[llvm] [InstCombine] Extend folding of aggregate construction to cases when source aggregates are partially available (PR #100828)

[via llvm-commits]

weiguozhi wrote:


> > How did you run it?
> 
> I run it with `opt -O3`. `UseLoopInfo` is disabled by default due to compilation time regression: [ef6f235](https://github.com/llvm/llvm-project/commit/ef6f23535d4e2b437913b48bdbdef00f000594c2)

With -O3 I got
```
opt -O3 reduced2.ll -S

; ModuleID = 'reduced2.ll'
source_filename = "reduced2.ll"

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none)
define hidden { i64, i64 } @"_ZN4core6result19Result$LT$T$C$E$GT$7map_err17h84015741f1851E.llvm"(i64 noundef %0, i64 %1) unnamed_addr #0 {
  %3 = insertvalue { i64, i64 } poison, i64 %0, 0
  %4 = insertvalue { i64, i64 } %3, i64 %1, 1
  ret { i64, i64 } %4
}
```

Thank you for the LoopInfo information. In order to make it more usable I  should avoid the LoopInfo usage. I will think it more.


https://github.com/llvm/llvm-project/pull/100828