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0f6643694d
Runtime unrolling is an expensive optimization which can bring benefit only if the loop is hot and iteration number is relatively large enough. For some loops, we know they are not worth to be runtime unrolled. The scalar loop from vectorization is one of the cases. llvm-svn: 231631
48 lines
2.0 KiB
LLVM
48 lines
2.0 KiB
LLVM
; RUN: opt < %s -disable-loop-unrolling -debug-only=loop-vectorize -O3 -S 2>&1 | FileCheck %s
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; REQUIRES: asserts
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; We want to make sure that we don't even try to vectorize loops again
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; The vectorizer used to mark the un-vectorized loop only as already vectorized
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; thus, trying to vectorize the vectorized loop again
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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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target triple = "x86_64-unknown-linux-gnu"
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@a = external global [255 x i32]
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; Function Attrs: nounwind readonly uwtable
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define i32 @vect() {
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; CHECK: LV: Checking a loop in "vect"
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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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; We need to make sure we did vectorize the loop
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; CHECK: LV: Found a loop: for.body
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; CHECK: LV: We can vectorize this loop!
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%red.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
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%arrayidx = getelementptr inbounds [255 x i32], [255 x i32]* @a, i64 0, i64 %indvars.iv
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%0 = load i32, i32* %arrayidx, align 4
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%add = add nsw i32 %0, %red.05
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, 255
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br i1 %exitcond, label %for.end, label %for.body
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; If it did, we have two loops:
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; CHECK: vector.body:
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; CHECK: br {{.*}} label %vector.body, !llvm.loop [[vect:![0-9]+]]
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; CHECK: for.body:
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; CHECK: br {{.*}} label %for.body, !llvm.loop [[scalar:![0-9]+]]
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for.end: ; preds = %for.body
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ret i32 %add
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}
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; Now, we check for the Hint metadata
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; CHECK: [[vect]] = distinct !{[[vect]], [[width:![0-9]+]], [[unroll:![0-9]+]]}
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; CHECK: [[width]] = !{!"llvm.loop.vectorize.width", i32 1}
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; CHECK: [[unroll]] = !{!"llvm.loop.interleave.count", i32 1}
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; CHECK: [[scalar]] = distinct !{[[scalar]], [[runtime_unroll:![0-9]+]], [[width]], [[unroll]]}
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; CHECK: [[runtime_unroll]] = !{!"llvm.loop.unroll.runtime.disable"}
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