Run a simplification pass before code generation.

The code generators assume things that only the instruction
simplier ensures. So it has to be run last in case previous
optimiziations broke those assumptions.

bug:21865464

Change-Id: I1f84016017bf691c2a34982e202a505b269f609a

1 files changed, 7 insertions, 1 deletions

diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index c695abea14..8d43adaada 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -340,9 +340,11 @@ static void RunOptimizations(HGraph* graph,
   InstructionSimplifier* simplify2 = new (arena) InstructionSimplifier(
       graph, stats, "instruction_simplifier_after_types");
   InstructionSimplifier* simplify3 = new (arena) InstructionSimplifier(
-      graph, stats, "last_instruction_simplifier");
+      graph, stats, "instruction_simplifier_after_bce");
   ReferenceTypePropagation* type_propagation2 =
       new (arena) ReferenceTypePropagation(graph, handles);
+  InstructionSimplifier* simplify4 = new (arena) InstructionSimplifier(
+      graph, stats, "instruction_simplifier_before_codegen");
 
   IntrinsicsRecognizer* intrinsics = new (arena) IntrinsicsRecognizer(graph, driver);
 
@@ -367,6 +369,10 @@ static void RunOptimizations(HGraph* graph,
     bce,
     simplify3,
     dce2,
+    // The codegen has a few assumptions that only the instruction simplifier can
+    // satisfy. For example, the code generator does not expect to see a
+    // HTypeConversion from a type to the same type.
+    simplify4,
   };
 
   RunOptimizations(optimizations, arraysize(optimizations), pass_info_printer);