Support conversion of clamped double values for pixel arrays in Crankshaft.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index f5f2879afd3ec8f836d37b578bc9a5e383d9f46f..69c8c476b9332c101419af852f8aac87471ccabd 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1742,6 +1742,27 @@ LInstruction* LChunkBuilder::DoCheckMap(HCheckMap* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoClampToUint8(HClampToUint8* instr) {
+  HValue* value = instr->value();
+  Representation input_rep = value->representation();
+  LOperand* reg = UseRegister(value);
+  if (input_rep.IsDouble()) {
+    return DefineAsRegister(new LClampDoubleToUint8(reg,
+                                                    TempRegister()));
+  } else if (input_rep.IsInteger32()) {
+    return DefineSameAsFirst(new LClampIToUint8(reg));
+  } else {
+    ASSERT(input_rep.IsTagged());
+    // Register allocator doesn't (yet) support allocation of double
+    // temps. Reserve xmm1 explicitly.
+    LClampTaggedToUint8* result = new LClampTaggedToUint8(reg,
+                                                          TempRegister(),
+                                                          FixedTemp(xmm1));
+    return AssignEnvironment(DefineSameAsFirst(result));
+  }
+}
+
+
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
   return new LReturn(UseFixed(instr->value(), rax));
 }