commit 9e23df5c21bed53ead79e3131b67105abc8871e4
author Vladimir Marko <vmarko@google.com> Tue Nov 10 17:14:35 2015 +0000
committer Vladimir Marko <vmarko@google.com> Tue Nov 10 18:19:47 2015 +0000
tree b04e042b8de54e631f8f2452eb8ae4de9e23e39e
parent 8a6463a7052ec69e7c0b94a65b26807f570e6359

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

compiler/optimizing/inliner.cc

diff --git a/compiler/optimizing/inliner.cc b/compiler/optimizing/inliner.cc
index 353881e..c9319f5 100644
--- a/compiler/optimizing/inliner.cc
+++ b/compiler/optimizing/inliner.cc
@@ -406,8 +406,8 @@
     &type_propagation,
     &sharpening,
     &simplify,
-    &dce,
     &fold,
+    &dce,
   };
 
   for (size_t i = 0; i < arraysize(optimizations); ++i) {

compiler/optimizing/nodes.cc

diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index f006df1..1a46853 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -1090,6 +1090,8 @@
     } else if (GetRight()->IsLongConstant()) {
       return Evaluate(GetLeft()->AsLongConstant(), GetRight()->AsLongConstant());
     }
+  } else if (GetLeft()->IsNullConstant() && GetRight()->IsNullConstant()) {
+    return Evaluate(GetLeft()->AsNullConstant(), GetRight()->AsNullConstant());
   }
   return nullptr;
 }

compiler/optimizing/nodes.h

diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 4421419..ba140af 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -2612,6 +2612,11 @@
     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 @@
     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 @@
     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);