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llvm-project/llvm/test/Linker/uniqued-distinct-cycles.ll

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Linker: Fix references to uniqued nodes after r243883 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... llvm-svn: 243961
2015-08-04 14:42:31 +08:00
; RUN: llvm-link -o - %s | llvm-dis | FileCheck %s
; CHECK: !named = !{!0, !2}
!named = !{!0, !2}
; CHECK: !0 = !{!1}
; CHECK-NEXT: !1 = distinct !{!0}
!0 = !{!1}
!1 = distinct !{!0}
; CHECK-NEXT: !2 = distinct !{!3}
; CHECK-NEXT: !3 = !{!2}
!2 = distinct !{!3}
!3 = !{!2}