *st) const {
   }
 
   if (do_polling() && C->is_method_compilation()) {
-    st->print("# touch polling page\n\t");
-    st->print("ldr rscratch1, [rthread],#polling_page_offset\n\t");
-    st->print("ldr zr, [rscratch1]");
+    st->print("# test polling word\n\t");
+    st->print("ldr  rscratch1, [rthread],#%d\n\t", in_bytes(JavaThread::polling_word_offset()));
+    st->print("cmp  sp, rscratch1\n\t");
+    st->print("bhi #slow_path");
   }
 }
 #endif
@@ -1985,7 +1986,13 @@ void MachEpilogNode::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {
   }
 
   if (do_polling() && C->is_method_compilation()) {
-    __ fetch_and_read_polling_page(rscratch1, relocInfo::poll_return_type);
+    Label dummy_label;
+    Label* code_stub = &dummy_label;
+    if (!C->output()->in_scratch_emit_size()) {
+      code_stub = &C->output()->safepoint_poll_table()->add_safepoint(__ offset());
+    }
+    __ relocate(relocInfo::poll_return_type);
+    __ safepoint_poll(*code_stub, true /* at_return */, false /* acquire */, true /* in_nmethod */);
   }
 }
 

src/hotspot/cpu/aarch64/c1_CodeStubs_aarch64.cpp

@@ -38,6 +38,19 @@
 
 #define __ ce->masm()->
 
+void C1SafepointPollStub::emit_code(LIR_Assembler* ce) {
+  __ bind(_entry);
+  InternalAddress safepoint_pc(ce->masm()->pc() - ce->masm()->offset() + safepoint_offset());
+  __ adr(rscratch1, safepoint_pc);
+  __ str(rscratch1, Address(rthread, JavaThread::saved_exception_pc_offset()));
+
+  assert(SharedRuntime::polling_page_return_handler_blob() != NULL,
+         "polling page return stub not created yet");
+  address stub = SharedRuntime::polling_page_return_handler_blob()->entry_point();
+
+  __ far_jump(RuntimeAddress(stub));
+}
+
 void CounterOverflowStub::emit_code(LIR_Assembler* ce) {
   __ bind(_entry);
   Metadata *m = _method->as_constant_ptr()->as_metadata();

src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp

@@ -504,7 +504,7 @@ void LIR_Assembler::add_debug_info_for_branch(address adr, CodeEmitInfo* info) {
   }
 }
 
-void LIR_Assembler::return_op(LIR_Opr result) {
+void LIR_Assembler::return_op(LIR_Opr result, C1SafepointPollStub* code_stub) {
   assert(result->is_illegal() || !result->is_single_cpu() || result->as_register() == r0, "word returns are in r0,");
 
   // Pop the stack before the safepoint code
@@ -514,7 +514,9 @@ void LIR_Assembler::return_op(LIR_Opr result) {
     __ reserved_stack_check();
   }
 
-  __ fetch_and_read_polling_page(rscratch1, relocInfo::poll_return_type);
+  code_stub->set_safepoint_offset(__ offset());
+  __ relocate(relocInfo::poll_return_type);
+  __ safepoint_poll(*code_stub->entry(), true /* at_return */, false /* acquire */, true /* in_nmethod */);
   __ ret(lr);
 }
 

src/hotspot/cpu/aarch64/c2_safepointPollStubTable_aarch64.cpp

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "asm/macroAssembler.hpp"
+#include "opto/compile.hpp"
+#include "opto/node.hpp"
+#include "opto/output.hpp"
+#include "runtime/sharedRuntime.hpp"
+
+#define __ masm.
+void C2SafepointPollStubTable::emit_stub_impl(MacroAssembler& masm, C2SafepointPollStub* entry) const {
+  assert(SharedRuntime::polling_page_return_handler_blob() != NULL,
+         "polling page return stub not created yet");
+  address stub = SharedRuntime::polling_page_return_handler_blob()->entry_point();
+
+  RuntimeAddress callback_addr(stub);
+
+  __ bind(entry->_stub_label);
+  InternalAddress safepoint_pc(masm.pc() - masm.offset() + entry->_safepoint_offset);
+  __ adr(rscratch1, safepoint_pc);
+  __ str(rscratch1, Address(rthread, JavaThread::saved_exception_pc_offset()));
+  __ far_jump(callback_addr);
+}
+#undef __

src/hotspot/cpu/aarch64/frame_aarch64.cpp

@@ -37,6 +37,7 @@
 #include "runtime/monitorChunk.hpp"
 #include "runtime/os.inline.hpp"
 #include "runtime/signature.hpp"
+#include "runtime/stackWatermarkSet.hpp"
 #include "runtime/stubCodeGenerator.hpp"
 #include "runtime/stubRoutines.hpp"
 #include "vmreg_aarch64.inline.hpp"
@@ -476,8 +477,8 @@ frame frame::sender_for_compiled_frame(RegisterMap* map) const {
 }
 
 //------------------------------------------------------------------------------
-// frame::sender
-frame frame::sender(RegisterMap* map) const {
+// frame::sender_raw
+frame frame::sender_raw(RegisterMap* map) const {
   // Default is we done have to follow them. The sender_for_xxx will
   // update it accordingly
    map->set_include_argument_oops(false);
@@ -499,6 +500,16 @@ frame frame::sender(RegisterMap* map) const {
   return frame(sender_sp(), link(), sender_pc());
 }
 
+frame frame::sender(RegisterMap* map) const {
+  frame result = sender_raw(map);
+
+  if (map->process_frames()) {
+    StackWatermarkSet::on_iteration(map->thread(), result);
+  }
+
+  return result;
+}
+
 bool frame::is_interpreted_frame_valid(JavaThread* thread) const {
   assert(is_interpreted_frame(), "Not an interpreted frame");
   // These are reasonable sanity checks

src/hotspot/cpu/aarch64/frame_aarch64.hpp

@@ -161,4 +161,7 @@
 
   static jint interpreter_frame_expression_stack_direction() { return -1; }
 
+  // returns the sending frame, without applying any barriers
+  frame sender_raw(RegisterMap* map) const;
+
 #endif // CPU_AARCH64_FRAME_AARCH64_HPP

src/hotspot/cpu/aarch64/gc/z/zGlobals_aarch64.hpp

@@ -24,10 +24,9 @@
 #ifndef CPU_AARCH64_GC_Z_ZGLOBALS_AARCH64_HPP
 #define CPU_AARCH64_GC_Z_ZGLOBALS_AARCH64_HPP
 
-const size_t ZPlatformGranuleSizeShift      = 21; // 2MB
-const size_t ZPlatformHeapViews             = 3;
-const size_t ZPlatformNMethodDisarmedOffset = 4;
-const size_t ZPlatformCacheLineSize         = 64;
+const size_t ZPlatformGranuleSizeShift = 21; // 2MB
+const size_t ZPlatformHeapViews        = 3;
+const size_t ZPlatformCacheLineSize    = 64;
 
 size_t ZPlatformAddressOffsetBits();
 size_t ZPlatformAddressMetadataShift();

src/hotspot/cpu/aarch64/interp_masm_aarch64.cpp

@@ -473,7 +473,7 @@ void InterpreterMacroAssembler::dispatch_base(TosState state,
 
   if (needs_thread_local_poll) {
     NOT_PRODUCT(block_comment("Thread-local Safepoint poll"));
-    ldr(rscratch2, Address(rthread, Thread::polling_page_offset()));
+    ldr(rscratch2, Address(rthread, Thread::polling_word_offset()));
     tbnz(rscratch2, exact_log2(SafepointMechanism::poll_bit()), safepoint);
   }
 
@@ -521,6 +521,7 @@ void InterpreterMacroAssembler::dispatch_via(TosState state, address* table) {
 
 // remove activation
 //
+// Apply stack watermark barrier.
 // Unlock the receiver if this is a synchronized method.
 // Unlock any Java monitors from syncronized blocks.
 // Remove the activation from the stack.
@@ -541,6 +542,19 @@ void InterpreterMacroAssembler::remove_activation(
   // result check if synchronized method
   Label unlocked, unlock, no_unlock;
 
+  // The below poll is for the stack watermark barrier. It allows fixing up frames lazily,
+  // that would normally not be safe to use. Such bad returns into unsafe territory of
+  // the stack, will call InterpreterRuntime::at_unwind.
+  Label slow_path;
+  Label fast_path;
+  safepoint_poll(slow_path, true /* at_return */, false /* acquire */, false /* in_nmethod */);
+  br(Assembler::AL, fast_path);
+  bind(slow_path);
+  push(state);
+  call_VM(noreg, CAST_FROM_FN_PTR(address, InterpreterRuntime::at_unwind));
+  pop(state);
+  bind(fast_path);
+
   // get the value of _do_not_unlock_if_synchronized into r3
   const Address do_not_unlock_if_synchronized(rthread,
     in_bytes(JavaThread::do_not_unlock_if_synchronized_offset()));

src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp

@@ -288,27 +288,21 @@ address MacroAssembler::target_addr_for_insn(address insn_addr, unsigned insn) {
   return address(((uint64_t)insn_addr + (offset << 2)));
 }
 
-void MacroAssembler::safepoint_poll(Label& slow_path) {
-  ldr(rscratch1, Address(rthread, Thread::polling_page_offset()));
-  tbnz(rscratch1, exact_log2(SafepointMechanism::poll_bit()), slow_path);
-}
-
-// Just like safepoint_poll, but use an acquiring load for thread-
-// local polling.
-//
-// We need an acquire here to ensure that any subsequent load of the
-// global SafepointSynchronize::_state flag is ordered after this load
-// of the local Thread::_polling page.  We don't want this poll to
-// return false (i.e. not safepointing) and a later poll of the global
-// SafepointSynchronize::_state spuriously to return true.
-//
-// This is to avoid a race when we're in a native->Java transition
-// racing the code which wakes up from a safepoint.
-//
-void MacroAssembler::safepoint_poll_acquire(Label& slow_path) {
-  lea(rscratch1, Address(rthread, Thread::polling_page_offset()));
-  ldar(rscratch1, rscratch1);
-  tbnz(rscratch1, exact_log2(SafepointMechanism::poll_bit()), slow_path);
+void MacroAssembler::safepoint_poll(Label& slow_path, bool at_return, bool acquire, bool in_nmethod) {
+  if (acquire) {
+    lea(rscratch1, Address(rthread, Thread::polling_word_offset()));
+    ldar(rscratch1, rscratch1);
+  } else {
+    ldr(rscratch1, Address(rthread, Thread::polling_word_offset()));
+  }
+  if (at_return) {
+    // Note that when in_nmethod is set, the stack pointer is incremented before the poll. Therefore,
+    // we may safely use the sp instead to perform the stack watermark check.
+    cmp(in_nmethod ? sp : rfp, rscratch1);
+    br(Assembler::HI, slow_path);
+  } else {
+    tbnz(rscratch1, exact_log2(SafepointMechanism::poll_bit()), slow_path);
+  }
 }
 
 void MacroAssembler::reset_last_Java_frame(bool clear_fp) {
@@ -4405,13 +4399,6 @@ void MacroAssembler::get_polling_page(Register dest, relocInfo::relocType rtype)
   ldr(dest, Address(rthread, Thread::polling_page_offset()));
 }
 
-// Move the address of the polling page into r, then read the polling
-// page.
-address MacroAssembler::fetch_and_read_polling_page(Register r, relocInfo::relocType rtype) {
-  get_polling_page(r, rtype);
-  return read_polling_page(r, rtype);
-}
-
 // Read the polling page.  The address of the polling page must
 // already be in r.
 address MacroAssembler::read_polling_page(Register r, relocInfo::relocType rtype) {

src/hotspot/cpu/aarch64/macroAssembler_aarch64.hpp

@@ -102,8 +102,7 @@ class MacroAssembler: public Assembler {
  virtual void check_and_handle_popframe(Register java_thread);
  virtual void check_and_handle_earlyret(Register java_thread);
 
-  void safepoint_poll(Label& slow_path);
-  void safepoint_poll_acquire(Label& slow_path);
+  void safepoint_poll(Label& slow_path, bool at_return, bool acquire, bool in_nmethod);
 
   // Biased locking support
   // lock_reg and obj_reg must be loaded up with the appropriate values.
@@ -1231,7 +1230,6 @@ class MacroAssembler: public Assembler {
 
   address read_polling_page(Register r, relocInfo::relocType rtype);
   void get_polling_page(Register dest, relocInfo::relocType rtype);
-  address fetch_and_read_polling_page(Register r, relocInfo::relocType rtype);
 
   // CRC32 code for java.util.zip.CRC32::updateBytes() instrinsic.
   void update_byte_crc32(Register crc, Register val, Register table);