dart2js: Constant folding and specialization for remainder

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

Index: pkg/compiler/lib/src/ssa/value_range_analyzer.dart
diff --git a/pkg/compiler/lib/src/ssa/value_range_analyzer.dart b/pkg/compiler/lib/src/ssa/value_range_analyzer.dart
index 3f041a062f07a78d68f9fa31ad680fdf7fb753c9..7e53d06bac62445d1de327e18783a02ace8c910c 100644
--- a/pkg/compiler/lib/src/ssa/value_range_analyzer.dart
+++ b/pkg/compiler/lib/src/ssa/value_range_analyzer.dart
@@ -814,8 +814,8 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
     HInstruction right = invoke.inputs[2];
     Range divisor = ranges[right];
     if (divisor != null) {
-      // For Integer values we can be precise in the upper bound,
-      // so special case those.
+      // For Integer values we can be precise in the upper bound, so special
+      // case those.
       if (left.isInteger(closedWorld) && right.isInteger(closedWorld)) {
         if (divisor.isPositive) {
           return info.newNormalizedRange(
@@ -836,6 +836,30 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
     return info.newUnboundRange();
   }
 
+  Range visitRemainder(HRemainder instruction) {
+    HInstruction left = instruction.inputs[0];
+    HInstruction right = instruction.inputs[1];
+    Range dividend = ranges[left];
+    // If both operands are >=0, the result is >= 0 and bounded by the divisor.
+    if ((dividend != null && dividend.isPositive) ||
+        left.isPositiveInteger(closedWorld)) {
+      Range divisor = ranges[right];
+      if (divisor != null) {
+        if (divisor.isPositive) {
+          // For Integer values we can be precise in the upper bound.
+          if (left.isInteger(closedWorld) && right.isInteger(closedWorld)) {
+            return info.newNormalizedRange(
+                info.intZero, divisor.upper - info.intOne);
+          }
+          if (left.isNumber(closedWorld) && right.isNumber(closedWorld)) {
+            return info.newNormalizedRange(info.intZero, divisor.upper);
+          }
+        }
+      }
+    }
+    return info.newUnboundRange();
+  }
+
   Range visitInvokeDynamicMethod(HInvokeDynamicMethod invoke) {
     if ((invoke.inputs.length == 3) && (invoke.selector.name == "%"))
       return handleInvokeModulo(invoke);