[llvm] [SLP]Remove operands upon marking instruction for deletion. (PR #97409)

[Alan Zhao via llvm-commits]

alanzhao1 wrote:

> > See [repro.tar.gz](https://github.com/user-attachments/files/16149916/repro.tar.gz)
> > I'll see if I can get a reduced repro.
> 
> Ok, able to reproduce, will try to investigate

Here's a (much) reduced repro with CReduce:

```c
int a, b, c;
double d, e, f, g;
void h() {
  do {
    while (a)
      ;
    d = f - (0 * f + e * g);
    g = e * f - 0 * g + g;
    f = d * g;
    a = a - c;
  } while (b);
}
```

Reduced command: `clang -cc1 -triple i386-pc-windows-msvc19.34.0 -target-feature +sse3 -O2 -vectorize-slp -emit-llvm fft-06e938.reduced.c`


https://github.com/llvm/llvm-project/pull/97409