[Stack Switching] wasm-ctor-eval: Properly ignore unhandled suspends (#7855)

We treated them as breaks, which meant we thought they could be
precomputed into nops in some cases.

Author: kripken

src/tools/wasm-ctor-eval.cpp

@@ -1162,6 +1162,16 @@ EvalCtorOutcome evalCtor(EvallingModuleRunner& instance,
       results = flow.values;
 
       if (flow.breaking()) {
+        if (flow.suspendTag) {
+          // A suspend reached the exit of the function, so it is unhandled in
+          // it. TODO: We could support the case of the calling function
+          // handling it.
+          if (!quiet) {
+            std::cout << "  ...stopping due to unhandled suspend\n";
+          }
+          return EvalCtorOutcome();
+        }
+
         // We are returning out of the function (either via a return, or via a
         // break to |block|, which has the same outcome. That means we don't
         // need to execute any more lines, and can consider them to be

test/lit/ctor-eval/cont.wast

@@ -1,12 +1,16 @@
 ;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
-;; RUN: foreach %s %t wasm-ctor-eval --ctors=test --kept-exports=test --quiet -all -S -o - | filecheck %s
+;; RUN: foreach %s %t wasm-ctor-eval --ctors=test,test2 --kept-exports=test,test2 --quiet -all -S -o - | filecheck %s
 
 ;; Test that we can precompute continuations.
 
 (module
+  ;; CHECK:      (type $f (func))
   (type $f (func))
   (type $k (cont $f))
 
+  ;; CHECK:      (type $1 (func (result i32)))
+
+  ;; CHECK:      (tag $more (type $f))
   (tag $more)
 
   (global $g (mut i32) (i32.const 0))
@@ -45,11 +49,19 @@
     )
     (global.get $g)
   )
-)
-;; CHECK:      (type $0 (func (result i32)))
 
-;; CHECK:      (export "test" (func $test_3))
+  ;; CHECK:      (export "test" (func $test_4))
+
+  ;; CHECK:      (export "test2" (func $test2))
 
-;; CHECK:      (func $test_3 (type $0) (result i32)
+  ;; CHECK:      (func $test2 (type $f)
+  ;; CHECK-NEXT:  (suspend $more)
+  ;; CHECK-NEXT: )
+  (func $test2 (export "test2")
+    ;; This unhandled suspend will trap, and should not be precomputed.
+    (suspend $more)
+  )
+)
+;; CHECK:      (func $test_4 (type $1) (result i32)
 ;; CHECK-NEXT:  (i32.const 3)
 ;; CHECK-NEXT: )