don't remove unreachable nodes in vaccuum, it can alter types, and dce does that anyhow, let it do it's thing

Author: kripken

src/passes/Vacuum.cpp

@@ -49,6 +49,8 @@ struct Vacuum : public WalkerPass<PostWalker<Vacuum>> {
 
   // returns nullptr if curr is dead, curr if it must stay as is, or another node if it can be replaced
   Expression* optimize(Expression* curr, bool resultUsed) {
+    // an unreachable node must not be changed
+    if (curr->type == unreachable) return curr;
     while (1) {
       switch (curr->_id) {
         case Expression::Id::NopId: return nullptr; // never needed

test/passes/vacuum.txt

@@ -28,16 +28,25 @@
   (nop)
  )
  (func $unary (type $2) (result f32)
-  (unreachable)
+  (f32.abs
+   (unreachable)
+  )
  )
  (func $binary (type $2) (result f32)
   (drop
-   (unreachable)
+   (f32.add
+    (unreachable)
+    (f32.const 3)
+   )
   )
  )
  (func $select (type $3) (result i32)
   (drop
-   (unreachable)
+   (select
+    (unreachable)
+    (i32.const 4)
+    (i32.const 5)
+   )
   )
  )
  (func $block-to-one (type $0)
@@ -198,4 +207,18 @@
   (local $2 i32)
   (nop)
  )
+ (func $a (type $0)
+  (block $block
+   (i32.store
+    (i32.const 1)
+    (i32.const 2)
+   )
+   (f64.div
+    (f64.const -nan:0xfffffffffa361)
+    (loop $label$1
+     (br $label$1)
+    )
+   )
+  )
+ )
 )

test/passes/vacuum.wast

@@ -509,4 +509,15 @@
     )
    )
   )
+  (func $a
+    (block
+      (i32.store (i32.const 1) (i32.const 2))
+      (f64.div
+        (f64.const -nan:0xfffffffffa361)
+        (loop $label$1 ;; unreachable, so the div is too. keep
+          (br $label$1)
+        )
+      )
+    )
+  )
 )