[lworld] RFR: 8377480: [lworld] incorrect execution due to EA pointer comparison optimization at scalarized call [v2]

[Tobias Hartmann]

On Thu, 12 Feb 2026 09:31:17 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> EA goes over arguments to a non inlined call and uses
>> `BCEscapeAnalyzer` to add edges to the `ConnectionGraph`. With
>> valhalla, that code goes over inputs to a `CallNode` using the
>> scalarized calling convention and queries `BCEscapeAnalyzer` with the
>> index of the argument in the scalarized CC but `BCEscapeAnalyzer` has
>> no knowledge of the scalarized CC. So `is_arg_returned()` for instance
>> is passed the wrong argument number and EA, as a result, can add
>> incorrect edges to the `ConnectionGraph`.
>> 
>> In the test case:
>> 
>> 
>>     static value class MyValue {
>>         Object o;
>> 
>>         MyValue(Object o) {
>>             this.o = o;
>>         }
>>     }
>> 
>>     static int test1(Object o) {
>>         MyValue v = new MyValue(null);
>>         Object res = notInlined(v, o);
>>         if (res == null) {
>>             return 1;
>>         }
>>         return 2;
>>     }
>> 
>>     static Object notInlined(MyValue arg1, Object arg2) {
>>         return arg2;
>>     }
>> 
>> 
>> 2nd argument is returned by `notInlined()`. The second argument in the
>> scalarized CC in `test1()` is `Myvalue.o`. So EA deduces that the
>> return value of `notInlined()` is `v.o` (which is `null`) instead of
>> `o` which is non null.
>> 
>> With this EA:
>> 
>>     public static void test2() {
>>         MyValue arg = new MyValue(null);
>>         MyValue res = notInlined2(arg);
>>         if (res.o != null) {
>>             throw new RuntimeException("never taken");
>>         }
>>     }
>>     
>>     static MyValue notInlined2(MyValue v) {
>>         return v;
>>     }
>> 
>> 
>> 
>> the fixed logic connects the return of `notInlined2` with `v.o`.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Good catch! The fix looks good to me.

-------------

Marked as reviewed by thartmann (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/2079#pullrequestreview-3789973021