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following branches and Sista

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Eliot Miranda-2

following branches and Sista

Hi Clément,

I’m looking at following branches through unconditional jumps and through pushBoolean; branchIf’s and notice that the code in SistaCogit>>genJumpIf:to: preferentially adds a counter to the innermost conditional branch in a sequence of and:s and or:s. I think we would prefer to have the counter at the outermost send, because this is the most counted. Have you thought about this? What do you think?

_,,,^..^,,,_

best, Eliot

Clément Béra

Re: following branches and Sista

Hi Eliot,

I've never realised this.

My problem was that in benchmarks such as Richards I had issues with methods such as:

SMarkRichTaskState>>isTaskHoldingOrWaiting

^taskHolding or: [packetPending not and: [taskWaiting]]

which would get really slow due to counters. I believe this method should have zero or one counter, not 2. I implemented the cheap heuristic to remove counters on and:/or: for this purpose.

It would be better to have counters on the outermost if (in this case the or:) instead of the innermost (in this case the and:) for sure.

Now I don't think it matters that much because most counters trip on loops and most loops are following the #to:by:do: pattern where there is one condition then branch.

I would like to experiment in the future with other counting logic (more counters for more accurate profiling information), so I don't know if it matters to fix that now. I think the next step is either profiling more accurately, allocation optimisations or changes in the in-image compiler to decrease compilation time (DeltaBlue can get -30% execution time with high magic settings but unfortunately that means a huge slow down at first run due to high compilation time).

On Mon, Jan 16, 2017 at 7:09 PM, Eliot Miranda <[hidden email]> wrote:

Hi Clément,

I’m looking at following branches through unconditional jumps and through pushBoolean; branchIf’s and notice that the code in SistaCogit>>genJumpIf:to: preferentially adds a counter to the innermost conditional branch in a sequence of and:s and or:s. I think we would prefer to have the counter at the outermost send, because this is the most counted. Have you thought about this? What do you think?

_,,,^..^,,,_
best, Eliot