[wasm][jspi] Fix JSPI + lazy deopt

thibaudmichaud · V8 LUCI CQ · commit 906e41b88fa5 · 2024-09-10T11:14:36.000Z
With JSPI, the stack frame iterator stops at the end of the current stack segment. Follow the chain of stacks to find all frames marked for deoptimization. R=mliedtke@chromium.org Fixed: 365376497 Change-Id: Iff1112dbd2a86a014c8de6d844f585fd568ad552 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5850428 Commit-Queue: Thibaud Michaud <thibaudm@chromium.org> Reviewed-by: Matthias Liedtke <mliedtke@chromium.org> Cr-Commit-Position: refs/heads/main@{#96028}
diff --git a/src/deoptimizer/deoptimizer.cc b/src/deoptimizer/deoptimizer.cc
@@ -341,6 +341,21 @@ class ActivationsFinder : public ThreadVisitor {
   // for the trampoline to the deoptimizer call respective to each code, and use
   // it to replace the current pc on the stack.
   void VisitThread(Isolate* isolate, ThreadLocalTop* top) override {
+#if V8_ENABLE_WEBASSEMBLY
+    // Also visit the ancestors of the active stack for wasm stack switching.
+    // We don't need to visit suspended stacks at the moment, because 1) they
+    // only contain wasm frames and 2) wasm does not do lazy deopt. Revisit this
+    // if one of these assumptions changes.
+    Tagged<WasmContinuationObject> continuation;
+    if (top == isolate->thread_local_top()) {
+      Tagged<Object> maybe_continuation =
+          isolate->root(RootIndex::kActiveContinuation);
+      if (!IsUndefined(maybe_continuation)) {
+        continuation = Cast<WasmContinuationObject>(maybe_continuation);
+      }
+    }
+#endif
+
     for (StackFrameIterator it(isolate, top); !it.done(); it.Advance()) {
       if (it.frame()->is_optimized()) {
         Tagged<GcSafeCode> code = it.frame()->GcSafeLookupCode();
@@ -379,6 +394,19 @@ class ActivationsFinder : public ThreadVisitor {
           }
         }
       }
+
+#if V8_ENABLE_WEBASSEMBLY
+      // We reached the base of the wasm stack. Follow the chain of
+      // continuations to find the parent stack and reset the iterator.
+      if (it.frame()->type() == StackFrame::STACK_SWITCH) {
+        CHECK_EQ(top, isolate->thread_local_top());
+        DCHECK(!continuation.is_null());
+        continuation = Cast<WasmContinuationObject>(continuation->parent());
+        wasm::StackMemory* parent =
+            reinterpret_cast<wasm::StackMemory*>(continuation->stack());
+        it.Reset(top, parent);
+      }
+#endif
     }
   }
 
