OptimizeInstructions: Add missing invalidation check in consecutive equality test

src/passes/OptimizeInstructions.cpp

@@ -2501,11 +2501,33 @@ struct OptimizeInstructions
     // Ignore extraneous things and compare them syntactically. We can also
     // look at the full fallthrough for both sides now.
     left = Properties::getFallthrough(left, passOptions, *getModule());
+    auto* originalRight = right;
     right = Properties::getFallthrough(right, passOptions, *getModule());
     if (!ExpressionAnalyzer::equal(left, right)) {
       return false;
     }
 
+    // We must also not have non-fallthrough effects that invalidate us, such as
+    // this situation:
+    //
+    //  (local.get $x)
+    //  (block
+    //    (local.set $x ..)
+    //    (local.get $x)
+    //  )
+    //
+    // The fallthroughs are identical, but the set may cause us to read a
+    // different value.
+    if (originalRight != right) {
+      // TODO: We could be more precise here and ignore right itself in
+      //       originalRightEffects.
+      auto originalRightEffects = effects(originalRight);
+      auto rightEffects = effects(right);
+      if (originalRightEffects.invalidates(rightEffects)) {
+        return false;
+      }
+    }
+
     // To be equal, they must also be known to return the same result
     // deterministically.
     return !Properties::isGenerative(left);

test/lit/passes/j2cl-inline.wast

@@ -6,16 +6,23 @@
 (module
 
   ;; A once function that has become empty
+  ;; CHECK:      (type $0 (func))
+
+  ;; CHECK:      (global $$class-initialized@Zoo (mut i32) (i32.const 0))
+
+  ;; CHECK:      (func $clinit-trivial-1_<once>_@Foo (type $0)
+  ;; CHECK-NEXT:  (nop)
+  ;; CHECK-NEXT: )
   (func $clinit-trivial-1_<once>_@Foo  )
 
   ;; A once function that just calls another
+  ;; CHECK:      (func $clinit-trivial-2_<once>_@Bar (type $0)
+  ;; CHECK-NEXT:  (nop)
+  ;; CHECK-NEXT: )
   (func $clinit-trivial-2_<once>_@Bar
     (call $clinit-trivial-1_<once>_@Foo)
   )
 
-  ;; CHECK:      (type $0 (func))
-
-  ;; CHECK:      (global $$class-initialized@Zoo (mut i32) (i32.const 0))
   (global $$class-initialized@Zoo (mut i32) (i32.const 0))
 
   ;; Not hoisted but trivial.