Reuse existing function types for blocks (#6022)

Type annotations on multivalue blocks (and loops, ifs, and trys) are type
indices that refer to function types in the type section. For these type
annotations, the identities of the function types does not matter. As long as
the referenced type has the correct parameters and results, it will be valid to
use.

Previously, when collecting module types, we always used the "default" function
type for multivalue control flow, i.e. we used a final function type with no
supertypes in a singleton rec group. However, in cases where the program already
contains another function type with the expected signature, using the default
type is unnecessary and bloats the type section.

Update the type collecting code to reuse existing function types for multivalue
control flow where possible rather than unconditionally adding the default
function type. Similarly, update the binary writer to use the first heap type
with the required signature when emitting annotations on multivalue control flow
structures. To make this all testable, update the printer to print the type
annotations as well, rather than just the result types. Since the parser was not
able to parse those newly emitted type annotations, update the parser as well.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/lit/passes/roundtrip.wast b/test/lit/passes/roundtrip.wast
index f41761c2e..2f3fd4009 100644
--- a/test/lit/passes/roundtrip.wast
+++ b/test/lit/passes/roundtrip.wast
@@ -8,7 +8,7 @@
  ;; CHECK-NEXT:  (local $0 (funcref (ref $none)))
  ;; CHECK-NEXT:  (local $1 funcref)
  ;; CHECK-NEXT:  (local.set $0
- ;; CHECK-NEXT:   (block $label$1 (result funcref (ref $none))
+ ;; CHECK-NEXT:   (block $label$1 (type $1) (result funcref (ref $none))
  ;; CHECK-NEXT:    (tuple.make
  ;; CHECK-NEXT:     (ref.null nofunc)
  ;; CHECK-NEXT:     (ref.func $foo)