jdk

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/*
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 * Copyright (c) 1998, 2023, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#ifdef COMPILER2
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#include "asm/macroAssembler.hpp"
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#include "asm/macroAssembler.inline.hpp"
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#include "code/vmreg.hpp"
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#include "compiler/oopMap.hpp"
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#include "interpreter/interpreter.hpp"
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#include "memory/resourceArea.hpp"
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#include "opto/runtime.hpp"
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#include "runtime/sharedRuntime.hpp"
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#include "runtime/stubRoutines.hpp"
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#include "runtime/vframeArray.hpp"
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#include "utilities/globalDefinitions.hpp"
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#include "vmreg_x86.inline.hpp"
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#endif
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#define __ masm->
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//------------------------------generate_exception_blob---------------------------
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// creates exception blob at the end
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// Using exception blob, this code is jumped from a compiled method.
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//
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// Given an exception pc at a call we call into the runtime for the
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// handler in this method. This handler might merely restore state
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// (i.e. callee save registers) unwind the frame and jump to the
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// exception handler for the nmethod if there is no Java level handler
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// for the nmethod.
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//
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// This code is entered with a jmp.
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//
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// Arguments:
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//   rax: exception oop
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//   rdx: exception pc
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//
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// Results:
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//   rax: exception oop
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//   rdx: exception pc in caller or ???
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//   destination: exception handler of caller
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//
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// Note: the exception pc MUST be at a call (precise debug information)
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//       Only register rax, rdx, rcx are not callee saved.
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//
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void OptoRuntime::generate_exception_blob() {
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  // Capture info about frame layout
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  enum layout {
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    thread_off,                 // last_java_sp
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    // The frame sender code expects that rbp will be in the "natural" place and
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    // will override any oopMap setting for it. We must therefore force the layout
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    // so that it agrees with the frame sender code.
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    rbp_off,
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    return_off,                 // slot for return address
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    framesize
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  };
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  // allocate space for the code
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  ResourceMark rm;
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  // setup code generation tools
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  CodeBuffer   buffer("exception_blob", 512, 512);
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  MacroAssembler* masm = new MacroAssembler(&buffer);
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  OopMapSet *oop_maps = new OopMapSet();
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  address start = __ pc();
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  __ push(rdx);
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  __ subptr(rsp, return_off * wordSize);   // Prolog!
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  // rbp, location is implicitly known
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  __ movptr(Address(rsp,rbp_off  *wordSize), rbp);
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  // Store exception in Thread object. We cannot pass any arguments to the
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  // handle_exception call, since we do not want to make any assumption
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  // about the size of the frame where the exception happened in.
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  __ get_thread(rcx);
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  __ movptr(Address(rcx, JavaThread::exception_oop_offset()), rax);
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  __ movptr(Address(rcx, JavaThread::exception_pc_offset()),  rdx);
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  // This call does all the hard work.  It checks if an exception handler
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  // exists in the method.
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  // If so, it returns the handler address.
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  // If not, it prepares for stack-unwinding, restoring the callee-save
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  // registers of the frame being removed.
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  //
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  __ movptr(Address(rsp, thread_off * wordSize), rcx); // Thread is first argument
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  __ set_last_Java_frame(rcx, noreg, noreg, nullptr, noreg);
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  __ call(RuntimeAddress(CAST_FROM_FN_PTR(address, OptoRuntime::handle_exception_C)));
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  // No registers to map, rbp is known implicitly
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  oop_maps->add_gc_map( __ pc() - start,  new OopMap( framesize, 0 ));
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  __ get_thread(rcx);
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  __ reset_last_Java_frame(rcx, false);
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  // Restore callee-saved registers
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  __ movptr(rbp, Address(rsp, rbp_off * wordSize));
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  __ addptr(rsp, return_off * wordSize);   // Epilog!
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  __ pop(rdx); // Exception pc
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  // rax: exception handler for given <exception oop/exception pc>
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  // We have a handler in rax, (could be deopt blob)
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  // rdx - throwing pc, deopt blob will need it.
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  __ push(rax);
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  // Get the exception
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  __ movptr(rax, Address(rcx, JavaThread::exception_oop_offset()));
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  // Get the exception pc in case we are deoptimized
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  __ movptr(rdx, Address(rcx, JavaThread::exception_pc_offset()));
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#ifdef ASSERT
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  __ movptr(Address(rcx, JavaThread::exception_handler_pc_offset()), NULL_WORD);
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  __ movptr(Address(rcx, JavaThread::exception_pc_offset()), NULL_WORD);
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#endif
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  // Clear the exception oop so GC no longer processes it as a root.
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  __ movptr(Address(rcx, JavaThread::exception_oop_offset()), NULL_WORD);
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  __ pop(rcx);
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  // rax: exception oop
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  // rcx: exception handler
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  // rdx: exception pc
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  __ jmp (rcx);
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  // -------------
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  // make sure all code is generated
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  masm->flush();
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  _exception_blob = ExceptionBlob::create(&buffer, oop_maps, framesize);
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}
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