From 97d302aaae37ff697ab589eaa0fe8a84646a2752 Mon Sep 17 00:00:00 2001
From: Ryan Macnak <rmacnak@google.com>
Date: Mon, 13 Feb 2023 18:24:32 +0000
Subject: [PATCH] [vm] Remove KBC support from NativeArguments.

TEST=ci
Change-Id: If28557e41839ac767992e4dc342d47cce3a6d93a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/282122
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
---
 runtime/vm/native_arguments.h | 22 ++--------------------
 runtime/vm/simulator_arm.cc   |  2 +-
 2 files changed, 3 insertions(+), 21 deletions(-)

diff --git a/runtime/vm/native_arguments.h b/runtime/vm/native_arguments.h
index d2df92c20d1..7b7360398f5 100644
--- a/runtime/vm/native_arguments.h
+++ b/runtime/vm/native_arguments.h
@@ -84,8 +84,7 @@ class NativeArguments {
 
   ObjectPtr ArgAt(int index) const {
     ASSERT((index >= 0) && (index < ArgCount()));
-    ObjectPtr* arg_ptr =
-        &(argv_[ReverseArgOrderBit::decode(argc_tag_) ? index : -index]);
+    ObjectPtr* arg_ptr = &(argv_[-index]);
     // Tell MemorySanitizer the ObjectPtr was initialized (by generated code).
     MSAN_UNPOISON(arg_ptr, kWordSize);
     return *arg_ptr;
@@ -94,9 +93,7 @@ class NativeArguments {
   void SetArgAt(int index, const Object& value) const {
     ASSERT(thread_->execution_state() == Thread::kThreadInVM);
     ASSERT((index >= 0) && (index < ArgCount()));
-    ObjectPtr* arg_ptr =
-        &(argv_[ReverseArgOrderBit::decode(argc_tag_) ? index : -index]);
-    *arg_ptr = value.ptr();
+    argv_[-index] = value.ptr();
   }
 
   // Does not include hidden type arguments vector.
@@ -224,29 +221,14 @@ class NativeArguments {
     kArgcSize = 24,
     kFunctionBit = kArgcBit + kArgcSize,
     kFunctionSize = 3,
-    kReverseArgOrderBit = kFunctionBit + kFunctionSize,
-    kReverseArgOrderSize = 1,
   };
   class ArgcBits : public BitField<intptr_t, int32_t, kArgcBit, kArgcSize> {};
   class FunctionBits
       : public BitField<intptr_t, int, kFunctionBit, kFunctionSize> {};
-  class ReverseArgOrderBit
-      : public BitField<intptr_t, bool, kReverseArgOrderBit, 1> {};
   friend class Api;
   friend class NativeEntry;
   friend class Simulator;
 
-  // Allow simulator to create NativeArguments in reverse order
-  // on the stack.
-  NativeArguments(Thread* thread,
-                  int argc_tag,
-                  ObjectPtr* argv,
-                  ObjectPtr* retval)
-      : thread_(thread),
-        argc_tag_(ReverseArgOrderBit::update(true, argc_tag)),
-        argv_(argv),
-        retval_(retval) {}
-
   // Since this function is passed a RawObject directly, we need to be
   // exceedingly careful when we use it.  If there are any other side
   // effects in the statement that may cause GC, it could lead to
diff --git a/runtime/vm/simulator_arm.cc b/runtime/vm/simulator_arm.cc
index d52c9808d36..b714100b724 100644
--- a/runtime/vm/simulator_arm.cc
+++ b/runtime/vm/simulator_arm.cc
@@ -1419,7 +1419,7 @@ void Simulator::SupervisorCall(Instr* instr) {
           THR_Print("Call to host function at 0x%" Pd "\n", external);
         }
         if (redirection->call_kind() == kRuntimeCall) {
-          NativeArguments arguments(NULL, 0, NULL, NULL);
+          NativeArguments arguments;
           ASSERT(sizeof(NativeArguments) == 4 * kWordSize);
           arguments.thread_ = reinterpret_cast<Thread*>(get_register(R0));
           arguments.argc_tag_ = get_register(R1);