src/hotspot/cpu/riscv/jniFastGetField_riscv.cpp

/*
 * Copyright (c) 2004, 2025, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2014, 2020, Red Hat Inc. All rights reserved.
 * Copyright (c) 2020, 2023, Huawei Technologies Co., Ltd. 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
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 */

#include "asm/macroAssembler.hpp"
#include "gc/shared/barrierSet.hpp"
#include "gc/shared/barrierSetAssembler.hpp"
#include "memory/resourceArea.hpp"
#include "prims/jniFastGetField.hpp"
#include "prims/jvm_misc.hpp"
#include "prims/jvmtiExport.hpp"
#include "runtime/safepoint.hpp"

#define __ masm->

#define BUFFER_SIZE 30*wordSize

// Instead of issuing a LoadLoad barrier we create an address
// dependency between loads; this might be more efficient.

// Common register usage:
// x10/f10:      result
// c_rarg0:    jni env
// c_rarg1:    obj
// c_rarg2:    jfield id

static const Register robj          = x13;
static const Register rcounter      = x14;
static const Register roffset       = x15;
static const Register rcounter_addr = x16;
static const Register result        = x17;

address JNI_FastGetField::generate_fast_get_int_field0(BasicType type) {
  const char *name;
  switch (type) {
    case T_BOOLEAN: name = "jni_fast_GetBooleanField"; break;
    case T_BYTE:    name = "jni_fast_GetByteField";    break;
    case T_CHAR:    name = "jni_fast_GetCharField";    break;
    case T_SHORT:   name = "jni_fast_GetShortField";   break;
    case T_INT:     name = "jni_fast_GetIntField";     break;
    case T_LONG:    name = "jni_fast_GetLongField";    break;
    case T_FLOAT:   name = "jni_fast_GetFloatField";   break;
    case T_DOUBLE:  name = "jni_fast_GetDoubleField";  break;
    default:        ShouldNotReachHere();
      name = nullptr;  // unreachable
  }
  ResourceMark rm;
  BufferBlob* blob = BufferBlob::create(name, BUFFER_SIZE);
  CodeBuffer cbuf(blob);
  MacroAssembler* masm = new MacroAssembler(&cbuf);
  address fast_entry = __ pc();

  Label slow;
  ExternalAddress counter(SafepointSynchronize::safepoint_counter_addr());
  __ la(rcounter_addr, counter);
  __ lwu(rcounter, Address(rcounter_addr));
  // An even value means there are no ongoing safepoint operations
  __ test_bit(t0, rcounter, 0);
  __ bnez(t0, slow);

  if (JvmtiExport::can_post_field_access()) {
    // Using barrier to order wrt. JVMTI check and load of result.
    __ membar(MacroAssembler::LoadLoad);

    // Check to see if a field access watch has been set before we
    // take the fast path.
    __ lwu(result, ExternalAddress(JvmtiExport::get_field_access_count_addr()));
    __ bnez(result, slow);

    __ mv(robj, c_rarg1);
  } else {
    // Using address dependency to order wrt. load of result.
    __ xorr(robj, c_rarg1, rcounter);
    __ xorr(robj, robj, rcounter);               // obj, since
                                                 // robj ^ rcounter ^ rcounter == robj
                                                 // robj is address dependent on rcounter.
  }

  // Both robj and t0 are clobbered by try_resolve_jobject_in_native.
  BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
  assert_cond(bs != nullptr);
  bs->try_resolve_jobject_in_native(masm, c_rarg0, robj, t0, slow);

  __ srli(roffset, c_rarg2, 2);                // offset

  assert(count < LIST_CAPACITY, "LIST_CAPACITY too small");
  speculative_load_pclist[count] = __ pc();   // Used by the segfault handler
  __ add(roffset, robj, roffset);

  switch (type) {
    case T_BOOLEAN: __ lbu(result, Address(roffset, 0)); break;
    case T_BYTE:    __ lb(result, Address(roffset, 0)); break;
    case T_CHAR:    __ lhu(result, Address(roffset, 0)); break;
    case T_SHORT:   __ lh(result, Address(roffset, 0)); break;
    case T_INT:     __ lw(result, Address(roffset, 0)); break;
    case T_LONG:    __ ld(result, Address(roffset, 0)); break;
    case T_FLOAT: {
      __ flw(f28, Address(roffset, 0)); // f28 as temporaries
      __ fmv_x_w(result, f28); // f{31--0}-->x
      break;
    }
    case T_DOUBLE: {
      __ fld(f28, Address(roffset, 0)); // f28 as temporaries
      __ fmv_x_d(result, f28); // d{63--0}-->x
      break;
    }
    default:        ShouldNotReachHere();
  }

  // Using acquire: Order JVMTI check and load of result wrt. succeeding check
  // (LoadStore for volatile field).
  __ membar(MacroAssembler::LoadLoad | MacroAssembler::LoadStore);

  __ lw(t0, Address(rcounter_addr));
  __ bne(rcounter, t0, slow);

  switch (type) {
    case T_FLOAT:   __ fmv_w_x(f10, result); break;
    case T_DOUBLE:  __ fmv_d_x(f10, result); break;
    default:        __ mv(x10, result);   break;
  }
  __ ret();

  slowcase_entry_pclist[count++] = __ pc();
  __ bind(slow);
  address slow_case_addr;
  switch (type) {
    case T_BOOLEAN: slow_case_addr = jni_GetBooleanField_addr(); break;
    case T_BYTE:    slow_case_addr = jni_GetByteField_addr();    break;
    case T_CHAR:    slow_case_addr = jni_GetCharField_addr();    break;
    case T_SHORT:   slow_case_addr = jni_GetShortField_addr();   break;
    case T_INT:     slow_case_addr = jni_GetIntField_addr();     break;
    case T_LONG:    slow_case_addr = jni_GetLongField_addr();    break;
    case T_FLOAT:   slow_case_addr = jni_GetFloatField_addr();   break;
    case T_DOUBLE:  slow_case_addr = jni_GetDoubleField_addr();  break;
    default:        ShouldNotReachHere();
      slow_case_addr = nullptr;  // unreachable
  }

  {
    __ enter();
    __ rt_call(slow_case_addr);
    __ leave();
    __ ret();
  }
  __ flush();

  return fast_entry;
}


address JNI_FastGetField::generate_fast_get_boolean_field() {
  return generate_fast_get_int_field0(T_BOOLEAN);
}

address JNI_FastGetField::generate_fast_get_byte_field() {
  return generate_fast_get_int_field0(T_BYTE);
}

address JNI_FastGetField::generate_fast_get_char_field() {
  return generate_fast_get_int_field0(T_CHAR);
}

address JNI_FastGetField::generate_fast_get_short_field() {
  return generate_fast_get_int_field0(T_SHORT);
}

address JNI_FastGetField::generate_fast_get_int_field() {
  return generate_fast_get_int_field0(T_INT);
}

address JNI_FastGetField::generate_fast_get_long_field() {
  return generate_fast_get_int_field0(T_LONG);
}

address JNI_FastGetField::generate_fast_get_float_field() {
  return generate_fast_get_int_field0(T_FLOAT);
}

address JNI_FastGetField::generate_fast_get_double_field() {
  return generate_fast_get_int_field0(T_DOUBLE);
}