A strange and easily reproducible problem in the AOT-compiled code.

[haodong404]

Problem Code

Normally, the following code should print [2, 2, 10]. However, in practice, if I execute it using dart run, it prints the correct result [2, 2, 10]. But if I first compile it into AOT code using dart compile aot-snapshot and then run it using dartaotruntime, it prints [0, 0, 10], which is clearly an incorrect result.

List<int> encode() {
  int offset = 0;
  List<int> part = [0, 0, 0];

  for (int i = 0; i < 2; i++) {
    part[offset] = 2;
    offset++;
  }

  // Everything will be okay if without the line below.
  part[offset] = 10;

  // And everything will be okay if with the `print` line.
  // print(part);
  return part;
}

void main() {
  print(encode());
}

Dart Infomation

- Dart 3.3.2 (stable) (Tue Mar 19 20:44:48 2024 +0000) on "macos_arm64"
- on macos / Version 14.4.1 (Build 23E224)

Actually, I have tried the latest dev version (3.5.0-109.0.dev), and this issue still exists.

[mraleph]

I think it is a bug in DSE: it probably thinks that both of these stores are storing to the same place, but they are not - because offset is a phi. Can you look at this @alexmarkov?