VM: Explicitly load function and context before calling a closure.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 5469 matching lines @@
                                         BranchInstr* branch) {
   ASSERT(kind() == Token::kEQ_STRICT || kind() == Token::kNE_STRICT);
 
   BranchLabels labels = compiler->CreateBranchLabels(branch);
   Condition true_condition = EmitComparisonCode(compiler, labels);
   EmitBranchOnCondition(compiler, true_condition, labels);
 }
 
 
 LocationSummary* ClosureCallInstr::MakeLocationSummary(bool opt) const {
-  return MakeCallSummary();
+  const intptr_t kNumInputs = 1;
+  const intptr_t kNumTemps = 0;
+  LocationSummary* summary =
+      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kCall);
+  summary->set_in(0, Location::RegisterLocation(RAX));  // Function.
+  summary->set_out(0, Location::RegisterLocation(RAX));
+  return summary;
 }
 
 
 void ClosureCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  // Load closure object (first argument) in R13.
+  // Arguments descriptor is expected in R10.
   intptr_t argument_count = ArgumentCount();
-  __ movq(R13, Address(RSP, (argument_count - 1) * kWordSize));
-
-  // Arguments descriptor is expected in R10.
   const Array& arguments_descriptor =
       Array::ZoneHandle(ArgumentsDescriptor::New(argument_count,
                                                  argument_names()));
   __ LoadObject(R10, arguments_descriptor, PP);
 
-  // Load the actual closure function.
-  __ movq(RAX, FieldAddress(R13, Closure::function_offset()));
-
-  // Load closure context in CTX; note that CTX has already been preserved.
-  __ movq(CTX, FieldAddress(R13, Closure::context_offset()));
-
-  // Load closure function code in RAX.
+  // Function in RAX.
+  ASSERT(locs()->in(0).reg() == RAX);
   __ movq(RCX, FieldAddress(RAX, Function::code_offset()));
 
   // RAX: Function.
   // R10: Arguments descriptor array.
   // RBX: Smi 0 (no IC data; the lazy-compile stub expects a GC-safe value).
   __ xorq(RBX, RBX);
   __ movq(RCX, FieldAddress(RCX, Code::instructions_offset()));
   __ addq(RCX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
   __ call(RCX);
   compiler->AddCurrentDescriptor(PcDescriptors::kClosureCall,
                                  deopt_id(),
                                  token_pos());
   compiler->RecordSafepoint(locs());
   // Marks either the continuation point in unoptimized code or the
   // deoptimization point in optimized code, after call.
   const intptr_t deopt_id_after = Isolate::ToDeoptAfter(deopt_id());
   if (compiler->is_optimizing()) {
-    compiler->AddDeoptIndexAtCall(deopt_id_after, token_pos());
+    compiler->AddDeoptIndexAtCall(deopt_id_after, token_pos(), InputCount());
   } else {
     // Add deoptimization continuation point after the call and before the
     // arguments are removed.
     compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
                                    deopt_id_after,
                                    token_pos());
   }
   __ Drop(argument_count);
 }
 
@@ skipping 31 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64