[wasm] Fix {InstantiateAsmJs} builtin on x64.

src/builtins/x64/builtins-x64.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 1102 matching lines @@
 void Builtins::Generate_InstantiateAsmJs(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax : argument count (preserved for callee)
   //  -- rdx : new target (preserved for callee)
   //  -- rdi : target function (preserved for callee)
   // -----------------------------------
   Label failed;
   {
     FrameScope scope(masm, StackFrame::INTERNAL);
     // Preserve argument count for later compare.
-    __ movp(kScratchRegister, rax);
+    __ movp(rcx, rax);
     // Push the number of arguments to the callee.
     __ Integer32ToSmi(rax, rax);
     __ Push(rax);
     // Push a copy of the target function and the new target.
     __ Push(rdi);
     __ Push(rdx);
 
     // The function.
     __ Push(rdi);
     // Copy arguments from caller (stdlib, foreign, heap).
     Label args_done;
     for (int j = 0; j < 4; ++j) {
       Label over;
       if (j < 3) {
-        __ cmpp(kScratchRegister, Immediate(j));
+        __ cmpp(rcx, Immediate(j));
         __ j(not_equal, &over, Label::kNear);
       }
       for (int i = j - 1; i >= 0; --i) {
         __ Push(Operand(
             rbp, StandardFrameConstants::kCallerSPOffset + i * kPointerSize));
       }
       for (int i = 0; i < 3 - j; ++i) {
         __ PushRoot(Heap::kUndefinedValueRootIndex);
       }
       if (j < 3) {
         __ jmp(&args_done, Label::kNear);
         __ bind(&over);
       }
     }
     __ bind(&args_done);
 
     // Call runtime, on success unwind frame, and parent frame.
     __ CallRuntime(Runtime::kInstantiateAsmJs, 4);
     // A smi 0 is returned on failure, an object on success.
     __ JumpIfSmi(rax, &failed, Label::kNear);
 
     __ Drop(2);
-    __ Pop(kScratchRegister);
-    __ SmiToInteger32(kScratchRegister, kScratchRegister);
+    __ Pop(rcx);
+    __ SmiToInteger32(rcx, rcx);
     scope.GenerateLeaveFrame();
 
     __ PopReturnAddressTo(rbx);
-    __ incp(kScratchRegister);
-    __ leap(rsp, Operand(rsp, kScratchRegister, times_pointer_size, 0));
+    __ incp(rcx);
+    __ leap(rsp, Operand(rsp, rcx, times_pointer_size, 0));
     __ PushReturnAddressFrom(rbx);
     __ ret(0);
 
     __ bind(&failed);
     // Restore target function and new target.
     __ Pop(rdx);
     __ Pop(rdi);
     __ Pop(rax);
     __ SmiToInteger32(rax, rax);
   }
@@ skipping 1877 matching lines @@
 void Builtins::Generate_InterpreterOnStackReplacement(MacroAssembler* masm) {
   Generate_OnStackReplacementHelper(masm, true);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64