2 files changed, 202 insertions, 1 deletions
diff --git a/test/lit/passes/optimize-instructions-gc-iit.wast b/test/lit/passes/optimize-instructions-gc-iit.wast
index 10bbbfc4a..5409e14c4 100644
--- a/test/lit/passes/optimize-instructions-gc-iit.wast
+++ b/test/lit/passes/optimize-instructions-gc-iit.wast
@@ -136,4 +136,22 @@
       )
     )
   )
+
+  ;; CHECK:      (func $ref-eq-ref-cast (param $x eqref)
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (i32.const 1)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $ref-eq-ref-cast (param $x eqref)
+    ;; we can look through a ref.cast if we ignore traps
+    (drop
+      (ref.eq
+        (local.get $x)
+        (ref.cast
+          (local.get $x)
+          (rtt.canon $parent)
+        )
+      )
+    )
+  )
 )
diff --git a/test/lit/passes/optimize-instructions-gc.wast b/test/lit/passes/optimize-instructions-gc.wast
index b00d08193..33f7bef78 100644
--- a/test/lit/passes/optimize-instructions-gc.wast
+++ b/test/lit/passes/optimize-instructions-gc.wast
@@ -1,5 +1,5 @@
 ;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
-;; RUN: wasm-opt %s --optimize-instructions --enable-reference-types --enable-gc -S -o - \
+;; RUN: wasm-opt %s --remove-unused-names --optimize-instructions --enable-reference-types --enable-gc -S -o - \
 ;; RUN:   | filecheck %s
 
 (module
@@ -533,4 +533,187 @@
       )
     )
   )
+
+  ;; CHECK:      (func $get-eqref (result eqref)
+  ;; CHECK-NEXT:  (unreachable)
+  ;; CHECK-NEXT: )
+  (func $get-eqref (result eqref)
+    (unreachable)
+  )
+
+  ;; CHECK:      (func $ref-eq (param $x eqref) (param $y eqref)
+  ;; CHECK-NEXT:  (local $lx eqref)
+  ;; CHECK-NEXT:  (local $ly eqref)
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (i32.const 1)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (ref.eq
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:    (local.get $y)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (local.set $lx
+  ;; CHECK-NEXT:   (call $get-eqref)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (i32.const 1)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (i32.const 1)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $ref-eq (param $x eqref) (param $y eqref)
+    (local $lx eqref)
+    (local $ly eqref)
+    ;; identical parameters are equal
+    (drop
+      (ref.eq
+        (local.get $x)
+        (local.get $x)
+      )
+    )
+    ;; different ones might not be
+    (drop
+      (ref.eq
+        (local.get $x)
+        (local.get $y)
+      )
+    )
+    ;; identical locals are
+    (local.set $lx
+      (call $get-eqref)
+    )
+    (drop
+      (ref.eq
+        (local.get $lx)
+        (local.get $lx)
+      )
+    )
+    ;; fallthroughs work ok (but we need --remove-unused-names so that we can
+    ;; trivially tell that there are no breaks)
+    (drop
+      (ref.eq
+        (block (result eqref)
+          (nop)
+          (local.get $x)
+        )
+        (block (result eqref)
+          (nop)
+          (drop
+            (i32.const 10)
+          )
+          (nop)
+          (local.get $x)
+        )
+      )
+    )
+  )
+
+  (func $nothing)
+
+  ;; CHECK:      (func $ref-eq-corner-cases (param $x eqref)
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (ref.eq
+  ;; CHECK-NEXT:    (block (result eqref)
+  ;; CHECK-NEXT:     (call $nothing)
+  ;; CHECK-NEXT:     (local.get $x)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:    (block (result eqref)
+  ;; CHECK-NEXT:     (call $nothing)
+  ;; CHECK-NEXT:     (local.get $x)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (ref.eq
+  ;; CHECK-NEXT:    (struct.new_default_with_rtt $struct
+  ;; CHECK-NEXT:     (rtt.canon $struct)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:    (struct.new_default_with_rtt $struct
+  ;; CHECK-NEXT:     (rtt.canon $struct)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (i32.const 1)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $ref-eq-corner-cases (param $x eqref)
+    ;; side effects prevent optimization
+    (drop
+      (ref.eq
+        (block (result eqref)
+          (call $nothing)
+          (local.get $x)
+        )
+        (block (result eqref)
+          (call $nothing)
+          (local.get $x)
+        )
+      )
+    )
+    ;; allocation prevents optimization
+    (drop
+      (ref.eq
+        (struct.new_default_with_rtt $struct
+          (rtt.canon $struct)
+        )
+        (struct.new_default_with_rtt $struct
+          (rtt.canon $struct)
+        )
+      )
+    )
+    ;; but irrelevant allocations do not prevent optimization
+    (drop
+      (ref.eq
+        (block (result eqref)
+          ;; an allocation that does not trouble us
+          (drop
+            (struct.new_default_with_rtt $struct
+              (rtt.canon $struct)
+            )
+          )
+          (local.get $x)
+        )
+        (block (result eqref)
+          (drop
+            (struct.new_default_with_rtt $struct
+              (rtt.canon $struct)
+            )
+          )
+          ;; add a nop to make the two inputs to ref.eq not structurally equal,
+          ;; but in a way that does not matter (since only the value falling
+          ;; out does)
+          (nop)
+          (local.get $x)
+        )
+      )
+    )
+  )
+
+  ;; CHECK:      (func $ref-eq-ref-cast (param $x eqref)
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (ref.eq
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:    (ref.cast
+  ;; CHECK-NEXT:     (local.get $x)
+  ;; CHECK-NEXT:     (rtt.canon $struct)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $ref-eq-ref-cast (param $x eqref)
+    ;; it is almost valid to look through a cast, except that it might trap so
+    ;; there is a side effect
+    (drop
+      (ref.eq
+        (local.get $x)
+        (ref.cast
+          (local.get $x)
+          (rtt.canon $struct)
+        )
+      )
+    )
+  )
 )