From 54fb3ca96e261f7107cb1b5778c34cb0e0808be6 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Wed, 27 Jan 2021 10:43:51 -0800 Subject: [ThinLTO] Add Visibility bits to GlobalValueSummary::GVFlags Imported functions and variable get the visibility from the module supplying the definition. However, non-imported definitions do not get the visibility from (ELF) the most constraining visibility among all modules (Mach-O) the visibility of the prevailing definition. This patch * adds visibility bits to GlobalValueSummary::GVFlags * computes the result visibility and propagates it to all definitions Protected/hidden can imply dso_local which can enable some optimizations (this is stronger than GVFlags::DSOLocal because the implied dso_local can be leveraged for ELF -shared while default visibility dso_local has to be cleared for ELF -shared). Note: we don't have summaries for declarations, so for ELF if a declaration has the most constraining visibility, the result visibility may not be that one. Differential Revision: https://reviews.llvm.org/D92900 --- llvm/lib/IR/ModuleSummaryIndex.cpp | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'llvm/lib/IR/ModuleSummaryIndex.cpp') diff --git a/llvm/lib/IR/ModuleSummaryIndex.cpp b/llvm/lib/IR/ModuleSummaryIndex.cpp index 5d21ca7..df3e801 100644 --- a/llvm/lib/IR/ModuleSummaryIndex.cpp +++ b/llvm/lib/IR/ModuleSummaryIndex.cpp @@ -40,6 +40,18 @@ constexpr uint32_t FunctionSummary::ParamAccess::RangeWidth; FunctionSummary FunctionSummary::ExternalNode = FunctionSummary::makeDummyFunctionSummary({}); +GlobalValue::VisibilityTypes ValueInfo::getELFVisibility() const { + bool HasProtected = false; + for (const auto &S : make_pointee_range(getSummaryList())) { + if (S.getVisibility() == GlobalValue::HiddenVisibility) + return GlobalValue::HiddenVisibility; + if (S.getVisibility() == GlobalValue::ProtectedVisibility) + HasProtected = true; + } + return HasProtected ? GlobalValue::ProtectedVisibility + : GlobalValue::DefaultVisibility; +} + bool ValueInfo::isDSOLocal() const { // Need to check all summaries are local in case of hash collisions. return getSummaryList().size() && @@ -564,6 +576,8 @@ void ModuleSummaryIndex::exportToDot( if (Flags.Live && hasConstantFlag(SummaryIt.second)) A.addComment("constant"); } + if (Flags.Visibility) + A.addComment("visibility"); if (Flags.DSOLocal) A.addComment("dsoLocal"); if (Flags.CanAutoHide) -- cgit v1.1