8255606: Enable concurrent stack processing on x86_32 platforms

Reviewed-by: shade, rkennke, eosterlund

src/hotspot/cpu/x86/c1_CodeStubs_x86.cpp

@@ -80,19 +80,29 @@ void ConversionStub::emit_code(LIR_Assembler* ce) {
 #endif // !_LP64
 
 void C1SafepointPollStub::emit_code(LIR_Assembler* ce) {
-#ifdef _LP64
   __ bind(_entry);
   InternalAddress safepoint_pc(ce->masm()->pc() - ce->masm()->offset() + safepoint_offset());
+#ifdef _LP64
   __ lea(rscratch1, safepoint_pc);
   __ movptr(Address(r15_thread, JavaThread::saved_exception_pc_offset()), rscratch1);
+#else
+  const Register tmp1 = rcx;
+  const Register tmp2 = rdx;
+  __ push(tmp1);
+  __ push(tmp2);
 
+  __ lea(tmp1, safepoint_pc);
+  __ get_thread(tmp2);
+  __ movptr(Address(tmp2, JavaThread::saved_exception_pc_offset()), tmp1);
+
+  __ pop(tmp2);
+  __ pop(tmp1);
+#endif /* _LP64 */
   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();
   __ jump(RuntimeAddress(stub));
-#else
-  ShouldNotReachHere();
-#endif /* _LP64 */
 }
 
 void CounterOverflowStub::emit_code(LIR_Assembler* ce) {

src/hotspot/cpu/x86/c1_LIRAssembler_x86.cpp

@@ -535,17 +535,14 @@ void LIR_Assembler::return_op(LIR_Opr result, C1SafepointPollStub* code_stub) {
   // the poll sets the condition code, but no data registers
 
 #ifdef _LP64
+  const Register thread = r15_thread;
+#else
+  const Register thread = rbx;
+  __ get_thread(thread);
+#endif
   code_stub->set_safepoint_offset(__ offset());
   __ relocate(relocInfo::poll_return_type);
-  __ safepoint_poll(*code_stub->entry(), r15_thread, true /* at_return */, true /* in_nmethod */);
-#else
-  const Register poll_addr = rbx;
-  assert(FrameMap::is_caller_save_register(poll_addr), "will overwrite");
-  __ get_thread(poll_addr);
-  __ movptr(poll_addr, Address(poll_addr, Thread::polling_page_offset()));
-  __ relocate(relocInfo::poll_return_type);
-  __ testl(rax, Address(poll_addr, 0));
-#endif
+  __ safepoint_poll(*code_stub->entry(), thread, true /* at_return */, true /* in_nmethod */);
   __ ret(0);
 }
 

src/hotspot/cpu/x86/c2_safepointPollStubTable_x86.cpp

@@ -31,7 +31,6 @@
 
 #define __ masm.
 void C2SafepointPollStubTable::emit_stub_impl(MacroAssembler& masm, C2SafepointPollStub* entry) const {
-#ifdef _LP64
   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();
@@ -40,11 +39,22 @@ void C2SafepointPollStubTable::emit_stub_impl(MacroAssembler& masm, C2SafepointP
 
   __ bind(entry->_stub_label);
   InternalAddress safepoint_pc(masm.pc() - masm.offset() + entry->_safepoint_offset);
+#ifdef _LP64
   __ lea(rscratch1, safepoint_pc);
   __ movptr(Address(r15_thread, JavaThread::saved_exception_pc_offset()), rscratch1);
-  __ jump(callback_addr);
 #else
-  ShouldNotReachHere();
+  const Register tmp1 = rcx;
+  const Register tmp2 = rdx;
+  __ push(tmp1);
+  __ push(tmp2);
+
+  __ lea(tmp1, safepoint_pc);
+  __ get_thread(tmp2);
+  __ movptr(Address(tmp2, JavaThread::saved_exception_pc_offset()), tmp1);
+
+  __ pop(tmp2);
+  __ pop(tmp1);
 #endif
+  __ jump(callback_addr);
 }
 #undef __

src/hotspot/cpu/x86/macroAssembler_x86.cpp

@@ -2761,15 +2761,13 @@ void MacroAssembler::save_rax(Register tmp) {
 }
 
 void MacroAssembler::safepoint_poll(Label& slow_path, Register thread_reg, bool at_return, bool in_nmethod) {
-#ifdef _LP64
   if (at_return) {
     // Note that when in_nmethod is set, the stack pointer is incremented before the poll. Therefore,
     // we may safely use rsp instead to perform the stack watermark check.
-    cmpq(in_nmethod ? rsp : rbp, Address(thread_reg, Thread::polling_word_offset()));
+    cmpptr(in_nmethod ? rsp : rbp, Address(thread_reg, Thread::polling_word_offset()));
     jcc(Assembler::above, slow_path);
     return;
   }
-#endif
   testb(Address(thread_reg, Thread::polling_word_offset()), SafepointMechanism::poll_bit());
   jcc(Assembler::notZero, slow_path); // handshake bit set implies poll
 }

src/hotspot/cpu/x86/vm_version_x86.hpp

@@ -1023,7 +1023,7 @@ public:
   }
 
   constexpr static bool supports_stack_watermark_barrier() {
-    return LP64_ONLY(true) NOT_LP64(false);
+    return true;
   }
 
   // there are several insns to force cache line sync to memory which

src/hotspot/cpu/x86/x86_32.ad

@@ -653,8 +653,9 @@ void MachEpilogNode::format( PhaseRegAlloc *ra_, outputStream* st ) const {
   }
   st->print_cr("POPL   EBP"); st->print("\t");
   if (do_polling() && C->is_method_compilation()) {
-    st->print("TEST   PollPage,EAX\t! Poll Safepoint");
-    st->cr(); st->print("\t");
+    st->print("CMPL     rsp, poll_offset[thread]  \n\t"
+              "JA       #safepoint_stub\t"
+              "# Safepoint: poll for GC");
   }
 }
 #endif
@@ -697,12 +698,16 @@ void MachEpilogNode::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {
   }
 
   if (do_polling() && C->is_method_compilation()) {
-    Register pollReg = as_Register(EBX_enc);
+    Register thread = as_Register(EBX_enc);
     MacroAssembler masm(&cbuf);
-    masm.get_thread(pollReg);
-    masm.movl(pollReg, Address(pollReg, in_bytes(Thread::polling_page_offset())));
-    masm.relocate(relocInfo::poll_return_type);
-    masm.testl(rax, Address(pollReg, 0));
+    __ get_thread(thread);
+    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, thread, true /* at_return */, true /* in_nmethod */);
   }
 }
 

src/hotspot/cpu/x86/x86_64.ad

@@ -930,7 +930,7 @@ void MachEpilogNode::format(PhaseRegAlloc* ra_, outputStream* st) const
   st->print_cr("popq    rbp");
   if (do_polling() && C->is_method_compilation()) {
     st->print("\t");
-    st->print_cr("cmpq    poll_offset[r15_thread], rsp\n\t"
+    st->print_cr("cmpq     rsp, poll_offset[r15_thread] \n\t"
                  "ja       #safepoint_stub\t"
                  "# Safepoint: poll for GC");
   }