JIT: move optOptimizeBools later in the phase list

[AndyAyersMS]

This transformation blocks assertion prop and RBO and does not enable any global optimizations. So defer it until later, after all the optimization phases have run.

[ghost]

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Issue Details

---

This transformation blocks assertion prop and RBO and does not enable any global optimizations. So defer it until later, after all the optimization phases have run.

Author:	AndyAyersMS
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[AndyAyersMS]

This should also address some of the regressions seen in #62689.

@jakobbotsch PTAL
cc @dotnet/jit-contrib

It also causes a few regressions. Last I looked it was from losing assertions; I will double-check if that's still the case.

[AndyAyersMS]

It also causes a few regressions. Last I looked it was from losing assertions; I will double-check if that's still the case.

Some of these come from us now skipping fgComputeEdgeWeights -- going to try adding a call to this to OOB if it makes any changes and see what that does.

[AndyAyersMS]

It also causes a few regressions. Last I looked it was from losing assertions; I will double-check if that's still the case.

Some of these come from us now skipping fgComputeEdgeWeights -- going to try adding a call to this to OOB if it makes any changes and see what that does.

That seems pretty disruptive. Let me look at more diffs from the current PR.

[AndyAyersMS]

Looked through a handful of the worst regressions and there is one common theme.

RBO now fires on one tree in a branch pair that would have been merged by OOB, because one of the branches is redundant higher up. This has a variety of knock-on effects, either not rerunning edge weights (hence changing how block opts runs), modifying the CSE candidates, making CSEs more widely available and hence likely to be seen as call-crossing, etc.

I don't think there is any simple mitigation and I like OOB a lot better running later than earlier, so I think we should just live with these.