dart2js: improve ssa utilization of bool value types

pkg/compiler/lib/src/ssa/optimize.dart

 // 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.
 
 part of ssa;
 
 abstract class OptimizationPhase {
   String get name;
   void visitGraph(HGraph graph);
 }
@@ skipping 182 matching lines @@
         block.remove(instruction);
       }
       instruction = next;
     }
   }
 
   HInstruction visitInstruction(HInstruction node) {
     return node;
   }
 
+  void replaceUsesWithConstant(HInstruction known) {
+    if (known.isValue() && !known.canBeNull()) {
+      ValueTypeMask valueMask = known.instructionType;
+      if (valueMask.value.isBool) {
+        bool knownValue = valueMask.value.isTrue;
+        var users = new List.from(known.usedBy);
+        users.forEach((HInstruction user) {

[sra1, 2015/09/30 16:49:39]

maybe just write:

for (HInstruction user in known.usedBy.toList()) {
}

[Harry Terkelsen, 2015/09/30 18:39:26]

Done.

+          user.changeUse(known, graph.addConstantBool(knownValue, compiler));

[sra1, 2015/09/30 16:49:39]

Factor this into (1) finding the HConstant (if any) (2) doing the replacement
(which can reuse the constant).

If (1) is extended (replace ints, small strings, etc) this will be cleaner.

First check usedBy is not empty (it will be on second pass) to avoid computing
the constant.

[Harry Terkelsen, 2015/09/30 18:39:26]

Done.

+        });
+      }
+    }
+  }
+
+  HInstruction visitParameterValue(HParameterValue node) {
+    replaceUsesWithConstant(node);

[sra1, 2015/09/30 16:49:40]

Reading this I ask 'why'?
Maybe call it propagateConstantValueToUses

[Harry Terkelsen, 2015/09/30 18:39:26]

Done.

+    return node;
+  }
+
   HInstruction visitBoolify(HBoolify node) {
     List<HInstruction> inputs = node.inputs;
     assert(inputs.length == 1);
     HInstruction input = inputs[0];
     if (input.isBoolean(compiler)) return input;
 
     // If the code is unreachable, remove the HBoolify.  This can happen when
     // there is a throw expression in a short-circuit conditional.  Removing the
     // unreachable HBoolify makes it easier to reconstruct the short-circuit
     // operation.
@@ skipping 182 matching lines @@
         // TODO(ngeoffray): If the method has optional parameters,
         // we should pass the default values.
         FunctionSignature parameters = method.functionSignature;
         if (parameters.optionalParameterCount == 0 ||
             parameters.parameterCount ==
                 node.selector.argumentCount) {
           node.element = element;
         }
       }
     }
+    replaceUsesWithConstant(node);

[sra1, 2015/09/30 16:49:40]

Any reason not to do this first?
It might require more mock_library changes.

[Harry Terkelsen, 2015/09/30 18:39:26]

Done.

     return node;
   }
 
   HInstruction tryInlineNativeMethod(HInvokeDynamicMethod node,
                                      FunctionElement method) {
     // Enable direct calls to a native method only if we don't run in checked
     // mode, where the Dart version may have type annotations on parameters and
     // return type that it should check.
     // Also check that the parameters are not functions: it's the callee that
     // will translate them to JS functions.
@@ skipping 389 matching lines @@
     }
     return node;
   }
 
   HInstruction visitInvokeDynamicGetter(HInvokeDynamicGetter node) {
     if (node.isInterceptedCall) {
       HInstruction folded = handleInterceptedCall(node);
       if (folded != node) return folded;
     }
     HInstruction receiver = node.getDartReceiver(compiler);
+    replaceUsesWithConstant(node);

[sra1, 2015/09/30 16:49:39]

Any reason not to do this first?
We might know we are calling (const EmptyIterator()).isEmpty; which returns
true.

[Harry Terkelsen, 2015/09/30 18:39:26]

Done.

     Element field = findConcreteFieldForDynamicAccess(
         receiver, node.selector);
     if (field == null) return node;
     return directFieldGet(receiver, field);
   }
 
   HInstruction directFieldGet(HInstruction receiver, Element field) {
     bool isAssignable = !compiler.world.fieldNeverChanges(field);
 
     TypeMask type;
@@ skipping 36 matching lines @@
           HTypeConversion.CHECKED_MODE_CHECK);
       if (other != value) {
         node.block.addBefore(node, other);
         value = other;
       }
     }
     return new HFieldSet(field, receiver, value);
   }
 
   HInstruction visitInvokeStatic(HInvokeStatic node) {
+    replaceUsesWithConstant(node);
     if (node.element == backend.getCheckConcurrentModificationError()) {
       if (node.inputs.length == 2) {
         HInstruction firstArgument = node.inputs[0];
         if (firstArgument is HConstant) {
           HConstant constant = firstArgument;
           if (constant.constant.isTrue) return constant;
         }
       }
     }
     return node;
@@ skipping 419 matching lines @@
   }
 
   void visitIf(HIf instruction) {
     HInstruction condition = instruction.condition;
     if (condition.isConstant()) {
       if (condition.isConstantTrue()) {
         markBlockLive(instruction.thenBlock);
       } else {
         markBlockLive(instruction.elseBlock);
       }
-    } else if (condition.isValue()) {
-      ValueTypeMask valueType = condition.instructionType;
-      if (valueType.value == true) {
-        markBlockLive(instruction.thenBlock);
-      } else {
-        markBlockLive(instruction.elseBlock);
-      }
     } else {
       visitControlFlow(instruction);
     }
   }
 
   void visitSwitch(HSwitch node) {
     if (node.expression.isInteger(compiler)) {
       Range switchRange = ranges[node.expression];
       if (switchRange != null &&
           switchRange.lower is IntValue &&
@@ skipping 1033 matching lines @@
 
     keyedValues.forEach((receiver, values) {
       result.keyedValues[receiver] =
           new Map<HInstruction, HInstruction>.from(values);
     });
 
     result.nonEscapingReceivers.addAll(nonEscapingReceivers);
     return result;
   }
 }