[Mlir-commits] [mlir] [mlir][Transforms] Fix crash in `-remove-dead-values` on private functions (PR #169269)

[Matthias Springer]

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@@ -118,6 +118,17 @@ func.func @main(%arg0 : i32) {
 
 // -----
 
+// CHECK-LABEL: func.func private @clean_func_op_remove_side_effecting_op() {
+// CHECK-NEXT:    return
+// CHECK-NEXT:  }
+func.func private @clean_func_op_remove_side_effecting_op(%arg0: i32) -> (i32) {
+  // vector.print has a side effect but the op is dead.
+  vector.print %arg0 : i32
+  return %arg0 : i32
+}
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matthias-springer wrote:

#162038 touches the same pass, but it looks like it's solving a different issue. The problem there is related to public functions.

> this logic that you quote makes somehow sense to me: based on liveness of the results we figure that an op is dead.
> Doing the same based on operands is less clear to me.

My reasoning is: If the liveness analysis determines that an SSA value is dead, so must be all users of that SSA values. If there were live users (with a side effect), the analysis would not have marked the SSA value as "dead". Is there a flaw in my conclusion?

https://github.com/llvm/llvm-project/pull/169269