changing a set to a tee or vice versa needs to take into account the value may be unreachable

Author: kripken

src/asm2wasm.h

@@ -1984,9 +1984,9 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
             // No wasm support, so use a temp local
             ensureI32Temp();
             auto set = allocator.alloc<SetLocal>();
-            set->setTee(false);
             set->index = function->getLocalIndex(I32_TEMP);
             set->value = value;
+            set->setTee(false);
             set->finalize();
             auto get = [&]() {
               auto ret = allocator.alloc<GetLocal>();

src/wasm/wasm.cpp

@@ -324,6 +324,7 @@ bool SetLocal::isTee() {
 void SetLocal::setTee(bool is) {
   if (is) type = value->type;
   else type = none;
+  finalize(); // type may need to be unreachable
 }
 
 void SetLocal::finalize() {

test/passes/simplify-locals-nostructure.txt

@@ -64,8 +64,6 @@
  )
  (func $no-unreachable (type $0)
   (local $x i32)
-  (drop
-   (unreachable)
-  )
+  (unreachable)
  )
 )

test/passes/simplify-locals.txt

@@ -866,4 +866,13 @@
    )
   )
  )
+ (func $drop-tee-unreachable (type $FUNCSIG$v)
+  (local $x i32)
+  (tee_local $x
+   (unreachable)
+  )
+  (drop
+   (get_local $x)
+  )
+ )
 )

test/passes/simplify-locals.wast

@@ -860,4 +860,15 @@
     )
     (get_local $label)
   )
+  (func $drop-tee-unreachable
+    (local $x i32)
+    (drop
+      (tee_local $x
+        (unreachable)
+      )
+    )
+    (drop
+      (get_local $x)
+    )
+  )
 )