[LTO][ThinLTO] Use the linker resolutions to mark global values as dso_local.
Now that we have a way to mark GlobalValues as local we can use the symbol
resolutions that the linker plugin provides as part of lto/thinlto link
step to refine the compilers view on what symbols will end up being local.
Differential Revision: https://reviews.llvm.org/D35702
llvm-svn: 317374
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index 017dd20..9c73779 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -630,6 +630,9 @@
NonPrevailingComdats.insert(GV->getComdat());
cast<GlobalObject>(GV)->setComdat(nullptr);
}
+
+ // Set the 'local' flag based on the linker resolution for this symbol.
+ GV->setDSOLocal(Res.FinalDefinitionInLinkageUnit);
}
// Common resolution: collect the maximum size/alignment over all commons.
// We also record if we see an instance of a common as prevailing, so that
@@ -643,7 +646,6 @@
CommonRes.Prevailing |= Res.Prevailing;
}
- // FIXME: use proposed local attribute for FinalDefinitionInLinkageUnit.
}
if (!M.getComdatSymbolTable().empty())
for (GlobalValue &GV : M.global_values())
@@ -698,10 +700,10 @@
assert(ResI != ResE);
SymbolResolution Res = *ResI++;
- if (Res.Prevailing) {
- if (!Sym.getIRName().empty()) {
- auto GUID = GlobalValue::getGUID(GlobalValue::getGlobalIdentifier(
- Sym.getIRName(), GlobalValue::ExternalLinkage, ""));
+ if (!Sym.getIRName().empty()) {
+ auto GUID = GlobalValue::getGUID(GlobalValue::getGlobalIdentifier(
+ Sym.getIRName(), GlobalValue::ExternalLinkage, ""));
+ if (Res.Prevailing) {
ThinLTO.PrevailingModuleForGUID[GUID] = BM.getModuleIdentifier();
// For linker redefined symbols (via --wrap or --defsym) we want to
@@ -713,6 +715,15 @@
GUID, BM.getModuleIdentifier()))
S->setLinkage(GlobalValue::WeakAnyLinkage);
}
+
+ // If the linker resolved the symbol to a local definition then mark it
+ // as local in the summary for the module we are adding.
+ if (Res.FinalDefinitionInLinkageUnit) {
+ if (auto S = ThinLTO.CombinedIndex.findSummaryInModule(
+ GUID, BM.getModuleIdentifier())) {
+ S->setDSOLocal(true);
+ }
+ }
}
}