From bf6b06a4ed80d1dd6a781abba713da9bfb631ea8 Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Wed, 6 May 2026 07:58:39 -0700
Subject: [PATCH 1/2] fix

---
 src/passes/SignatureRefining.cpp             |  7 ++---
 test/lit/passes/signature-refining-cont.wast | 31 ++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)
 create mode 100644 test/lit/passes/signature-refining-cont.wast

diff --git a/src/passes/SignatureRefining.cpp b/src/passes/SignatureRefining.cpp
index 792aedd9d5c..c1d72bc8d77 100644
--- a/src/passes/SignatureRefining.cpp
+++ b/src/passes/SignatureRefining.cpp
@@ -168,13 +168,12 @@ struct SignatureRefining : public Pass {
         false;
     }
 
-    // Continuations must not have params refined, because we do not update
-    // their users (e.g. cont.bind, resume) with new types.
-    // TODO: support refining continuations
+    // Continuations must not have params or results refined, because we do not
+    // update their users (e.g. cont.bind, resume) with new types.
     if (module->features.hasStackSwitching()) {
       for (auto type : ModuleUtils::collectHeapTypes(*module)) {
         if (type.isContinuation()) {
-          allInfo[type.getContinuation().type].canModifyParams = false;
+          allInfo[type.getContinuation().type].canModify = false;
         }
       }
     }
diff --git a/test/lit/passes/signature-refining-cont.wast b/test/lit/passes/signature-refining-cont.wast
new file mode 100644
index 00000000000..c99ecd8da58
--- /dev/null
+++ b/test/lit/passes/signature-refining-cont.wast
@@ -0,0 +1,31 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+;; RUN: wasm-opt %s --signature-refining -all -S -o - | filecheck %s
+
+;; cont.bind places restrictions on signature refining.
+(module
+ (rec
+  (type $A (func (result (ref null $cont-A))))
+
+  (type $B (func (result (ref null $cont-A))))
+
+  (type $cont-A (cont $A))
+
+  (type $cont-B (cont $B))
+ )
+
+ (func $1 (type $A) (result (ref null $cont-A))
+  ;; cont.bind requires that the continuation type's results match, so we
+  ;; cannot refine the type $A: if we make it return an exact result, we would
+  ;; be binding a continuation that returns an inexact result to an exact one.
+  (cont.bind $cont-B $cont-A
+   (cont.new $cont-B
+    (ref.func $0)
+   )
+  )
+ )
+
+ (func $0 (type $B) (result (ref null $cont-A))
+  (unreachable)
+ )
+)
+

From 0eb92eeb84ec5b1b05da9bc8a9dfa55a89a8b374 Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Wed, 6 May 2026 07:59:26 -0700
Subject: [PATCH 2/2] test

---
 test/lit/passes/signature-refining-cont.wast | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/test/lit/passes/signature-refining-cont.wast b/test/lit/passes/signature-refining-cont.wast
index c99ecd8da58..060dba2026e 100644
--- a/test/lit/passes/signature-refining-cont.wast
+++ b/test/lit/passes/signature-refining-cont.wast
@@ -4,15 +4,29 @@
 ;; cont.bind places restrictions on signature refining.
 (module
  (rec
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $A (func (result (ref null $cont-A))))
   (type $A (func (result (ref null $cont-A))))
 
+  ;; CHECK:       (type $B (func (result (ref null $cont-A))))
   (type $B (func (result (ref null $cont-A))))
 
+  ;; CHECK:       (type $cont-A (cont $A))
   (type $cont-A (cont $A))
 
+  ;; CHECK:       (type $cont-B (cont $B))
   (type $cont-B (cont $B))
  )
 
+ ;; CHECK:      (elem declare func $0)
+
+ ;; CHECK:      (func $1 (type $A) (result (ref null $cont-A))
+ ;; CHECK-NEXT:  (cont.bind $cont-B $cont-A
+ ;; CHECK-NEXT:   (cont.new $cont-B
+ ;; CHECK-NEXT:    (ref.func $0)
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
  (func $1 (type $A) (result (ref null $cont-A))
   ;; cont.bind requires that the continuation type's results match, so we
   ;; cannot refine the type $A: if we make it return an exact result, we would
@@ -24,6 +38,9 @@
   )
  )
 
+ ;; CHECK:      (func $0 (type $B) (result (ref null $cont-A))
+ ;; CHECK-NEXT:  (unreachable)
+ ;; CHECK-NEXT: )
  (func $0 (type $B) (result (ref null $cont-A))
   (unreachable)
  )