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81032088a7
r243883 started moving 'distinct' nodes instead of duplicated them in
lib/Linker. This had the side-effect of sometimes not cloning uniqued
nodes that reference them. I missed a corner case:
!named = !{!0}
!0 = !{!1}
!1 = distinct !{!0}
!0 is the entry point for "remapping", and a temporary clone (say,
!0-temp) is created and mapped in case we need to model a uniquing
cycle.
Recursive descent into !1. !1 is distinct, so we leave it alone,
but update its operand to !0-temp.
Pop back out to !0. Its only operand, !1, hasn't changed, so we don't
need to use !0-temp. !0-temp goes out of scope, and we're finished
remapping, but we're left with:
!named = !{!0}
!0 = !{!1}
!1 = distinct !{null} ; uh oh...
Previously, if !0 and !0-temp ended up with identical operands, then
!0-temp couldn't have been referenced at all. Now that distinct nodes
don't get duplicated, that assumption is invalid. We need to
!0-temp->replaceAllUsesWith(!0) before freeing !0-temp.
I found this while running an internal `-flto -g` bootstrap. Strangely,
there was no case of this in the open source bootstrap I'd done before
commit...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243961 91177308-0d34-0410-b5e6-96231b3b80d8
15 lines
281 B
LLVM
15 lines
281 B
LLVM
; RUN: llvm-link -o - %s | llvm-dis | FileCheck %s
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; CHECK: !named = !{!0, !2}
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!named = !{!0, !2}
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; CHECK: !0 = !{!1}
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; CHECK-NEXT: !1 = distinct !{!0}
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!0 = !{!1}
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!1 = distinct !{!0}
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; CHECK-NEXT: !2 = distinct !{!3}
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; CHECK-NEXT: !3 = !{!2}
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!2 = distinct !{!3}
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!3 = !{!2}
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