Allow read side effects for removing dead instructions.

Rationale:
Instructions that only have the harmless read side effect may
be removed when dead as well, we were too strict previously.
As proof of concept, this cl also provides more accurate information
on a few string related intrinsics. This removes the dead indexOf
from CaffeineString (17% performance improvement, big bottleneck
of the StringBuffer's toString() still remains in loop).

Test: test-art-host
Change-Id: Id835a8e287e13e1f09be6b46278a039b8865802e

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index ce2edde1c1..7890183229 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -1956,7 +1956,7 @@ class HInstruction : public ArenaObject<kArenaAllocInstruction> {
 
   bool IsRemovable() const {
     return
-        !HasSideEffects() &&
+        !DoesAnyWrite() &&
         !CanThrow() &&
         !IsSuspendCheck() &&
         !IsControlFlow() &&
@@ -3782,6 +3782,8 @@ class HInvoke : public HInstruction {
     return GetEnvironment()->IsFromInlinedInvoke();
   }
 
+  void SetCanThrow(bool can_throw) { SetPackedFlag<kFlagCanThrow>(can_throw); }
+
   bool CanThrow() const OVERRIDE { return GetPackedFlag<kFlagCanThrow>(); }
 
   bool CanBeMoved() const OVERRIDE { return IsIntrinsic(); }
@@ -3840,8 +3842,6 @@ class HInvoke : public HInstruction {
     SetPackedFlag<kFlagCanThrow>(true);
   }
 
-  void SetCanThrow(bool can_throw) { SetPackedFlag<kFlagCanThrow>(can_throw); }
-
   uint32_t number_of_arguments_;
   ArtMethod* const resolved_method_;
   ArenaVector<HUserRecord<HInstruction*>> inputs_;