Merge (x & y) == 0 pattern to emit a single test instruction.

runtime/vm/intermediate_language.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
@@ skipping 742 matching lines @@
   set_previous(NULL);
   set_next(NULL);
 }
 
 
 BranchInstr::BranchInstr(ComparisonInstr* comparison, bool is_checked)
     : comparison_(comparison),
       is_checked_(is_checked),
       constrained_type_(NULL),
       constant_target_(NULL) {
+  ASSERT(comparison->env() == NULL);
   for (intptr_t i = comparison->InputCount() - 1; i >= 0; --i) {
     comparison->InputAt(i)->set_instruction(this);
   }
 }
 
 
 void BranchInstr::RawSetInputAt(intptr_t i, Value* value) {
   comparison()->RawSetInputAt(i, value);
 }
 
 
 // A misleadingly named function for use in template functions that replace
 // both definitions with definitions and branch comparisons with
 // comparisons.  In the branch case, leave the branch intact and replace its
 // comparison with a new comparison not currently in the graph.
 void BranchInstr::ReplaceWith(ComparisonInstr* other,
                               ForwardInstructionIterator* ignored) {
   SetComparison(other);
 }
 
 
-void BranchInstr::SetComparison(ComparisonInstr* comp) {
-  for (intptr_t i = comp->InputCount() - 1; i >= 0; --i) {
-    Value* input = comp->InputAt(i);
+void BranchInstr::SetComparison(ComparisonInstr* new_comparison) {
+  for (intptr_t i = new_comparison->InputCount() - 1; i >= 0; --i) {
+    Value* input = new_comparison->InputAt(i);
     input->definition()->AddInputUse(input);
     input->set_instruction(this);
   }
   // There should be no need to copy or unuse an environment.
   ASSERT(comparison()->env() == NULL);
+  ASSERT(new_comparison->env() == NULL);
   // Remove the current comparison's input uses.
   comparison()->UnuseAllInputs();
-  ASSERT(!comp->HasUses());
-  comparison_ = comp;
+  ASSERT(!new_comparison->HasUses());
+  comparison_ = new_comparison;
 }
 
 
 // ==== Postorder graph traversal.
 static bool IsMarked(BlockEntryInstr* block,
                      GrowableArray<BlockEntryInstr*>* preorder) {
   // Detect that a block has been visited as part of the current
   // DiscoverBlocks (we can call DiscoverBlocks multiple times).  The block
   // will be 'marked' by (1) having a preorder number in the range of the
   // preorder array and (2) being in the preorder array at that index.
@@ skipping 804 matching lines @@
       other_defn->IsComparison() &&
       (other->Type()->ToCid() == kBoolCid) &&
       other_defn->HasOnlyUse(other)) {
     *negated = true;
     return other_defn;
   }
   return compare;
 }
 
 
+// Recognize the pattern (a & b) == 0 where left is a bitwise and operation
+// and right is a constant 0.
+static bool RecognizeTestPattern(Value* left, Value* right) {
+  if (!right->BindsToConstant()) {
+    return false;
+  }
+
+  const Object& value = right->BoundConstant();
+  if (!value.IsSmi() || (Smi::Cast(value).Value() != 0)) {
+    return false;
+  }
+
+  Definition* left_defn = left->definition();
+  return left_defn->IsBinarySmiOp() &&
+      (left_defn->AsBinarySmiOp()->op_kind() == Token::kBIT_AND) &&
+      left_defn->HasOnlyUse(left);
+}
+
+
 Instruction* BranchInstr::Canonicalize(FlowGraph* flow_graph) {
   // Only handle strict-compares.
   if (comparison()->IsStrictCompare()) {
     bool negated = false;
     Definition* replacement =
         CanonicalizeStrictCompare(comparison()->AsStrictCompare(), &negated);
     if (replacement == comparison()) {
       return this;
     }
     ComparisonInstr* comp = replacement->AsComparison();
@@ skipping 27 matching lines @@
       SetComparison(comp);
       if (FLAG_trace_optimization) {
         OS::Print("Merging comparison v%" Pd "\n", comp->ssa_temp_index());
       }
       // Clear the comparison's temp index and ssa temp index since the
       // value of the comparison is not used outside the branch anymore.
       ASSERT(comp->input_use_list() == NULL);
       comp->ClearSSATempIndex();
       comp->ClearTempIndex();
     }
+  } else if (comparison()->IsEqualityCompare() &&
+             comparison()->operation_cid() == kSmiCid) {
+    BinarySmiOpInstr* bit_and = NULL;
+    if (RecognizeTestPattern(comparison()->left(), comparison()->right())) {
+      bit_and = comparison()->left()->definition()->AsBinarySmiOp();
+    } else if (RecognizeTestPattern(comparison()->right(),
+                                    comparison()->left())) {
+      bit_and = comparison()->right()->definition()->AsBinarySmiOp();
+    }
+    if (bit_and != NULL) {
+      if (FLAG_trace_optimization) {
+        OS::Print("Merging test smi v%" Pd "\n", bit_and->ssa_temp_index());
+      }
+      TestSmiInstr* test = new TestSmiInstr(comparison()->token_pos(),
+                                            comparison()->kind(),
+                                            bit_and->left()->Copy(),
+                                            bit_and->right()->Copy());
+      ASSERT(!CanDeoptimize());
+      RemoveEnvironment();
+      flow_graph->CopyDeoptTarget(this, bit_and);
+      SetComparison(test);
+      bit_and->RemoveFromGraph();
+    }
   }
   return this;
 }
 
 
 Definition* StrictCompareInstr::Canonicalize(FlowGraph* flow_graph) {
   bool negated = false;
   Definition* replacement = CanonicalizeStrictCompare(this, &negated);
   if (negated && replacement->IsComparison()) {
     ASSERT(replacement != this);
@@ skipping 1200 matching lines @@
       return kCosRuntimeEntry;
     default:
       UNREACHABLE();
   }
   return kSinRuntimeEntry;
 }
 
 #undef __
 
 }  // namespace dart