ART: Fix Quick/Optimizing suspend check assumption mismatch.
Quick's SuspendCheckElimination (SCE) expects that every
method contains a suspend check and it eliminates suspend
checks in loops containing an invoke. Optimizing eliminates
the suspend check from leaf methods, so the combination of
a Quick-compiled loop calling an Optimizing-compiled leaf
method can lead to missing suspend checks and potentially
leading to ANRs.
Enable Quick's kLeafOptimization flag to remove suspend
checks from leaf methods and disable Quick's SCE. This
aligns the suspend check placement for the two backends
and avoids the broken combination.
Currently, all methods containing a try-catch are compiled
with Quick, so it's relatively easy to create a regression
test. However, this test will not be valid when Optimizing
starts supporting try-catch.
Bug: 22657404
Change-Id: I3bc40bf3f5c1e7d18704d1547b139e939950b770
diff --git a/compiler/dex/mir_graph.h b/compiler/dex/mir_graph.h
index dbe9062..23b7c42 100644
--- a/compiler/dex/mir_graph.h
+++ b/compiler/dex/mir_graph.h
@@ -173,7 +173,17 @@
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,