text: /*
   * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2012, 2015 SAP SE. 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 "asm/macroAssembler.inline.hpp"
  #include "code/compiledIC.hpp"
  #include "code/icBuffer.hpp"
  #include "code/nmethod.hpp"
  #include "memory/resourceArea.hpp"
  #include "runtime/mutexLocker.hpp"
  #include "runtime/safepoint.hpp"
  #ifdef COMPILER2
  #include "opto/matcher.hpp"
  #endif
  
  // ----------------------------------------------------------------------------
  
  // A PPC CompiledDirectStaticCall looks like this:
  //
  // >>>> consts
  //
  // [call target1]
  // [IC cache]
  // [call target2]
  //
  // <<<< consts
  // >>>> insts
  //
  // bl offset16               -+  -+             ??? // How many bits available?
  //                            |   |
  // <<<< insts                 |   |
  // >>>> stubs                 |   |
  //                            |   |- trampoline_stub_Reloc
  // trampoline stub:           | <-+
  //   r2 = toc                 |
  //   r2 = [r2 + offset]       |       // Load call target1 from const section
  //   mtctr r2                 |
  //   bctr                     |- static_stub_Reloc
  // comp_to_interp_stub:   <---+
  //   r1 = toc
  //   ICreg = [r1 + IC_offset]         // Load IC from const section
  //   r1    = [r1 + offset]            // Load call target2 from const section
  //   mtctr r1
  //   bctr
  //
  // <<<< stubs
  //
  // The call instruction in the code either
  // - branches directly to a compiled method if offset encodable in instruction
  // - branches to the trampoline stub if offset to compiled method not encodable
  // - branches to the compiled_to_interp stub if target interpreted
  //
  // Further there are three relocations from the loads to the constants in
  // the constant section.
  //
  // Usage of r1 and r2 in the stubs allows to distinguish them.
  
  const int IC_pos_in_java_to_interp_stub = 8;
  #define __ _masm.
  address CompiledStaticCall::emit_to_interp_stub(CodeBuffer &cbuf, address mark/* = NULL*/) {
  #ifdef COMPILER2
    if (mark == NULL) {
      // Get the mark within main instrs section which is set to the address of the call.
      mark = cbuf.insts_mark();
    }
  
    // Note that the code buffer's insts_mark is always relative to insts.
    // That's why we must use the macroassembler to generate a stub.
    MacroAssembler _masm(&cbuf);
  
    // Start the stub.
    address stub = __ start_a_stub(CompiledStaticCall::to_interp_stub_size());
    if (stub == NULL) {
      return NULL; // CodeCache is full
    }
  
    // For java_to_interp stubs we use R11_scratch1 as scratch register
    // and in call trampoline stubs we use R12_scratch2. This way we
    // can distinguish them (see is_NativeCallTrampolineStub_at()).
    Register reg_scratch = R11_scratch1;
  
    // Create a static stub relocation which relates this stub
    // with the call instruction at insts_call_instruction_offset in the
    // instructions code-section.
    __ relocate(static_stub_Relocation::spec(mark));
    const int stub_start_offset = __ offset();
  
    // Now, create the stub's code:
    // - load the TOC
    // - load the inline cache oop from the constant pool
    // - load the call target from the constant pool
    // - call
    __ calculate_address_from_global_toc(reg_scratch, __ method_toc());
    AddressLiteral ic = __ allocate_metadata_address((Metadata *)NULL);
    bool success = __ load_const_from_method_toc(as_Register(Matcher::inline_cache_reg_encode()),
                                                 ic, reg_scratch, /*fixed_size*/ true);
    if (!success) {
      return NULL; // CodeCache is full
    }
  
    if (ReoptimizeCallSequences) {
      __ b64_patchable((address)-1, relocInfo::none);
    } else {
      AddressLiteral a((address)-1);
      success = __ load_const_from_method_toc(reg_scratch, a, reg_scratch, /*fixed_size*/ true);
      if (!success) {
        return NULL; // CodeCache is full
      }
      __ mtctr(reg_scratch);
      __ bctr();
    }
  
    // FIXME: Assert that the stub can be identified and patched.
  
    // Java_to_interp_stub_size should be good.
    assert((__ offset() - stub_start_offset) <= CompiledStaticCall::to_interp_stub_size(),
           "should be good size");
    assert(!is_NativeCallTrampolineStub_at(__ addr_at(stub_start_offset)),
           "must not confuse java_to_interp with trampoline stubs");
  
   // End the stub.
    __ end_a_stub();
    return stub;
  #else
    ShouldNotReachHere();
    return NULL;
  #endif
  }
  #undef __
  
  // Size of java_to_interp stub, this doesn't need to be accurate but it must
  // be larger or equal to the real size of the stub.
  // Used for optimization in Compile::Shorten_branches.
  int CompiledStaticCall::to_interp_stub_size() {
    return 12 * BytesPerInstWord;
  }
  
  // Relocation entries for call stub, compiled java to interpreter.
  // Used for optimization in Compile::Shorten_branches.
  int CompiledStaticCall::reloc_to_interp_stub() {
    return 5;
  }
  
  void CompiledDirectStaticCall::set_to_interpreted(const methodHandle& callee, address entry) {
    address stub = find_stub(/*is_aot*/ false);
    guarantee(stub != NULL, "stub not found");
  
    if (TraceICs) {
      ResourceMark rm;
      tty->print_cr("CompiledDirectStaticCall@" INTPTR_FORMAT ": set_to_interpreted %s",
                    p2i(instruction_address()),
                    callee->name_and_sig_as_C_string());
    }
  
    // Creation also verifies the object.
    NativeMovConstReg* method_holder = nativeMovConstReg_at(stub + IC_pos_in_java_to_interp_stub);
    NativeJump*        jump          = nativeJump_at(method_holder->next_instruction_address());
  
    verify_mt_safe(callee, entry, method_holder, jump);
  
    // Update stub.
    method_holder->set_data((intptr_t)callee());
    jump->set_jump_destination(entry);
  
    // Update jump to call.
    set_destination_mt_safe(stub);
  }
  
  void CompiledDirectStaticCall::set_stub_to_clean(static_stub_Relocation* static_stub) {
    // Reset stub.
    address stub = static_stub->addr();
    assert(stub != NULL, "stub not found");
    assert(CompiledICLocker::is_safe(stub), "mt unsafe call");
    // Creation also verifies the object.
    NativeMovConstReg* method_holder = nativeMovConstReg_at(stub + IC_pos_in_java_to_interp_stub);
    NativeJump*        jump          = nativeJump_at(method_holder->next_instruction_address());
    method_holder->set_data(0);
    jump->set_jump_destination((address)-1);
  }
  
  //-----------------------------------------------------------------------------
  // Non-product mode code
  #ifndef PRODUCT
  
  void CompiledDirectStaticCall::verify() {
    // Verify call.
    _call->verify();
    _call->verify_alignment();
  
    // Verify stub.
    address stub = find_stub(/*is_aot*/ false);
    assert(stub != NULL, "no stub found for static call");
    // Creation also verifies the object.
    NativeMovConstReg* method_holder = nativeMovConstReg_at(stub + IC_pos_in_java_to_interp_stub);
    NativeJump*        jump          = nativeJump_at(method_holder->next_instruction_address());
  
    // Verify state.
    assert(is_clean() || is_call_to_compiled() || is_call_to_interpreted(), "sanity check");
  }
  
  #endif // !PRODUCT
  