diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -886,8 +886,9 @@ [, partition "name"] The linkage must be one of ``private``, ``internal``, ``linkonce``, ``weak``, -``linkonce_odr``, ``weak_odr``, ``external``. Note that some system linkers -might not correctly handle dropping a weak symbol that is aliased. +``linkonce_odr``, ``weak_odr``, ``external``, ``available_externally``. Note +that some system linkers might not correctly handle dropping a weak symbol that +is aliased. Aliases that are not ``unnamed_addr`` are guaranteed to have the same address as the aliasee expression. ``unnamed_addr`` ones are only guaranteed to point diff --git a/llvm/include/llvm/IR/GlobalAlias.h b/llvm/include/llvm/IR/GlobalAlias.h --- a/llvm/include/llvm/IR/GlobalAlias.h +++ b/llvm/include/llvm/IR/GlobalAlias.h @@ -93,8 +93,8 @@ } static bool isValidLinkage(LinkageTypes L) { - return isExternalLinkage(L) || isLocalLinkage(L) || - isWeakLinkage(L) || isLinkOnceLinkage(L); + return isExternalLinkage(L) || isLocalLinkage(L) || isWeakLinkage(L) || + isLinkOnceLinkage(L) || isAvailableExternallyLinkage(L); } // Methods for support type inquiry through isa, cast, and dyn_cast: diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp --- a/llvm/lib/IR/Verifier.cpp +++ b/llvm/lib/IR/Verifier.cpp @@ -816,8 +816,8 @@ void Verifier::visitAliaseeSubExpr(SmallPtrSetImpl &Visited, const GlobalAlias &GA, const Constant &C) { if (const auto *GV = dyn_cast(&C)) { - Check(!GV->isDeclarationForLinker(), "Alias must point to a definition", - &GA); + Check(GA.hasAvailableExternallyLinkage() || !GV->isDeclarationForLinker(), + "Alias must point to a definition", &GA); if (const auto *GA2 = dyn_cast(GV)) { Check(Visited.insert(GA2).second, "Aliases cannot form a cycle", &GA); @@ -844,8 +844,10 @@ } void Verifier::visitGlobalAlias(const GlobalAlias &GA) { - Check(GlobalAlias::isValidLinkage(GA.getLinkage()), - "Alias should have private, internal, linkonce, weak, linkonce_odr, " + Check(GlobalAlias::isValidLinkage(GA.getLinkage()) || + GA.hasAvailableExternallyLinkage(), + "Alias should have available_externally, private, internal, linkonce, " + "weak, linkonce_odr, " "weak_odr, or external linkage!", &GA); const Constant *Aliasee = GA.getAliasee(); diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp --- a/llvm/lib/LTO/LTO.cpp +++ b/llvm/lib/LTO/LTO.cpp @@ -712,11 +712,11 @@ if (!NonPrevailingComdats.count(C)) return; - // Additionally need to drop externally visible global values from the comdat - // to available_externally, so that there aren't multiply defined linker - // errors. - if (!GV.hasLocalLinkage()) - GV.setLinkage(GlobalValue::AvailableExternallyLinkage); + // Additionally need to drop all global values from the comdat to + // available_externally, to satisfy the COMDAT requirement that all members + // are discarded as a unit. The non-local linkage global values avoid + // duplicate definition linker errors. + GV.setLinkage(GlobalValue::AvailableExternallyLinkage); if (auto GO = dyn_cast(&GV)) GO->setComdat(nullptr); diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp --- a/llvm/lib/Transforms/IPO/FunctionImport.cpp +++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp @@ -1051,6 +1051,7 @@ void llvm::thinLTOFinalizeInModule(Module &TheModule, const GVSummaryMapTy &DefinedGlobals, bool PropagateAttrs) { + DenseSet NonPrevailingComdats; auto FinalizeInModule = [&](GlobalValue &GV, bool Propagate = false) { // See if the global summary analysis computed a new resolved linkage. const auto &GS = DefinedGlobals.find(GV.getGUID()); @@ -1128,8 +1129,10 @@ // as this is a declaration for the linker, and will be dropped eventually. // It is illegal for comdats to contain declarations. auto *GO = dyn_cast_or_null(&GV); - if (GO && GO->isDeclarationForLinker() && GO->hasComdat()) + if (GO && GO->isDeclarationForLinker() && GO->hasComdat()) { + NonPrevailingComdats.insert(GO->getComdat()); GO->setComdat(nullptr); + } }; // Process functions and global now @@ -1139,6 +1142,34 @@ FinalizeInModule(GV); for (auto &GV : TheModule.aliases()) FinalizeInModule(GV); + + // For a non-prevailing comdat, all its members must be available_externally. + // FinalizeInModule has handled non-local-linkage GlobalValues. Here we handle + // local linkage GlobalValues. + if (NonPrevailingComdats.empty()) + return; + for (auto &GO : TheModule.global_objects()) { + if (auto *C = GO.getComdat(); C && NonPrevailingComdats.count(C)) { + GO.setComdat(nullptr); + GO.setLinkage(GlobalValue::AvailableExternallyLinkage); + } + } + bool Changed; + do { + Changed = false; + // If an alias references a GlobalValue in a non-prevailing comdat, change + // it to available_externally. For simplicity we don't handle ConstantExpr + // aliasee, which is unlikely used in a COMDAT. + for (auto &GA : TheModule.aliases()) { + if (GA.hasAvailableExternallyLinkage()) + continue; + if (const auto *GV = dyn_cast(GA.getAliasee())) + if (GV->hasAvailableExternallyLinkage()) { + GA.setLinkage(GlobalValue::AvailableExternallyLinkage); + Changed = true; + } + } + } while (Changed); } /// Run internalization on \p TheModule based on symmary analysis. diff --git a/llvm/test/LTO/Resolution/X86/comdat-mixed-lto.ll b/llvm/test/LTO/Resolution/X86/comdat-mixed-lto.ll --- a/llvm/test/LTO/Resolution/X86/comdat-mixed-lto.ll +++ b/llvm/test/LTO/Resolution/X86/comdat-mixed-lto.ll @@ -8,7 +8,7 @@ ; The copy of C from this module is prevailing. The copy of C from the ; regular LTO module is not prevailing, and will be dropped to ; available_externally. -; RUN: llvm-lto2 run -r=%t1.o,C,pl -r=%t2.o,C,l -r=%t2.o,testglobfunc,lxp -r=%t1.o,testglobfunc,lx -o %t3 %t1.o %t2.o -save-temps +; RUN: llvm-lto2 run -r=%t1.o,C,pl -r=%t2.o,C,l -r=%t1.o,testglobfunc,lxp -r=%t2.o,testglobfunc,lx -o %t3 %t1.o %t2.o -save-temps ; The Input module (regular LTO) is %t3.0. Check to make sure that we removed ; __cxx_global_var_init and testglobfunc from comdat. Also check to ensure @@ -16,8 +16,21 @@ ; have linker multiply defined errors as it is no longer in a comdat and ; would clash with the copy from this module. ; RUN: llvm-dis %t3.0.0.preopt.bc -o - | FileCheck %s -; CHECK: define internal void @__cxx_global_var_init() section ".text.startup" { -; CHECK: define available_externally dso_local void @testglobfunc() section ".text.startup" { + +; CHECK: @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr @__cxx_global_var_init, ptr @C }] +; CHECK: @C = available_externally dso_local global %"class.Test::ptr" zeroinitializer, align 4 +; CHECK-NOT: declare +; CHECK: declare dso_local void @__cxx_global_var_init() section ".text.startup" +; CHECK-NOT: declare + +; Check the behavior with the prevailing testglobfunc in %t2.o. +; RUN: llvm-lto2 run -r=%t1.o,C,pl -r=%t2.o,C,l -r=%t1.o,testglobfunc,lx -r=%t2.o,testglobfunc,plx -o %t4 %t1.o %t2.o -save-temps +; RUN: llvm-dis %t4.0.0.preopt.bc -o - | FileCheck %s --check-prefix=CHECK2 + +; CHECK2: @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr @__cxx_global_var_init, ptr @C }] +; CHECK2: @C = available_externally dso_local global %"class.Test::ptr" zeroinitializer, align 4 +; CHECK2: declare dso_local void @__cxx_global_var_init() section ".text.startup" +; CHECK2: define available_externally dso_local void @testglobfunc() section ".text.startup" { ; ModuleID = 'comdat-mixed-lto.o' source_filename = "comdat-mixed-lto.cpp" diff --git a/llvm/test/ThinLTO/X86/Inputs/linkonce_resolution_comdat.ll b/llvm/test/ThinLTO/X86/Inputs/linkonce_resolution_comdat.ll --- a/llvm/test/ThinLTO/X86/Inputs/linkonce_resolution_comdat.ll +++ b/llvm/test/ThinLTO/X86/Inputs/linkonce_resolution_comdat.ll @@ -1,13 +1,24 @@ target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" -$c2 = comdat any +$f = comdat any +$g = comdat any -define linkonce_odr i32 @f(i8*) unnamed_addr comdat($c2) { +@g_private = private global i32 41, comdat($g) + +define linkonce_odr i32 @f(i8*) unnamed_addr comdat($f) { + ret i32 41 +} + +define linkonce_odr i32 @g() unnamed_addr comdat($g) { ret i32 41 } -define i32 @g() { +define internal void @g_internal() unnamed_addr comdat($g) { + ret void +} + +define i32 @h() { %i = call i32 @f(i8* null) ret i32 %i } diff --git a/llvm/test/ThinLTO/X86/constructor-alias.ll b/llvm/test/ThinLTO/X86/constructor-alias.ll new file mode 100644 --- /dev/null +++ b/llvm/test/ThinLTO/X86/constructor-alias.ll @@ -0,0 +1,44 @@ +;; The constructor alias example is reduced from +;; +;; template +;; struct A { A() {} virtual ~A() {} }; +;; template struct A; +;; void *foo() { return new A; } +;; +;; clang -c -fpic -O1 -flto=thin a.cc && cp a.o b.o && ld.lld -shared a.o b.so + +; RUN: opt -module-summary %s -o %t1.bc +; RUN: cp %t1.bc %t2.bc +; RUN: llvm-lto2 run %t1.bc %t2.bc -r=%t1.bc,_ZTV1A,pl -r=%t1.bc,_ZN1AD0Ev,pl -r=%t1.bc,_ZN1AD1Ev,pl -r=%t1.bc,_ZN1AD2Ev,pl -r=%t1.bc,D1_a,pl -r=%t1.bc,D1_a_a,pl \ +; RUN: -r=%t2.bc,_ZTV1A,l -r=%t2.bc,_ZN1AD0Ev,l -r=%t2.bc,_ZN1AD1Ev,l -r=%t2.bc,_ZN1AD2Ev,l -r=%t2.bc,D1_a,l -r=%t2.bc,D1_a_a,l -o %t3 --save-temps +; RUN: llvm-dis < %t3.2.1.promote.bc | FileCheck %s + +; CHECK: @_ZTV1A = available_externally dso_local unnamed_addr constant { [4 x ptr] } { [4 x ptr] [ptr null, ptr null, ptr @_ZN1AD1Ev, ptr @_ZN1AD0Ev] } +; CHECK: @D1_a = available_externally dso_local unnamed_addr alias void (ptr), ptr @_ZN1AD1Ev +; CHECK: @_ZN1AD1Ev = available_externally dso_local unnamed_addr alias void (ptr), ptr @_ZN1AD2Ev +; CHECK: @D1_a_a = available_externally dso_local unnamed_addr alias void (ptr), ptr @D1_a +; CHECK: define available_externally dso_local void @_ZN1AD2Ev(ptr noundef nonnull %0) unnamed_addr { +; CHECK: define available_externally dso_local void @_ZN1AD0Ev(ptr noundef nonnull %0) unnamed_addr { + +target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +$_ZN1AD5Ev = comdat any +$_ZTV1A = comdat any + +@_ZTV1A = weak_odr unnamed_addr constant { [4 x ptr] } { [4 x ptr] [ptr null, ptr null, ptr @_ZN1AD1Ev, ptr @_ZN1AD0Ev] }, comdat + +@D1_a = weak_odr unnamed_addr alias void (ptr), ptr @_ZN1AD1Ev +@_ZN1AD1Ev = weak_odr unnamed_addr alias void (ptr), ptr @_ZN1AD2Ev +@D1_a_a = weak_odr unnamed_addr alias void (ptr), ptr @D1_a + +define weak_odr void @_ZN1AD2Ev(ptr noundef nonnull %0) unnamed_addr comdat($_ZN1AD5Ev) { + ret void +} + +define weak_odr void @_ZN1AD0Ev(ptr noundef nonnull %0) unnamed_addr comdat($_ZN1AD5Ev) { + call void @D1_a(ptr noundef nonnull %0) + call void @D1_a_a(ptr noundef nonnull %0) + call void @_ZN1AD1Ev(ptr noundef nonnull %0) + ret void +} diff --git a/llvm/test/ThinLTO/X86/linkonce_resolution_comdat.ll b/llvm/test/ThinLTO/X86/linkonce_resolution_comdat.ll --- a/llvm/test/ThinLTO/X86/linkonce_resolution_comdat.ll +++ b/llvm/test/ThinLTO/X86/linkonce_resolution_comdat.ll @@ -1,33 +1,54 @@ -; This test ensures that we drop the preempted copy of @f from %t2.bc from its -; comdat after making it available_externally. If not we would get a -; verification error. +; This test ensures that we drop the preempted copy of @f/@g from %t2.bc from their +; comdats after making it available_externally. If not we would get a +; verification error. g_internal/g_private are changed to available_externally +; as well since it is in the same comdat of g. ; RUN: opt -module-summary %s -o %t1.bc ; RUN: opt -module-summary %p/Inputs/linkonce_resolution_comdat.ll -o %t2.bc -; RUN: llvm-lto -thinlto-action=run -disable-thinlto-funcattrs=0 %t1.bc %t2.bc -exported-symbol=f -exported-symbol=g -thinlto-save-temps=%t3. +; RUN: llvm-lto -thinlto-action=run -disable-thinlto-funcattrs=0 %t1.bc %t2.bc -exported-symbol=f -exported-symbol=g -exported-symbol=h -thinlto-save-temps=%t3. ; RUN: llvm-dis %t3.0.3.imported.bc -o - | FileCheck %s --check-prefix=IMPORT1 ; RUN: llvm-dis %t3.1.3.imported.bc -o - | FileCheck %s --check-prefix=IMPORT2 ; Copy from first module is prevailing and converted to weak_odr, copy ; from second module is preempted and converted to available_externally and ; removed from comdat. -; IMPORT1: define weak_odr i32 @f(i8* %0) unnamed_addr [[ATTR:#[0-9]+]] comdat($c1) { +; IMPORT1: @g_private = private global i32 43, comdat($g) +; IMPORT1: define weak_odr i32 @f(i8* %0) unnamed_addr [[ATTR:#[0-9]+]] comdat { +; IMPORT1: define weak_odr i32 @g() unnamed_addr [[ATTR]] comdat { +; IMPORT1: define internal void @g_internal() unnamed_addr comdat($g) { + +; IMPORT2: @g_private = available_externally dso_local global i32 41{{$}} ; IMPORT2: define available_externally i32 @f(i8* %0) unnamed_addr [[ATTR:#[0-9]+]] { +; IMPORT2: define available_externally i32 @g() unnamed_addr [[ATTR]] { +; IMPORT2: define available_externally dso_local void @g_internal() unnamed_addr { ; CHECK-DAG: attributes [[ATTR]] = { norecurse nounwind } -; RUN: llvm-nm -o - < %t1.bc.thinlto.o | FileCheck %s --check-prefix=NM1 +; RUN: llvm-nm %t1.bc.thinlto.o | FileCheck %s --check-prefix=NM1 ; NM1: W f +; NM1: W g -; RUN: llvm-nm -o - < %t2.bc.thinlto.o | FileCheck %s --check-prefix=NM2 +; RUN: llvm-nm %t2.bc.thinlto.o | FileCheck %s --check-prefix=NM2 ; f() would have been turned into available_externally since it is preempted, -; and inlined into g() +; and inlined into h() ; NM2-NOT: f +; NM2-NOT: g target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" -$c1 = comdat any +$f = comdat any +$g = comdat any -define linkonce_odr i32 @f(i8*) unnamed_addr comdat($c1) { +@g_private = private global i32 43, comdat($g) + +define linkonce_odr i32 @f(i8*) unnamed_addr comdat { + ret i32 43 +} + +define linkonce_odr i32 @g() unnamed_addr comdat { ret i32 43 } + +define internal void @g_internal() unnamed_addr comdat($g) { + ret void +} diff --git a/llvm/test/Verifier/alias.ll b/llvm/test/Verifier/alias.ll --- a/llvm/test/Verifier/alias.ll +++ b/llvm/test/Verifier/alias.ll @@ -1,4 +1,4 @@ -; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s +; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s --implicit-check-not=Alias declare void @f() @@ -31,3 +31,5 @@ @test3_c = alias i32, i32* @test3_b ; CHECK: Alias cannot point to an interposable alias ; CHECK-NEXT: i32* @test3_c + +@test4_a = available_externally global i32 42