Fuse Comparison->BooleanNegate->Branch.

runtime/vm/flow_graph_optimizer.cc

 // Copyright (c) 2012, 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/flow_graph_optimizer.h"
 
 #include "vm/flow_graph_builder.h"
 #include "vm/il_printer.h"
 #include "vm/object_store.h"
 
@@ skipping 464 matching lines @@
     case kArray:
     case kGrowableObjectArray:
       comp->set_receiver_type(static_cast<ObjectKind>(class_id));
   }
 }
 
 
 static void TryFuseComparisonWithBranch(ComparisonComp* comp) {
   Instruction* instr = comp->instr();
   Instruction* next_instr = instr->StraightLineSuccessor();
-  if (next_instr != NULL && next_instr->IsBranch()) {
+  if ((next_instr != NULL) && next_instr->IsBranch()) {
     BranchInstr* branch = next_instr->AsBranch();
     UseVal* use = branch->value()->AsUse();
     if (instr == use->definition()) {
       comp->MarkFusedWithBranch(branch);
       branch->MarkFusedWithComparison();
+      return;
+    }
+  }
+  if ((next_instr != NULL) && next_instr->IsBind()) {
+    Computation* next_comp = next_instr->AsBind()->computation();
+    if (next_comp->IsBooleanNegate()) {
+      Instruction* next_next_instr = next_instr->StraightLineSuccessor();
+      if ((next_next_instr != NULL) && next_next_instr->IsBranch()) {
+        BooleanNegateComp* negate = next_comp->AsBooleanNegate();
+        BranchInstr* branch = next_next_instr->AsBranch();
+        if ((branch->value()->AsUse()->definition() == negate->instr()) &&
+            (negate->value()->AsUse()->definition() == instr)) {
+          comp->MarkFusedWithBranch(branch);
+          branch->MarkFusedWithComparison();
+          branch->set_is_negated(true);
+          instr->SetSuccessor(next_next_instr);
+          return;
+        }
+      }
     }
   }
 }
 
 
 void FlowGraphOptimizer::VisitRelationalOp(RelationalOpComp* comp) {
   if (!comp->HasICData()) return;
 
   const ICData& ic_data = *comp->ic_data();
   if (ic_data.NumberOfChecks() == 0) return;
   // TODO(srdjan): Add multiple receiver type support.
   if (ic_data.NumberOfChecks() != 1) return;
   ASSERT(HasOneTarget(ic_data));
 
   if (HasTwoSmi(ic_data)) {
     comp->set_operands_class_id(kSmi);
   } else if (HasTwoDouble(ic_data)) {
     comp->set_operands_class_id(kDouble);
   } else {
     return;
   }
 
   // For smi and double comparisons if the next instruction is a conditional
   // branch that uses the value of this comparison mark them as fused together
   // to avoid materializing a boolean value.
-  // TODO(vegorov): recognize the pattern with BooleanNegate between comparsion
-  // and a branch.
   TryFuseComparisonWithBranch(comp);

[Vyacheslav Egorov (Google), 2012/06/20 12:17:40]

there is a special NaN branch inside the Double relational op. Just negating the
branch itself is not enough.

[srdjan, 2012/06/20 16:16:07]

Thanks for catching it. Added following code in intermediate_language_<arch>.cc:
     BlockEntryInstr* nan_result = branch->is_negated() ?
        branch->true_successor() : branch->false_successor();
    __ j(PARITY_EVEN, compiler->GetBlockLabel(nan_result));

 }
 
 
 void FlowGraphOptimizer::VisitStrictCompareComp(StrictCompareComp* comp) {
-  // TODO(vegorov): recognize the pattern with BooleanNegate between comparsion
-  // and a branch.
   TryFuseComparisonWithBranch(comp);
 }
 
 
 void FlowGraphOptimizer::VisitEqualityCompare(EqualityCompareComp* comp) {
   const intptr_t kMaxChecks = 4;
   if (comp->HasICData() && (comp->ic_data()->num_args_tested() <= kMaxChecks)) {
     // Replace binary checks with unary ones.
     ICData& unary_checks =
         ICData::Handle(ToUnaryClassChecks(*comp->ic_data()));
     comp->set_ic_data(&unary_checks);
   }
 
-  // TODO(vegorov): recognize the pattern with BooleanNegate between comparsion
-  // and a branch.
   TryFuseComparisonWithBranch(comp);
 }
 
 
 void FlowGraphOptimizer::VisitDo(DoInstr* instr) {
   instr->computation()->Accept(this);
 }
 
 
 void FlowGraphOptimizer::VisitBind(BindInstr* instr) {
   instr->computation()->Accept(this);
 }
 
 
 }  // namespace dart