[LV] Add test case for PR54427.

Reduced test for #54427.

Author: fhahn

llvm/test/Transforms/LoopVectorize/induction-unroll-novec.ll

@@ -0,0 +1,46 @@
+; RUN: opt -passes=loop-vectorize -force-vector-interleave=2 -force-vector-width=1 -S %s | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+
+; Test for PR54427.
+define void @test_nonconst_start_and_step(i32* %dst, i32 %start, i32 %step, i64 %N) {
+; CHECK-LABEL: @test_nonconst_start_and_step(
+; CHECK:         [[NEG_STEP:%.+]] = sub i32 0, %step
+; CHECK:       vector.body:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %vector.ph ], [ [[INDEX_NEXT:%.*]], %vector.body ]
+; CHECK-NEXT:    [[INDUCTION3:%.*]] = add i64 [[INDEX]], 0
+; CHECK-NEXT:    [[INDUCTION4:%.*]] = add i64 [[INDEX]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = trunc i64 [[INDEX]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = mul i32 [[TMP2]], [[NEG_STEP]]
+; CHECK-NEXT:    [[OFFSET_IDX:%.*]] = add i32 %start, [[TMP3]]
+; CHECK-NEXT:    [[TMP4:%.*]] = mul i32 0, [[NEG_STEP]]
+; CHECK-NEXT:    [[INDUCTION:%.*]] = sub i32 [[OFFSET_IDX]], [[TMP4]]
+; CHECK-NEXT:    [[TMP5:%.*]] = mul i32 1, [[NEG_STEP]]
+; CHECK-NEXT:    [[INDUCTION2:%.*]] = sub i32 [[OFFSET_IDX]], [[TMP5]]
+; CHECK-NEXT:    [[TMP6:%.*]] = sub nsw i32 [[INDUCTION]], %step
+; CHECK-NEXT:    [[TMP7:%.*]] = sub nsw i32 [[INDUCTION2]], %step
+; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i32, i32* [[DST:%.*]], i64 [[INDUCTION3]]
+; CHECK-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i32, i32* [[DST]], i64 [[INDUCTION4]]
+; CHECK-NEXT:    store i32 [[TMP6]], i32* [[TMP8]], align 2
+; CHECK-NEXT:    store i32 [[TMP7]], i32* [[TMP9]], align 2
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp eq i64 [[INDEX_NEXT]]
+; CHECK-NEXT:    br i1 [[TMP10]], label %middle.block, label %vector.body
+;
+entry:
+  br label %loop
+
+loop:
+  %primary.iv = phi i64 [ 0, %entry ], [ %primary.iv.next, %loop ]
+  %iv.down = phi i32 [ %start, %entry ], [ %iv.down.next, %loop ]
+  %iv.down.next = sub nsw i32 %iv.down, %step
+  %gep.dst = getelementptr inbounds i32, i32* %dst, i64 %primary.iv
+  store i32 %iv.down.next, i32* %gep.dst, align 2
+  %primary.iv.next = add nuw nsw i64 %primary.iv, 1
+  %exitcond = icmp eq i64 %primary.iv.next, %N
+  br i1 %exitcond, label %exit, label %loop
+
+exit:
+  ret void
+}