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duckstation/dep/vixl/include/vixl/pool-manager-impl.h

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// Copyright 2017, VIXL authors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of ARM Limited nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef VIXL_POOL_MANAGER_IMPL_H_
#define VIXL_POOL_MANAGER_IMPL_H_
#include <algorithm>
#include "assembler-base-vixl.h"
#include "pool-manager.h"
namespace vixl {
template <typename T>
T PoolManager<T>::Emit(MacroAssemblerInterface* masm,
T pc,
int num_bytes,
ForwardReference<T>* new_reference,
LocationBase<T>* new_object,
EmitOption option) {
// Make sure that the buffer still has the alignment we think it does.
VIXL_ASSERT(IsAligned(masm->AsAssemblerBase()
->GetBuffer()
->GetStartAddress<uintptr_t>(),
buffer_alignment_));
// We should not call this method when the pools are blocked.
VIXL_ASSERT(!IsBlocked());
if (objects_.empty()) return pc;
// Emit header.
if (option == kBranchRequired) {
masm->EmitPoolHeader();
// TODO: The pc at this point might not actually be aligned according to
// alignment_. This is to support the current AARCH32 MacroAssembler which
// does not have a fixed size instruction set. In practice, the pc will be
// aligned to the alignment instructions need for the current instruction
// set, so we do not need to align it here. All other calculations do take
// the alignment into account, which only makes the checkpoint calculations
// more conservative when we use T32. Uncomment the following assertion if
// the AARCH32 MacroAssembler is modified to only support one ISA at the
// time.
// VIXL_ASSERT(pc == AlignUp(pc, alignment_));
pc += header_size_;
} else {
// If the header is optional, we might need to add some extra padding to
// meet the minimum location of the first object.
if (pc < objects_[0].min_location_) {
int32_t padding = objects_[0].min_location_ - pc;
masm->EmitNopBytes(padding);
pc += padding;
}
}
PoolObject<T>* existing_object = GetObjectIfTracked(new_object);
// Go through all objects and emit one by one.
for (objects_iter iter = objects_.begin(); iter != objects_.end();) {
PoolObject<T>& current = *iter;
if (ShouldSkipObject(&current,
pc,
num_bytes,
new_reference,
new_object,
existing_object)) {
++iter;
continue;
}
LocationBase<T>* label_base = current.label_base_;
T aligned_pc = AlignUp(pc, current.alignment_);
masm->EmitPaddingBytes(aligned_pc - pc);
pc = aligned_pc;
VIXL_ASSERT(pc >= current.min_location_);
VIXL_ASSERT(pc <= current.max_location_);
// First call SetLocation, which will also resolve the references, and then
// call EmitPoolObject, which might add a new reference.
label_base->SetLocation(masm->AsAssemblerBase(), pc);
label_base->EmitPoolObject(masm);
int object_size = label_base->GetPoolObjectSizeInBytes();
if (label_base->ShouldDeletePoolObjectOnPlacement()) {
label_base->MarkBound();
iter = RemoveAndDelete(iter);
} else {
VIXL_ASSERT(!current.label_base_->ShouldDeletePoolObjectOnPlacement());
current.label_base_->UpdatePoolObject(&current);
VIXL_ASSERT(current.alignment_ >= label_base->GetPoolObjectAlignment());
++iter;
}
pc += object_size;
}
// Recalculate the checkpoint before emitting the footer. The footer might
// call Bind() which will check if we need to emit.
RecalculateCheckpoint();
// Always emit footer - this might add some padding.
masm->EmitPoolFooter();
pc = AlignUp(pc, alignment_);
return pc;
}
template <typename T>
bool PoolManager<T>::ShouldSkipObject(PoolObject<T>* pool_object,
T pc,
int num_bytes,
ForwardReference<T>* new_reference,
LocationBase<T>* new_object,
PoolObject<T>* existing_object) const {
// We assume that all objects before this have been skipped and all objects
// after this will be emitted, therefore we will emit the whole pool. Add
// the header size and alignment, as well as the number of bytes we are
// planning to emit.
T max_actual_location = pc + num_bytes + max_pool_size_;
if (new_reference != NULL) {
// If we're adding a new object, also assume that it will have to be emitted
// before the object we are considering to skip.
VIXL_ASSERT(new_object != NULL);
T new_object_alignment = std::max(new_reference->object_alignment_,
new_object->GetPoolObjectAlignment());
if ((existing_object != NULL) &&
(existing_object->alignment_ > new_object_alignment)) {
new_object_alignment = existing_object->alignment_;
}
max_actual_location +=
(new_object->GetPoolObjectSizeInBytes() + new_object_alignment - 1);
}
// Hard limit.
if (max_actual_location >= pool_object->max_location_) return false;
// Use heuristic.
return (pc < pool_object->skip_until_location_hint_);
}
template <typename T>
T PoolManager<T>::UpdateCheckpointForObject(T checkpoint,
const PoolObject<T>* object) {
checkpoint -= object->label_base_->GetPoolObjectSizeInBytes();
if (checkpoint > object->max_location_) checkpoint = object->max_location_;
checkpoint = AlignDown(checkpoint, object->alignment_);
return checkpoint;
}
template <typename T>
static T MaxCheckpoint() {
return std::numeric_limits<T>::max();
}
template <typename T>
static inline bool CheckCurrentPC(T pc, T checkpoint) {
VIXL_ASSERT(pc <= checkpoint);
// We must emit the pools if we are at the checkpoint now.
return pc == checkpoint;
}
template <typename T>
static inline bool CheckFuturePC(T pc, T checkpoint) {
// We do not need to emit the pools now if the projected future PC will be
// equal to the checkpoint (we will need to emit the pools then).
return pc > checkpoint;
}
template <typename T>
bool PoolManager<T>::MustEmit(T pc,
int num_bytes,
ForwardReference<T>* reference,
LocationBase<T>* label_base) const {
// Check if we are at or past the checkpoint.
if (CheckCurrentPC(pc, checkpoint_)) return true;
// Check if the future PC will be past the checkpoint.
pc += num_bytes;
if (CheckFuturePC(pc, checkpoint_)) return true;
// No new reference - nothing to do.
if (reference == NULL) {
VIXL_ASSERT(label_base == NULL);
return false;
}
if (objects_.empty()) {
// Basic assertions that restrictions on the new (and only) reference are
// possible to satisfy.
VIXL_ASSERT(AlignUp(pc + header_size_, alignment_) >=
reference->min_object_location_);
VIXL_ASSERT(pc <= reference->max_object_location_);
return false;
}
// Check if the object is already being tracked.
const PoolObject<T>* existing_object = GetObjectIfTracked(label_base);
if (existing_object != NULL) {
// If the existing_object is already in existing_objects_ and its new
// alignment and new location restrictions are not stricter, skip the more
// expensive check.
if ((reference->min_object_location_ <= existing_object->min_location_) &&
(reference->max_object_location_ >= existing_object->max_location_) &&
(reference->object_alignment_ <= existing_object->alignment_)) {
return false;
}
}
// Create a temporary object.
PoolObject<T> temp(label_base);
temp.RestrictRange(reference->min_object_location_,
reference->max_object_location_);
temp.RestrictAlignment(reference->object_alignment_);
if (existing_object != NULL) {
temp.RestrictRange(existing_object->min_location_,
existing_object->max_location_);
temp.RestrictAlignment(existing_object->alignment_);
}
// Check if the new reference can be added after the end of the current pool.
// If yes, we don't need to emit.
T last_reachable = AlignDown(temp.max_location_, temp.alignment_);
const PoolObject<T>& last = objects_.back();
T after_pool = AlignDown(last.max_location_, last.alignment_) +
last.label_base_->GetPoolObjectSizeInBytes();
// The current object can be placed at the end of the pool, even if the last
// object is placed at the last possible location.
if (last_reachable >= after_pool) return false;
// The current object can be placed after the code we are about to emit and
// after the existing pool (with a pessimistic size estimate).
if (last_reachable >= pc + num_bytes + max_pool_size_) return false;
// We're not in a trivial case, so we need to recalculate the checkpoint.
// Check (conservatively) if we can fit it into the objects_ array, without
// breaking our assumptions. Here we want to recalculate the checkpoint as
// if the new reference was added to the PoolManager but without actually
// adding it (as removing it is non-trivial).
T checkpoint = MaxCheckpoint<T>();
// Will temp be the last object in objects_?
if (PoolObjectLessThan(last, temp)) {
checkpoint = UpdateCheckpointForObject(checkpoint, &temp);
if (checkpoint < temp.min_location_) return true;
}
bool temp_not_placed_yet = true;
for (int i = static_cast<int>(objects_.size()) - 1; i >= 0; --i) {
const PoolObject<T>& current = objects_[i];
if (temp_not_placed_yet && PoolObjectLessThan(current, temp)) {
checkpoint = UpdateCheckpointForObject(checkpoint, &temp);
if (checkpoint < temp.min_location_) return true;
if (CheckFuturePC(pc, checkpoint)) return true;
temp_not_placed_yet = false;
}
if (current.label_base_ == label_base) continue;
checkpoint = UpdateCheckpointForObject(checkpoint, &current);
if (checkpoint < current.min_location_) return true;
if (CheckFuturePC(pc, checkpoint)) return true;
}
// temp is the object with the smallest max_location_.
if (temp_not_placed_yet) {
checkpoint = UpdateCheckpointForObject(checkpoint, &temp);
if (checkpoint < temp.min_location_) return true;
}
// Take the header into account.
checkpoint -= header_size_;
checkpoint = AlignDown(checkpoint, alignment_);
return CheckFuturePC(pc, checkpoint);
}
template <typename T>
void PoolManager<T>::RecalculateCheckpoint(SortOption sort_option) {
// TODO: Improve the max_pool_size_ estimate by starting from the
// min_location_ of the first object, calculating the end of the pool as if
// all objects were placed starting from there, and in the end adding the
// maximum object alignment found minus one (which is the maximum extra
// padding we would need if we were to relocate the pool to a different
// address).
max_pool_size_ = 0;
if (objects_.empty()) {
checkpoint_ = MaxCheckpoint<T>();
return;
}
// Sort objects by their max_location_.
if (sort_option == kSortRequired) {
std::sort(objects_.begin(), objects_.end(), PoolObjectLessThan);
}
// Add the header size and header and footer max alignment to the maximum
// pool size.
max_pool_size_ += header_size_ + 2 * (alignment_ - 1);
T checkpoint = MaxCheckpoint<T>();
int last_object_index = static_cast<int>(objects_.size()) - 1;
for (int i = last_object_index; i >= 0; --i) {
// Bring back the checkpoint by the size of the current object, unless
// we need to bring it back more, then align.
PoolObject<T>& current = objects_[i];
checkpoint = UpdateCheckpointForObject(checkpoint, &current);
VIXL_ASSERT(checkpoint >= current.min_location_);
max_pool_size_ += (current.alignment_ - 1 +
current.label_base_->GetPoolObjectSizeInBytes());
}
// Take the header into account.
checkpoint -= header_size_;
checkpoint = AlignDown(checkpoint, alignment_);
// Update the checkpoint of the pool manager.
checkpoint_ = checkpoint;
// NOTE: To handle min_location_ in the generic case, we could make a second
// pass of the objects_ vector, increasing the checkpoint as needed, while
// maintaining the alignment requirements.
// It should not be possible to have any issues with min_location_ with actual
// code, since there should always be some kind of branch over the pool,
// whether introduced by the pool emission or by the user, which will make
// sure the min_location_ requirement is satisfied. It's possible that the
// user could emit code in the literal pool and intentionally load the first
// value and then fall-through into the pool, but that is not a supported use
// of VIXL and we will assert in that case.
}
template <typename T>
bool PoolManager<T>::PoolObjectLessThan(const PoolObject<T>& a,
const PoolObject<T>& b) {
if (a.max_location_ != b.max_location_)
return (a.max_location_ < b.max_location_);
int a_size = a.label_base_->GetPoolObjectSizeInBytes();
int b_size = b.label_base_->GetPoolObjectSizeInBytes();
if (a_size != b_size) return (a_size < b_size);
if (a.alignment_ != b.alignment_) return (a.alignment_ < b.alignment_);
if (a.min_location_ != b.min_location_)
return (a.min_location_ < b.min_location_);
return false;
}
template <typename T>
void PoolManager<T>::AddObjectReference(const ForwardReference<T>* reference,
LocationBase<T>* label_base) {
VIXL_ASSERT(reference->object_alignment_ <= buffer_alignment_);
VIXL_ASSERT(label_base->GetPoolObjectAlignment() <= buffer_alignment_);
PoolObject<T>* object = GetObjectIfTracked(label_base);
if (object == NULL) {
PoolObject<T> new_object(label_base);
new_object.RestrictRange(reference->min_object_location_,
reference->max_object_location_);
new_object.RestrictAlignment(reference->object_alignment_);
Insert(new_object);
} else {
object->RestrictRange(reference->min_object_location_,
reference->max_object_location_);
object->RestrictAlignment(reference->object_alignment_);
// Move the object, if needed.
if (objects_.size() != 1) {
PoolObject<T> new_object(*object);
ptrdiff_t distance = std::distance(objects_.data(), object);
objects_.erase(objects_.begin() + distance);
Insert(new_object);
}
}
// No need to sort, we inserted the object in an already sorted array.
RecalculateCheckpoint(kNoSortRequired);
}
template <typename T>
void PoolManager<T>::Insert(const PoolObject<T>& new_object) {
bool inserted = false;
// Place the object in the right position.
for (objects_iter iter = objects_.begin(); iter != objects_.end(); ++iter) {
PoolObject<T>& current = *iter;
if (!PoolObjectLessThan(current, new_object)) {
objects_.insert(iter, new_object);
inserted = true;
break;
}
}
if (!inserted) {
objects_.push_back(new_object);
}
}
template <typename T>
void PoolManager<T>::RemoveAndDelete(PoolObject<T>* object) {
for (objects_iter iter = objects_.begin(); iter != objects_.end(); ++iter) {
PoolObject<T>& current = *iter;
if (current.label_base_ == object->label_base_) {
(void)RemoveAndDelete(iter);
return;
}
}
VIXL_UNREACHABLE();
}
template <typename T>
typename PoolManager<T>::objects_iter PoolManager<T>::RemoveAndDelete(
objects_iter iter) {
PoolObject<T>& object = *iter;
LocationBase<T>* label_base = object.label_base_;
// Check if we also need to delete the LocationBase object.
if (label_base->ShouldBeDeletedOnPoolManagerDestruction()) {
delete_on_destruction_.push_back(label_base);
}
if (label_base->ShouldBeDeletedOnPlacementByPoolManager()) {
VIXL_ASSERT(!label_base->ShouldBeDeletedOnPoolManagerDestruction());
delete label_base;
}
return objects_.erase(iter);
}
template <typename T>
T PoolManager<T>::Bind(MacroAssemblerInterface* masm,
LocationBase<T>* object,
T location) {
PoolObject<T>* existing_object = GetObjectIfTracked(object);
int alignment;
T min_location;
if (existing_object == NULL) {
alignment = object->GetMaxAlignment();
min_location = object->GetMinLocation();
} else {
alignment = existing_object->alignment_;
min_location = existing_object->min_location_;
}
// Align if needed, and add necessary padding to reach the min_location_.
T aligned_location = AlignUp(location, alignment);
masm->EmitNopBytes(aligned_location - location);
location = aligned_location;
while (location < min_location) {
masm->EmitNopBytes(alignment);
location += alignment;
}
object->SetLocation(masm->AsAssemblerBase(), location);
object->MarkBound();
if (existing_object != NULL) {
RemoveAndDelete(existing_object);
// No need to sort, we removed the object from a sorted array.
RecalculateCheckpoint(kNoSortRequired);
}
// We assume that the maximum padding we can possibly add here is less
// than the header alignment - hence that we're not going to go past our
// checkpoint.
VIXL_ASSERT(!CheckFuturePC(location, checkpoint_));
return location;
}
template <typename T>
void PoolManager<T>::Release(T pc) {
USE(pc);
if (--monitor_ == 0) {
// Ensure the pool has not been blocked for too long.
VIXL_ASSERT(pc <= checkpoint_);
}
}
template <typename T>
PoolManager<T>::~PoolManager<T>() VIXL_NEGATIVE_TESTING_ALLOW_EXCEPTION {
#ifdef VIXL_DEBUG
// Check for unbound objects.
for (objects_iter iter = objects_.begin(); iter != objects_.end(); ++iter) {
// There should not be any bound objects left in the pool. For unbound
// objects, we will check in the destructor of the object itself.
VIXL_ASSERT(!(*iter).label_base_->IsBound());
}
#endif
// Delete objects the pool manager owns.
for (typename std::vector<LocationBase<T>*>::iterator
iter = delete_on_destruction_.begin(),
end = delete_on_destruction_.end();
iter != end;
++iter) {
delete *iter;
}
}
template <typename T>
int PoolManager<T>::GetPoolSizeForTest() const {
// Iterate over objects and return their cumulative size. This does not take
// any padding into account, just the size of the objects themselves.
int size = 0;
for (const_objects_iter iter = objects_.begin(); iter != objects_.end();
++iter) {
size += (*iter).label_base_->GetPoolObjectSizeInBytes();
}
return size;
}
} // namespace vixl
#endif // VIXL_POOL_MANAGER_IMPL_H_
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