/*

 * Copyright (c) 1999, 2019, 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 "ci/ciCallSite.hpp"

#include "ci/ciConstant.hpp"

#include "ci/ciField.hpp"

#include "ci/ciStreams.hpp"

#include "ci/ciUtilities.inline.hpp"

#include "runtime/handles.inline.hpp"

// ciExceptionHandlerStream

//

// Walk over some selected set of a methods exception handlers.

// ------------------------------------------------------------------

// ciExceptionHandlerStream::count

//

// How many exception handlers are there in this stream?

//

// Implementation note: Compiler2 needs this functionality, so I had

int ciExceptionHandlerStream::count() {

  int save_pos = _pos;

  int save_end = _end;

  int count = 0;

  _pos = -1;

  _end = _method->_handler_count;

  next();

  while (!is_done()) {

    count++;

    next();

  }

  _pos = save_pos;

  _end = save_end;

  return count;

}

int ciExceptionHandlerStream::count_remaining() {

  int save_pos = _pos;

  int save_end = _end;

  int count = 0;

  while (!is_done()) {

    count++;

    next();

  }

  _pos = save_pos;

  _end = save_end;

  return count;

}

// ciBytecodeStream

//

// The class is used to iterate over the bytecodes of a method.

// It hides the details of constant pool structure/access by

// providing accessors for constant pool items.

// ------------------------------------------------------------------

// ciBytecodeStream::next_wide_or_table

//

// Special handling for switch ops

Bytecodes::Code ciBytecodeStream::next_wide_or_table(Bytecodes::Code bc) {

  switch (bc) {                // Check for special bytecode handling

  case Bytecodes::_wide:

    // Special handling for the wide bytcode

    // Get following bytecode; do not return wide

    assert(Bytecodes::Code(_pc[0]) == Bytecodes::_wide, "");

    bc = Bytecodes::java_code(_raw_bc = (Bytecodes::Code)_pc[1]);

    assert(Bytecodes::wide_length_for(bc) > 2, "must make progress");

    _pc += Bytecodes::wide_length_for(bc);

    _was_wide = _pc;              // Flag last wide bytecode found

    assert(is_wide(), "accessor works right");

    break;

  case Bytecodes::_lookupswitch:

    _pc++;                      // Skip wide bytecode

    _pc += (_start-_pc)&3;      // Word align

    _table_base = (jint*)_pc;   // Capture for later usage

                                // table_base[0] is default far_dest

    // Table has 2 lead elements (default, length), then pairs of u4 values.

    // So load table length, and compute address at end of table

    _pc = (address)&_table_base[2+ 2*Bytes::get_Java_u4((address)&_table_base[1])];

    break;

  case Bytecodes::_tableswitch: {

    _pc++;                      // Skip wide bytecode

    _pc += (_start-_pc)&3;      // Word align

    _table_base = (jint*)_pc;   // Capture for later usage

                                // table_base[0] is default far_dest

    int lo = Bytes::get_Java_u4((address)&_table_base[1]);// Low bound

    int hi = Bytes::get_Java_u4((address)&_table_base[2]);// High bound

    int len = hi - lo + 1;      // Dense table size

    _pc = (address)&_table_base[3+len]; // Skip past table

    break;

  }

  default:

    fatal("unhandled bytecode");

  }

  return bc;

}

// ------------------------------------------------------------------

// ciBytecodeStream::reset_to_bci

void ciBytecodeStream::reset_to_bci( int bci ) {

  _bc_start=_was_wide=0;

  _pc = _start+bci;

}

// ------------------------------------------------------------------

// ciBytecodeStream::force_bci

void ciBytecodeStream::force_bci(int bci) {

  if (bci < 0) {

    reset_to_bci(0);

    _bc_start = _start + bci;

    _bc = EOBC();

  } else {

    reset_to_bci(bci);

    next();

  }

}

// ------------------------------------------------------------------

// Constant pool access

// ------------------------------------------------------------------

// ------------------------------------------------------------------

// ciBytecodeStream::get_klass_index

//

// If this bytecodes references a klass, return the index of the

// referenced klass.

int ciBytecodeStream::get_klass_index() const {

  switch(cur_bc()) {

  case Bytecodes::_ldc:

    return get_index_u1();

  case Bytecodes::_ldc_w:

  case Bytecodes::_ldc2_w:

  case Bytecodes::_checkcast:

  case Bytecodes::_instanceof:

  case Bytecodes::_anewarray:

  case Bytecodes::_multianewarray:

  case Bytecodes::_new:

  case Bytecodes::_newarray:

    return get_index_u2();

  default:

    ShouldNotReachHere();

    return 0;

  }

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_klass

//

// If this bytecode is a new, newarray, multianewarray, instanceof,

// or checkcast, get the referenced klass.

ciKlass* ciBytecodeStream::get_klass(bool& will_link) {

  VM_ENTRY_MARK;

  return CURRENT_ENV->get_klass_by_index(cpool, get_klass_index(), will_link, _holder);

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_constant_raw_index

//

// If this bytecode is one of the ldc variants, get the index of the

// referenced constant.

int ciBytecodeStream::get_constant_raw_index() const {

  // work-alike for Bytecode_loadconstant::raw_index()

  switch (cur_bc()) {

  case Bytecodes::_ldc:

    return get_index_u1();

  case Bytecodes::_ldc_w:

  case Bytecodes::_ldc2_w:

    return get_index_u2();

  default:

    ShouldNotReachHere();

    return 0;

  }

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_constant_pool_index

// Decode any reference index into a regular pool index.

int ciBytecodeStream::get_constant_pool_index() const {

  // work-alike for Bytecode_loadconstant::pool_index()

  int index = get_constant_raw_index();

  if (has_cache_index()) {

    VM_ENTRY_MARK;

    return cpool->object_to_cp_index(index);

  }

  return index;

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_constant

//

// If this bytecode is one of the ldc variants, get the referenced

// constant.

ciConstant ciBytecodeStream::get_constant() {

  int pool_index = get_constant_raw_index();

  int cache_index = -1;

  if (has_cache_index()) {

    cache_index = pool_index;

    pool_index = -1;

  }

  VM_ENTRY_MARK;

  return CURRENT_ENV->get_constant_by_index(cpool, pool_index, cache_index, _holder);

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_constant_pool_tag

//

// If this bytecode is one of the ldc variants, get the referenced

// constant.

constantTag ciBytecodeStream::get_constant_pool_tag(int index) const {

  VM_ENTRY_MARK;

  return _method->get_Method()->constants()->constant_tag_at(index);

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_field_index

//

// If this is a field access bytecode, get the constant pool

// index of the referenced field.

int ciBytecodeStream::get_field_index() {

  assert(cur_bc() == Bytecodes::_getfield ||

         cur_bc() == Bytecodes::_putfield ||

         cur_bc() == Bytecodes::_getstatic ||

         cur_bc() == Bytecodes::_putstatic, "wrong bc");

  return get_index_u2_cpcache();

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_field

//

// If this bytecode is one of get_field, get_static, put_field,

// or put_static, get the referenced field.

ciField* ciBytecodeStream::get_field(bool& will_link) {

  ciField* f = CURRENT_ENV->get_field_by_index(_holder, get_field_index());

  will_link = f->will_link(_method, _bc);

  return f;

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_declared_field_holder

//

// Get the declared holder of the currently referenced field.

//

// Usage note: the holder() of a ciField class returns the canonical

// holder of the field, rather than the holder declared in the

// bytecodes.

//

// There is no "will_link" result passed back.  The user is responsible

// for checking linkability when retrieving the associated field.

ciInstanceKlass* ciBytecodeStream::get_declared_field_holder() {

  VM_ENTRY_MARK;

  int holder_index = get_field_holder_index();

  bool ignore;

  return CURRENT_ENV->get_klass_by_index(cpool, holder_index, ignore, _holder)

      ->as_instance_klass();

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_field_holder_index

//

// Get the constant pool index of the declared holder of the field

// referenced by the current bytecode.  Used for generating

// deoptimization information.

int ciBytecodeStream::get_field_holder_index() {

  GUARDED_VM_ENTRY(

    ConstantPool* cpool = _holder->get_instanceKlass()->constants();

    return cpool->klass_ref_index_at(get_field_index());

  )

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_method_index

//

// If this is a method invocation bytecode, get the constant pool

// index of the invoked method.

int ciBytecodeStream::get_method_index() {

  assert(Bytecodes::is_invoke(cur_bc()), "invalid bytecode: %s", Bytecodes::name(cur_bc()));

  if (has_index_u4())

    return get_index_u4();  // invokedynamic

  return get_index_u2_cpcache();

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_method

//

// If this is a method invocation bytecode, get the invoked method.

// Additionally return the declared signature to get more concrete

// type information if required (Cf. invokedynamic and invokehandle).

ciMethod* ciBytecodeStream::get_method(bool& will_link, ciSignature* *declared_signature_result) {

  VM_ENTRY_MARK;

  ciEnv* env = CURRENT_ENV;

  constantPoolHandle cpool(THREAD, _method->get_Method()->constants());

  ciMethod* m = env->get_method_by_index(cpool, get_method_index(), cur_bc(), _holder);

  will_link = m->is_loaded();

  // Use the signature stored in the CP cache to create a signature

  // with correct types (in respect to class loaders).

  //

  // In classic Java (before Java 7) there is never the slightest

  // difference between the signature at the call site and that of the

  // method.  Such a difference would have been a type error in the

  // JVM.

  //

  // Now there are a few circumstances where the signature of a call

  // site (which controls the outgoing stacked arguments) can differ

  // from the signature of the method (which controls the receipt of

  // those arguments at the method entry point).

  //

  // A. The signatures can differ if the callee is a static method and

  // the caller thinks it is calling a non-static method (VH.get).

  // This requires the method signature to have an explicit leading

  // argument for the implicit 'this', not present at the call site.

  //

  // B. The call site can have less specific parameter types than the

  // method, allowing loosely-typed code to handle strongly-typed

  // methods.  This happens with linkToStatic and related linker

  // commands.  Obviously the loosely-typed code has to ensure that

  // the strongly typed method's invariants are respected, and this is

  // done by issuing dynamic casts.

  //

  // C. The call site can have more specific parameter types than the

  // method, allowing loosely-typed methods to handle strongly-typed

  // requests.

  //

  // D. There are corresponding effects with return values, such as

  // boolean method returning an int to an int-receiving call site,

  // even though the method thought it returned just a boolean.

  //

  // E. The calling sequence at a particular call site may add an

  // "appendix" argument not mentioned in the call site signature.  It

  // is expected by the method signature, though, and this adds to the

  // method's arity, even after 'this' parameter effects (A) are

  // discounted.  Appendixes are used by invokehandle and

  // invokedynamic instructions.

  //

  // F. A linker method (linkToStatic, etc.) can also take an extra

  // argument, a MemberName which routes the call to a concrete

  // strongly-typed method.  In this case the linker method may also

  // differ in any of the ways A-D.  The eventual method will ignore

  // the presence of the extra argument.

  //

  // None of these changes to calling sequences requires an argument

  // to be moved or reformatted in any way.  This works because all

  // references look alike to the JVM, as do all primitives (except

  // float/long/double).  Another required property of the JVM is

  // that, if a trailing argument is added or dropped, the placement

  // of other arguments does not change.  This allows cases E and F to

  // work smoothly, against without any moving or reformatting,

  // despite the arity change.

  //

  if (has_local_signature()) {

    Symbol* local_signature = cpool->symbol_at(get_method_signature_index(cpool));

    ciSymbol* sig_sym  = env->get_symbol(local_signature);

    ciKlass* pool_holder = env->get_klass(cpool->pool_holder());

    ciSignature* call_site_sig = new (env->arena()) ciSignature(pool_holder, cpool, sig_sym);

    // Examples of how the call site signature can differ from the method's own signature:

    //

    //  meth = static jboolean java.lang.invoke.VarHandleGuards.guard_LII_Z(jobject, jobject, jint, jint, jobject)

    //  msig = (Ljava/lang/invoke/VarHandle;Ljava/lang/Object;IILjava/lang/invoke/VarHandle$AccessDescriptor;)Z

    //  call = (Ljava/util/concurrent/locks/AbstractQueuedSynchronizer;II)Z

    //

    //  meth = static jobject java.lang.invoke.LambdaForm$MH/0x0000000800066840.linkToTargetMethod(jobject, jobject)

    //  msig = (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;

    //  call = (Ljava/lang/String;)Ljava/util/function/Predicate;

    //

    (*declared_signature_result) = call_site_sig;

  } else {

    // We can just use the method's own signature.  It may differ from the call site, but not by much.

    //

    // Examples of how the call site signature can differ from the method's signature:

    //

    // meth = static final native jint java.lang.invoke.MethodHandle.linkToStatic(jobject, jobject, jint, jint, jobject)

    // msig = (Ljava/lang/Object;Ljava/lang/Object;IILjava/lang/invoke/MemberName;)I

    // call = (Ljava/lang/invoke/VarHandle;Ljava/lang/Object;IILjava/lang/invoke/MemberName;)Z

    //

    // meth = final native jint java.lang.invoke.MethodHandle.invokeBasic(jobject, jobject, jint, jint)

    // msig = (Ljava/lang/Object;Ljava/lang/Object;II)I

    // call = (Ljava/lang/invoke/VarHandle;Ljava/lang/Object;II)Z

    //

    (*declared_signature_result) = m->signature();

  }

  return m;

}

// ------------------------------------------------------------------

// ciBytecodeStream::has_appendix

//

// Returns true if there is an appendix argument stored in the

// constant pool cache at the current bci.

bool ciBytecodeStream::has_appendix() {

  VM_ENTRY_MARK;

  return ConstantPool::has_appendix_at_if_loaded(cpool, get_method_index());

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_appendix

//

// Return the appendix argument stored in the constant pool cache at

// the current bci.

ciObject* ciBytecodeStream::get_appendix() {

  VM_ENTRY_MARK;

  oop appendix_oop = ConstantPool::appendix_at_if_loaded(cpool, get_method_index());

  return CURRENT_ENV->get_object(appendix_oop);

}

// ------------------------------------------------------------------

// ciBytecodeStream::has_local_signature

//

// Returns true if the method stored in the constant

// pool cache at the current bci has a local signature.

bool ciBytecodeStream::has_local_signature() {

  GUARDED_VM_ENTRY(

    return ConstantPool::has_local_signature_at_if_loaded(cpool, get_method_index());

  )

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_declared_method_holder

//

// Get the declared holder of the currently referenced method.

//

// Usage note: the holder() of a ciMethod class returns the canonical

// holder of the method, rather than the holder declared in the

// bytecodes.

//

// There is no "will_link" result passed back.  The user is responsible

// for checking linkability when retrieving the associated method.

ciKlass* ciBytecodeStream::get_declared_method_holder() {

  VM_ENTRY_MARK;

  bool ignore;

  // report as MethodHandle for invokedynamic, which is syntactically classless

  if (cur_bc() == Bytecodes::_invokedynamic)

    return CURRENT_ENV->get_klass_by_name(_holder, ciSymbol::java_lang_invoke_MethodHandle(), false);

  return CURRENT_ENV->get_klass_by_index(cpool, get_method_holder_index(), ignore, _holder);

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_method_holder_index

//

// Get the constant pool index of the declared holder of the method

// referenced by the current bytecode.  Used for generating

// deoptimization information.

int ciBytecodeStream::get_method_holder_index() {

  ConstantPool* cpool = _method->get_Method()->constants();

  return cpool->klass_ref_index_at(get_method_index());

}

// ------------------------------------------------------------------

// ciBytecodeStream::get_method_signature_index

//

// Get the constant pool index of the signature of the method

// referenced by the current bytecode.  Used for generating

// deoptimization information.

int ciBytecodeStream::get_method_signature_index(const constantPoolHandle& cpool) {

  GUARDED_VM_ENTRY(

    const int method_index = get_method_index();

    const int name_and_type_index = cpool->name_and_type_ref_index_at(method_index);

    return cpool->signature_ref_index_at(name_and_type_index);

  )

}