On 11/9/23 10:40, Alexander Monakov wrote:
On Thu, 9 Nov 2023, Maxim Kuvyrkov wrote:
Hi Kewen,
Below are my comments. I don't want to override Alexander's review, and if
the patch looks good to him, it's fine to ignore my concerns.
My main concern is that this adds a new entity -- forceful skipping of
DEBUG_INSN-only basic blocks -- to the scheduler for a somewhat minor change
in behavior. Unlike NOTEs and LABELs, DEBUG_INSNs are INSNS, and there is
already quite a bit of logic in the scheduler to skip them _as part of normal
operation_.
I agree with the concern. I hoped that solving the problem by skipping the BB
like the (bit-rotted) debug code needs to would be a minor surgery. As things
look now, it may be better to remove the non-working sched_block debug counter
entirely and implement a good solution for the problem at hand.
I wouldn't lose sleep over this -- if removing a debug counter from this
code simplifies the implementation, that's fine with me. I believe they
were all added when significant work in the scheduler was more common.
Can we teach haifa-sched to emit RTX NOTEs with hashes of DFA states on BB
boundaries with -fcompare-debug is enabled? It should make the problem
readily detectable by -fcompare-debug even when scheduling did not diverge.
I like it.
jeff
