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2ceba77dfa
When creating a scev for sext({X,+,Y}), scev checks if the expression
is equivalent to {sext X,+,zext Y}. If it can prove that, it also
tags the original {X,+,Y} as <nsw>, which is not correct.
In the test case I run `-scalar-evolution` twice because the bug
manifests only once SCEV has run through and seen the `sext`
expressions (and then does a in-place mutation on {X,+,Y}).
Differential Revision: http://reviews.llvm.org/D7495
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228586 91177308-0d34-0410-b5e6-96231b3b80d8
27 lines
689 B
LLVM
27 lines
689 B
LLVM
; RUN: opt -analyze -scalar-evolution -scalar-evolution < %s | FileCheck %s
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define void @bad.nsw() {
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; CHECK-LABEL: Classifying expressions for: @bad.nsw
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; CHECK-LABEL: Classifying expressions for: @bad.nsw
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entry:
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br label %loop
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loop:
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%i = phi i8 [ -1, %entry ], [ %i.inc, %loop ]
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; CHECK: %i = phi i8 [ -1, %entry ], [ %i.inc, %loop ]
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; CHECK-NEXT: --> {-1,+,-128}<nw><%loop>
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; CHECK-NOT: --> {-1,+,-128}<nsw><%loop>
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%counter = phi i8 [ 0, %entry ], [ %counter.inc, %loop ]
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%i.inc = add i8 %i, -128
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%i.sext = sext i8 %i to i16
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%counter.inc = add i8 %counter, 1
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%continue = icmp eq i8 %counter, 1
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br i1 %continue, label %exit, label %loop
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exit:
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ret void
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}
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