[llvm-bugs] [Bug 37884] New: ModuleSummaryAnalysis does not preserve alias-to-alias information

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https://bugs.llvm.org/show_bug.cgi?id=37884

            Bug ID: 37884
           Summary: ModuleSummaryAnalysis does not preserve alias-to-alias
                    information
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Interprocedural Analyses
          Assignee: vlad at tsyrklevich.net
          Reporter: vlad at tsyrklevich.net
                CC: eugeni.stepanov at gmail.com, llvm-bugs at lists.llvm.org

The following IR:
@Alias = dso_preemptable alias void(), void()* @foo
@AliasToAlias = dso_local alias void(), void()* @Alias
define dso_local void @foo() { ret void }

will generate the following (textual) ThinLTO summary:
^1 = gv: (name: "foo", summaries: (function: (module: ^0, flags: (linkage:
external, notEligibleToImport: 0, live: 0, dsoLocal: 1), insts: 1))) ; guid =
6699318081062747564
^2 = gv: (name: "AliasToAlias", summaries: (alias: (module: ^0, flags:
(linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 1), aliasee:
^1))) ; guid = 15479319319369236563
^3 = gv: (name: "Alias", summaries: (alias: (module: ^0, flags: (linkage:
external, notEligibleToImport: 0, live: 0, dsoLocal: 0), aliasee: ^1))) ; guid
= 16088086490780401135

In the summary data, the aliasee for @AliasToAlias is @foo, not @Alias. This is
a problem because as I'm performing an interprocedural analysis I need to
ensure that every call is dso_local to perform a sound analysis. The summary
data above hides that @Alias is dso_preemptable.

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