[VectorCombine] Apply InstSimplify in scalarizeOpOrCmp to avoid infinite loop (#153069)

Fixes #153012

As we tolerate unfoldable constant expressions in `scalarizeOpOrCmp`, we
may fold
```llvm
define void @bug(ptr %ptr1, ptr %ptr2, i64 %idx) #0 {
entry:
  %158 = insertelement <2 x i64> <i64 5, i64 ptrtoint (ptr @val to i64)>, i64 %idx, i32 0
  %159 = or disjoint <2 x i64> splat (i64 2), %158
  store <2 x i64> %159, ptr %ptr2
  ret void
}
```

to

```llvm
define void @bug(ptr %ptr1, ptr %ptr2, i64 %idx) {
entry:
  %.scalar = or disjoint i64 2, %idx
  %0 = or <2 x i64> splat (i64 2), <i64 5, i64 ptrtoint (ptr @val to i64)>
  %1 = insertelement <2 x i64> %0, i64 %.scalar, i64 0
  store <2 x i64> %1, ptr %ptr2, align 16
  ret void
}
```
And it would be folded back in `foldInsExtBinop`, resulting in an
infinite loop.

This patch forces scalarization iff InstSimplify can fold the constant
expression.

0 files changed, 0 insertions, 0 deletions