[llvm] [AArch64] Improve non-SVE popcount for 32bit and 64 bit using udot (PR #95881)

[David Green via llvm-commits]

================
@@ -1,17 +1,40 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc < %s -O0 -mtriple=aarch64-unknown-unknown | FileCheck %s
----------------
davemgreen wrote:

I think we've lost some of the -O0 check lines. Maybe do:
```
; RUN: llc < %s -O0 -mtriple=aarch64-unknown-unknown | FileCheck %s --check-prefix=CHECKO0
; RUN: llc < %s -mtriple=aarch64-unknown-unknown -mattr=+neon | FileCheck %s --check-prefixes=CHECK,NEON
; RUN: llc < %s -mtriple=aarch64-unknown-unknown -mattr=+neon,+dotprod | FileCheck %s --check-prefixes=CHECK,DOT
; RUN: llc < %s -mtriple=aarch64-unknown-unknown -mattr=+sve | FileCheck %s --check-prefixes=CHECK,SVE
```

https://github.com/llvm/llvm-project/pull/95881