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36 lines
1.2 KiB
LLVM
36 lines
1.2 KiB
LLVM
; RUN: opt < %s -analyze -scalar-evolution \
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; RUN: | grep {Loop %bb: Unpredictable backedge-taken count\\.}
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; ScalarEvolution can't compute a trip count because it doesn't know if
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; dividing by the stride will have a remainder. This could theoretically
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; be teaching it how to use a more elaborate trip count computation.
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define i32 @f(i32 %x) nounwind readnone {
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entry:
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%0 = icmp ugt i32 %x, 4 ; <i1> [#uses=1]
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br i1 %0, label %bb.nph, label %bb2
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bb.nph: ; preds = %entry
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br label %bb
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bb: ; preds = %bb.nph, %bb1
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%indvar = phi i32 [ 0, %bb.nph ], [ %indvar.next, %bb1 ] ; <i32> [#uses=2]
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%tmp = mul i32 %indvar, -3 ; <i32> [#uses=1]
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%x_addr.04 = add i32 %tmp, %x ; <i32> [#uses=1]
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%1 = add i32 %x_addr.04, -3 ; <i32> [#uses=2]
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br label %bb1
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bb1: ; preds = %bb
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%2 = icmp ugt i32 %1, 4 ; <i1> [#uses=1]
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%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
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br i1 %2, label %bb, label %bb1.bb2_crit_edge
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bb1.bb2_crit_edge: ; preds = %bb1
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%.lcssa = phi i32 [ %1, %bb1 ] ; <i32> [#uses=1]
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br label %bb2
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bb2: ; preds = %bb1.bb2_crit_edge, %entry
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%x_addr.0.lcssa = phi i32 [ %.lcssa, %bb1.bb2_crit_edge ], [ %x, %entry ] ; <i32> [#uses=1]
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ret i32 %x_addr.0.lcssa
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}
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