[SROA] Add Stored Value Size Check for Tree-Structured Merge (#162921)

The change fixes a bug in the SROA where tree-structured merge
optimization was incorrectly applied when the size of the stored value
was not a multiple of the new allocated element type size. The original
change is https://github.com/llvm/llvm-project/pull/152793. A simple
repro would be

```
define <1 x i32> @foo(<1 x i16> %a, <1 x i16> %b) {
entry:
  %alloca = alloca [1 x i32]

  %ptr0 = getelementptr inbounds [2 x i16], ptr %alloca, i32 0, i32 0
  store <1 x i16> %a, ptr %ptr0

  %ptr1 = getelementptr inbounds [2 x i16], ptr %alloca, i32 0, i32 1
  store <1 x i16> %b, ptr %ptr1

  %result = load <1 x i32>, ptr %alloca
  ret <1 x i32> %result
}
```

Currently, this will lead to a compile time crash.

In this change, we will skip the tree-structured merge for this case and
fall back to normal SROA.

0 files changed, 0 insertions, 0 deletions