From: Peter Collingbourne Date: Thu, 7 Jul 2016 18:31:51 +0000 (+0000) Subject: ThinLTO: Do not take into account whether a definition has multiple copies when promo... X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=28925b5350201e8592609c8ca8fc470a5287e615;p=llvm ThinLTO: Do not take into account whether a definition has multiple copies when promoting. We currently do not touch a symbol's linkage in the case where a definition has a single copy. However, this code is effectively unnecessary: either the definition is not exported, in which case the internalize phase sets its linkage to internal, or it is exported, in which case we need to promote linkage to weak. Those two cases are already handled by existing code. I believe that the only real functional change here is in the case where we have a single definition which does not prevail (e.g. because the definition in a native object file prevails). In that case we now lower linkage to available_externally following the existing code path for that case. As a result we can remove the isExported function parameter from the thinLTOResolveWeakForLinkerInIndex function. Differential Revision: http://reviews.llvm.org/D21883 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274784 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/LTO/LTO.h b/include/llvm/LTO/LTO.h index 0670af8eda0..5154c0007aa 100644 --- a/include/llvm/LTO/LTO.h +++ b/include/llvm/LTO/LTO.h @@ -60,7 +60,6 @@ void thinLTOResolveWeakForLinkerInIndex( ModuleSummaryIndex &Index, function_ref isPrevailing, - function_ref isExported, function_ref recordNewLinkage); diff --git a/lib/LTO/LTO.cpp b/lib/LTO/LTO.cpp index 11bfc94082e..10226c4a3ff 100644 --- a/lib/LTO/LTO.cpp +++ b/lib/LTO/LTO.cpp @@ -45,26 +45,17 @@ static void thinLTOResolveWeakForLinkerGUID( DenseSet &GlobalInvolvedWithAlias, function_ref isPrevailing, - function_ref isExported, function_ref recordNewLinkage) { - auto HasMultipleCopies = GVSummaryList.size() > 1; - for (auto &S : GVSummaryList) { if (GlobalInvolvedWithAlias.count(S.get())) continue; GlobalValue::LinkageTypes OriginalLinkage = S->linkage(); if (!GlobalValue::isWeakForLinker(OriginalLinkage)) continue; - // We need to emit only one of these, the first module will keep it, + // We need to emit only one of these. The prevailing module will keep it, // but turned into a weak, while the others will drop it when possible. - if (!HasMultipleCopies) { - // Exported Linkonce needs to be promoted to not be discarded. - if (GlobalValue::isLinkOnceLinkage(OriginalLinkage) && - isExported(S->modulePath(), GUID)) - S->setLinkage(GlobalValue::getWeakLinkage( - GlobalValue::isLinkOnceODRLinkage(OriginalLinkage))); - } else if (isPrevailing(GUID, S.get())) { + if (isPrevailing(GUID, S.get())) { if (GlobalValue::isLinkOnceLinkage(OriginalLinkage)) S->setLinkage(GlobalValue::getWeakLinkage( GlobalValue::isLinkOnceODRLinkage(OriginalLinkage))); @@ -89,7 +80,6 @@ void thinLTOResolveWeakForLinkerInIndex( ModuleSummaryIndex &Index, function_ref isPrevailing, - function_ref isExported, function_ref recordNewLinkage) { // We won't optimize the globals that are referenced by an alias for now @@ -103,7 +93,7 @@ void thinLTOResolveWeakForLinkerInIndex( for (auto &I : Index) thinLTOResolveWeakForLinkerGUID(I.second, I.first, GlobalInvolvedWithAlias, - isPrevailing, isExported, recordNewLinkage); + isPrevailing, recordNewLinkage); } static void thinLTOInternalizeAndPromoteGUID( diff --git a/lib/LTO/ThinLTOCodeGenerator.cpp b/lib/LTO/ThinLTOCodeGenerator.cpp index 5c97e4d69e1..2aa1e3f69a8 100644 --- a/lib/LTO/ThinLTOCodeGenerator.cpp +++ b/lib/LTO/ThinLTOCodeGenerator.cpp @@ -393,8 +393,6 @@ ProcessThinLTOModule(Module &TheModule, ModuleSummaryIndex &Index, /// copies when possible). static void resolveWeakForLinkerInIndex( ModuleSummaryIndex &Index, - const StringMap &ExportLists, - const DenseSet &GUIDPreservedSymbols, StringMap> &ResolvedODR) { @@ -409,21 +407,13 @@ static void resolveWeakForLinkerInIndex( return Prevailing->second == S; }; - auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) { - const auto &ExportList = ExportLists.find(ModuleIdentifier); - return (ExportList != ExportLists.end() && - ExportList->second.count(GUID)) || - GUIDPreservedSymbols.count(GUID); - }; - auto recordNewLinkage = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID, GlobalValue::LinkageTypes NewLinkage) { ResolvedODR[ModuleIdentifier][GUID] = NewLinkage; }; - thinLTOResolveWeakForLinkerInIndex(Index, isPrevailing, isExported, - recordNewLinkage); + thinLTOResolveWeakForLinkerInIndex(Index, isPrevailing, recordNewLinkage); } // Initialize the TargetMachine builder for a given Triple @@ -537,14 +527,9 @@ void ThinLTOCodeGenerator::promote(Module &TheModule, ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists, ExportLists); - // Convert the preserved symbols set from string to GUID - auto GUIDPreservedSymbols = - computeGUIDPreservedSymbols(PreservedSymbols, TMBuilder.TheTriple); - // Resolve LinkOnce/Weak symbols. StringMap> ResolvedODR; - resolveWeakForLinkerInIndex(Index, ExportLists, GUIDPreservedSymbols, - ResolvedODR); + resolveWeakForLinkerInIndex(Index, ResolvedODR); thinLTOResolveWeakForLinkerModule( TheModule, ModuleToDefinedGVSummaries[ModuleIdentifier]); @@ -750,8 +735,7 @@ void ThinLTOCodeGenerator::run() { // Resolve LinkOnce/Weak symbols, this has to be computed early because it // impacts the caching. - resolveWeakForLinkerInIndex(*Index, ExportLists, GUIDPreservedSymbols, - ResolvedODR); + resolveWeakForLinkerInIndex(*Index, ResolvedODR); auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) { const auto &ExportList = ExportLists.find(ModuleIdentifier); diff --git a/test/ThinLTO/X86/alias_import.ll b/test/ThinLTO/X86/alias_import.ll index 198b44c78a3..f708ead641e 100644 --- a/test/ThinLTO/X86/alias_import.ll +++ b/test/ThinLTO/X86/alias_import.ll @@ -11,36 +11,36 @@ ; available_externally, i.e linkOnceODR. (FIXME this limitation could be lifted) ; PROMOTE-DAG: @globalfuncAlias = alias void (...), bitcast (void ()* @globalfunc to void (...)*) ; PROMOTE-DAG: @globalfuncWeakAlias = weak alias void (...), bitcast (void ()* @globalfunc to void (...)*) -; PROMOTE-DAG: @globalfuncLinkonceAlias = linkonce alias void (...), bitcast (void ()* @globalfunc to void (...)*) +; PROMOTE-DAG: @globalfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @globalfunc to void (...)*) ; PROMOTE-DAG: @globalfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @globalfunc to void (...)*) -; PROMOTE-DAG: @globalfuncLinkonceODRAlias = linkonce_odr alias void (...), bitcast (void ()* @globalfunc to void (...)*) +; PROMOTE-DAG: @globalfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @globalfunc to void (...)*) ; PROMOTE-DAG: @internalfuncAlias = alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*) ; PROMOTE-DAG: @internalfuncWeakAlias = weak alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*) -; PROMOTE-DAG: @internalfuncLinkonceAlias = linkonce alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*) +; PROMOTE-DAG: @internalfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*) ; PROMOTE-DAG: @internalfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*) -; PROMOTE-DAG: @internalfuncLinkonceODRAlias = linkonce_odr alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*) +; PROMOTE-DAG: @internalfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*) ; PROMOTE-DAG: @linkoncefuncAlias = alias void (...), bitcast (void ()* @linkoncefunc to void (...)*) ; PROMOTE-DAG: @linkoncefuncWeakAlias = weak alias void (...), bitcast (void ()* @linkoncefunc to void (...)*) -; PROMOTE-DAG: @linkoncefuncLinkonceAlias = linkonce alias void (...), bitcast (void ()* @linkoncefunc to void (...)*) +; PROMOTE-DAG: @linkoncefuncLinkonceAlias = weak alias void (...), bitcast (void ()* @linkoncefunc to void (...)*) ; PROMOTE-DAG: @linkoncefuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @linkoncefunc to void (...)*) -; PROMOTE-DAG: @linkoncefuncLinkonceODRAlias = linkonce_odr alias void (...), bitcast (void ()* @linkoncefunc to void (...)*) +; PROMOTE-DAG: @linkoncefuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @linkoncefunc to void (...)*) ; PROMOTE-DAG: @weakfuncAlias = alias void (...), bitcast (void ()* @weakfunc to void (...)*) ; PROMOTE-DAG: @weakfuncWeakAlias = weak alias void (...), bitcast (void ()* @weakfunc to void (...)*) -; PROMOTE-DAG: @weakfuncLinkonceAlias = linkonce alias void (...), bitcast (void ()* @weakfunc to void (...)*) +; PROMOTE-DAG: @weakfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @weakfunc to void (...)*) ; PROMOTE-DAG: @weakfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @weakfunc to void (...)*) -; PROMOTE-DAG: @weakfuncLinkonceODRAlias = linkonce_odr alias void (...), bitcast (void ()* @weakfunc to void (...)*) +; PROMOTE-DAG: @weakfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @weakfunc to void (...)*) ; PROMOTE-DAG: @weakODRfuncAlias = alias void (...), bitcast (void ()* @weakODRfunc to void (...)*) ; PROMOTE-DAG: @weakODRfuncWeakAlias = weak alias void (...), bitcast (void ()* @weakODRfunc to void (...)*) -; PROMOTE-DAG: @weakODRfuncLinkonceAlias = linkonce alias void (...), bitcast (void ()* @weakODRfunc to void (...)*) +; PROMOTE-DAG: @weakODRfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @weakODRfunc to void (...)*) ; PROMOTE-DAG: @weakODRfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @weakODRfunc to void (...)*) -; PROMOTE-DAG: @weakODRfuncLinkonceODRAlias = linkonce_odr alias void (...), bitcast (void ()* @weakODRfunc to void (...)*) +; PROMOTE-DAG: @weakODRfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @weakODRfunc to void (...)*) ; Only alias to LinkonceODR aliasee can be imported ; PROMOTE-DAG: @linkonceODRfuncAlias = alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*) ; PROMOTE-DAG: @linkonceODRfuncWeakAlias = weak alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*) ; PROMOTE-DAG: @linkonceODRfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*) ; Amongst these that are imported, check that we promote only linkonce->weak -; PROMOTE-DAG: @linkonceODRfuncLinkonceAlias = linkonce alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*) +; PROMOTE-DAG: @linkonceODRfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*) ; PROMOTE-DAG: @linkonceODRfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*) ; These will be imported, check the linkage/renaming after promotion diff --git a/test/ThinLTO/X86/weak_resolution.ll b/test/ThinLTO/X86/weak_resolution.ll index bf3b3b82171..5c23a362897 100644 --- a/test/ThinLTO/X86/weak_resolution.ll +++ b/test/ThinLTO/X86/weak_resolution.ll @@ -67,7 +67,7 @@ entry: ret void } -; MOD1: define linkonce_odr void @linkonceodrfuncInSingleModule() +; MOD1: define weak_odr void @linkonceodrfuncInSingleModule() ; MOD1-INT: define internal void @linkonceodrfuncInSingleModule() ; EXPORTED: define weak_odr void @linkonceodrfuncInSingleModule() define linkonce_odr void @linkonceodrfuncInSingleModule() #0 {