Revert "Reland "[wasm] Resume suspender on resolved promise""

This reverts commit f942f656.

Reason for revert: Breaks gc-stress

Original change's description:
> Reland "[wasm] Resume suspender on resolved promise"
>
> This is a reland of a865d16b
>
> Changes:
> - Make the next ID atomic
> - Leave more space for runtime calls in debug mode
>
> Original change's description:
> > [wasm] Resume suspender on resolved promise
> >
> > Implement the WasmResume builtin, which resumes a wasm suspender
> > when the corresponding JS promise resolves.
> >
> > Drive-by 1: Fix detection of empty stacks in the stack frame iterator.
> > Drive-by 2: Add a stack ID for better tracing.
> >
> > R=ahaas@chromium.org
> > CC=​fgm@chromium.org
> >
> > Bug: v8:12191
> > Change-Id: Ifa3f00c4259f802292b04d426c739e9b551f87b9
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3420827
> > Reviewed-by: Andreas Haas <ahaas@chromium.org>
> > Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> > Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#78842}
>
> Bug: v8:12191
> Change-Id: I3c231690b27be79a0c00e13043342bb4a3628886
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3427203
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#78890}

Bug: v8:12191
Change-Id: I5037419b6cee7a3bb49c1649e5a5d11a935a9b28
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Auto-submit: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3429500
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Thibaud Michaud <thibaudm@chromium.org>
Owners-Override: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78893}

src/builtins/x64/builtins-x64.cc

@@ -3847,26 +3847,15 @@ void Builtins::Generate_WasmReturnPromiseOnSuspend(MacroAssembler* masm) {
   // -------------------------------------------
   active_continuation = rbx;
   __ LoadRoot(active_continuation, RootIndex::kActiveContinuation);
-  // Set a null pointer in the jump buffer's SP slot to indicate to the stack
-  // frame iterator that this stack is empty.
-  foreign_jmpbuf = rcx;
-  __ LoadAnyTaggedField(
-      foreign_jmpbuf,
-      FieldOperand(active_continuation, WasmContinuationObject::kJmpbufOffset));
-  jmpbuf = foreign_jmpbuf;
-  __ LoadExternalPointerField(
-      jmpbuf, FieldOperand(foreign_jmpbuf, Foreign::kForeignAddressOffset),
-      kForeignForeignAddressTag, rdx);
-  __ movq(Operand(jmpbuf, wasm::kJmpBufSpOffset), Immediate(kNullAddress));
   Register parent = rdx;
   __ LoadAnyTaggedField(
       parent,
       FieldOperand(active_continuation, WasmContinuationObject::kParentOffset));
   active_continuation = no_reg;
-  // live: [rsi, rdx]
+  // live: [rsi]
 
   // -------------------------------------------
-  // Update active continuation.
+  // Update instance active continuation.
   // -------------------------------------------
   __ movq(masm->RootAsOperand(RootIndex::kActiveContinuation), parent);
   foreign_jmpbuf = rax;
@@ -4030,122 +4019,10 @@ void Builtins::Generate_WasmSuspend(MacroAssembler* masm) {
   __ ret(0);
 }
 
-// Resume the suspender stored in the closure.
 void Builtins::Generate_WasmResume(MacroAssembler* masm) {
   __ EnterFrame(StackFrame::STACK_SWITCH);
-
-  Register param_count = rax;
-  Register closure = kJSFunctionRegister;  // rdi
-  __ subq(rsp, Immediate(ReturnPromiseOnSuspendFrameConstants::kSpillAreaSize));
-
-  // This slot is not used in this builtin. But when we return from the resumed
-  // continuation, we return to the ReturnPromiseOnSuspend code, which expects
-  // this slot to be set.
-  __ movq(
-      MemOperand(rbp, ReturnPromiseOnSuspendFrameConstants::kParamCountOffset),
-      param_count);
-  param_count = no_reg;
-
-  // -------------------------------------------
-  // Load suspender from closure.
-  // -------------------------------------------
-  Register sfi = closure;
-  __ LoadAnyTaggedField(
-      sfi,
-      MemOperand(
-          closure,
-          wasm::ObjectAccess::SharedFunctionInfoOffsetInTaggedJSFunction()));
-  Register function_data = sfi;
-  __ LoadAnyTaggedField(
-      function_data,
-      FieldOperand(sfi, SharedFunctionInfo::kFunctionDataOffset));
-  Register suspender = rax;
-  __ LoadAnyTaggedField(
-      suspender,
-      FieldOperand(function_data, WasmOnFulfilledData::kSuspenderOffset));
-  // Check the suspender state.
-  Label suspender_is_suspended;
-  Register state = rdx;
-  __ LoadTaggedSignedField(
-      state, FieldOperand(suspender, WasmSuspenderObject::kStateOffset));
-  __ SmiCompare(state, Smi::FromInt(WasmSuspenderObject::Suspended));
-  __ j(equal, &suspender_is_suspended);
-  __ Trap();  // TODO(thibaudm): Throw a wasm trap.
-  closure = no_reg;
-  sfi = no_reg;
-
-  __ bind(&suspender_is_suspended);
-  // -------------------------------------------
-  // Save current state.
-  // -------------------------------------------
-  Label suspend;
-  Register active_continuation = r9;
-  __ LoadRoot(active_continuation, RootIndex::kActiveContinuation);
-  Register current_jmpbuf = rdi;
-  __ LoadAnyTaggedField(
-      current_jmpbuf,
-      FieldOperand(active_continuation, WasmContinuationObject::kJmpbufOffset));
-  __ LoadExternalPointerField(
-      current_jmpbuf,
-      FieldOperand(current_jmpbuf, Foreign::kForeignAddressOffset),
-      kForeignForeignAddressTag, rdx);
-  FillJumpBuffer(masm, current_jmpbuf, &suspend);
-  current_jmpbuf = no_reg;
-
-  // -------------------------------------------
-  // Set suspender's parent to active continuation.
-  // -------------------------------------------
-  __ StoreTaggedSignedField(
-      FieldOperand(suspender, WasmSuspenderObject::kStateOffset),
-      Smi::FromInt(WasmSuspenderObject::Active));
-  Register target_continuation = rdi;
-  __ LoadAnyTaggedField(
-      target_continuation,
-      FieldOperand(suspender, WasmSuspenderObject::kContinuationOffset));
-  Register slot_address = WriteBarrierDescriptor::SlotAddressRegister();
-  __ StoreTaggedField(
-      FieldOperand(target_continuation, WasmContinuationObject::kParentOffset),
-      active_continuation);
-  __ RecordWriteField(
-      target_continuation, WasmContinuationObject::kParentOffset,
-      active_continuation, slot_address, SaveFPRegsMode::kIgnore);
-  active_continuation = no_reg;
-
-  // -------------------------------------------
-  // Update roots.
-  // -------------------------------------------
-  __ movq(masm->RootAsOperand(RootIndex::kActiveContinuation),
-          target_continuation);
-  __ movq(masm->RootAsOperand(RootIndex::kActiveSuspender), suspender);
-  suspender = no_reg;
-
-  MemOperand GCScanSlotPlace =
-      MemOperand(rbp, BuiltinWasmWrapperConstants::kGCScanSlotCountOffset);
-  __ Move(GCScanSlotPlace, 1);
-  __ Push(target_continuation);
-  __ Move(kContextRegister, Smi::zero());
-  __ CallRuntime(Runtime::kWasmSyncStackLimit);
-  __ Pop(target_continuation);
-
-  // -------------------------------------------
-  // Load state from target jmpbuf (longjmp).
-  // -------------------------------------------
-  Register target_jmpbuf = target_continuation;
-  __ LoadAnyTaggedField(
-      target_jmpbuf,
-      FieldOperand(target_continuation, WasmContinuationObject::kJmpbufOffset));
-  __ LoadExternalPointerField(
-      target_jmpbuf,
-      FieldOperand(target_jmpbuf, Foreign::kForeignAddressOffset),
-      kForeignForeignAddressTag, rax);
-  // Move resolved value to return register.
-  __ movq(kReturnRegister0, Operand(rbp, 3 * kSystemPointerSize));
-  __ Move(GCScanSlotPlace, 0);
-  LoadJumpBuffer(masm, target_jmpbuf, true);
-  __ Trap();
-  __ bind(&suspend);
   __ LeaveFrame(StackFrame::STACK_SWITCH);
-  __ ret(3);
+  __ ret(0);
 }
 
 void Builtins::Generate_WasmOnStackReplace(MacroAssembler* masm) {

src/execution/frames.cc

@@ -162,9 +162,8 @@ void StackFrameIterator::Reset(ThreadLocalTop* top) {
 
 #if V8_ENABLE_WEBASSEMBLY
 void StackFrameIterator::Reset(ThreadLocalTop* top, wasm::StackMemory* stack) {
-  if (stack->jmpbuf()->sp == kNullAddress) {
-    // A null SP indicates that the computation associated with this stack has
-    // returned, leaving the stack segment empty.
+  if (stack->jmpbuf()->sp == stack->base()) {
+    // Empty stack.
     return;
   }
   StackFrame::State state;

src/runtime/runtime-wasm.cc

@@ -731,9 +731,6 @@ void SyncStackLimit(Isolate* isolate) {
   auto continuation = WasmContinuationObject::cast(
       *isolate->roots_table().slot(RootIndex::kActiveContinuation));
   auto stack = Managed<wasm::StackMemory>::cast(continuation.stack()).get();
-  if (FLAG_trace_wasm_stack_switching) {
-    PrintF("Switch to stack #%d\n", stack->id());
-  }
   uintptr_t limit = reinterpret_cast<uintptr_t>(stack->jmpbuf()->stack_limit);
   isolate->stack_guard()->SetStackLimit(limit);
 }

src/wasm/stacks.h

@@ -44,7 +44,7 @@ class StackMemory {
 
   ~StackMemory() {
     if (FLAG_trace_wasm_stack_switching) {
-      PrintF("Delete stack #%d\n", id_);
+      PrintF("Delete stack (sp: %p)\n", reinterpret_cast<void*>(jmpbuf_.sp));
     }
     PageAllocator* allocator = GetPlatformPageAllocator();
     if (owned_) allocator->DecommitPages(limit_, size_);
@@ -59,7 +59,6 @@ class StackMemory {
   void* jslimit() const { return limit_ + kJSLimitOffsetKB; }
   Address base() const { return reinterpret_cast<Address>(limit_ + size_); }
   JumpBuffer* jmpbuf() { return &jmpbuf_; }
-  int id() { return id_; }
 
   // Insert a stack in the linked list after this stack.
   void Add(StackMemory* stack) {
@@ -79,16 +78,10 @@ class StackMemory {
   }
 
  private:
-#ifdef DEBUG
-  static constexpr int kJSLimitOffsetKB = 80;
-#else
   static constexpr int kJSLimitOffsetKB = 40;
-#endif
 
   // This constructor allocates a new stack segment.
   explicit StackMemory(Isolate* isolate) : isolate_(isolate), owned_(true) {
-    static std::atomic<int> next_id(1);
-    id_ = next_id.fetch_add(1);
     PageAllocator* allocator = GetPlatformPageAllocator();
     int kJsStackSizeKB = 4;
     size_ = (kJsStackSizeKB + kJSLimitOffsetKB) * KB;
@@ -96,9 +89,8 @@ class StackMemory {
     limit_ = static_cast<byte*>(
         allocator->AllocatePages(nullptr, size_, allocator->AllocatePageSize(),
                                  PageAllocator::kReadWrite));
-    if (FLAG_trace_wasm_stack_switching) {
-      PrintF("Allocate stack #%d\n", id_);
-    }
+    if (FLAG_trace_wasm_stack_switching)
+      PrintF("Allocate stack (sp: %p, limit: %p)\n", limit_ + size_, limit_);
   }
 
   // Overload to represent a view of the libc stack.
@@ -106,16 +98,13 @@ class StackMemory {
       : isolate_(isolate),
         limit_(limit),
         size_(reinterpret_cast<size_t>(limit)),
-        owned_(false) {
-    id_ = 0;
-  }
+        owned_(false) {}
 
   Isolate* isolate_;
   byte* limit_;
   size_t size_;
   bool owned_;
   JumpBuffer jmpbuf_;
-  int id_;
   // Stacks form a circular doubly linked list per isolate.
   StackMemory* next_ = this;
   StackMemory* prev_ = this;

test/mjsunit/wasm/stack-switching.js

@@ -48,49 +48,6 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   let wrapped_export = suspender.returnPromiseOnSuspend(instance.exports.test);
   let combined_promise = wrapped_export();
   assertEquals(0, instance.exports.g.value);
-  combined_promise.then(_ => assertEquals(42, instance.exports.g.value));
-})();
-
-// Check that we can suspend back out of a resumed computation.
-(function TestStackSwitchSuspendLoop() {
-  print(arguments.callee.name);
-  let builder = new WasmModuleBuilder();
-  builder.addGlobal(kWasmI32, true).exportAs('g');
-  import_index = builder.addImport('m', 'import', kSig_i_v);
-  // Pseudo-code for the wasm function:
-  // for (i = 0; i < 5; ++i) {
-  //   g = g + import();
-  // }
-  builder.addFunction("test", kSig_v_v)
-      .addLocals(kWasmI32, 1)
-      .addBody([
-          kExprI32Const, 5,
-          kExprLocalSet, 0,
-          kExprLoop, kWasmVoid,
-            kExprCallFunction, import_index, // suspend
-            kExprGlobalGet, 0, // resume
-            kExprI32Add,
-            kExprGlobalSet, 0,
-            kExprLocalGet, 0,
-            kExprI32Const, 1,
-            kExprI32Sub,
-            kExprLocalTee, 0,
-            kExprBrIf, 0,
-          kExprEnd,
-      ]).exportFunc();
-  let suspender = new WebAssembly.Suspender();
-  let i = 0;
-  // The n-th call to the import returns a promise that resolves to n.
-  function js_import() {
-    return new Promise((resolve) => { resolve(++i); });
-  };
-  let wasm_js_import = new WebAssembly.Function({parameters: [], results: ['i32']}, js_import);
-  let suspending_wasm_js_import = suspender.suspendOnReturnedPromise(wasm_js_import);
-  let instance = builder.instantiate({m: {import: suspending_wasm_js_import}});
-  let wrapped_export = suspender.returnPromiseOnSuspend(instance.exports.test);
-  let chained_promise = wrapped_export();
-  assertEquals(0, instance.exports.g.value);
-  chained_promise.then(_ => assertEquals(15, instance.exports.g.value));
 })();
 
 (function TestStackSwitchGC() {