RegisterCoalescer: Fix assert on remat to copy-to-physreg with subregs#121734

arsenm merged 2 commits intomainllvm/llvm-project:mainfrom

users/arsenm/issue120970/fix-assert-clobber-rematerialize-super-reg-def-at-subreg-extractllvm/llvm-project:users/arsenm/issue120970/fix-assert-clobber-rematerialize-super-reg-def-at-subreg-extractCopy head branch name to clipboard