don't simplify locals out of loops if they contain branching, as it may invalidate the branch

3 files changed, 52 insertions, 0 deletions

diff --git a/src/ast_utils.h b/src/ast_utils.h
index b81413d78..0bb0a821e 100644
--- a/src/ast_utils.h
+++ b/src/ast_utils.h
@@ -130,6 +130,9 @@ struct EffectAnalyzer : public PostWalker<EffectAnalyzer, Visitor<EffectAnalyzer
 
   bool checkPost(Expression* curr) {
     visit(curr);
+    if (curr->is<Loop>()) {
+      branches = true;
+    }
     return hasAnything();
   }
 
diff --git a/test/passes/simplify-locals.txt b/test/passes/simplify-locals.txt
index 60e07f3fb..ee4418953 100644
--- a/test/passes/simplify-locals.txt
+++ b/test/passes/simplify-locals.txt
@@ -7,6 +7,7 @@
   (type $4 (func (param i32)))
   (type $5 (func (param i32) (result i32)))
   (type $6 (func (param i32 i32 i32 i32 i32 i32)))
+  (type $7 (func (param i32 i32)))
   (import $waka "env" "waka")
   (import $waka_int "env" "waka_int" (result i32))
   (import $_i64Subtract "env" "i64sub" (param i32 i32 i32 i32) (result i32))
@@ -673,4 +674,32 @@
       (get_local $i1)
     )
   )
+  (func $no-out-of-label (type $7) (param $x i32) (param $y i32)
+    (loop $moar
+      (set_local $x
+        (block $block0
+          (br_if $moar
+            (get_local $x)
+          )
+          (i32.const 0)
+        )
+      )
+    )
+    (drop
+      (get_local $x)
+    )
+    (block $moar
+      (set_local $y
+        (block $block1
+          (br_if $moar
+            (get_local $y)
+          )
+          (i32.const 0)
+        )
+      )
+    )
+    (drop
+      (get_local $y)
+    )
+  )
 )
diff --git a/test/passes/simplify-locals.wast b/test/passes/simplify-locals.wast
index d74ebe054..2b5b84a5f 100644
--- a/test/passes/simplify-locals.wast
+++ b/test/passes/simplify-locals.wast
@@ -731,4 +731,24 @@
       (get_local $i1)
     )
   )
+  (func $no-out-of-label (param $x i32) (param $y i32)
+    (loop $moar
+      (set_local $x
+        (block
+          (br_if $moar (get_local $x))
+          (i32.const 0)
+        )
+      )
+    )
+    (drop (get_local $x))
+    (block $moar
+      (set_local $y
+        (block
+          (br_if $moar (get_local $y))
+          (i32.const 0)
+        )
+      )
+    )
+    (drop (get_local $y))
+  )
 )