[PATCH] D155726: [InstCombine] Test case for D155718+D154064

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/test/Transforms/InstCombine/icmp-fold-into-phi.ll:97
+declare zeroext i1 @StrCmp(ptr noundef, ptr noundef)
+declare zeroext i1 @CheckCond()
----------------
nikic wrote:
> This test looks too complicated for what we actually want to test. I think something like this should be sufficient:
> ```
> define i1 @test(i32 %x, i32 %y) {
> entry:
>   switch i32 %x, label %bb1 [
>     i32 0, label %bb2
>     i32 1, label %bb3
>   ]
> 
> bb1:
>   br label %bb2
> 
> bb2:
>   %phi1 = phi i32 [ 1, %entry ], [ %y, %bb1 ]
>   br label %bb3
> 
> bb3:
>   %phi2 = phi i32 [ %phi1, %bb2 ], [ 0, %entry ]
>   %cmp = icmp ugt i32 %phi2, 1
>   ret i1 %cmp
> }
> ```
> This would also make it independent of D154064 and allow us to land this patch first.
Well, I guess it would make sense to //also// add your test to make sure that D154064 doesn't regress it, but in that case we should cut it down a bit. There's a lot of parts that aren't really relevant, e.g. the final block could be just this I think:
```

  %cond3       = phi i32 [ %cond2, %sw.bb ], [ 134, %cond.false2 ], [ 2, %cond.false ], [ 1, %entry ]
  %cmp         = icmp ult i32 %cond3, 2
  ret i1 %cmp
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D155726/new/

https://reviews.llvm.org/D155726