/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=4 sw=4 et tw=99:
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla SpiderMonkey JavaScript 1.9 code, released
 * May 28, 2008.
 *
 * The Initial Developer of the Original Code is
 *   Brendan Eich <brendan@mozilla.org>
 *
 * Contributor(s):
 *   David Anderson <danderson@mozilla.com>
 *   David Mandelin <dmandelin@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
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 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "StubCalls.h"
#include "StubCompiler.h"
#include "Compiler.h"
#include "assembler/assembler/LinkBuffer.h"
#include "FrameState-inl.h"

using namespace js;
using namespace mjit;

StubCompiler::StubCompiler(JSContext *cx, mjit::Compiler &cc, FrameState &frame, JSScript *script)
: cx(cx),
  cc(cc),
  frame(frame),
  script(script),
  generation(1),
  lastGeneration(0),
  exits(CompilerAllocPolicy(cx, cc)),
  joins(CompilerAllocPolicy(cx, cc)),
  scriptJoins(CompilerAllocPolicy(cx, cc)),
  jumpList(SystemAllocPolicy())
{
#ifdef DEBUG
    masm.setSpewPath(true);
#endif
}

void
StubCompiler::linkExitDirect(Jump j, Label L)
{
    exits.append(CrossPatch(j, L));
}

JSC::MacroAssembler::Label
StubCompiler::syncExit(Uses uses)
{
    JaegerSpew(JSpew_Insns, " ---- BEGIN SLOW MERGE CODE ---- \n");

    if (lastGeneration == generation) {
        Jump j2 = masm.jump();
        jumpList.append(j2);
    }

    Label l = masm.label();
    frame.sync(masm, uses);
    lastGeneration = generation;

    JaegerSpew(JSpew_Insns, " ---- END SLOW MERGE CODE ---- \n");
    
    return l;
}

JSC::MacroAssembler::Label
StubCompiler::syncExitAndJump(Uses uses)
{
    Label l = syncExit(uses);
    Jump j2 = masm.jump();
    jumpList.append(j2);
    /* Suppress jumping on next sync/link. */
    generation++;
    return l;
}

// Link an exit from the fast path to a slow path. This does two main things:
// (a) links the given jump to the slow path, and (b) generates a prolog for
// the slow path that syncs frame state for a slow call that uses |uses|
// values from the top of the stack.
//
// The return value is the label for the start of the merge code. This is
// the correct place to jump to in order to execute the slow path being
// generated here.
//
// Note 1: Slow path generation is interleaved with fast path generation, but
// the slow path goes into a separate buffer. The slow path code is appended
// to the fast path code to keep it nearby in code memory.
//
// Note 2: A jump from the fast path to the slow path is called an "exit".
//         A jump from the slow path to the fast path is called a "rejoin".
JSC::MacroAssembler::Label
StubCompiler::linkExit(Jump j, Uses uses)
{
    Label l = syncExit(uses);
    linkExitDirect(j, l);
    return l;
}

// Special version of linkExit that is used when there is a JavaScript
// control-flow branch after the slow path. Our compilation strategy
// requires the JS frame to be fully materialized in memory across branches.
// This function does a linkExit and also fully materializes the frame.
void
StubCompiler::linkExitForBranch(Jump j)
{
    Label l = syncExit(Uses(frame.frameSlots()));
    linkExitDirect(j, l);
}

void
StubCompiler::leave()
{
    JaegerSpew(JSpew_Insns, " ---- BEGIN SLOW LEAVE CODE ---- \n");
    for (size_t i = 0; i < jumpList.length(); i++)
        jumpList[i].linkTo(masm.label(), &masm);
    jumpList.clear();
    generation++;
    JaegerSpew(JSpew_Insns, " ---- END SLOW LEAVE CODE ---- \n");
}
 
void
StubCompiler::rejoin(Changes changes)
{
    JaegerSpew(JSpew_Insns, " ---- BEGIN SLOW RESTORE CODE ---- \n");

    frame.merge(masm, changes);

    Jump j = masm.jump();
    crossJump(j, cc.getLabel());

    JaegerSpew(JSpew_Insns, " ---- END SLOW RESTORE CODE ---- \n");
}

void
StubCompiler::linkRejoin(Jump j)
{
    crossJump(j, cc.getLabel());
}

typedef JSC::MacroAssembler::RegisterID RegisterID;
typedef JSC::MacroAssembler::ImmPtr ImmPtr;
typedef JSC::MacroAssembler::Imm32 Imm32;

JSC::MacroAssembler::Call
StubCompiler::emitStubCall(void *ptr, uint32 id)
{
    return emitStubCall(ptr, frame.stackDepth() + script->nfixed, id);
}

JSC::MacroAssembler::Call
StubCompiler::emitStubCall(void *ptr, int32 slots, uint32 id)
{
    JaegerSpew(JSpew_Insns, " ---- BEGIN SLOW CALL CODE ---- \n");
    Call cl = masm.fallibleVMCall(ptr, cc.getPC(), slots);
    JaegerSpew(JSpew_Insns, " ---- END SLOW CALL CODE ---- \n");
    if (cc.debugMode()) {
        Compiler::InternalCallSite site(masm.callReturnOffset(cl), cc.getPC(), id, true, true);
        cc.addCallSite(site);
    }
    return cl;
}

void
StubCompiler::fixCrossJumps(uint8 *ncode, size_t offset, size_t total)
{
    JSC::LinkBuffer fast(ncode, total);
    JSC::LinkBuffer slow(ncode + offset, total - offset);

    for (size_t i = 0; i < exits.length(); i++)
        fast.link(exits[i].from, slow.locationOf(exits[i].to));

    for (size_t i = 0; i < scriptJoins.length(); i++) {
        const CrossJumpInScript &cj = scriptJoins[i];
        slow.link(cj.from, fast.locationOf(cc.labelOf(cj.pc)));
    }

    for (size_t i = 0; i < joins.length(); i++)
        slow.link(joins[i].from, fast.locationOf(joins[i].to));
}

void
StubCompiler::crossJump(Jump j, Label L)
{
    joins.append(CrossPatch(j, L));
}

bool
StubCompiler::jumpInScript(Jump j, jsbytecode *target)
{
    if (cc.knownJump(target)) {
        crossJump(j, cc.labelOf(target));
        return true;
    } else {
        return scriptJoins.append(CrossJumpInScript(j, target));
    }
}