Fix representation change insertion for phis.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 9ccd4ed5ef7d303c156898c6aa138f952e3719ff..bcd697b69495d55fb30286505c8461ccd4ef7a61 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -255,12 +255,14 @@ class RepresentationSelector {
   void VisitPhi(Node* node, MachineTypeUnion use) {
     // First, propagate the usage information to inputs of the phi.
     int values = OperatorProperties::GetValueInputCount(node->op());

[Michael Starzinger, 2014/09/02 08:37:01]

nit: Can we move the values into the condition (i.e. one line below). Having it
be decremented to zero in two exclusive conditions looks dangerous to me.

[titzer, 2014/09/02 10:14:58]

Done.

-    Node::Inputs inputs = node->inputs();
-    for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end();
-         ++iter, --values) {
+    if (!lower()) {
       // Propagate {use} of the phi to value inputs, and 0 to control.
-      // TODO(titzer): it'd be nice to have distinguished edge kinds here.
-      ProcessInput(node, iter.index(), values > 0 ? use : 0);
+      Node::Inputs inputs = node->inputs();
+      for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end();
+           ++iter, --values) {
+        // TODO(titzer): it'd be nice to have distinguished edge kinds here.
+        ProcessInput(node, iter.index(), values > 0 ? use : 0);
+      }
     }
     // Phis adapt to whatever output representation their uses demand,
     // pushing representation changes to their inputs.
@@ -296,7 +298,18 @@ class RepresentationSelector {
     }
     // Preserve the usage type, but set the representation.
     Type* upper = NodeProperties::GetBounds(node).upper;
-    SetOutput(node, rep | changer_->TypeFromUpperBound(upper));
+    MachineTypeUnion output_type = rep | changer_->TypeFromUpperBound(upper);
+    SetOutput(node, output_type);
+
+    if (lower()) {
+      // Convert inputs to the output representation of this phi.
+      Node::Inputs inputs = node->inputs();
+      for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end();
+           ++iter, --values) {
+        // TODO(titzer): it'd be nice to have distinguished edge kinds here.
+        ProcessInput(node, iter.index(), values > 0 ? output_type : 0);
+      }
+    }
   }
 
   Operator* Int32Op(Node* node) {