From 4508b5dfb26e86f975fc57cf04350d67071fe98e Mon Sep 17 00:00:00 2001
From: Victor Gomes <[email protected]>
Date: Fri, 30 Jan 2026 15:18:32 +0100
Subject: [PATCH] [maglev] Module variables can be the hole

Module variables are lowered in Maglev to
LoadTaggedField(cell, Cell:kValueOffset).

Drive-by: order opcodes alphabetically in CanBeTheHoleValue.

Fixed: 479726070
Change-Id: I2be5752906cf2ec8fdb4df497724a4d9ad55648d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7534881
Auto-Submit: Victor Gomes <[email protected]>
Reviewed-by: Leszek Swirski <[email protected]>
Commit-Queue: Leszek Swirski <[email protected]>
Commit-Queue: Victor Gomes <[email protected]>
Cr-Commit-Position: refs/heads/main@{#105008}
---

diff --git a/src/maglev/maglev-ir.cc b/src/maglev/maglev-ir.cc
index 47c5e09..dd35ce7 100644
--- a/src/maglev/maglev-ir.cc
+++ b/src/maglev/maglev-ir.cc
@@ -669,6 +669,13 @@
   if (const RootConstant* cst = TryCast<RootConstant>()) {
     return ToTribool(cst->index() == RootIndex::kTheHoleValue);
   }
+  if (const LoadTaggedField* load = TryCast<LoadTaggedField>()) {
+    // Modules variables can be the hole.
+    if (load->offset() == Cell::kValueOffset) {
+      return Tribool::kMaybe;
+    }
+    return Tribool::kFalse;
+  }
   if (const LoadFixedArrayElement* load = TryCast<LoadFixedArrayElement>()) {
     if (load->load_type() != LoadType::kUnknown) {
       return Tribool::kFalse;
diff --git a/src/maglev/maglev-ir.h b/src/maglev/maglev-ir.h
index 11bc7d48..f4c0ff8 100644
--- a/src/maglev/maglev-ir.h
+++ b/src/maglev/maglev-ir.h
@@ -733,17 +733,18 @@
 
 constexpr bool CanBeTheHoleValue(Opcode opcode) {
   switch (opcode) {
-    case Opcode::kInitialValue:
-    case Opcode::kCallRuntime:
     // TODO(victorgomes): Should we have a list of builtins that could
     // return the hole?
     case Opcode::kCallBuiltin:
+    case Opcode::kCallRuntime:
     case Opcode::kGeneratorRestoreRegister:
-    case Opcode::kRootConstant:
+    case Opcode::kInitialValue:
     case Opcode::kLoadContextSlot:
     case Opcode::kLoadContextSlotNoCells:
     case Opcode::kLoadFixedArrayElement:
+    case Opcode::kLoadTaggedField:
     case Opcode::kPhi:
+    case Opcode::kRootConstant:
       return true;
     default:
       return false;