Refactor handling of input records.

Introduce HInstruction::GetInputRecords(), a new virtual
function that returns an ArrayRef<> to all input records.
Implement all other functions dealing with input records as
wrappers around GetInputRecords(). Rewrite functions that
previously used multiple virtual calls to deal with input
records, especially in loops, to prefetch the ArrayRef<>
only once for each instruction.  Besides avoiding all the
extra calls, this also allows the compiler (clang++) to
perform additional optimizations.

This speeds up the Nexus 5 boot image compilation by ~0.5s
(4% of "Compile Dex File", 2% of dex2oat time) on AOSP ToT.

Change-Id: Id8ebe0fb9405e38d918972a11bd724146e4ca578

1 files changed, 4 insertions, 4 deletions

diff --git a/compiler/optimizing/ssa_liveness_analysis.h b/compiler/optimizing/ssa_liveness_analysis.h
index 1fcba8bc77..dc98864d9b 100644
--- a/compiler/optimizing/ssa_liveness_analysis.h
+++ b/compiler/optimizing/ssa_liveness_analysis.h
@@ -797,8 +797,8 @@ class LiveInterval : public ArenaObject<kArenaAllocSsaLiveness> {
   bool IsUsingInputRegister() const {
     CHECK(kIsDebugBuild) << "Function should be used only for DCHECKs";
     if (defined_by_ != nullptr && !IsSplit()) {
-      for (HInputIterator it(defined_by_); !it.Done(); it.Advance()) {
-        LiveInterval* interval = it.Current()->GetLiveInterval();
+      for (const HInstruction* input : defined_by_->GetInputs()) {
+        LiveInterval* interval = input->GetLiveInterval();
 
         // Find the interval that covers `defined_by`_. Calls to this function
         // are made outside the linear scan, hence we need to use CoversSlow.
@@ -828,8 +828,8 @@ class LiveInterval : public ArenaObject<kArenaAllocSsaLiveness> {
       if (locations->OutputCanOverlapWithInputs()) {
         return false;
       }
-      for (HInputIterator it(defined_by_); !it.Done(); it.Advance()) {
-        LiveInterval* interval = it.Current()->GetLiveInterval();
+      for (const HInstruction* input : defined_by_->GetInputs()) {
+        LiveInterval* interval = input->GetLiveInterval();
 
         // Find the interval that covers `defined_by`_. Calls to this function
         // are made outside the linear scan, hence we need to use CoversSlow.