wasm-merge: Refine call results (#8018)

When a call's type is refined, the results may change, and need to be
updated.

Author: kripken

src/tools/wasm-merge.cpp

@@ -574,6 +574,16 @@ void updateTypes(Module& wasm) {
       curr->type = getModule()->getGlobal(curr->name)->type;
     }
 
+    void visitCall(Call* curr) {
+      if (curr->type != Type::unreachable) {
+        curr->type = getModule()
+                       ->getFunction(curr->target)
+                       ->type.getHeapType()
+                       .getSignature()
+                       .results;
+      }
+    }
+
     void visitRefFunc(RefFunc* curr) {
       curr->finalize(getModule()->getFunction(curr->func)->type.getHeapType());
     }

test/lit/merge/func_subtyping_return.wat

@@ -0,0 +1,45 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+
+;; RUN: wasm-merge %s primary %s.second secondary --skip-export-conflicts -all -S -o - | filecheck %s
+
+;; Export a function with a subtype. It is imported using the supertype, and
+;; after we merge, the refined return type must be updated - the call
+;; instruction now returns something new.
+(module
+ ;; CHECK:      (type $0 (func (result anyref)))
+
+ ;; CHECK:      (type $super (sub (func (param i32) (result anyref))))
+ (type $super (sub (func (param i32) (result anyref))))
+
+ ;; CHECK:      (type $sub (sub final $super (func (param i32) (result (ref any)))))
+ (type $sub (sub final $super (func (param i32) (result (ref any)))))
+
+ ;; CHECK:      (export "sub" (func $sub))
+
+ ;; CHECK:      (export "caller" (func $caller))
+
+ ;; CHECK:      (export "caller-unreachable" (func $caller-unreachable))
+
+ ;; CHECK:      (func $sub (type $sub) (param $0 i32) (result (ref any))
+ ;; CHECK-NEXT:  (unreachable)
+ ;; CHECK-NEXT: )
+ (func $sub (export "sub") (type $sub)
+  (unreachable)
+ )
+)
+
+;; CHECK:      (func $caller (type $0) (result anyref)
+;; CHECK-NEXT:  (block $block (result (ref any))
+;; CHECK-NEXT:   (call $sub
+;; CHECK-NEXT:    (i32.const 42)
+;; CHECK-NEXT:   )
+;; CHECK-NEXT:  )
+;; CHECK-NEXT: )
+
+;; CHECK:      (func $caller-unreachable (type $0) (result anyref)
+;; CHECK-NEXT:  (block $block
+;; CHECK-NEXT:   (call $sub
+;; CHECK-NEXT:    (unreachable)
+;; CHECK-NEXT:   )
+;; CHECK-NEXT:  )
+;; CHECK-NEXT: )

test/lit/merge/func_subtyping_return.wat.second

@@ -0,0 +1,24 @@
+(module
+ (type $second-super (sub (func (param i32) (result anyref))))
+
+ (import "primary" "sub" (func $import (type $second-super)))
+
+ (func $caller (export "caller") (result anyref)
+  ;; This will get refined from anyref to non-nullable.
+  (block $block (result anyref)
+   (call $import
+    (i32.const 42)
+   )
+  )
+ )
+
+ (func $caller-unreachable (export "caller-unreachable") (result anyref)
+  ;; Unreachable code is not modified.
+  (block $block (result anyref)
+   (call $import
+    (unreachable)
+   )
+  )
+ )
+)
+