Missed redundant load elimination across blocks: `getelementptr [8 x i8], ptr %2, i64 %0` vs. `getelementptr i8, ptr %2, i64 (shl i64 %0, 3)`

The following reduced IR is derived from https://github.com/ruby/ruby/blob/3379c7efbdc34b7936f322a6bc2de4834c8c65fc/ext/-test-/memory_view/memory_view.c#L263

https://godbolt.org/z/cqbYqWfnP
alive2: https://alive2.llvm.org/ce/z/pxn7S3

In the reduced IR, the load from `%scevgep` reads the same location just written by `store i64 0, ptr %3`, since both `%scevgep` and `%3` denote `%2 + 8 * %0`. Therefore `%load_initial` is always 0, and the later store can be simplified to `store i64 0, ptr %gep, align 8`.

```llvm
define noundef i1 @mdview_get_memory_view(i64 %0) local_unnamed_addr {
%2 = tail call ptr @ruby_xmalloc2()
%3 = getelementptr [8 x i8], ptr %2, i64 %0
store i64 0, ptr %3, align 8
%4 = icmp sgt i64 %0, 0
br i1 %4, label %.lr.ph.preheader, label %._crit_edge

.lr.ph.preheader:
%5 = shl i64 %0, 3
%scevgep = getelementptr i8, ptr %2, i64 %5
%load_initial = load i64, ptr %scevgep, align 8
%invariant.gep = getelementptr i8, ptr %2, i64 -8
%gep = getelementptr [8 x i8], ptr %invariant.gep, i64 %0
store i64 %load_initial, ptr %gep, align 8
br label %._crit_edge

._crit_edge:
ret i1 false
}
```

Expected:
```llvm
define noundef i1 @tgt(i64 %0) local_unnamed_addr {
%2 = tail call ptr @ruby_xmalloc2()
%3 = getelementptr [8 x i8], ptr %2, i64 %0
store i64 0, ptr %3, align 8
%4 = icmp sgt i64 %0, 0
br i1 %4, label %.lr.ph.preheader, label %._crit_edge

.lr.ph.preheader:
%invariant.gep = getelementptr i8, ptr %2, i64 -8
%gep = getelementptr [8 x i8], ptr %invariant.gep, i64 %0
store i64 0, ptr %gep, align 8
br label %._crit_edge

._crit_edge:
ret i1 false
}
```

Reproduce the reduced IR in the linked Godbolt example and validate the equivalence with the Alive2 link. Trace the LLVM optimization pass responsible for redundant load elimination across blocks, then add coverage for this IR pattern; done means the load is eliminated and the later store uses value 0 as shown in the expected IR.

Written by the indexing model from the issue text.