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On X86 (and similar OOO cores) unrolling is very limited, and even if the runtime unrolling is otherwise profitable, the expense of a division to compute the trip count could greatly outweigh the benefits. On the A2, we unroll a lot, and the benefits of unrolling are more significant (seeing a 5x or 6x speedup is not uncommon), so we're more able to tolerate the expense, on average, of a division to compute the trip count. llvm-svn: 237947
28 lines
965 B
LLVM
28 lines
965 B
LLVM
; RUN: opt < %s -S -mtriple=powerpc64-unknown-linux-gnu -mcpu=a2 -loop-unroll | FileCheck %s
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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"
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;; Check that we do emit expensive instructions to compute trip
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;; counts when unrolling loops on the a2 (because we unroll a lot).
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define i32 @test(i64 %v12, i8* %array, i64* %loc) {
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; CHECK-LABEL: @test(
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; CHECK: udiv
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entry:
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%step = load i64, i64* %loc, !range !0
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br label %loop
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loop: ; preds = %entry, %loop
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%k.015 = phi i64 [ %v15, %loop ], [ %v12, %entry ]
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%v14 = getelementptr inbounds i8, i8* %array, i64 %k.015
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store i8 0, i8* %v14
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%v15 = add nuw nsw i64 %k.015, %step
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%v16 = icmp slt i64 %v15, 8193
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br i1 %v16, label %loop, label %loopexit
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loopexit: ; preds = %loop
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ret i32 0
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}
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!0 = !{i64 1, i64 100}
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