Use iterators "before" the use node in HUserRecord<>.
Create a new template class IntrusiveForwardList<> that
mimicks std::forward_list<> except that all allocations
are handled externally. This is essentially the same as
boost::intrusive::slist<> but since we're not using Boost
we have to reinvent the wheel.
Use the new container to replace the HUseList and use the
iterators to "before" use nodes in HUserRecord<> to avoid
the extra pointer to the previous node which was used
exclusively for removing nodes from the list. This reduces
the size of the HUseListNode by 25%, 32B to 24B in 64-bit
compiler, 16B to 12B in 32-bit compiler. This translates
directly to overall memory savings for the 64-bit compiler
but due to rounding up of the arena allocations to 8B, we
do not get any improvement in the 32-bit compiler.
Compiling the Nexus 5 boot image with the 64-bit dex2oat
on host this CL reduces the memory used for compiling the
most hungry method, BatteryStats.dumpLocked(), by ~3.3MiB:
Before:
MEM: used: 47829200, allocated: 48769120, lost: 939920
Number of arenas allocated: 345,
Number of allocations: 815492, avg size: 58
...
UseListNode 13744640
...
After:
MEM: used: 44393040, allocated: 45361248, lost: 968208
Number of arenas allocated: 319,
Number of allocations: 815492, avg size: 54
...
UseListNode 10308480
...
Note that while we do not ship the 64-bit dex2oat to the
device, the JIT compilation for 64-bit processes is using
the 64-bit libart-compiler.
Bug: 28173563
Change-Id: I985eabd4816f845372d8aaa825a1489cf9569208
diff --git a/compiler/optimizing/ssa_phi_elimination.cc b/compiler/optimizing/ssa_phi_elimination.cc
index 6816b6a..aeb3109 100644
--- a/compiler/optimizing/ssa_phi_elimination.cc
+++ b/compiler/optimizing/ssa_phi_elimination.cc
@@ -43,8 +43,8 @@
bool keep_alive = (graph_->IsDebuggable() && phi->HasEnvironmentUses());
if (!keep_alive) {
- for (HUseIterator<HInstruction*> use_it(phi->GetUses()); !use_it.Done(); use_it.Advance()) {
- if (!use_it.Current()->GetUser()->IsPhi()) {
+ for (const HUseListNode<HInstruction*>& use : phi->GetUses()) {
+ if (!use.GetUser()->IsPhi()) {
keep_alive = true;
break;
}
@@ -94,9 +94,8 @@
if (phi->IsDead()) {
// Make sure the phi is only used by other dead phis.
if (kIsDebugBuild) {
- for (HUseIterator<HInstruction*> use_it(phi->GetUses()); !use_it.Done();
- use_it.Advance()) {
- HInstruction* user = use_it.Current()->GetUser();
+ for (const HUseListNode<HInstruction*>& use : phi->GetUses()) {
+ HInstruction* user = use.GetUser();
DCHECK(user->IsLoopHeaderPhi());
DCHECK(user->AsPhi()->IsDead());
}
@@ -106,11 +105,9 @@
phi->RemoveAsUserOfInput(i);
}
// Remove the phi from environments that use it.
- for (HUseIterator<HEnvironment*> use_it(phi->GetEnvUses()); !use_it.Done();
- use_it.Advance()) {
- HUseListNode<HEnvironment*>* user_node = use_it.Current();
- HEnvironment* user = user_node->GetUser();
- user->SetRawEnvAt(user_node->GetIndex(), nullptr);
+ for (const HUseListNode<HEnvironment*>& use : phi->GetEnvUses()) {
+ HEnvironment* user = use.GetUser();
+ user->SetRawEnvAt(use.GetIndex(), nullptr);
}
// Delete it from the instruction list.
block->RemovePhi(phi, /*ensure_safety=*/ false);
@@ -233,9 +230,8 @@
// Because we're updating the users of this phi, we may have new candidates
// for elimination. Add phis that use this phi to the worklist.
- for (HUseIterator<HInstruction*> it(current->GetUses()); !it.Done(); it.Advance()) {
- HUseListNode<HInstruction*>* use = it.Current();
- HInstruction* user = use->GetUser();
+ for (const HUseListNode<HInstruction*>& use : current->GetUses()) {
+ HInstruction* user = use.GetUser();
if (user->IsPhi() && !ContainsElement(visited_phis_in_cycle, user->GetId())) {
worklist_.push_back(user->AsPhi());
}