Fix range-analysis.

sdk/lib/_internal/compiler/implementation/ssa/value_range_analyzer.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/value_range_analyzer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/value_range_analyzer.dart b/sdk/lib/_internal/compiler/implementation/ssa/value_range_analyzer.dart
index f58002930542c2b2d5ecb7d53e5696386a7f60cf..dc3f53ed12440bf1d3c90f986a5320d58c09d172 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/value_range_analyzer.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/value_range_analyzer.dart
@@ -899,6 +899,20 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
     }
   }
 
+  static BinaryOperation mirrorOperation(BinaryOperation operation) {

[Kevin Millikin (Google), 2014/07/07 14:23:31]

'flipOperation'?  Since mirrors is a thing in Dart.

[floitsch, 2014/07/07 16:02:49]

Done.

+    if (operation == const LessOperation()) {
+      return const GreaterOperation();
+    } else if (operation == const LessEqualOperation()) {
+      return const GreaterEqualOperation();
+    } else if (operation == const GreaterOperation()) {
+      return const LessOperation();
+    } else if (operation == const GreaterEqualOperation()) {
+      return const LessEqualOperation();
+    } else {
+      return null;
+    }
+  }
+
   Range computeConstrainedRange(BinaryOperation operation,
                                 Range leftRange,
                                 Range rightRange) {
@@ -932,7 +946,7 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
     Range rightRange = ranges[right];
     Range leftRange = ranges[left];
     Operation operation = condition.operation(constantSystem);
-    Operation reverse = reverseOperation(operation);
+    Operation mirrorOp = mirrorOperation(operation);
     // Only update the true branch if this block is the only
     // predecessor.
     if (branch.trueBranch.predecessors.length == 1) {
@@ -946,7 +960,7 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
         ranges[instruction] = range;
       }
 
-      range = computeConstrainedRange(reverse, rightRange, leftRange);
+      range = computeConstrainedRange(mirrorOp, rightRange, leftRange);
       if (rightRange != range) {
         HInstruction instruction =
             createRangeConversion(branch.trueBranch.first, right);
@@ -958,6 +972,8 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
     // predecessor.
     if (branch.falseBranch.predecessors.length == 1) {
       assert(branch.falseBranch.predecessors[0] == branch.block);
+      Operation reverse = reverseOperation(operation);
+      Operation reversedMirror = mirrorOperation(reverse);
       // Update the false branch to use narrower ranges for [left] and
       // [right].
       Range range = computeConstrainedRange(reverse, leftRange, rightRange);
@@ -967,7 +983,7 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
         ranges[instruction] = range;
       }
 
-      range = computeConstrainedRange(operation, rightRange, leftRange);
+      range = computeConstrainedRange(reversedMirror, rightRange, leftRange);
       if (rightRange != range) {
         HInstruction instruction =
             createRangeConversion(branch.falseBranch.first, right);