[PATCH] D107148: [InstCombine] Fold two-value clamp patterns

[Qiu Chaofan via Phabricator via llvm-commits]

qiucf added a comment.

In D107148#3081328 <https://reviews.llvm.org/D107148#3081328>, @spatel wrote:

> Not with the direction - as noted earlier, we're already trying this with the intrinsics, so doing it with cmp+select just makes things consistent. There are a few implementation/test questions:
>
> 1. What logic diffs are there between this and 025bb5290379 <https://reviews.llvm.org/rG025bb52903792de3dd29667d42c97fdf13a00f2b> ?
> 2. Add/adjust tests based on those diffs.
> 3. Use m_APInt so we get splat vectors.
>
> @qiucf - will you continue this patch soon?

I applied D98152 <https://reviews.llvm.org/D98152> and try. The two currently affected cases (minmax-fold.ll, icmp-dom.ll) here are still passed with it but without my patch. But for below vector case:

  define <4 x i32> @twoway_clamp_gt(<4 x i32> %num) {
  entry:
    %cmp1 = icmp sgt <4 x i32> %num, <i32 13767, i32 13767, i32 13767, i32 13767>
    %s1 = select <4 x i1> %cmp1, <4 x i32> %num, <4 x i32> <i32 13767, i32 13767, i32 13767, i32 13767>
    %cmp2 = icmp slt <4 x i32> %s1, <i32 13768, i32 13768, i32 13768, i32 13768>
    %r = select <4 x i1> %cmp2, <4 x i32> %s1, <4 x i32> <i32 13768, i32 13768, i32 13768, i32 13768>
    ret <4 x i32> %r
  }
  
  ; Got
  define <4 x i32> @twoway_clamp_gt(<4 x i32> %num) {
  entry:
    %0 = call <4 x i32> @llvm.smax.v4i32(<4 x i32> %num, <4 x i32> <i32 13767, i32 13767, i32 13767, i32 13767>)
    %1 = call <4 x i32> @llvm.umin.v4i32(<4 x i32> %0, <4 x i32> <i32 13768, i32 13768, i32 13768, i32 13768>)
    ret <4 x i32> %1
  }
  
  ; Not
  define <4 x i32> @twoway_clamp_gt(<4 x i32> %num) {
  entry:
    %0 = icmp slt <4 x i32> %num, <i32 13768, i32 13768, i32 13768, i32 13768>
    %r = select <4 x i1> %0, <4 x i32> <i32 13767, i32 13767, i32 13767, i32 13767>, <4 x i32> <i32 13768, i32 13768, i32 13768, i32 13768>
    ret <4 x i32> %r
  }

Seems not covered by that?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107148/new/

https://reviews.llvm.org/D107148