[Wasm GC] Fix handleNonDefaultableLocals on tees (#3830)

When we change a local's type, as we do in that method when we
turn a non-nullable (invalid) local into a nullable (valid) one, we must
update tees as well as gets - their type must match the changed
local type, and we must cast them so that their users do not see
a change.

1 files changed, 49 insertions, 0 deletions

diff --git a/test/lit/passes/dae-gc.wast b/test/lit/passes/dae-gc.wast
new file mode 100644
index 000000000..87e480cc8
--- /dev/null
+++ b/test/lit/passes/dae-gc.wast
@@ -0,0 +1,49 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
+;; RUN: wasm-opt %s -all --dae -S -o - | filecheck %s
+
+(module
+ ;; CHECK:      (func $foo
+ ;; CHECK-NEXT:  (call $bar)
+ ;; CHECK-NEXT: )
+ (func $foo
+  (call $bar
+   (i31.new
+    (i32.const 1)
+   )
+  )
+ )
+ ;; CHECK:      (func $bar
+ ;; CHECK-NEXT:  (local $0 (ref null i31))
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (ref.as_non_null
+ ;; CHECK-NEXT:    (local.tee $0
+ ;; CHECK-NEXT:     (i31.new
+ ;; CHECK-NEXT:      (i32.const 2)
+ ;; CHECK-NEXT:     )
+ ;; CHECK-NEXT:    )
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (local.tee $0
+ ;; CHECK-NEXT:   (unreachable)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $bar (param $0 i31ref)
+  (drop
+   ;; after the parameter is removed, we create a nullable local to replace it,
+   ;; and must update the tee's type accordingly to avoid a validation error,
+   ;; and also add a ref.as_non_null so that the outside still receives the
+   ;; same type as before
+   (local.tee $0
+    (i31.new
+     (i32.const 2)
+    )
+   )
+  )
+  ;; test for an unreachable tee, whose type must be unreachable even after
+  ;; the change (the tee would need to be dropped if it were not unreachable,
+  ;; so the correctness in this case is visible in the output)
+  (local.tee $0
+   (unreachable)
+  )
+ )
+)