Optimizing: Improve constant folding + DCE for inlining.

Run constant folding before DCE in inliner to eliminate more
code that can prevent inlining. Improve the constant folding
to evaluate Equals and NotEquals for null inputs.

Change-Id: I876ffb903ef39484370b6c8793f0f8467a977362

1 files changed, 13 insertions, 0 deletions

diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 4421419f10..ba140afc6b 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -2612,6 +2612,11 @@ class HBinaryOperation : public HExpression<2> {
     VLOG(compiler) << DebugName() << " is not defined for the (long, int) case.";
     return nullptr;
   }
+  virtual HConstant* Evaluate(HNullConstant* x ATTRIBUTE_UNUSED,
+                              HNullConstant* y ATTRIBUTE_UNUSED) const {
+    VLOG(compiler) << DebugName() << " is not defined for the (null, null) case.";
+    return nullptr;
+  }
 
   // Returns an input that can legally be used as the right input and is
   // constant, or null.
@@ -2702,6 +2707,10 @@ class HEqual : public HCondition {
     return GetBlock()->GetGraph()->GetIntConstant(
         Compute(x->GetValue(), y->GetValue()), GetDexPc());
   }
+  HConstant* Evaluate(HNullConstant* x ATTRIBUTE_UNUSED,
+                      HNullConstant* y ATTRIBUTE_UNUSED) const OVERRIDE {
+    return GetBlock()->GetGraph()->GetConstant(GetType(), 1);
+  }
 
   DECLARE_INSTRUCTION(Equal);
 
@@ -2734,6 +2743,10 @@ class HNotEqual : public HCondition {
     return GetBlock()->GetGraph()->GetIntConstant(
         Compute(x->GetValue(), y->GetValue()), GetDexPc());
   }
+  HConstant* Evaluate(HNullConstant* x ATTRIBUTE_UNUSED,
+                      HNullConstant* y ATTRIBUTE_UNUSED) const OVERRIDE {
+    return GetBlock()->GetGraph()->GetConstant(GetType(), 0);
+  }
 
   DECLARE_INSTRUCTION(NotEqual);