[PATCH] D147243: [X86] MatchVectorAllZeroTest - add support for icmp(bitcast(icmp_ne(X,Y)),0) vector reduction patterns

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: llvm/test/CodeGen/X86/vector-reduce-or-cmp.ll:1031
+; AVX2-NEXT:    vpbroadcastd {{.*#+}} xmm1 = [15,15,15,15]
+; AVX2-NEXT:    vptest %xmm1, %xmm0
 ; AVX2-NEXT:    sete %al
----------------
pengfei wrote:
> goldstein.w.n wrote:
> > why doesn't this micro-fuse anymore? Likewise below.
> I found broadcast change in several places. It increases code size but reduces data size. I'm not sure which one is better.
I'd dearly like to move most of the constant build vector data lowering out of DAG as it makes far too many premature judgements.

We could just lower it to a regular constant pool if we have to (keeping it as BUILD_VECTOR nodes would be even better like we do zero/allones) - and leave a later pass to judge whether we should make it a load/broadcast/extend/etc. depending on uses, folding, register pressure etc. We could even materialize some easy uniform constants (e.g. shifted masks + gfni) in code.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147243/new/

https://reviews.llvm.org/D147243