[llvm] [VPlan] Explicitly unroll replicate-regions without live-outs by VF. (PR #170212)

[via llvm-commits]

================
@@ -77,7 +77,7 @@ define void @test_widen_exp_v2(ptr noalias %p2, ptr noalias %p, i64 %n) #5 {
 ; TFCOMMON-NEXT:    [[TMP14:%.*]] = extractelement <2 x i1> [[ACTIVE_LANE_MASK]], i32 1
 ; TFCOMMON-NEXT:    br i1 [[TMP14]], label [[PRED_STORE_IF1:%.*]], label [[PRED_STORE_CONTINUE6]]
 ; TFCOMMON:       pred.store.if1:
-; TFCOMMON-NEXT:    [[TMP19:%.*]] = extractelement <2 x double> [[PREDPHI]], i32 0
+; TFCOMMON-NEXT:    [[TMP19:%.*]] = extractelement <2 x double> [[PREDPHI]], i32 1
----------------
ayalz wrote:

Hmm, both extract 0 and extract 1 are fine in this case as they extract from <0.0, 0.0> or <1.0, 1.0>, but could this change affect non-uniform extractions, possibly fixing a bug? Additional occurrences below.

https://github.com/llvm/llvm-project/pull/170212