JIT: propagate some block assertions after expansion

[AndyAyersMS]

In #74384 I modified morph to generate assertions before a block op was morphed, but after the source and dest were morphed. This misses generating some assertions that arise once the expanded form is known.

We now re-run assertion gen on the expanded tree, when we do an OneAsgBlock expansion. Other cases my also prove profitable.

Closes #75229.

Diffs

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Issue Details

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In #74384 I modified morph to generate assertions before a block op was morphed, but after the source and dest were morphed. This misses generating some assertions that arise once the expanded form is known.

We now re-run assertion gen on the expanded tree, when we do an OneAsgBlock expansion. Other cases my also prove profitable.

Closes #75229.

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

[AndyAyersMS]

@kunalspathak PTAL
cc @dotnet/jit-contrib

[kunalspathak]

LGTM

[AndyAyersMS]

Note the two methods that were regressed by #74384 show size increases here. This is from alignment padding; the loop body is actually smaller than before.

Top method regressions (bytes):
          10 (18.87 % of base) : 36547.dasm - System.Collections.IndexerSetReverse`1[System.__Canon]:Array():<unnamed>:this
           8 (14.04 % of base) : 32204.dasm - System.Collections.IndexerSet`1[System.__Canon]:Array():<unnamed>:this

[kunalspathak]

This is from alignment padding; the loop body is actually smaller than before.

Yep, I downloaded and double checked that. :)