The vectorisation analysis collects strides for loop invariant
pointers, which is wrong because they are not strided. We don't
need to generate SCEV checks (which are costly performancewise)
for such pointers, we just need to do the appropriate aliasing
checks.
This patch fixes the problem by changing getStrideFromPointer()
to treat loop invariant pointers as having no stride.
Originally proposed by David Sherwood with further suggestions
from Florian Hahn.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D146958
This commit introduces a test for the change introduced by the
`[SCEV] Do not plant SCEV checks unnecessarily` commit,
D146958.
Reviewed By: fhahn, david-arm
Differential Revision: https://reviews.llvm.org/D146974
