From 1196f7088d2ed3ec1227343d9a50eccd0aa4e18e Mon Sep 17 00:00:00 2001
From: Thomas Lively <tlively@google.com>
Date: Mon, 23 Mar 2026 15:40:31 -0700
Subject: [PATCH] Do not copy function annotations when copying expressions

When copying expressions from one function to another, we previously also copied the function-level annotations from the source function to the destination. This is not correct, and caused a bug where the @binaryen.removable.if.unused annotation was copied from an inlined function to its caller, resulting in side effects being dropped. Fix the problem by moving responsibility for copying function annotations from `copyBetweenFunctions to `copyFunctionWithoutAdd`.
---
 src/ir/metadata.cpp                           |  6 +---
 src/ir/module-utils.cpp                       |  1 +
 ...lining-optimizing-removable-if-unused.wast | 33 +++++++++++++++++++
 3 files changed, 35 insertions(+), 5 deletions(-)
 create mode 100644 test/lit/passes/inlining-optimizing-removable-if-unused.wast

diff --git a/src/ir/metadata.cpp b/src/ir/metadata.cpp
index 6ac749b1fff..61c5da9bc06 100644
--- a/src/ir/metadata.cpp
+++ b/src/ir/metadata.cpp
@@ -44,8 +44,7 @@ void copyBetweenFunctions(Expression* origin,
                           Function* originFunc,
                           Function* copyFunc) {
   if (originFunc->debugLocations.empty() &&
-      originFunc->codeAnnotations.empty() &&
-      originFunc->funcAnnotations.empty()) {
+      originFunc->codeAnnotations.empty()) {
     // Nothing to copy.
     return;
   }
@@ -75,9 +74,6 @@ void copyBetweenFunctions(Expression* origin,
       }
     }
   }
-
-  // Also copy function-level annotations.
-  copyFunc->funcAnnotations = originFunc->funcAnnotations;
 }
 
 #pragma GCC diagnostic push
diff --git a/src/ir/module-utils.cpp b/src/ir/module-utils.cpp
index ea83a7e05bd..5b815eb4fea 100644
--- a/src/ir/module-utils.cpp
+++ b/src/ir/module-utils.cpp
@@ -73,6 +73,7 @@ copyFunctionWithoutAdd(Function* func,
   ret->localIndices = func->localIndices;
   ret->body = ExpressionManipulator::copy(func->body, out);
   metadata::copyBetweenFunctions(func->body, ret->body, func, ret.get());
+  ret->funcAnnotations = func->funcAnnotations;
   ret->prologLocation = func->prologLocation;
   ret->epilogLocation = func->epilogLocation;
   // Update file indices if needed
diff --git a/test/lit/passes/inlining-optimizing-removable-if-unused.wast b/test/lit/passes/inlining-optimizing-removable-if-unused.wast
new file mode 100644
index 00000000000..50e2be8dabc
--- /dev/null
+++ b/test/lit/passes/inlining-optimizing-removable-if-unused.wast
@@ -0,0 +1,33 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
+
+;; RUN: wasm-opt %s --inlining-optimizing -S -o - | filecheck %s
+
+(module
+ ;; CHECK:      (import "" "" (func $import (param i32)))
+ (import "" "" (func $import (param i32)))
+ ;; CHECK:      (export "test" (func $test))
+ (export "test" (func $test))
+ ;; CHECK:      (func $test
+ ;; CHECK-NEXT:  (call $import
+ ;; CHECK-NEXT:   (i32.const 0)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $test
+  (call $main)
+ )
+ (func $main
+  (call $print)
+ )
+ (func $print
+  ;; $print should not inherit the removable.if.unused attribute from the
+  ;; inlined call to $removable. (If it did, then we would incorrectly remove
+  ;; the call to the import.)
+  (call $import
+   (call $removable)
+  )
+ )
+ (@binaryen.removable.if.unused)
+ (func $removable (result i32)
+  (i32.const 0)
+ )
+)