src/hotspot/cpu/aarch64/runtime_aarch64.cpp

/*
 * Copyright (c) 2003, 2025, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2014, Red Hat Inc. 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.
 *
 */

#ifdef COMPILER2
#include "asm/macroAssembler.hpp"
#include "asm/macroAssembler.inline.hpp"
#include "code/aotCodeCache.hpp"
#include "code/vmreg.hpp"
#include "interpreter/interpreter.hpp"
#include "opto/runtime.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/vframeArray.hpp"
#include "utilities/globalDefinitions.hpp"
#include "vmreg_aarch64.inline.hpp"

class SimpleRuntimeFrame {

  public:

  // Most of the runtime stubs have this simple frame layout.
  // This class exists to make the layout shared in one place.
  // Offsets are for compiler stack slots, which are jints.
  enum layout {
    // The frame sender code expects that rbp will be in the "natural" place and
    // will override any oopMap setting for it. We must therefore force the layout
    // so that it agrees with the frame sender code.
    // we don't expect any arg reg save area so aarch64 asserts that
    // frame::arg_reg_save_area_bytes == 0
    rfp_off = 0,
    rfp_off2,
    return_off, return_off2,
    framesize
  };
};

#define __ masm->

//------------------------------generate_uncommon_trap_blob--------------------
UncommonTrapBlob* OptoRuntime::generate_uncommon_trap_blob() {
  const char* name = OptoRuntime::stub_name(OptoStubId::uncommon_trap_id);
  CodeBlob* blob = AOTCodeCache::load_code_blob(AOTCodeEntry::C2Blob, (uint)OptoStubId::uncommon_trap_id, name);
  if (blob != nullptr) {
    return blob->as_uncommon_trap_blob();
  }

  // Allocate space for the code
  ResourceMark rm;
  // Setup code generation tools
  CodeBuffer buffer(name, 2048, 1024);
  if (buffer.blob() == nullptr) {
    return nullptr;
  }
  MacroAssembler* masm = new MacroAssembler(&buffer);

  assert(SimpleRuntimeFrame::framesize % 4 == 0, "sp not 16-byte aligned");

  address start = __ pc();

  // Push self-frame.  We get here with a return address in LR
  // and sp should be 16 byte aligned
  // push rfp and retaddr by hand
  __ protect_return_address();
  __ stp(rfp, lr, Address(__ pre(sp, -2 * wordSize)));
  // we don't expect an arg reg save area
#ifndef PRODUCT
  assert(frame::arg_reg_save_area_bytes == 0, "not expecting frame reg save area");
#endif
  // compiler left unloaded_class_index in j_rarg0 move to where the
  // runtime expects it.
  if (c_rarg1 != j_rarg0) {
    __ movw(c_rarg1, j_rarg0);
  }

  // we need to set the past SP to the stack pointer of the stub frame
  // and the pc to the address where this runtime call will return
  // although actually any pc in this code blob will do).
  Label retaddr;
  __ set_last_Java_frame(sp, noreg, retaddr, rscratch1);

  // Call C code.  Need thread but NOT official VM entry
  // crud.  We cannot block on this call, no GC can happen.  Call should
  // capture callee-saved registers as well as return values.
  //
  // UnrollBlock* uncommon_trap(JavaThread* thread, jint unloaded_class_index);
  //
  // n.b. 2 gp args, 0 fp args, integral return type

  __ mov(c_rarg0, rthread);
  __ movw(c_rarg2, (unsigned)Deoptimization::Unpack_uncommon_trap);
  __ lea(rscratch1,
         RuntimeAddress(CAST_FROM_FN_PTR(address,
                                         Deoptimization::uncommon_trap)));
  __ blr(rscratch1);
  __ bind(retaddr);

  // Set an oopmap for the call site
  OopMapSet* oop_maps = new OopMapSet();
  OopMap* map = new OopMap(SimpleRuntimeFrame::framesize, 0);

  // location of rfp is known implicitly by the frame sender code

  oop_maps->add_gc_map(__ pc() - start, map);

  __ reset_last_Java_frame(false);

  // move UnrollBlock* into r4
  __ mov(r4, r0);

#ifdef ASSERT
  { Label L;
    __ ldrw(rscratch1, Address(r4, Deoptimization::UnrollBlock::unpack_kind_offset()));
    __ cmpw(rscratch1, (unsigned)Deoptimization::Unpack_uncommon_trap);
    __ br(Assembler::EQ, L);
    __ stop("OptoRuntime::generate_uncommon_trap_blob: expected Unpack_uncommon_trap");
    __ bind(L);
  }
#endif

  // Pop all the frames we must move/replace.
  //
  // Frame picture (youngest to oldest)
  // 1: self-frame (no frame link)
  // 2: deopting frame  (no frame link)
  // 3: caller of deopting frame (could be compiled/interpreted).

  // Pop self-frame.  We have no frame, and must rely only on r0 and sp.
  __ add(sp, sp, (SimpleRuntimeFrame::framesize) << LogBytesPerInt); // Epilog!

  // Pop deoptimized frame (int)
  __ ldrw(r2, Address(r4,
                      Deoptimization::UnrollBlock::
                      size_of_deoptimized_frame_offset()));
  __ sub(r2, r2, 2 * wordSize);
  __ add(sp, sp, r2);
  __ ldp(rfp, zr, __ post(sp, 2 * wordSize));

#ifdef ASSERT
  // Compilers generate code that bang the stack by as much as the
  // interpreter would need. So this stack banging should never
  // trigger a fault. Verify that it does not on non product builds.
  __ ldrw(r1, Address(r4,
                      Deoptimization::UnrollBlock::
                      total_frame_sizes_offset()));
  __ bang_stack_size(r1, r2);
#endif

  // Load address of array of frame pcs into r2 (address*)
  __ ldr(r2, Address(r4,
                     Deoptimization::UnrollBlock::frame_pcs_offset()));

  // Load address of array of frame sizes into r5 (intptr_t*)
  __ ldr(r5, Address(r4,
                     Deoptimization::UnrollBlock::
                     frame_sizes_offset()));

  // Counter
  __ ldrw(r3, Address(r4,
                      Deoptimization::UnrollBlock::
                      number_of_frames_offset())); // (int)

  // Now adjust the caller's stack to make up for the extra locals but
  // record the original sp so that we can save it in the skeletal
  // interpreter frame and the stack walking of interpreter_sender
  // will get the unextended sp value and not the "real" sp value.

  const Register sender_sp = r8;

  __ mov(sender_sp, sp);
  __ ldrw(r1, Address(r4,
                      Deoptimization::UnrollBlock::
                      caller_adjustment_offset())); // (int)
  __ sub(sp, sp, r1);

  // Push interpreter frames in a loop
  Label loop;
  __ bind(loop);
  __ ldr(r1, Address(r5, 0));       // Load frame size
  __ sub(r1, r1, 2 * wordSize);     // We'll push pc and rfp by hand
  __ ldr(lr, Address(r2, 0));       // Save return address
  __ enter();                       // and old rfp & set new rfp
  __ sub(sp, sp, r1);               // Prolog
  __ str(sender_sp, Address(rfp, frame::interpreter_frame_sender_sp_offset * wordSize)); // Make it walkable
  // This value is corrected by layout_activation_impl
  __ str(zr, Address(rfp, frame::interpreter_frame_last_sp_offset * wordSize));
  __ mov(sender_sp, sp);          // Pass sender_sp to next frame
  __ add(r5, r5, wordSize);       // Bump array pointer (sizes)
  __ add(r2, r2, wordSize);       // Bump array pointer (pcs)
  __ subsw(r3, r3, 1);            // Decrement counter
  __ br(Assembler::GT, loop);
  __ ldr(lr, Address(r2, 0));     // save final return address
  // Re-push self-frame
  __ enter();                     // & old rfp & set new rfp

  // Use rfp because the frames look interpreted now
  // Save "the_pc" since it cannot easily be retrieved using the last_java_SP after we aligned SP.
  // Don't need the precise return PC here, just precise enough to point into this code blob.
  address the_pc = __ pc();
  __ set_last_Java_frame(sp, rfp, the_pc, rscratch1);

  // Call C code.  Need thread but NOT official VM entry
  // crud.  We cannot block on this call, no GC can happen.  Call should
  // restore return values to their stack-slots with the new SP.
  // Thread is in rdi already.
  //
  // BasicType unpack_frames(JavaThread* thread, int exec_mode);
  //
  // n.b. 2 gp args, 0 fp args, integral return type

  // sp should already be aligned
  __ mov(c_rarg0, rthread);
  __ movw(c_rarg1, (unsigned)Deoptimization::Unpack_uncommon_trap);
  __ lea(rscratch1, RuntimeAddress(CAST_FROM_FN_PTR(address, Deoptimization::unpack_frames)));
  __ blr(rscratch1);

  // Set an oopmap for the call site
  // Use the same PC we used for the last java frame
  oop_maps->add_gc_map(the_pc - start, new OopMap(SimpleRuntimeFrame::framesize, 0));

  // Clear fp AND pc
  __ reset_last_Java_frame(true);

  // Pop self-frame.
  __ leave();                 // Epilog

  // Jump to interpreter
  __ ret(lr);

  // Make sure all code is generated
  masm->flush();

  UncommonTrapBlob *ut_blob = UncommonTrapBlob::create(&buffer, oop_maps,
                                                       SimpleRuntimeFrame::framesize >> 1);
  AOTCodeCache::store_code_blob(*ut_blob, AOTCodeEntry::C2Blob, (uint)OptoStubId::uncommon_trap_id, name);
  return ut_blob;
}

//------------------------------generate_exception_blob---------------------------
// creates exception blob at the end
// Using exception blob, this code is jumped from a compiled method.
// (see emit_exception_handler in aarch64.ad file)
//
// Given an exception pc at a call we call into the runtime for the
// handler in this method. This handler might merely restore state
// (i.e. callee save registers) unwind the frame and jump to the
// exception handler for the nmethod if there is no Java level handler
// for the nmethod.
//
// This code is entered with a jmp.
//
// Arguments:
//   r0: exception oop
//   r3: exception pc
//
// Results:
//   r0: exception oop
//   r3: exception pc in caller or ???
//   destination: exception handler of caller
//
// Note: the exception pc MUST be at a call (precise debug information)
//       Registers r0, r3, r2, r4, r5, r8-r11 are not callee saved.
//

ExceptionBlob* OptoRuntime::generate_exception_blob() {
  assert(!OptoRuntime::is_callee_saved_register(R3_num), "");
  assert(!OptoRuntime::is_callee_saved_register(R0_num), "");
  assert(!OptoRuntime::is_callee_saved_register(R2_num), "");

  assert(SimpleRuntimeFrame::framesize % 4 == 0, "sp not 16-byte aligned");

  const char* name = OptoRuntime::stub_name(OptoStubId::exception_id);
  CodeBlob* blob = AOTCodeCache::load_code_blob(AOTCodeEntry::C2Blob, (uint)OptoStubId::exception_id, name);
  if (blob != nullptr) {
    return blob->as_exception_blob();
  }

  // Allocate space for the code
  ResourceMark rm;
  // Setup code generation tools
  CodeBuffer buffer(name, 2048, 1024);
  if (buffer.blob() == nullptr) {
    return nullptr;
  }
  MacroAssembler* masm = new MacroAssembler(&buffer);

  // TODO check various assumptions made here
  //
  // make sure we do so before running this

  address start = __ pc();

  // push rfp and retaddr by hand
  // Exception pc is 'return address' for stack walker
  __ protect_return_address();
  __ stp(rfp, lr, Address(__ pre(sp, -2 * wordSize)));
  // there are no callee save registers and we don't expect an
  // arg reg save area
#ifndef PRODUCT
  assert(frame::arg_reg_save_area_bytes == 0, "not expecting frame reg save area");
#endif
  // Store exception in Thread object. We cannot pass any arguments to the
  // handle_exception call, since we do not want to make any assumption
  // about the size of the frame where the exception happened in.
  __ str(r0, Address(rthread, JavaThread::exception_oop_offset()));
  __ str(r3, Address(rthread, JavaThread::exception_pc_offset()));

  // This call does all the hard work.  It checks if an exception handler
  // exists in the method.
  // If so, it returns the handler address.
  // If not, it prepares for stack-unwinding, restoring the callee-save
  // registers of the frame being removed.
  //
  // address OptoRuntime::handle_exception_C(JavaThread* thread)
  //
  // n.b. 1 gp arg, 0 fp args, integral return type

  // the stack should always be aligned
  address the_pc = __ pc();
  __ set_last_Java_frame(sp, noreg, the_pc, rscratch1);
  __ mov(c_rarg0, rthread);
  __ lea(rscratch1, RuntimeAddress(CAST_FROM_FN_PTR(address, OptoRuntime::handle_exception_C)));
  __ blr(rscratch1);
  // handle_exception_C is a special VM call which does not require an explicit
  // instruction sync afterwards.

  // May jump to SVE compiled code
  __ reinitialize_ptrue();

  // Set an oopmap for the call site.  This oopmap will only be used if we
  // are unwinding the stack.  Hence, all locations will be dead.
  // Callee-saved registers will be the same as the frame above (i.e.,
  // handle_exception_stub), since they were restored when we got the
  // exception.

  OopMapSet* oop_maps = new OopMapSet();

  oop_maps->add_gc_map(the_pc - start, new OopMap(SimpleRuntimeFrame::framesize, 0));

  __ reset_last_Java_frame(false);

  // Restore callee-saved registers

  // rfp is an implicitly saved callee saved register (i.e. the calling
  // convention will save restore it in prolog/epilog) Other than that
  // there are no callee save registers now that adapter frames are gone.
  // and we dont' expect an arg reg save area
  __ ldp(rfp, r3, Address(__ post(sp, 2 * wordSize)));
  __ authenticate_return_address(r3);

  // r0: exception handler

  // We have a handler in r0 (could be deopt blob).
  __ mov(r8, r0);

  // Get the exception oop
  __ ldr(r0, Address(rthread, JavaThread::exception_oop_offset()));
  // Get the exception pc in case we are deoptimized
  __ ldr(r4, Address(rthread, JavaThread::exception_pc_offset()));
#ifdef ASSERT
  __ str(zr, Address(rthread, JavaThread::exception_handler_pc_offset()));
  __ str(zr, Address(rthread, JavaThread::exception_pc_offset()));
#endif
  // Clear the exception oop so GC no longer processes it as a root.
  __ str(zr, Address(rthread, JavaThread::exception_oop_offset()));

  // r0: exception oop
  // r8:  exception handler
  // r4: exception pc
  // Jump to handler

  __ br(r8);

  // Make sure all code is generated
  masm->flush();

  // Set exception blob
  ExceptionBlob* ex_blob = ExceptionBlob::create(&buffer, oop_maps, SimpleRuntimeFrame::framesize >> 1);
  AOTCodeCache::store_code_blob(*ex_blob, AOTCodeEntry::C2Blob, (uint)OptoStubId::exception_id, name);
  return ex_blob;
}
#endif // COMPILER2