src/hotspot/cpu/arm/runtime_arm.cpp

/*
 * Copyright (c) 2008, 2025, 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.
 *
 */

#ifdef COMPILER2
#include "asm/assembler.inline.hpp"
#include "code/vmreg.hpp"
#include "compiler/oopMap.hpp"
#include "interpreter/interpreter.hpp"
#include "memory/resourceArea.hpp"
#include "nativeInst_arm.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_arm.inline.hpp"

#define __ masm->

//------------------------------generate_uncommon_trap_blob--------------------
// Ought to generate an ideal graph & compile, but here's some ASM
// instead.
UncommonTrapBlob* OptoRuntime::generate_uncommon_trap_blob() {
  // allocate space for the code
  ResourceMark rm;

  // setup code generation tools
  const char* name = OptoRuntime::stub_name(OptoStubId::uncommon_trap_id);
#ifdef _LP64
  CodeBuffer buffer(name, 2700, 512);
#else
  // Measured 8/7/03 at 660 in 32bit debug build
  CodeBuffer buffer(name, 2000, 512);
#endif
  if (buffer.blob() == nullptr) {
    return nullptr;
  }
  // bypassed when code generation useless
  MacroAssembler* masm               = new MacroAssembler(&buffer);
  const Register Rublock = R6;
  const Register Rsender = altFP_7_11;
  assert_different_registers(Rublock, Rsender, Rexception_obj, R0, R1, R2, R3, R8, Rtemp);

  //
  // This is the entry point for all traps the compiler takes when it thinks
  // it cannot handle further execution of compilation code. The frame is
  // deoptimized in these cases and converted into interpreter frames for
  // execution
  // The steps taken by this frame are as follows:
  //   - push a fake "unpack_frame"
  //   - call the C routine Deoptimization::uncommon_trap (this function
  //     packs the current compiled frame into vframe arrays and returns
  //     information about the number and size of interpreter frames which
  //     are equivalent to the frame which is being deoptimized)
  //   - deallocate the "unpack_frame"
  //   - deallocate the deoptimization frame
  //   - in a loop using the information returned in the previous step
  //     push interpreter frames;
  //   - create a dummy "unpack_frame"
  //   - call the C routine: Deoptimization::unpack_frames (this function
  //     lays out values on the interpreter frame which was just created)
  //   - deallocate the dummy unpack_frame
  //   - return to the interpreter entry point
  //
  //  Refer to the following methods for more information:
  //   - Deoptimization::uncommon_trap
  //   - Deoptimization::unpack_frame

  // the unloaded class index is in R0 (first parameter to this blob)

  __ raw_push(FP, LR);
  __ set_last_Java_frame(SP, FP, false, Rtemp);
  __ mov(R2, Deoptimization::Unpack_uncommon_trap);
  __ mov(R1, R0);
  __ mov(R0, Rthread);
  __ call(CAST_FROM_FN_PTR(address, Deoptimization::uncommon_trap));
  __ mov(Rublock, R0);
  __ reset_last_Java_frame(Rtemp);
  __ raw_pop(FP, LR);

#ifdef ASSERT
  { Label L;
    __ ldr_s32(Rtemp, Address(Rublock, Deoptimization::UnrollBlock::unpack_kind_offset()));
    __ cmp_32(Rtemp, Deoptimization::Unpack_uncommon_trap);
    __ b(L, eq);
    __ stop("OptoRuntime::generate_uncommon_trap_blob: expected Unpack_uncommon_trap");
    __ bind(L);
  }
#endif


  // Set initial stack state before pushing interpreter frames
  __ ldr_s32(Rtemp, Address(Rublock, Deoptimization::UnrollBlock::size_of_deoptimized_frame_offset()));
  __ ldr(R2, Address(Rublock, Deoptimization::UnrollBlock::frame_pcs_offset()));
  __ ldr(R3, Address(Rublock, Deoptimization::UnrollBlock::frame_sizes_offset()));

  __ add(SP, SP, Rtemp);

  // See if it is enough stack to push deoptimized frames.
#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.
  //
  // The compiled method that we are deoptimizing was popped from the stack.
  // If the stack bang results in a stack overflow, we don't return to the
  // method that is being deoptimized. The stack overflow exception is
  // propagated to the caller of the deoptimized method. Need to get the pc
  // from the caller in LR and restore FP.
  __ ldr(LR, Address(R2, 0));
  __ ldr(FP, Address(Rublock, Deoptimization::UnrollBlock::initial_info_offset()));
  __ ldr_s32(R8, Address(Rublock, Deoptimization::UnrollBlock::total_frame_sizes_offset()));
  __ arm_stack_overflow_check(R8, Rtemp);
#endif
  __ ldr_s32(R8, Address(Rublock, Deoptimization::UnrollBlock::number_of_frames_offset()));
  __ ldr_s32(Rtemp, Address(Rublock, Deoptimization::UnrollBlock::caller_adjustment_offset()));
  __ mov(Rsender, SP);
  __ sub(SP, SP, Rtemp);
  //  __ ldr(FP, Address(FP));
  __ ldr(FP, Address(Rublock, Deoptimization::UnrollBlock::initial_info_offset()));

  // Push interpreter frames in a loop
  Label loop;
  __ bind(loop);
  __ ldr(LR, Address(R2, wordSize, post_indexed));         // load frame pc
  __ ldr(Rtemp, Address(R3, wordSize, post_indexed));      // load frame size

  __ raw_push(FP, LR);                                     // create new frame
  __ mov(FP, SP);
  __ sub(Rtemp, Rtemp, 2*wordSize);

  __ sub(SP, SP, Rtemp);

  __ str(Rsender, Address(FP, frame::interpreter_frame_sender_sp_offset * wordSize));
  __ mov(LR, 0);
  __ str(LR, Address(FP, frame::interpreter_frame_last_sp_offset * wordSize));
  __ subs(R8, R8, 1);                               // decrement counter
  __ mov(Rsender, SP);
  __ b(loop, ne);

  // Re-push self-frame
  __ ldr(LR, Address(R2));
  __ raw_push(FP, LR);
  __ mov(FP, SP);

  // Call unpack_frames with proper arguments
  __ mov(R0, Rthread);
  __ mov(R1, Deoptimization::Unpack_uncommon_trap);
  __ set_last_Java_frame(SP, FP, true, Rtemp);
  __ call_VM_leaf(CAST_FROM_FN_PTR(address, Deoptimization::unpack_frames));
  //  oop_maps->add_gc_map(__ pc() - start, new OopMap(frame_size_in_words, 0));
  __ reset_last_Java_frame(Rtemp);

  __ mov(SP, FP);
  __ pop(RegisterSet(FP) | RegisterSet(PC));

  masm->flush();
  return UncommonTrapBlob::create(&buffer, nullptr, 2 /* LR+FP */);
}

//------------------------------ 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 sparc.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:
//   Rexception_obj (R4/R19): exception oop
//   Rexception_pc  (R5/R20): exception pc
//
// Results:
//   Rexception_obj (R4/R19): exception oop
//   O1: exception pc in caller or ???
//   destination: exception handler of caller
//
// Note: the exception pc MUST be at a call (precise debug information)
//
ExceptionBlob* OptoRuntime::generate_exception_blob() {
  // allocate space for code
  ResourceMark rm;

  // setup code generation tools
  // Measured 8/7/03 at 256 in 32bit debug build
  const char* name = OptoRuntime::stub_name(OptoStubId::exception_id);
  CodeBuffer buffer(name, 600, 512);
  if (buffer.blob() == nullptr) {
    return nullptr;
  }
  MacroAssembler* masm     = new MacroAssembler(&buffer);

  int framesize_in_words = 2; // FP + LR
  int framesize_in_bytes = framesize_in_words * wordSize;
  int framesize_in_slots = framesize_in_bytes / sizeof(jint);

  int start = __ offset();

  __ str(Rexception_obj, Address(Rthread, JavaThread::exception_oop_offset()));
  __ str(Rexception_pc, Address(Rthread, JavaThread::exception_pc_offset()));

  // This call does all the hard work. It checks if an exception catch
  // exists in the method.
  // If so, it returns the handler address.
  // If the nmethod has been deoptimized and it had a handler the handler
  // address is the deopt blob unpack_with_exception entry.
  //
  // If no handler exists it prepares for stack-unwinding, restoring the callee-save
  // registers of the frame being removed.
  //
  __ mov(LR, Rexception_pc);
  __ raw_push(FP, LR);
  int pc_offset = __ set_last_Java_frame(SP, FP, false, Rtemp);

  __ mov(R0, Rthread);

  // This call can block at exit and nmethod can be deoptimized at that
  // point. If the nmethod had a catch point we would jump to the
  // now deoptimized catch point and fall thru the vanilla deopt
  // path and lose the exception
  // Sure would be simpler if this call didn't block!
  __ call(CAST_FROM_FN_PTR(address, OptoRuntime::handle_exception_C));
  if (pc_offset == -1) {
    pc_offset = __ offset();
  }

  // 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(pc_offset - start, new OopMap(framesize_in_slots, 0));

  __ reset_last_Java_frame(Rtemp);

  __ raw_pop(FP, LR);

  // Restore SP from its saved reg (FP) if the exception PC is a MethodHandle call site.
  __ ldr(Rtemp, Address(Rthread, JavaThread::is_method_handle_return_offset()));
  __ cmp(Rtemp, 0);
  __ mov(SP, Rmh_SP_save, ne);

  // R0 contains handler address
  // Since this may be the deopt blob we must set R5 to look like we returned
  // from the original pc that threw the exception

  __ ldr(Rexception_pc,  Address(Rthread, JavaThread::exception_pc_offset()));  // R5/R20

  __ ldr(Rexception_obj, Address(Rthread, JavaThread::exception_oop_offset())); // R4/R19
  __ mov(Rtemp, 0);
#ifdef ASSERT
  __ str(Rtemp, Address(Rthread, JavaThread::exception_handler_pc_offset()));
  __ str(Rtemp, Address(Rthread, JavaThread::exception_pc_offset()));
#endif
  // Clear the exception oop so GC no longer processes it as a root.
  __ str(Rtemp, Address(Rthread, JavaThread::exception_oop_offset()));
  __ jump(R0);

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

  return ExceptionBlob::create(&buffer, oop_maps, framesize_in_words);
}

#endif // COMPILER2