1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/src/jit/Recover.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,110 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + * vim: set ts=8 sts=4 et sw=4 tw=99:
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "jit/Recover.h"
1.11 +
1.12 +#include "jit/IonSpewer.h"
1.13 +#include "jit/MIR.h"
1.14 +#include "jit/MIRGraph.h"
1.15 +
1.16 +using namespace js;
1.17 +using namespace js::jit;
1.18 +
1.19 +void
1.20 +RInstruction::readRecoverData(CompactBufferReader &reader, RInstructionStorage *raw)
1.21 +{
1.22 + uint32_t op = reader.readUnsigned();
1.23 + switch (Opcode(op)) {
1.24 + case Recover_ResumePoint:
1.25 + new (raw->addr()) RResumePoint(reader);
1.26 + break;
1.27 + default:
1.28 + MOZ_ASSUME_UNREACHABLE("Bad decoding of the previous instruction?");
1.29 + break;
1.30 + }
1.31 +}
1.32 +
1.33 +bool
1.34 +MResumePoint::writeRecoverData(CompactBufferWriter &writer) const
1.35 +{
1.36 + writer.writeUnsigned(uint32_t(RInstruction::Recover_ResumePoint));
1.37 +
1.38 + MBasicBlock *bb = block();
1.39 + JSFunction *fun = bb->info().funMaybeLazy();
1.40 + JSScript *script = bb->info().script();
1.41 + uint32_t exprStack = stackDepth() - bb->info().ninvoke();
1.42 +
1.43 +#ifdef DEBUG
1.44 + // Ensure that all snapshot which are encoded can safely be used for
1.45 + // bailouts.
1.46 + if (GetIonContext()->cx) {
1.47 + uint32_t stackDepth;
1.48 + bool reachablePC;
1.49 + jsbytecode *bailPC = pc();
1.50 +
1.51 + if (mode() == MResumePoint::ResumeAfter)
1.52 + bailPC = GetNextPc(pc());
1.53 +
1.54 + if (!ReconstructStackDepth(GetIonContext()->cx, script,
1.55 + bailPC, &stackDepth, &reachablePC))
1.56 + {
1.57 + return false;
1.58 + }
1.59 +
1.60 + if (reachablePC) {
1.61 + if (JSOp(*bailPC) == JSOP_FUNCALL) {
1.62 + // For fun.call(this, ...); the reconstructStackDepth will
1.63 + // include the this. When inlining that is not included. So the
1.64 + // exprStackSlots will be one less.
1.65 + MOZ_ASSERT(stackDepth - exprStack <= 1);
1.66 + } else if (JSOp(*bailPC) != JSOP_FUNAPPLY &&
1.67 + !IsGetPropPC(bailPC) && !IsSetPropPC(bailPC))
1.68 + {
1.69 + // For fun.apply({}, arguments) the reconstructStackDepth will
1.70 + // have stackdepth 4, but it could be that we inlined the
1.71 + // funapply. In that case exprStackSlots, will have the real
1.72 + // arguments in the slots and not be 4.
1.73 +
1.74 + // With accessors, we have different stack depths depending on
1.75 + // whether or not we inlined the accessor, as the inlined stack
1.76 + // contains a callee function that should never have been there
1.77 + // and we might just be capturing an uneventful property site,
1.78 + // in which case there won't have been any violence.
1.79 + MOZ_ASSERT(exprStack == stackDepth);
1.80 + }
1.81 + }
1.82 + }
1.83 +#endif
1.84 +
1.85 + // Test if we honor the maximum of arguments at all times. This is a sanity
1.86 + // check and not an algorithm limit. So check might be a bit too loose. +4
1.87 + // to account for scope chain, return value, this value and maybe
1.88 + // arguments_object.
1.89 + MOZ_ASSERT(CountArgSlots(script, fun) < SNAPSHOT_MAX_NARGS + 4);
1.90 +
1.91 + uint32_t implicit = StartArgSlot(script);
1.92 + uint32_t formalArgs = CountArgSlots(script, fun);
1.93 + uint32_t nallocs = formalArgs + script->nfixed() + exprStack;
1.94 +
1.95 + IonSpew(IonSpew_Snapshots, "Starting frame; implicit %u, formals %u, fixed %u, exprs %u",
1.96 + implicit, formalArgs - implicit, script->nfixed(), exprStack);
1.97 +
1.98 + uint32_t pcoff = script->pcToOffset(pc());
1.99 + IonSpew(IonSpew_Snapshots, "Writing pc offset %u, nslots %u", pcoff, nallocs);
1.100 + writer.writeUnsigned(pcoff);
1.101 + writer.writeUnsigned(nallocs);
1.102 + return true;
1.103 +}
1.104 +
1.105 +RResumePoint::RResumePoint(CompactBufferReader &reader)
1.106 +{
1.107 + static_assert(sizeof(*this) <= sizeof(RInstructionStorage),
1.108 + "Storage space is too small to decode this recover instruction.");
1.109 + pcOffset_ = reader.readUnsigned();
1.110 + numOperands_ = reader.readUnsigned();
1.111 + IonSpew(IonSpew_Snapshots, "Read RResumePoint (pc offset %u, nslots %u)",
1.112 + pcOffset_, numOperands_);
1.113 +}
