Add a new cost-based transform that replaces VPWidenCanonicalIVRecipe
with a canonical VPWidenIntOrFpInductionPHIRecipe, if it does not
increase spills.
The main benefit of VPWidenCanonicalIVRecipe is that it has shorter
live-ranges than wide IV phis. The new transform introduces wide IV
unless VPWidenCanonicalIVRecipe is cheaper or the wide IV introduces
additional spills.
This introduces wide IVs in a number of cases, where previously had
VPWidenCanonicalIVRecipe, because there was no existing wide canonical
IV we could re-use. It should also help avoid somewhat unrelated changes
in https://github.com/llvm/llvm-project/pull/190191.
PR: https://github.com/llvm/llvm-project/pull/194267
ec14a1f40c