Lazily save double registers for HCallRuntime instructions within Hydrogen code stubs.

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 ddaae82022cef07d66f42448d2bc2219633d583f..9b5403d9ab80b5f0c94eaf7b7ba7f5c39b4d78b7 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -862,6 +862,10 @@ void LChunkBuilder::VisitInstruction(HInstruction* current) {
   LInstruction* instr = current->CompileToLithium(this);
 
   if (instr != NULL) {
+    // Associate the hydrogen instruction first, since we may need it for
+    // the ClobbersRegisters() or ClobbersDoubleRegisters() calls below.
+    instr->set_hydrogen_value(current);
+
 #if DEBUG
     // Make sure that the lithium instruction has either no fixed register
     // constraints in temps or the result OR no uses that are only used at
@@ -898,7 +902,6 @@ void LChunkBuilder::VisitInstruction(HInstruction* current) {
     if (FLAG_stress_environments && !instr->HasEnvironment()) {
       instr = AssignEnvironment(instr);
     }
-    instr->set_hydrogen_value(current);
     chunk_->AddInstruction(instr, current_block_);
   }
   current_instruction_ = old_current;