3 files changed, 23 insertions, 3 deletions

diff --git a/compiler/dex/mir_graph.h b/compiler/dex/mir_graph.h
index dbe906280f..23b7c4292b 100644
--- a/compiler/dex/mir_graph.h
+++ b/compiler/dex/mir_graph.h
@@ -173,7 +173,17 @@ enum OatMethodAttributes {
 
 typedef uint16_t BasicBlockId;
 static const BasicBlockId NullBasicBlockId = 0;
-static constexpr bool kLeafOptimization = false;
+
+// Leaf optimization is basically the removal of suspend checks from leaf methods.
+// This is incompatible with SuspendCheckElimination (SCE) which eliminates suspend
+// checks from loops that call any non-intrinsic method, since a loop that calls
+// only a leaf method would end up without any suspend checks at all. So turning
+// this on automatically disables the SCE in MIRGraph::EliminateSuspendChecksGate().
+//
+// Since the Optimizing compiler is actually applying the same optimization, Quick
+// must not run SCE anyway, so we enable this optimization as a way to disable SCE
+// while keeping a consistent behavior across the backends, b/22657404.
+static constexpr bool kLeafOptimization = true;
 
 /*
  * In general, vreg/sreg describe Dalvik registers that originated with dx.  However,
diff --git a/compiler/dex/mir_optimization.cc b/compiler/dex/mir_optimization.cc
index 5bb0ce3ba5..80b7ac1e5b 100644
--- a/compiler/dex/mir_optimization.cc
+++ b/compiler/dex/mir_optimization.cc
@@ -1724,7 +1724,8 @@ void MIRGraph::StringChange() {
 
 
 bool MIRGraph::EliminateSuspendChecksGate() {
-  if ((cu_->disable_opt & (1 << kSuspendCheckElimination)) != 0 ||  // Disabled.
+  if (kLeafOptimization ||           // Incompatible (could create loops without suspend checks).
+      (cu_->disable_opt & (1 << kSuspendCheckElimination)) != 0 ||  // Disabled.
       GetMaxNestedLoops() == 0u ||   // Nothing to do.
       GetMaxNestedLoops() >= 32u ||  // Only 32 bits in suspend_checks_in_loops_[.].
                                      // Exclude 32 as well to keep bit shifts well-defined.
diff --git a/compiler/dex/mir_optimization_test.cc b/compiler/dex/mir_optimization_test.cc
index 10a4337cf5..47123ba28c 100644
--- a/compiler/dex/mir_optimization_test.cc
+++ b/compiler/dex/mir_optimization_test.cc
@@ -467,8 +467,17 @@ class SuspendCheckEliminationTest : public MirOptimizationTest {
     cu_.mir_graph->ComputeDominators();
     cu_.mir_graph->ComputeTopologicalSortOrder();
     cu_.mir_graph->SSATransformationEnd();
+
     bool gate_result = cu_.mir_graph->EliminateSuspendChecksGate();
-    ASSERT_TRUE(gate_result);
+    ASSERT_NE(gate_result, kLeafOptimization);
+    if (kLeafOptimization) {
+      // Even with kLeafOptimization on and Gate() refusing to allow SCE, we want
+      // to run the SCE test to avoid bitrot, so we need to initialize explicitly.
+      cu_.mir_graph->suspend_checks_in_loops_ =
+          cu_.mir_graph->arena_->AllocArray<uint32_t>(cu_.mir_graph->GetNumBlocks(),
+                                                      kArenaAllocMisc);
+    }
+
     TopologicalSortIterator iterator(cu_.mir_graph.get());
     bool change = false;
     for (BasicBlock* bb = iterator.Next(change); bb != nullptr; bb = iterator.Next(change)) {