Fix DeadArgumentElimination pass on non-nullable locals (#3751)

In this case, there is a natural place to fix things up right after
removing a parameter (which is where a local gets added). Doing it
there avoids doing work on all functions unnecessarily.

Note that we could do something even simpler here than calling
the generic code: the parameter was not used, so the new local
is not used, and we could just change the type of the local or not
add it at all. Those would be slightly more code though, and add
complexity to the parameter removal method itself.

3 files changed, 23 insertions, 0 deletions

diff --git a/src/passes/DeadArgumentElimination.cpp b/src/passes/DeadArgumentElimination.cpp
index 975b291b0..59337f75d 100644
--- a/src/passes/DeadArgumentElimination.cpp
+++ b/src/passes/DeadArgumentElimination.cpp
@@ -41,6 +41,7 @@
 #include "ir/effects.h"
 #include "ir/element-utils.h"
 #include "ir/module-utils.h"
+#include "ir/type-updating.h"
 #include "pass.h"
 #include "passes/opt-utils.h"
 #include "support/sorted_vector.h"
@@ -382,6 +383,7 @@ struct DAE : public Pass {
             // Wonderful, nothing stands in our way! Do it.
             // TODO: parallelize this?
             removeParameter(func, i, calls);
+            TypeUpdating::handleNonNullableLocals(func, *module);
             changed.insert(func);
           }
         }
diff --git a/test/passes/dae_all-features.txt b/test/passes/dae_all-features.txt
index ea439bc9e..773701396 100644
--- a/test/passes/dae_all-features.txt
+++ b/test/passes/dae_all-features.txt
@@ -312,3 +312,13 @@
   )
  )
 )
+(module
+ (type $none_=>_none (func))
+ (func $0
+  (local $0 (ref null i31))
+  (nop)
+ )
+ (func $1
+  (call $0)
+ )
+)
diff --git a/test/passes/dae_all-features.wast b/test/passes/dae_all-features.wast
index 55e935f3b..67244cc23 100644
--- a/test/passes/dae_all-features.wast
+++ b/test/passes/dae_all-features.wast
@@ -193,3 +193,14 @@
   )
  )
 )
+(module
+ ;; a removable non-nullable parameter
+ (func $0 (param $x i31ref)
+  (nop)
+ )
+ (func $1
+  (call $0
+   (i31.new (i32.const 0))
+  )
+ )
+)