[LAA] Refine stride checks for SCEVs during dependence analysis. (#99577)

Update getDependenceDistanceStrideAndSize to reason about different
combinations of strides directly and explicitly.

Upd

[LAA] Refine stride checks for SCEVs during dependence analysis. (#99577)

Update getDependenceDistanceStrideAndSize to reason about different
combinations of strides directly and explicitly.

Update getPtrStride to return 0 for invariant pointers.

Then proceed by checking the strides.

If either source or sink are not strided by a constant (i.e. not a
non-wrapping AddRec) or invariant, the accesses may overlap
with earlier or later iterations and we cannot generate runtime
checks to disambiguate them.

Otherwise they are either loop invariant or strided. In that case, we
can generate a runtime check to disambiguate them.

If both are strided by constants, we proceed as previously.

This is an alternative to
https://github.com/llvm/llvm-project/pull/99239 and also replaces
additional checks if the underlying object is loop-invariant.

Fixes https://github.com/llvm/llvm-project/issues/87189.

PR: https://github.com/llvm/llvm-project/pull/99577

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[LAA] Adjust test from a4f8705b05 so RT checks aren't always false.

Updated @B_indices_loaded_in_loop_A_stored to use a different offset
for one of the accesses we create runtime checks for; the ori

[LAA] Adjust test from a4f8705b05 so RT checks aren't always false.

Updated @B_indices_loaded_in_loop_A_stored to use a different offset
for one of the accesses we create runtime checks for; the original
version had a runtime check that was always true as the accesses always
overlapped.

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[LAA] Precommit test with loops where indices are loaded in each iter.

Add tests which are not safe to vectorize because %indices are loaded in
the loop and the same indices could be loaded in later

[LAA] Precommit test with loops where indices are loaded in each iter.

Add tests which are not safe to vectorize because %indices are loaded in
the loop and the same indices could be loaded in later iterations.

Tests for https://github.com/llvm/llvm-project/issues/87189.

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