Add EH support for CFGWalker (#2597)

This adds EH instruction support for `CFGWalker`. This also implements
`call` instruction handling within a try-catch; every call can possibly
throw and unwind to the innermost catch block.

This adds tests for RedundantSetElimination pass, which uses
`CFGWalker`.

2 files changed, 204 insertions, 0 deletions

diff --git a/test/passes/rse.txt b/test/passes/rse_all-features.txt
index 6eb7996bf..82dc115ac 100644
--- a/test/passes/rse.txt
+++ b/test/passes/rse_all-features.txt
@@ -3,6 +3,7 @@
  (type $i32_=>_none (func (param i32)))
  (type $i32_i32_=>_none (func (param i32 i32)))
  (type $i32_f64_=>_none (func (param i32 f64)))
+ (event $e (attr 0) (param i32))
  (func $basic (; 0 ;) (param $x i32) (param $y f64)
   (local $a f32)
   (local $b i64)
@@ -459,4 +460,128 @@
    )
   )
  )
+ (func $try1 (; 19 ;)
+  (local $x i32)
+  (try
+   (nop)
+   (catch
+    (drop
+     (exnref.pop)
+    )
+    (local.set $x
+     (i32.const 1)
+    )
+   )
+  )
+  (local.set $x
+   (i32.const 1)
+  )
+ )
+ (func $try2 (; 20 ;)
+  (local $x i32)
+  (try
+   (block $block
+    (throw $e
+     (i32.const 0)
+    )
+    (local.set $x
+     (i32.const 1)
+    )
+   )
+   (catch
+    (drop
+     (exnref.pop)
+    )
+   )
+  )
+  (local.set $x
+   (i32.const 1)
+  )
+ )
+ (func $try3 (; 21 ;)
+  (local $x i32)
+  (try
+   (throw $e
+    (i32.const 0)
+   )
+   (catch
+    (drop
+     (exnref.pop)
+    )
+    (local.set $x
+     (i32.const 1)
+    )
+   )
+  )
+  (drop
+   (i32.const 1)
+  )
+ )
+ (func $foo (; 22 ;)
+  (nop)
+ )
+ (func $try4 (; 23 ;)
+  (local $x i32)
+  (try
+   (block $block
+    (call $foo)
+    (local.set $x
+     (i32.const 1)
+    )
+   )
+   (catch
+    (drop
+     (exnref.pop)
+    )
+   )
+  )
+  (local.set $x
+   (i32.const 1)
+  )
+ )
+ (func $try5 (; 24 ;)
+  (local $x i32)
+  (try
+   (block $block
+    (local.set $x
+     (i32.const 1)
+    )
+    (call $foo)
+   )
+   (catch
+    (drop
+     (exnref.pop)
+    )
+   )
+  )
+  (drop
+   (i32.const 1)
+  )
+ )
+ (func $nested-try (; 25 ;)
+  (local $x i32)
+  (try
+   (try
+    (throw $e
+     (i32.const 0)
+    )
+    (catch
+     (rethrow
+      (exnref.pop)
+     )
+    )
+   )
+   (catch
+    (drop
+     (exnref.pop)
+    )
+    (local.set $x
+     (i32.const 1)
+    )
+   )
+  )
+  (drop
+   (i32.const 1)
+  )
+ )
 )
diff --git a/test/passes/rse.wast b/test/passes/rse_all-features.wast
index 22d13c491..09b0d720d 100644
--- a/test/passes/rse.wast
+++ b/test/passes/rse_all-features.wast
@@ -277,5 +277,84 @@
     )
    )
   )
+
+  (event $e (attr 0) (param i32))
+  (func $try1
+    (local $x i32)
+    (try
+      (catch
+        (drop (exnref.pop))
+        (local.set $x (i32.const 1))
+      )
+    )
+    (local.set $x (i32.const 1)) ;; should NOT be dropped
+  )
+  (func $try2
+    (local $x i32)
+    (try
+      (block
+        (throw $e (i32.const 0))
+        (local.set $x (i32.const 1))
+      )
+      (catch
+        (drop (exnref.pop))
+      )
+    )
+    (local.set $x (i32.const 1)) ;; should NOT be dropped
+  )
+  (func $try3
+    (local $x i32)
+    (try
+      (throw $e (i32.const 0))
+      (catch
+        (drop (exnref.pop))
+        (local.set $x (i32.const 1))
+      )
+    )
+    (local.set $x (i32.const 1)) ;; should be dropped
+  )
+  (func $foo)
+  (func $try4
+    (local $x i32)
+    (try
+      (block
+        (call $foo)
+        (local.set $x (i32.const 1))
+      )
+      (catch
+        (drop (exnref.pop))
+      )
+    )
+    (local.set $x (i32.const 1)) ;; should NOT be dropped
+  )
+  (func $try5
+    (local $x i32)
+    (try
+      (block
+        (local.set $x (i32.const 1))
+        (call $foo)
+      )
+      (catch
+        (drop (exnref.pop))
+      )
+    )
+    (local.set $x (i32.const 1)) ;; should be dropped
+  )
+  (func $nested-try
+    (local $x i32)
+    (try
+      (try
+        (throw $e (i32.const 0))
+        (catch
+          (rethrow (exnref.pop))
+        )
+      )
+      (catch
+        (drop (exnref.pop))
+        (local.set $x (i32.const 1))
+      )
+    )
+    (local.set $x (i32.const 1)) ;; should be dropped
+  )
 )