[llvm] [VPlan] Hoist loads with invariant addresses using noalias metadata. (PR #166247)

[Florian Hahn via llvm-commits]

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@@ -156,15 +156,15 @@ define void @trunc_store(ptr %dst, ptr %src, i16 %x) #1 {
 ; DEFAULT-NEXT:    [[VEC_EPILOG_RESUME_VAL:%.*]] = phi i64 [ 992, [[VEC_EPILOG_ITER_CHECK]] ], [ 0, [[VECTOR_MAIN_LOOP_ITER_CHECK]] ]
 ; DEFAULT-NEXT:    [[BROADCAST_SPLATINSERT4:%.*]] = insertelement <8 x i16> poison, i16 [[X]], i64 0
 ; DEFAULT-NEXT:    [[BROADCAST_SPLAT5:%.*]] = shufflevector <8 x i16> [[BROADCAST_SPLATINSERT4]], <8 x i16> poison, <8 x i32> zeroinitializer
-; DEFAULT-NEXT:    [[TMP7:%.*]] = trunc <8 x i16> [[BROADCAST_SPLAT5]] to <8 x i8>
-; DEFAULT-NEXT:    br label [[VEC_EPILOG_VECTOR_BODY:%.*]]
-; DEFAULT:       vec.epilog.vector.body:
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fhahn wrote:

Yes, this is using the noalias metadata the loop-vectorizer generates when emitting memory runtime checks; it will also work for cases where we already have !noalias in the scalar loop, but those cases are much less interesting I think, as then other transformations will do the hoisting earlier.

https://github.com/llvm/llvm-project/pull/166247