code-folding must propagate types when it optimizes something

3 files changed, 53 insertions, 3 deletions

diff --git a/src/passes/CodeFolding.cpp b/src/passes/CodeFolding.cpp
index ae2f81283..047eee452 100644
--- a/src/passes/CodeFolding.cpp
+++ b/src/passes/CodeFolding.cpp
@@ -226,13 +226,17 @@ struct CodeFolding : public WalkerPass<ControlFlowWalker<CodeFolding>> {
       // optimize returns at the end, so we can benefit from a fallthrough if there is a value TODO: separate passes for them?
       optimizeTerminatingTails(returnTails);
       // TODO add fallthrough for returns
-      // TODO optimzier returns not in blocks, a big return value can be worth it
+      // TODO optimize returns not in blocks, a big return value can be worth it
       // clean up
       breakTails.clear();
       unreachableTails.clear();
       returnTails.clear();
       unoptimizables.clear();
       modifieds.clear();
+      // if we did any work, types may need to be propagated
+      if (anotherPass) {
+        ReFinalize().walkFunctionInModule(func, getModule());
+      }
     }
   }
 
@@ -371,8 +375,7 @@ private:
       if (!tail.isFallthrough()) {
         tail.block->list.push_back(last);
       }
-      // the blocks lose their endings, so any values are gone, and the blocks
-      // are now either none or unreachable
+      // the block type may change if we removed final values
       tail.block->finalize();
     }
     // since we managed a merge, then it might open up more opportunities later
diff --git a/test/passes/code-folding.txt b/test/passes/code-folding.txt
new file mode 100644
index 000000000..9143b9615
--- /dev/null
+++ b/test/passes/code-folding.txt
@@ -0,0 +1,24 @@
+(module
+ (type $13 (func (param f32)))
+ (type $1 (func))
+ (table 282 282 anyfunc)
+ (memory $0 1 1)
+ (func $0 (type $1)
+  (block $label$1
+   (if
+    (i32.const 1)
+    (block
+     (block $label$3
+      (call_indirect $13
+       (block $label$4
+        (br $label$3)
+       )
+       (i32.const 105)
+      )
+     )
+     (nop)
+    )
+   )
+  )
+ )
+)
diff --git a/test/passes/code-folding.wast b/test/passes/code-folding.wast
new file mode 100644
index 000000000..2310f9721
--- /dev/null
+++ b/test/passes/code-folding.wast
@@ -0,0 +1,23 @@
+(module
+ (type $13 (func (param f32)))
+ (table 282 282 anyfunc)
+ (memory $0 1 1)
+ (func $0
+  (block $label$1
+   (if
+    (i32.const 1)
+    (block $label$3
+     (call_indirect $13
+      (block $label$4 (result f32) ;; but this type may change dangerously
+       (nop) ;; fold this
+       (br $label$3)
+      )
+      (i32.const 105)
+     )
+     (nop) ;; with this
+    )
+   )
+  )
+ )
+)
+