handle tee_local in getMaxBits

3 files changed, 45 insertions, 0 deletions

diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index cf5ad982e..d28bf21a5 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -228,6 +228,9 @@ static Index getMaxBits(Expression* curr) {
       case WrapInt64: return std::min(Index(32), getMaxBits(unary->value));
       default: {}
     }
+  } else if (auto* set = curr->dynCast<SetLocal>()) {
+    // a tee passes through the value
+    return getMaxBits(set->value);
   }
   switch (curr->type) {
     case i32: return 32;
diff --git a/test/passes/optimize-instructions.txt b/test/passes/optimize-instructions.txt
index d36f1ffad..9819cb8c7 100644
--- a/test/passes/optimize-instructions.txt
+++ b/test/passes/optimize-instructions.txt
@@ -1200,4 +1200,22 @@
       )
     )
   )
+  (func $sign-ext-tee (type $4) (param $0 i32) (param $1 i32)
+    (drop
+      (i32.shr_s
+        (i32.shl
+          (tee_local $0
+            (i32.const 128)
+          )
+          (i32.const 24)
+        )
+        (i32.const 24)
+      )
+    )
+    (drop
+      (tee_local $0
+        (i32.const 127)
+      )
+    )
+  )
 )
diff --git a/test/passes/optimize-instructions.wast b/test/passes/optimize-instructions.wast
index 6cba3d51f..1f0cd9094 100644
--- a/test/passes/optimize-instructions.wast
+++ b/test/passes/optimize-instructions.wast
@@ -1501,4 +1501,28 @@
       )
     )
   )
+  (func $sign-ext-tee (param $0 i32) (param $1 i32)
+    (drop
+      (i32.shr_s
+        (i32.shl
+          (tee_local $0
+            (i32.const 128) ;; too big
+          )
+          (i32.const 24)
+        )
+        (i32.const 24)
+      )
+    )
+    (drop
+      (i32.shr_s
+        (i32.shl
+          (tee_local $0
+            (i32.const 127) ;; just right
+          )
+          (i32.const 24)
+        )
+        (i32.const 24)
+      )
+    )
+  )
 )