66 lines
2.4 KiB
LLVM
66 lines
2.4 KiB
LLVM
; RUN: opt -loop-accesses -analyze < %s | FileCheck %s
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; RUN: opt -passes='require<scalar-evolution>,require<aa>,loop(print-access-info)' -disable-output < %s 2>&1 | FileCheck %s
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; Check that loop-indepedent forward dependences are discovered properly.
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;
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; FIXME: This does not actually always work which is pretty confusing. Right
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; now there is hack in LAA that tries to figure out loop-indepedent forward
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; dependeces *outside* of the MemoryDepChecker logic (i.e. proper dependence
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; analysis).
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;
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; Therefore if there is only loop-independent dependences for an array
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; (i.e. the same index is used), we don't discover the forward dependence.
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; So, at ***, we add another non-I-based access of A to trigger
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; MemoryDepChecker analysis for accesses of A.
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;
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; for (unsigned i = 0; i < 100; i++) {
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; A[i + 1] = B[i] + 1; // ***
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; A[i] = B[i] + 2;
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; C[i] = A[i] * 2;
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; }
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target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
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define void @f(i32* noalias %A, i32* noalias %B, i32* noalias %C, i64 %N) {
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; CHECK: Dependences:
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; CHECK-NEXT: Forward:
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; CHECK-NEXT: store i32 %b_p1, i32* %Aidx, align 4 ->
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; CHECK-NEXT: %a = load i32, i32* %Aidx, align 4
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; CHECK: ForwardButPreventsForwarding:
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; CHECK-NEXT: store i32 %b_p2, i32* %Aidx_next, align 4 ->
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; CHECK-NEXT: %a = load i32, i32* %Aidx, align 4
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; CHECK: Forward:
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; CHECK-NEXT: store i32 %b_p2, i32* %Aidx_next, align 4 ->
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; CHECK-NEXT: store i32 %b_p1, i32* %Aidx, align 4
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%Bidx = getelementptr inbounds i32, i32* %B, i64 %indvars.iv
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%Cidx = getelementptr inbounds i32, i32* %C, i64 %indvars.iv
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%Aidx_next = getelementptr inbounds i32, i32* %A, i64 %indvars.iv.next
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%Aidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
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%b = load i32, i32* %Bidx, align 4
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%b_p2 = add i32 %b, 1
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store i32 %b_p2, i32* %Aidx_next, align 4
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%b_p1 = add i32 %b, 2
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store i32 %b_p1, i32* %Aidx, align 4
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%a = load i32, i32* %Aidx, align 4
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%c = mul i32 %a, 2
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store i32 %c, i32* %Cidx, align 4
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%exitcond = icmp eq i64 %indvars.iv.next, %N
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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ret void
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}
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