[jdk17u-dev] RFR: 8317507: C2 compilation fails with "Exceeded _node_regs array"

[Aleksey Shipilev]

On Wed, 13 Dec 2023 07:46:08 GMT, Goetz Lindenmaier <goetz at openjdk.org> wrote:

> Won't this increase the memory consumption of the compiler significantly? As I understand it can push more nodes on the arenas now.

The footprint increase effect might be in that we would be able to carry more nodes in these degenerate situations before bailing. Currently it is capped by `PhaseRegAlloc::alloc_node_regs`, which is a small number: original report mentions 1118 nodes for the test case in question. But AFAIU, it is basically a choice what do you do if compiler/user over-unrolled: before this patch, C2 would eventually just bail; after this patch, C2 would still compile the thing.

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

PR Comment: https://git.openjdk.org/jdk17u-dev/pull/2039#issuecomment-1853503174