Complete unrolling of loops with small body and trip count one.

Rationale:
Avoids the unnecessary loop control overhead, suspend check,
and exposes more opportunities for constant folding in the
resulting loop body. Fully unrolls loop in execute() of
the Dhrystone benchmark (3% to 8% improvements).

Test: test-art-host

Change-Id: If30f38caea9e9f87a929df041dfb7ed1c227aba3

1 files changed, 6 insertions, 2 deletions

diff --git a/compiler/optimizing/induction_var_range.cc b/compiler/optimizing/induction_var_range.cc
index d5c4c2fa69..6d8ae75460 100644
--- a/compiler/optimizing/induction_var_range.cc
+++ b/compiler/optimizing/induction_var_range.cc
@@ -368,10 +368,14 @@ void InductionVarRange::Replace(HInstruction* instruction,
   }
 }
 
-bool InductionVarRange::IsFinite(HLoopInformation* loop) const {
+bool InductionVarRange::IsFinite(HLoopInformation* loop, /*out*/ int64_t* tc) const {
   HInductionVarAnalysis::InductionInfo *trip =
       induction_analysis_->LookupInfo(loop, GetLoopControl(loop));
-  return trip != nullptr && !IsUnsafeTripCount(trip);
+  if (trip != nullptr && !IsUnsafeTripCount(trip)) {
+    IsConstant(trip->op_a, kExact, tc);
+    return true;
+  }
+  return false;
 }
 
 //