3 files changed, 31 insertions, 0 deletions
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 561e7882c..51fb67065 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -561,6 +561,10 @@ private:
           }
         }
       }
+      if (auto* ext = getSignExt(binary)) {
+        // use a cheaper zero-extent, we just care about the boolean value anyhow
+        return makeZeroExt(ext, getSignExtBits(binary));
+      }
     } else if (auto* block = boolean->dynCast<Block>()) {
       if (block->type == i32 && block->list.size() > 0) {
         block->list.back() = optimizeBoolean(block->list.back());
diff --git a/test/passes/optimize-instructions.txt b/test/passes/optimize-instructions.txt
index eddb2b6b3..a170b3b8c 100644
--- a/test/passes/optimize-instructions.txt
+++ b/test/passes/optimize-instructions.txt
@@ -1121,4 +1121,16 @@
       )
     )
   )
+  (func $sign-ext-boolean (type $4) (param $0 i32) (param $1 i32)
+    (drop
+      (if i32
+        (i32.and
+          (get_local $0)
+          (i32.const 255)
+        )
+        (i32.const 100)
+        (i32.const 200)
+      )
+    )
+  )
 )
diff --git a/test/passes/optimize-instructions.wast b/test/passes/optimize-instructions.wast
index d9e6fcc71..035eb754b 100644
--- a/test/passes/optimize-instructions.wast
+++ b/test/passes/optimize-instructions.wast
@@ -1390,4 +1390,19 @@
       )
     )
   )
+  (func $sign-ext-boolean (param $0 i32) (param $1 i32)
+    (drop
+      (if i32
+        (i32.shr_s
+          (i32.shl
+            (get_local $0)
+            (i32.const 24)
+          )
+          (i32.const 24)
+        )
+        (i32.const 100)
+        (i32.const 200)
+      )
+    )
+  )
 )