[llvm] [SLP]Initial support for copyable elements (PR #147366)

[Hans Wennborg via llvm-commits]

zmodem wrote:

We're hitting verifier errors after this change when compiling the attached bitcode: [fwd_txfm.bc.gz](https://github.com/user-attachments/files/22137196/fwd_txfm.bc.gz)

```
$ build/bin/opt -O3 /tmp/fwd_txfm.bc -o /dev/null
Instruction does not dominate all uses!
  %7 = getelementptr i8, ptr %0, i32 240, !dbg !660
  %5 = load <2 x i64>, ptr %7, align 4, !dbg !660
Instruction does not dominate all uses!
  %23 = getelementptr i8, ptr %0, i32 120, !dbg !671
  %18 = load <6 x i64>, ptr %23, align 4, !dbg !671
LLVM ERROR: Broken module found, compilation aborted!
```

Can you please take a look?



https://github.com/llvm/llvm-project/pull/147366