The Tor Browser: js/src/jit/Safepoints.cpp@6474c204b198 (annotated)

js/src/jit/Safepoints.cpp@6474c204b198 (annotated)

js/src/jit/Safepoints.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "jit/Safepoints.h"
 #include "mozilla/MathAlgorithms.h"
 #include "jit/BitSet.h"
 #include "jit/IonSpewer.h"
 #include "jit/LIR.h"
 using namespace js;
 using namespace jit;
 using mozilla::FloorLog2;
 bool
 SafepointWriter::init(TempAllocator &alloc, uint32_t slotCount)
 {
     frameSlots_ = BitSet::New(alloc, slotCount / sizeof(intptr_t));
     if (!frameSlots_)
         return false;
     return true;
 }
 uint32_t
 SafepointWriter::startEntry()
 {
     IonSpew(IonSpew_Safepoints, "Encoding safepoint (position %d):", stream_.length());
     return uint32_t(stream_.length());
 }
 void
 SafepointWriter::writeOsiCallPointOffset(uint32_t osiCallPointOffset)
 {
     stream_.writeUnsigned(osiCallPointOffset);
 }
 static void
 WriteRegisterMask(CompactBufferWriter &stream, uint32_t bits)
 {
     if (sizeof(PackedRegisterMask) == 1)
         stream.writeByte(bits);
     else
         stream.writeUnsigned(bits);
 }
 static int32_t
 ReadRegisterMask(CompactBufferReader &stream)
 {
     if (sizeof(PackedRegisterMask) == 1)
         return stream.readByte();
     return stream.readUnsigned();
 }
 void
 SafepointWriter::writeGcRegs(LSafepoint *safepoint)
 {
     GeneralRegisterSet gc = safepoint->gcRegs();
     GeneralRegisterSet spilledGpr = safepoint->liveRegs().gprs();
     FloatRegisterSet spilledFloat = safepoint->liveRegs().fpus();
     GeneralRegisterSet slots = safepoint->slotsOrElementsRegs();
     GeneralRegisterSet valueRegs;
     WriteRegisterMask(stream_, spilledGpr.bits());
     if (!spilledGpr.empty()) {
         WriteRegisterMask(stream_, gc.bits());
         WriteRegisterMask(stream_, slots.bits());
 #ifdef JS_PUNBOX64
         valueRegs = safepoint->valueRegs();
         WriteRegisterMask(stream_, valueRegs.bits());
 #endif
     }
     // GC registers are a subset of the spilled registers.
     JS_ASSERT((valueRegs.bits() & ~spilledGpr.bits()) == 0);
     JS_ASSERT((gc.bits() & ~spilledGpr.bits()) == 0);
     WriteRegisterMask(stream_, spilledFloat.bits());
 #ifdef DEBUG
     if (IonSpewEnabled(IonSpew_Safepoints)) {
         for (GeneralRegisterForwardIterator iter(spilledGpr); iter.more(); iter++) {
             const char *type = gc.has(*iter)
                                ? "gc"
                                : slots.has(*iter)
                                  ? "slots"
                                  : valueRegs.has(*iter)
                                    ? "value"
                                    : "any";
             IonSpew(IonSpew_Safepoints, "    %s reg: %s", type, (*iter).name());
         }
         for (FloatRegisterForwardIterator iter(spilledFloat); iter.more(); iter++)
             IonSpew(IonSpew_Safepoints, "    float reg: %s", (*iter).name());
     }
 #endif
 }
 static void
 MapSlotsToBitset(BitSet *set, CompactBufferWriter &stream, uint32_t nslots, uint32_t *slots)
 {
     set->clear();
     for (uint32_t i = 0; i < nslots; i++) {
         // Slots are represented at a distance from |fp|. We divide by the
         // pointer size, since we only care about pointer-sized/aligned slots
         // here. Since the stack grows down, this means slots start at index 1,
         // so we subtract 1 to pack the bitset.
         JS_ASSERT(slots[i] % sizeof(intptr_t) == 0);
         JS_ASSERT(slots[i] / sizeof(intptr_t) > 0);
         set->insert(slots[i] / sizeof(intptr_t) - 1);
     }
     size_t count = set->rawLength();
     const uint32_t *words = set->raw();
     for (size_t i = 0; i < count; i++)
         stream.writeUnsigned(words[i]);
 }
 void
 SafepointWriter::writeGcSlots(LSafepoint *safepoint)
 {
     LSafepoint::SlotList &slots = safepoint->gcSlots();
 #ifdef DEBUG
     for (uint32_t i = 0; i < slots.length(); i++)
         IonSpew(IonSpew_Safepoints, "    gc slot: %d", slots[i]);
 #endif
     MapSlotsToBitset(frameSlots_,
                      stream_,
                      slots.length(),
                      slots.begin());
 }
 void
 SafepointWriter::writeSlotsOrElementsSlots(LSafepoint *safepoint)
 {
     LSafepoint::SlotList &slots = safepoint->slotsOrElementsSlots();
     stream_.writeUnsigned(slots.length());
     for (uint32_t i = 0; i < slots.length(); i++) {
 #ifdef DEBUG
         IonSpew(IonSpew_Safepoints, "    slots/elements slot: %d", slots[i]);
 #endif
         stream_.writeUnsigned(slots[i]);
     }
 }
 void
 SafepointWriter::writeValueSlots(LSafepoint *safepoint)
 {
     LSafepoint::SlotList &slots = safepoint->valueSlots();
 #ifdef DEBUG
     for (uint32_t i = 0; i < slots.length(); i++)
         IonSpew(IonSpew_Safepoints, "    gc value: %d", slots[i]);
 #endif
     MapSlotsToBitset(frameSlots_, stream_, slots.length(), slots.begin());
 }
 #if defined(DEBUG) && defined(JS_NUNBOX32)
 static void
 DumpNunboxPart(const LAllocation &a)
 {
     if (a.isStackSlot()) {
         fprintf(IonSpewFile, "stack %d", a.toStackSlot()->slot());
     } else if (a.isArgument()) {
         fprintf(IonSpewFile, "arg %d", a.toArgument()->index());
     } else {
         fprintf(IonSpewFile, "reg %s", a.toGeneralReg()->reg().name());
     }
 }
 #endif // DEBUG
 // Nunbox part encoding:
 //
 // Reg = 000
 // Stack = 001
 // Arg = 010
 //
 // [vwu] nentries:
 //    uint16_t:  tttp ppXX XXXY YYYY
 //
 //     If ttt = Reg, type is reg XXXXX
 //     If ppp = Reg, payload is reg YYYYY
 //
 //     If ttt != Reg, type is:
 //          XXXXX if not 11111, otherwise followed by [vwu]
 //     If ppp != Reg, payload is:
 //          YYYYY if not 11111, otherwise followed by [vwu]
 //
 enum NunboxPartKind {
     Part_Reg,
     Part_Stack,
     Part_Arg
 };
 static const uint32_t PART_KIND_BITS = 3;
 static const uint32_t PART_KIND_MASK = (1 << PART_KIND_BITS) - 1;
 static const uint32_t PART_INFO_BITS = 5;
 static const uint32_t PART_INFO_MASK = (1 << PART_INFO_BITS) - 1;
 static const uint32_t MAX_INFO_VALUE = (1 << PART_INFO_BITS) - 1;
 static const uint32_t TYPE_KIND_SHIFT = 16 - PART_KIND_BITS;
 static const uint32_t PAYLOAD_KIND_SHIFT = TYPE_KIND_SHIFT - PART_KIND_BITS;
 static const uint32_t TYPE_INFO_SHIFT = PAYLOAD_KIND_SHIFT - PART_INFO_BITS;
 static const uint32_t PAYLOAD_INFO_SHIFT = TYPE_INFO_SHIFT - PART_INFO_BITS;
 JS_STATIC_ASSERT(PAYLOAD_INFO_SHIFT == 0);
 #ifdef JS_NUNBOX32
 static inline NunboxPartKind
 AllocationToPartKind(const LAllocation &a)
 {
     if (a.isRegister())
         return Part_Reg;
     if (a.isStackSlot())
         return Part_Stack;
     JS_ASSERT(a.isArgument());
     return Part_Arg;
 }
 // gcc 4.5 doesn't actually inline CanEncodeInfoInHeader when only
 // using the "inline" keyword, and miscompiles the function as well
 // when doing block reordering with branch prediction information.
 // See bug 799295 comment 71.
 static MOZ_ALWAYS_INLINE bool
 CanEncodeInfoInHeader(const LAllocation &a, uint32_t *out)
 {
     if (a.isGeneralReg()) {
         *out = a.toGeneralReg()->reg().code();
         return true;
     }
     if (a.isStackSlot())
         *out = a.toStackSlot()->slot();
     else
         *out = a.toArgument()->index();
     return *out < MAX_INFO_VALUE;
 }
 void
 SafepointWriter::writeNunboxParts(LSafepoint *safepoint)
 {
     LSafepoint::NunboxList &entries = safepoint->nunboxParts();
 # ifdef DEBUG
     if (IonSpewEnabled(IonSpew_Safepoints)) {
         for (uint32_t i = 0; i < entries.length(); i++) {
             SafepointNunboxEntry &entry = entries[i];
             if (entry.type.isUse() || entry.payload.isUse())
                 continue;
             IonSpewHeader(IonSpew_Safepoints);
             fprintf(IonSpewFile, "    nunbox (type in ");
             DumpNunboxPart(entry.type);
             fprintf(IonSpewFile, ", payload in ");
             DumpNunboxPart(entry.payload);
             fprintf(IonSpewFile, ")\n");
         }
     }
 # endif
     // Safepoints are permitted to have partially filled in entries for nunboxes,
     // provided that only the type is live and not the payload. Omit these from
     // the written safepoint.
     uint32_t partials = safepoint->partialNunboxes();
     stream_.writeUnsigned(entries.length() - partials);
     for (size_t i = 0; i < entries.length(); i++) {
         SafepointNunboxEntry &entry = entries[i];
         if (entry.type.isUse() || entry.payload.isUse()) {
             partials--;
             continue;
         }
         uint16_t header = 0;
         header |= (AllocationToPartKind(entry.type) << TYPE_KIND_SHIFT);
         header |= (AllocationToPartKind(entry.payload) << PAYLOAD_KIND_SHIFT);
         uint32_t typeVal;
         bool typeExtra = !CanEncodeInfoInHeader(entry.type, &typeVal);
         if (!typeExtra)
             header |= (typeVal << TYPE_INFO_SHIFT);
         else
             header |= (MAX_INFO_VALUE << TYPE_INFO_SHIFT);
         uint32_t payloadVal;
         bool payloadExtra = !CanEncodeInfoInHeader(entry.payload, &payloadVal);
         if (!payloadExtra)
             header |= (payloadVal << PAYLOAD_INFO_SHIFT);
         else
             header |= (MAX_INFO_VALUE << PAYLOAD_INFO_SHIFT);
         stream_.writeFixedUint16_t(header);
         if (typeExtra)
             stream_.writeUnsigned(typeVal);
         if (payloadExtra)
             stream_.writeUnsigned(payloadVal);
     }
     JS_ASSERT(partials == 0);
 }
 #endif
 void
 SafepointWriter::encode(LSafepoint *safepoint)
 {
     uint32_t safepointOffset = startEntry();
     JS_ASSERT(safepoint->osiCallPointOffset());
     writeOsiCallPointOffset(safepoint->osiCallPointOffset());
     writeGcRegs(safepoint);
     writeGcSlots(safepoint);
     writeValueSlots(safepoint);
 #ifdef JS_NUNBOX32
     writeNunboxParts(safepoint);
 #endif
     writeSlotsOrElementsSlots(safepoint);
     endEntry();
     safepoint->setOffset(safepointOffset);
 }
 void
 SafepointWriter::endEntry()
 {
     IonSpew(IonSpew_Safepoints, "    -- entry ended at %d", uint32_t(stream_.length()));
 }
 SafepointReader::SafepointReader(IonScript *script, const SafepointIndex *si)
   : stream_(script->safepoints() + si->safepointOffset(),
             script->safepoints() + script->safepointsSize()),
     frameSlots_(script->frameSlots() / sizeof(intptr_t))
 {
     osiCallPointOffset_ = stream_.readUnsigned();
     // gcSpills is a subset of allGprSpills.
     allGprSpills_ = GeneralRegisterSet(ReadRegisterMask(stream_));
     if (allGprSpills_.empty()) {
         gcSpills_ = allGprSpills_;
         valueSpills_ = allGprSpills_;
         slotsOrElementsSpills_ = allGprSpills_;
     } else {
         gcSpills_ = GeneralRegisterSet(ReadRegisterMask(stream_));
         slotsOrElementsSpills_ = GeneralRegisterSet(ReadRegisterMask(stream_));
 #ifdef JS_PUNBOX64
         valueSpills_ = GeneralRegisterSet(ReadRegisterMask(stream_));
 #endif
     }
     allFloatSpills_ = FloatRegisterSet(ReadRegisterMask(stream_));
     advanceFromGcRegs();
 }
 uint32_t
 SafepointReader::osiReturnPointOffset() const
 {
     return osiCallPointOffset_ + Assembler::patchWrite_NearCallSize();
 }
 CodeLocationLabel
 SafepointReader::InvalidationPatchPoint(IonScript *script, const SafepointIndex *si)
 {
     SafepointReader reader(script, si);
     return CodeLocationLabel(script->method(), reader.osiCallPointOffset());
 }
 void
 SafepointReader::advanceFromGcRegs()
 {
     currentSlotChunk_ = 0;
     nextSlotChunkNumber_ = 0;
 }
 bool
 SafepointReader::getSlotFromBitmap(uint32_t *slot)
 {
     while (currentSlotChunk_ == 0) {
         // Are there any more chunks to read?
         if (nextSlotChunkNumber_ == BitSet::RawLengthForBits(frameSlots_))
             return false;
         // Yes, read the next chunk.
         currentSlotChunk_ = stream_.readUnsigned();
         nextSlotChunkNumber_++;
     }
     // The current chunk still has bits in it, so get the next bit, then mask
     // it out of the slot chunk.
     uint32_t bit = FloorLog2(currentSlotChunk_);
     currentSlotChunk_ &= ~(1 << bit);
     // Return the slot, taking care to add 1 back in since it was subtracted
     // when added in the original bitset, and re-scale it by the pointer size,
     // reversing the transformation in MapSlotsToBitset.
     *slot = (((nextSlotChunkNumber_ - 1) * BitSet::BitsPerWord) + bit + 1) * sizeof(intptr_t);
     return true;
 }
 bool
 SafepointReader::getGcSlot(uint32_t *slot)
 {
     if (getSlotFromBitmap(slot))
         return true;
     advanceFromGcSlots();
     return false;
 }
 void
 SafepointReader::advanceFromGcSlots()
 {
     // No, reset the counter.
     currentSlotChunk_ = 0;
     nextSlotChunkNumber_ = 0;
 }
 bool
 SafepointReader::getValueSlot(uint32_t *slot)
 {
     if (getSlotFromBitmap(slot))
         return true;
     advanceFromValueSlots();
     return false;
 }
 void
 SafepointReader::advanceFromValueSlots()
 {
 #ifdef JS_NUNBOX32
     nunboxSlotsRemaining_ = stream_.readUnsigned();
 #else
     nunboxSlotsRemaining_ = 0;
     advanceFromNunboxSlots();
 #endif
 }
 static inline LAllocation
 PartFromStream(CompactBufferReader &stream, NunboxPartKind kind, uint32_t info)
 {
     if (kind == Part_Reg)
         return LGeneralReg(Register::FromCode(info));
     if (info == MAX_INFO_VALUE)
         info = stream.readUnsigned();
     if (kind == Part_Stack)
         return LStackSlot(info);
     JS_ASSERT(kind == Part_Arg);
     return LArgument(info);
 }
 bool
 SafepointReader::getNunboxSlot(LAllocation *type, LAllocation *payload)
 {
     if (!nunboxSlotsRemaining_--) {
         advanceFromNunboxSlots();
         return false;
     }
     uint16_t header = stream_.readFixedUint16_t();
     NunboxPartKind typeKind = (NunboxPartKind)((header >> TYPE_KIND_SHIFT) & PART_KIND_MASK);
     NunboxPartKind payloadKind = (NunboxPartKind)((header >> PAYLOAD_KIND_SHIFT) & PART_KIND_MASK);
     uint32_t typeInfo = (header >> TYPE_INFO_SHIFT) & PART_INFO_MASK;
     uint32_t payloadInfo = (header >> PAYLOAD_INFO_SHIFT) & PART_INFO_MASK;
     *type = PartFromStream(stream_, typeKind, typeInfo);
     *payload = PartFromStream(stream_, payloadKind, payloadInfo);
     return true;
 }
 void
 SafepointReader::advanceFromNunboxSlots()
 {
     slotsOrElementsSlotsRemaining_ = stream_.readUnsigned();
 }
 bool
 SafepointReader::getSlotsOrElementsSlot(uint32_t *slot)
 {
     if (!slotsOrElementsSlotsRemaining_--)
         return false;
     *slot = stream_.readUnsigned();
     return true;
 }

The Tor Browser / annotate

js/src/jit/Safepoints.cpp@6474c204b198 (annotated)

js/src/jit/Safepoints.cpp