WIP: Implement ES6 Spread-calls

src/x64/code-stubs-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 1866 matching lines @@
   __ testb(FieldOperand(rcx, SharedFunctionInfo::kNativeByteOffset),
            Immediate(1 << SharedFunctionInfo::kNativeBitWithinByte));
   __ j(not_equal, cont);
 }
 
 
 static void EmitSlowCase(Isolate* isolate,
                          MacroAssembler* masm,
                          StackArgumentsAccessor* args,
                          int argc,
-                         Label* non_function) {
+                         Label* non_function,
+                         bool is_spread = false) {
   // Check for function proxy.
   __ CmpInstanceType(rcx, JS_FUNCTION_PROXY_TYPE);
   __ j(not_equal, non_function);
   __ PopReturnAddressTo(rcx);
   __ Push(rdi);  // put proxy as additional argument under return address
   __ PushReturnAddressFrom(rcx);
-  __ Set(rax, argc + 1);
+  if (!is_spread) {
+    __ Set(rax, argc + 1);
+  }
   __ Set(rbx, 0);
   __ GetBuiltinEntry(rdx, Builtins::CALL_FUNCTION_PROXY);
   {
     Handle<Code> adaptor =
         masm->isolate()->builtins()->ArgumentsAdaptorTrampoline();
     __ jmp(adaptor, RelocInfo::CODE_TARGET);
   }
 
   // CALL_NON_FUNCTION expects the non-function callee as receiver (instead
   // of the original receiver from the call site).
   __ bind(non_function);
   __ movp(args->GetReceiverOperand(), rdi);
-  __ Set(rax, argc);
+  if (!is_spread) {
+    __ Set(rax, argc);
+  }
   __ Set(rbx, 0);
   __ GetBuiltinEntry(rdx, Builtins::CALL_NON_FUNCTION);
   Handle<Code> adaptor =
       isolate->builtins()->ArgumentsAdaptorTrampoline();
   __ Jump(adaptor, RelocInfo::CODE_TARGET);
 }
 
 
 static void EmitWrapCase(MacroAssembler* masm,
                          StackArgumentsAccessor* args,
-                         Label* cont) {
+                         Label* cont, bool is_spread = false) {
   // Wrap the receiver and patch it back onto the stack.
   { FrameScope frame_scope(masm, StackFrame::INTERNAL);
+    // If is_spread is true, dynamic argument count is in $r8 temporarily
+    if (is_spread) __ Push(r8);
     __ Push(rdi);
     __ Push(rax);
     __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
     __ Pop(rdi);
+    if (is_spread) __ Pop(r8);
   }
-  __ movp(args->GetReceiverOperand(), rax);
+  if (is_spread) {
+    DCHECK(args->argument_count_reg().is(rax));
+    __ xchgp(rax, r8);
+    __ movp(args->GetReceiverOperand(), r8);
+  } else {
+    __ movp(args->GetReceiverOperand(), rax);
+  }
   __ jmp(cont);
 }
 
 
 static void CallFunctionNoFeedback(MacroAssembler* masm,
                                    int argc, bool needs_checks,
-                                   bool call_as_method) {
+                                   bool call_as_method,
+                                   bool is_spread = false) {
   // rdi : the function to call
+  // rcx : the dynamic argument count (if is_spread is true)
 
   // wrap_and_call can only be true if we are compiling a monomorphic method.
   Isolate* isolate = masm->isolate();
   Label slow, non_function, wrap, cont;
-  StackArgumentsAccessor args(rsp, argc);
-
+  StackArgumentsAccessor args = is_spread ?
+      StackArgumentsAccessor(rsp, rax) : StackArgumentsAccessor(rsp, argc);
   if (needs_checks) {
     // Check that the function really is a JavaScript function.
     __ JumpIfSmi(rdi, &non_function);
 
     // Goto slow case if we do not have a function.
     __ CmpObjectType(rdi, JS_FUNCTION_TYPE, rcx);
     __ j(not_equal, &slow);
   }
 
   // Fast-case: Just invoke the function.
-  ParameterCount actual(argc);
+  ParameterCount actual = is_spread ?
+      ParameterCount(rax) : ParameterCount(argc);
 
   if (call_as_method) {
+    // If is_spread is true, preserve dynamic argument count in r8
+    if (is_spread) __ xchgp(r8, rax);
+
     if (needs_checks) {
       EmitContinueIfStrictOrNative(masm, &cont);
     }
 
-    // Load the receiver from the stack.
+    // Load the receiver from the stack. If is_spread is true, args is now
+    // broken.
     __ movp(rax, args.GetReceiverOperand());
 
     if (needs_checks) {
       __ JumpIfSmi(rax, &wrap);
 
       __ CmpObjectType(rax, FIRST_SPEC_OBJECT_TYPE, rcx);
       __ j(below, &wrap);
     } else {
       __ jmp(&wrap);
     }
 
     __ bind(&cont);
   }
 
   __ InvokeFunction(rdi, actual, JUMP_FUNCTION, NullCallWrapper());
 
   if (needs_checks) {
     // Slow-case: Non-function called.
     __ bind(&slow);
-    EmitSlowCase(isolate, masm, &args, argc, &non_function);
+    EmitSlowCase(isolate, masm, &args, argc, &non_function, is_spread);
   }
 
   if (call_as_method) {
     __ bind(&wrap);
-    EmitWrapCase(masm, &args, &cont);
+    EmitWrapCase(masm, &args, &cont, is_spread);
   }
 }
 
 
 void CallFunctionStub::Generate(MacroAssembler* masm) {
-  CallFunctionNoFeedback(masm, argc(), NeedsChecks(), CallAsMethod());
+  CallFunctionNoFeedback(masm, argc(), NeedsChecks(), CallAsMethod(),
+                         is_spread());
 }
 
 
 void CallConstructStub::Generate(MacroAssembler* masm) {
   // rax : number of arguments
   // rbx : feedback vector
   // rdx : (only if rbx is not the megamorphic symbol) slot in feedback
   //       vector (Smi)
   // rdi : constructor function
   Label slow, non_function_call;
@@ skipping 106 matching lines @@
                          arg_count(),
                          true,
                          CallAsMethod());
 
   // Unreachable.
   __ int3();
 }
 
 
 void CallICStub::Generate(MacroAssembler* masm) {
+  // rax - argument count (only if call is a spread call)
   // rdi - function
   // rdx - slot id
   // rbx - vector
   Isolate* isolate = masm->isolate();
   const int with_types_offset =
       FixedArray::OffsetOfElementAt(TypeFeedbackVector::kWithTypesIndex);
   const int generic_offset =
       FixedArray::OffsetOfElementAt(TypeFeedbackVector::kGenericCountIndex);
   Label extra_checks_or_miss, slow_start;
   Label slow, non_function, wrap, cont;
   Label have_js_function;
   int argc = arg_count();
-  StackArgumentsAccessor args(rsp, argc);
-  ParameterCount actual(argc);
+  StackArgumentsAccessor args = is_spread() ?
+      StackArgumentsAccessor(rsp, rax) : StackArgumentsAccessor(rsp, argc);
+  ParameterCount actual = is_spread() ?
+      ParameterCount(rax) : ParameterCount(argc);
 
   // The checks. First, does rdi match the recorded monomorphic target?
   __ SmiToInteger32(rdx, rdx);
   __ movp(rcx,
           FieldOperand(rbx, rdx, times_pointer_size, FixedArray::kHeaderSize));
 
   // We don't know that we have a weak cell. We might have a private symbol
   // or an AllocationSite, but the memory is safe to examine.
   // AllocationSite::kTransitionInfoOffset - contains a Smi or pointer to
   // FixedArray.
@@ skipping 2929 matching lines @@
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref, getter_arg,
                            kStackSpace, nullptr, return_value_operand, NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64