RFR: 8357781: Deep recursion in PhaseCFG::set_next_call leads to stack overflow [v3]

[SendaoYan]

On Tue, 27 May 2025 09:43:11 GMT, Marc Chevalier <mchevalier at openjdk.org> wrote:

>> There is nothing very wrong here:
>> - the graph is not broken
>> - the algorithm is correct
>> 
>> It just happens that the graph is very deep, it has a very long, narrow chain of nodes because of crazy unrolling, because of `LoopUnrollLimit=8192`. This depth simply makes the algorithm recurse deeper than the stack size allows. This kind of graph shape is not quite trivial to reproduce. The proposed reproducer is very easy to change into a non-reproducer, with many kinds of change, even that seem harmless to me.
>> 
>> The fix is also pretty direct: let's change the recursive traversal, with a worklist-based iterative one. It's not as elegant, but it doesn't overflow.
>> 
>> How sad stacks are still so bounded...
>
> Marc Chevalier has updated the pull request incrementally with one additional commit since the last revision:
> 
>   address comment

test/hotspot/jtreg/compiler/c2/StackOverflowInSetNextCall.java line 65:

> 63:     public static void main(String[] args) {
> 64:         for (int i = 0; i < 400; ++i) {
> 65:             test();

Do we need to use the return value of function `test`, to avoid the compiler do the dead code elimination

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PR Review Comment: https://git.openjdk.org/jdk/pull/25448#discussion_r2108959027