[Mlir-commits] [mlir] [MLIR][LivenessAnalysis] Treat a public function as an external (PR #160648)

[Mehdi Amini]

================
@@ -569,6 +569,18 @@ module @return_void_with_unused_argument {
     call @fn_return_void_with_unused_argument(%arg0, %unused) : (i32, memref<4xi32>) -> ()
     return %unused : memref<4xi32>
   }
+  // the function signature is immutable because it is public.
+  func.func public @public_fn_with_unused_argument(%unused: i32) -> () {
+    return
+  }
+  // CHECK-LABEL: func.func @main2
+  // CHECK: %[[UNUSED:.*]] = arith.constant 0 : i32
+  // CHECK: call @public_fn_with_unused_argument(%[[UNUSED]]) : (i32) -> ()
+  func.func @main2(%arg0: i32) -> () {
+    %zero = arith.constant 0 : i32
+    call @public_fn_with_unused_argument(%zero) : (i32) -> ()
----------------
joker-eph wrote:

arg0 is unused here, so we can reduce further:


```suggestion
  func.func @main2(%arg0: i32) -> () {
    call @public_fn_with_unused_argument(%arg0) : (i32) -> ()
```

https://github.com/llvm/llvm-project/pull/160648