1; RUN: opt -loop-accesses -analyze -enable-new-pm=0 < %s | FileCheck %s
2; RUN: opt -passes='require<scalar-evolution>,require<aa>,loop(print-access-info)' -disable-output  < %s 2>&1 | FileCheck %s
3
4; Check that loop-indepedent forward dependences are discovered properly.
5;
6; FIXME: This does not actually always work which is pretty confusing.  Right
7; now there is hack in LAA that tries to figure out loop-indepedent forward
8; dependeces *outside* of the MemoryDepChecker logic (i.e. proper dependence
9; analysis).
10;
11; Therefore if there is only loop-independent dependences for an array
12; (i.e. the same index is used), we don't discover the forward dependence.
13; So, at ***, we add another non-I-based access of A to trigger
14; MemoryDepChecker analysis for accesses of A.
15;
16;   for (unsigned i = 0; i < 100; i++) {
17;     A[i + 1] = B[i] + 1;   // ***
18;     A[i] = B[i] + 2;
19;     C[i] = A[i] * 2;
20;   }
21
22target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
23
24define void @f(i32* noalias %A, i32* noalias %B, i32* noalias %C, i64 %N) {
25
26; CHECK: Dependences:
27; CHECK-NEXT:   Forward:
28; CHECK-NEXT:       store i32 %b_p1, i32* %Aidx, align 4 ->
29; CHECK-NEXT:       %a = load i32, i32* %Aidx, align 4
30; CHECK:        ForwardButPreventsForwarding:
31; CHECK-NEXT:       store i32 %b_p2, i32* %Aidx_next, align 4 ->
32; CHECK-NEXT:       %a = load i32, i32* %Aidx, align 4
33; CHECK:        Forward:
34; CHECK-NEXT:       store i32 %b_p2, i32* %Aidx_next, align 4 ->
35; CHECK-NEXT:       store i32 %b_p1, i32* %Aidx, align 4
36
37entry:
38  br label %for.body
39
40for.body:                                         ; preds = %for.body, %entry
41  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
42  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
43
44  %Bidx = getelementptr inbounds i32, i32* %B, i64 %indvars.iv
45  %Cidx = getelementptr inbounds i32, i32* %C, i64 %indvars.iv
46  %Aidx_next = getelementptr inbounds i32, i32* %A, i64 %indvars.iv.next
47  %Aidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
48
49  %b = load i32, i32* %Bidx, align 4
50  %b_p2 = add i32 %b, 1
51  store i32 %b_p2, i32* %Aidx_next, align 4
52
53  %b_p1 = add i32 %b, 2
54  store i32 %b_p1, i32* %Aidx, align 4
55
56  %a = load i32, i32* %Aidx, align 4
57  %c = mul i32 %a, 2
58  store i32 %c, i32* %Cidx, align 4
59
60  %exitcond = icmp eq i64 %indvars.iv.next, %N
61  br i1 %exitcond, label %for.end, label %for.body
62
63for.end:                                          ; preds = %for.body
64  ret void
65}
66