[llvm] LAA: version unit stride for stores (PR #124567)

[David Sherwood via llvm-commits]

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@@ -5,26 +5,27 @@ define void @test_variable_stride(ptr %dst, i32 %scale) {
 ; CHECK-LABEL: define void @test_variable_stride
 ; CHECK-SAME: (ptr [[DST:%.*]], i32 [[SCALE:%.*]]) {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
+; CHECK-NEXT:    br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_SCEVCHECK:%.*]]
+; CHECK:       vector.scevcheck:
+; CHECK-NEXT:    [[IDENT_CHECK:%.*]] = icmp ne i32 [[SCALE]], 1
+; CHECK-NEXT:    br i1 [[IDENT_CHECK]], label [[SCALAR_PH]], label [[VECTOR_PH:%.*]]
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david-arm wrote:

I think it depends whether you enter the loop or not, right? Certainly in the vector loop the code is faster without the mul. I would imagine that turning on symbolic stride predicates for loads would have done the same thing in the past? Is this not just a special case because we're (presumably) choosing VF=1, IC=2?

https://github.com/llvm/llvm-project/pull/124567