Add bool value types to type inference.

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 1288 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;

[sra1, 2015/09/29 01:02:05]

I don't think we should it like this.

We should rather replace values that are inferred to a constant bool with a
HConstant in SsaInstructionSimplifier.  That will (1) sever dependencies and (2)
enable constant folding.

E.g.

    r = massiveFnReturningArgument(false);
    if (r != null)
      print(r);

becomes

    massiveFnReturningArgument(false);
    P.printLine("false");


1. Add helper method to SsaInstructionSimplifier to check and replace all uses
of an instruction with the appropriate HConstant if appropriate.
2. Add SsaInstructionSimplifier.visitParameterValue and call the helper to
convert values coming in from call site arguments.
3. Add calls at a few of the visitInvokeXXX methods too convert values returned
from call sites.

[Harry Terkelsen, 2015/09/29 01:09:53]

I wanted to do this but I didn't know how to convert to an HConstant while also
doing calls for the effects. What is the correct way?

[Harry Terkelsen, 2015/09/29 01:16:34]

Oops, replied before fully reading your comment. I'll implement this

+      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;
   }
 }