Revert r313157 "ThinLTO: Correctly follow aliasee references when dead stripping."
This broke Chromium's CFI build; see crbug.com/765004.
> We were previously handling aliases during dead stripping by adding
> the aliased global's "original name" GUID to the worklist. This will
> lead to incorrect behaviour if the global has local linkage because
> the original name GUID will not correspond to the global's GUID in
> the summary.
>
> Because an alias is just another name for the global that it
> references, there is no need to mark the referenced global as used,
> or to follow references from any other copies of the global. So all
> we need to do is to follow references from the aliasee's summary
> instead of the alias.
>
> Differential Revision: https://reviews.llvm.org/D37789
llvm-svn: 313222
diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index b043687f..da763b1 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -488,14 +488,17 @@
while (!Worklist.empty()) {
auto VI = Worklist.pop_back_val();
for (auto &Summary : VI.getSummaryList()) {
- GlobalValueSummary *Base = Summary.get();
- if (auto *AS = dyn_cast<AliasSummary>(Base))
- Base = &AS->getAliasee();
- for (auto Ref : Base->refs())
+ for (auto Ref : Summary->refs())
visit(Ref);
- if (auto *FS = dyn_cast<FunctionSummary>(Base))
+ if (auto *FS = dyn_cast<FunctionSummary>(Summary.get()))
for (auto Call : FS->calls())
visit(Call.first);
+ if (auto *AS = dyn_cast<AliasSummary>(Summary.get())) {
+ auto AliaseeGUID = AS->getAliasee().getOriginalName();
+ ValueInfo AliaseeVI = Index.getValueInfo(AliaseeGUID);
+ if (AliaseeVI)
+ visit(AliaseeVI);
+ }
}
}
Index.setWithGlobalValueDeadStripping();