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c121f5dc26
A computable loop exit count does not imply the presence of an induction variable. Scalar evolution can return a value for an infinite loop. Fixes PR15926. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181495 91177308-0d34-0410-b5e6-96231b3b80d8
35 lines
1.3 KiB
LLVM
35 lines
1.3 KiB
LLVM
; RUN: opt -S -indvars -loop-vectorize -force-vector-width=2 < %s | FileCheck %s
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S128"
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@a = common global i64 0, align 8
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@x = common global i32 0, align 4
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; We used to assert on this loop because we could not find an induction
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; variable but assumed there must be one. Scalar evolution returned a exit
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; count for the loop below and from there on we assumed that there must be an
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; induction variable. This is not a valid assumption:
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; // getExitCount - Get the expression for the number of loop iterations for
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; // which this loop is *guaranteed not to exit* via ExitingBlock. Otherwise
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; // return SCEVCouldNotCompute.
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; For an infinite loop SE can return any number.
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; CHECK: fn1
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define void @fn1() {
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entry:
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store i64 0, i64* @a, align 8
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%inc1 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
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store volatile i32 0, i32* @x, align 4
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%inc = add nsw i64 %inc1, 1
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%cmp = icmp sgt i64 %inc1, -2
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br i1 %cmp, label %for.body, label %for.end
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for.end: ; preds = %for.body
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%inc.lcssa = phi i64 [ %inc, %for.body ]
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store i64 %inc.lcssa, i64* @a, align 8
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ret void
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}
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