Don't consider TryBoundary instruction as uncommon branches

We can construct a graph that ends with Return -> TryBoundary
-> Exit. We don't want to consider that path as an uncommon branch.

Test: art/test/testrunner/testrunner.py --host --64 --optimizing -b
Change-Id: Ia02beeca36f2e43a4b3bd49c253fc161d8307924

1 files changed, 17 insertions, 0 deletions

diff --git a/compiler/optimizing/code_sinking.cc b/compiler/optimizing/code_sinking.cc
index e7a4389ed2..76885ec0a6 100644
--- a/compiler/optimizing/code_sinking.cc
+++ b/compiler/optimizing/code_sinking.cc
@@ -37,6 +37,23 @@ bool CodeSinking::Run() {
   // as an indicator of an uncommon branch.
   for (HBasicBlock* exit_predecessor : exit->GetPredecessors()) {
     HInstruction* last = exit_predecessor->GetLastInstruction();
+
+    // TryBoundary instructions are sometimes inserted between the last instruction (e.g. Throw,
+    // Return) and Exit. We don't want to use that instruction for our "uncommon branch" heuristic
+    // because they are not as good an indicator as throwing branches, so we skip them and fetch the
+    // actual last instruction.
+    if (last->IsTryBoundary()) {
+      // We have an exit try boundary. Fetch the previous instruction.
+      DCHECK(!last->AsTryBoundary()->IsEntry());
+      if (last->GetPrevious() == nullptr) {
+        DCHECK(exit_predecessor->IsSingleTryBoundary());
+        exit_predecessor = exit_predecessor->GetSinglePredecessor();
+        last = exit_predecessor->GetLastInstruction();
+      } else {
+        last = last->GetPrevious();
+      }
+    }
+
     // Any predecessor of the exit that does not return, throws an exception.
     if (!last->IsReturn() && !last->IsReturnVoid()) {
       SinkCodeToUncommonBranch(exit_predecessor);