RyuJIT: support cloning loop nests with multi-dimensional array accesses

[BruceForstall]

As described in #60785, loop cloning should handle the case where a multi-dimensional (MD) array access occurs with a loop nest. Different from jagged arrays, with MD arrays, we should be able to hoist bounds checks out of an entire loop nest, as well as make the "fast path" loop assume arrays with lower bounds of zero (thus eliminating subtracting off the lower bound to get an "effective index").

category:cq
theme:md-arrays
skill-level:expert
cost:large
impact:large

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Issue Details

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As described in #60785, loop cloning should handle the case where a multi-dimensional (MD) array access occurs with a loop nest. Different from jagged arrays, with MD arrays, we should be able to hoist bounds checks out of an entire loop nest, as well as make the "fast path" loop assume arrays with lower bounds of zero (thus eliminating subtracting off the lower bound to get an "effective index").

category:cq
theme:md-arrays
skill-level:expert
cost:large

Author:	BruceForstall
Assignees:	BruceForstall
Labels:	area-CodeGen-coreclr
Milestone:	8.0.0