Handle throw and rethrow in DCE (#2844)

This adds missing handlings for `throw` and `rethrow` in DCE. They
should set `reachable` variable to `false`, like other branches.

2 files changed, 45 insertions, 0 deletions

diff --git a/test/passes/dce_all-features.txt b/test/passes/dce_all-features.txt
index 47b2e6cc2..e5af0bff9 100644
--- a/test/passes/dce_all-features.txt
+++ b/test/passes/dce_all-features.txt
@@ -503,6 +503,7 @@
 )
 (module
  (type $none_=>_none (func))
+ (event $e (attr 0) (param))
  (func $foo
   (nop)
  )
@@ -531,6 +532,15 @@
    )
   )
  )
+ (func $throw
+  (throw $e
+  )
+ )
+ (func $rethrow
+  (rethrow
+   (ref.null)
+  )
+ )
 )
 (module
  (type $none_=>_none (func))
diff --git a/test/passes/dce_all-features.wast b/test/passes/dce_all-features.wast
index cfdc58bbb..98b2b0ecd 100644
--- a/test/passes/dce_all-features.wast
+++ b/test/passes/dce_all-features.wast
@@ -739,6 +739,7 @@
 ;; reachable
 (module
   (func $foo)
+  (event $e (attr 0))
 
   (func $try_unreachable
     (try
@@ -767,6 +768,40 @@
     )
     (call $foo) ;; should be dce'd
   )
+
+  (func $throw
+    (drop
+      (block $label$0 (result nullref)
+        (if
+          (i32.clz
+            (block $label$1 (result i32)
+              (throw $e)
+            )
+          )
+          (nop)
+        )
+        (ref.null)
+      )
+    )
+  )
+
+  (func $rethrow
+    (drop
+      (block $label$0 (result nullref)
+        (if
+          (i32.clz
+            (block $label$1 (result i32)
+              (rethrow
+                (ref.null)
+              )
+            )
+          )
+          (nop)
+        )
+        (ref.null)
+      )
+    )
+  )
 )
 
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