5 files changed, 8 insertions, 18 deletions
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 003d2ff60..2315b9e8e 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -24,6 +24,7 @@
 #include <pass.h>
 #include <wasm-s-parser.h>
 #include <support/threads.h>
+#include <ast_utils.h>
 
 namespace wasm {
 
@@ -208,6 +209,13 @@ struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions,
           }
         }
       }
+    } else if (auto* set = curr->dynCast<SetGlobal>()) {
+      // optimize out a set of a get
+      auto* get = set->value->dynCast<GetGlobal>();
+      if (get && get->name == set->name) {
+        ExpressionManipulator::nop(curr);
+        return curr;
+      }
     }
     return nullptr;
   }
diff --git a/test/emcc_hello_world.fromasm b/test/emcc_hello_world.fromasm
index 36a6c1ff1..94eb84af9 100644
--- a/test/emcc_hello_world.fromasm
+++ b/test/emcc_hello_world.fromasm
@@ -17682,9 +17682,6 @@
     (set_global $STACKTOP
       (get_local $6)
     )
-    (set_global $tempRet0
-      (get_global $tempRet0)
-    )
     (get_local $0)
   )
   (func $___muldi3 (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (result i32)
diff --git a/test/emcc_hello_world.fromasm.imprecise b/test/emcc_hello_world.fromasm.imprecise
index cb25aad51..79b6acbc8 100644
--- a/test/emcc_hello_world.fromasm.imprecise
+++ b/test/emcc_hello_world.fromasm.imprecise
@@ -17675,9 +17675,6 @@
     (set_global $STACKTOP
       (get_local $6)
     )
-    (set_global $tempRet0
-      (get_global $tempRet0)
-    )
     (get_local $0)
   )
   (func $___muldi3 (param $0 i32) (param $1 i32) (param $2 i32) (param $3 i32) (result i32)
diff --git a/test/unit.fromasm b/test/unit.fromasm
index 578385db3..ed9248552 100644
--- a/test/unit.fromasm
+++ b/test/unit.fromasm
@@ -690,12 +690,6 @@
         (i32.const 12)
       )
     )
-    (set_global $Double
-      (get_global $Double)
-    )
-    (set_global $Int
-      (get_global $Int)
-    )
     (call $globalOpts)
     (set_local $0
       (get_global $Int)
diff --git a/test/unit.fromasm.imprecise b/test/unit.fromasm.imprecise
index 1f303aef6..5d43b9e04 100644
--- a/test/unit.fromasm.imprecise
+++ b/test/unit.fromasm.imprecise
@@ -671,12 +671,6 @@
         (i32.const 12)
       )
     )
-    (set_global $Double
-      (get_global $Double)
-    )
-    (set_global $Int
-      (get_global $Int)
-    )
     (call $globalOpts)
     (set_local $0
       (get_global $Int)