Reland [clang][AIX] add option mdefault-visibility-export-mapping

The option mdefault-visibility-export-mapping is created to allow mapping default visibility to an explicit shared library export (e.g. dllexport). Exactly how and if this is manifested is target dependent (since it depends on how they map dllexport in the IR). Three values are provided for the option: * none: the default and behavior without the option, no additional export linkage information is created. * explicit: add the export for entities with explict default visibility from the source, including RTTI * all: add the export for all entities with default visibility This option is useful for targets which do not export symbols as part of their usual default linkage behaviour (e.g. AIX), such targets traditionally specified such information in external files (e.g. export lists), but this mapping allows them to use the visibility information typically used for this purpose on other (e.g. ELF) platforms. This relands commit: 8c8a267 with fixes for the compile time and assert problems that were reported by: * making shouldMapVisibilityToDLLExport inline and provide an early return in the case where no mapping is in effect (aka non-AIX platforms) * don't try to export RTTI types which we will give internal linkage to Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D126340
llvm · Jun 13, 2022 · 6a86730 · 6a86730
1 parent 166d6ed
commit 6a86730
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diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
@@ -3626,6 +3626,23 @@ Clang expects the GCC executable "gcc.exe" compiled for
 `Some tests might fail <https://bugs.llvm.org/show_bug.cgi?id=9072>`_ on
 ``x86_64-w64-mingw32``.
 
+AIX
+^^^
+
+The ``-mdefault-visibility-export-mapping=`` option can be used to control
+mapping of default visibility to an explicit shared object export
+(i.e. XCOFF exported visibility). Three values are provided for the option:
+
+* ``-mdefault-visibility-export-mapping=none``: no additional export
+  information is created for entities with default visibility.
+* ``-mdefault-visibility-export-mapping=explicit``: mark entities for export
+  if they have explict (e.g. via an attribute) default visibility from the
+  source, including RTTI.
+* ``-mdefault-visibility-export-mapping=all``: set XCOFF exported visibility
+  for all entities with default visibility from any source. This gives a
+  export behavior similar to ELF platforms where all entities with default
+  visibility are exported.
+
 .. _spir-v:
 
 SPIR-V support

diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
@@ -290,6 +290,7 @@ BENIGN_LANGOPT(DumpRecordLayoutsComplete , 1, 0, "dumping the AST layout of all
 BENIGN_LANGOPT(DumpVTableLayouts , 1, 0, "dumping the layouts of emitted vtables")
 LANGOPT(NoConstantCFStrings , 1, 0, "no constant CoreFoundation strings")
 BENIGN_LANGOPT(InlineVisibilityHidden , 1, 0, "hidden visibility for inline C++ methods")
+BENIGN_ENUM_LANGOPT(DefaultVisibilityExportMapping, DefaultVisiblityExportMapping, 2, DefaultVisiblityExportMapping::None, "controls mapping of default visibility to dllexport")
 BENIGN_LANGOPT(IgnoreXCOFFVisibility, 1, 0, "All the visibility attributes that are specified in the source code are ignored in aix XCOFF.")
 BENIGN_LANGOPT(VisibilityInlinesHiddenStaticLocalVar, 1, 0,
                "hidden visibility for static local variables in inline C++ "

diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
@@ -350,6 +350,14 @@ class LangOptions : public LangOptionsBase {
     PerThread,
   };
 
+  enum class DefaultVisiblityExportMapping {
+    None,
+    /// map only explicit default visibilities to exported
+    Explicit,
+    /// map all default visibilities to exported
+    All,
+  };
+
 public:
   /// The used language standard.
   LangStandard::Kind LangStd;
@@ -581,6 +589,21 @@ class LangOptions : public LangOptionsBase {
 
   bool isSYCL() const { return SYCLIsDevice || SYCLIsHost; }
 
+  bool hasDefaultVisibilityExportMapping() const {
+    return getDefaultVisibilityExportMapping() !=
+           DefaultVisiblityExportMapping::None;
+  }
+
+  bool isExplicitDefaultVisibilityExportMapping() const {
+    return getDefaultVisibilityExportMapping() ==
+           DefaultVisiblityExportMapping::Explicit;
+  }
+
+  bool isAllDefaultVisibilityExportMapping() const {
+    return getDefaultVisibilityExportMapping() ==
+           DefaultVisiblityExportMapping::All;
+  }
+
   /// Remap path prefix according to -fmacro-prefix-path option.
   void remapPathPrefix(SmallVectorImpl<char> &Path) const;
 };

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -2918,6 +2918,13 @@ def fvisibility_ms_compat : Flag<["-"], "fvisibility-ms-compat">, Group<f_Group>
 def fvisibility_global_new_delete_hidden : Flag<["-"], "fvisibility-global-new-delete-hidden">, Group<f_Group>,
   HelpText<"Give global C++ operator new and delete declarations hidden visibility">, Flags<[CC1Option]>,
   MarshallingInfoFlag<LangOpts<"GlobalAllocationFunctionVisibilityHidden">>;
+def mdefault_visibility_export_mapping_EQ : Joined<["-"], "mdefault-visibility-export-mapping=">,
+  Values<"none,explicit,all">,
+  NormalizedValuesScope<"LangOptions::DefaultVisiblityExportMapping">,
+  NormalizedValues<["None", "Explicit", "All"]>,
+  HelpText<"Mapping between default visibility and export">,
+  Group<m_Group>, Flags<[CC1Option]>,
+  MarshallingInfoEnum<LangOpts<"DefaultVisibilityExportMapping">,"None">;
 defm new_infallible : BoolFOption<"new-infallible",
   LangOpts<"NewInfallible">, DefaultFalse,
   PosFlag<SetTrue, [], "Enable">, NegFlag<SetFalse, [], "Disable">,

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1214,7 +1214,9 @@ void CodeGenModule::setDLLImportDLLExport(llvm::GlobalValue *GV,
   if (D && D->isExternallyVisible()) {
     if (D->hasAttr<DLLImportAttr>())
       GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
-    else if (D->hasAttr<DLLExportAttr>() && !GV->isDeclarationForLinker())
+    else if ((D->hasAttr<DLLExportAttr>() ||
+              shouldMapVisibilityToDLLExport(D)) &&
+             !GV->isDeclarationForLinker())
       GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass);
   }
 }
@@ -3790,7 +3792,8 @@ llvm::Constant *CodeGenModule::GetOrCreateLLVMFunction(
     }
 
     // Handle dropped DLL attributes.
-    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>()) {
+    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>() &&
+        !shouldMapVisibilityToDLLExport(cast_or_null<NamedDecl>(D))) {
       Entry->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
       setDSOLocal(Entry);
     }
@@ -4102,7 +4105,8 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName, llvm::Type *Ty,
     }
 
     // Handle dropped DLL attributes.
-    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>())
+    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>() &&
+        !shouldMapVisibilityToDLLExport(D))
       Entry->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
 
     if (LangOpts.OpenMP && !LangOpts.OpenMPSimd && D)

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
@@ -798,6 +798,14 @@ class CodeGenModule : public CodeGenTypeCache {
 
   void setDSOLocal(llvm::GlobalValue *GV) const;
 
+  bool shouldMapVisibilityToDLLExport(const NamedDecl *D) const {
+    return getLangOpts().hasDefaultVisibilityExportMapping() && D &&
+           (D->getLinkageAndVisibility().getVisibility() ==
+            DefaultVisibility) &&
+           (getLangOpts().isAllDefaultVisibilityExportMapping() ||
+            (getLangOpts().isExplicitDefaultVisibilityExportMapping() &&
+             D->getLinkageAndVisibility().isVisibilityExplicit()));
+  }
   void setDLLImportDLLExport(llvm::GlobalValue *GV, GlobalDecl D) const;
   void setDLLImportDLLExport(llvm::GlobalValue *GV, const NamedDecl *D) const;
   /// Set visibility, dllimport/dllexport and dso_local.

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3680,12 +3680,14 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(QualType Ty) {
 
   llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass =
       llvm::GlobalValue::DefaultStorageClass;
-  if (CGM.getTriple().isWindowsItaniumEnvironment()) {
-    auto RD = Ty->getAsCXXRecordDecl();
-    if (RD && RD->hasAttr<DLLExportAttr>())
+  if (auto RD = Ty->getAsCXXRecordDecl()) {
+    if ((CGM.getTriple().isWindowsItaniumEnvironment() &&
+         RD->hasAttr<DLLExportAttr>()) ||
+        (CGM.shouldMapVisibilityToDLLExport(RD) &&
+         !llvm::GlobalValue::isLocalLinkage(Linkage) &&
+         llvmVisibility == llvm::GlobalValue::DefaultVisibility))
       DLLStorageClass = llvm::GlobalValue::DLLExportStorageClass;
   }
-
   return BuildTypeInfo(Ty, Linkage, llvmVisibility, DLLStorageClass);
 }
 
@@ -4168,9 +4170,9 @@ void ItaniumCXXABI::EmitFundamentalRTTIDescriptors(const CXXRecordDecl *RD) {
       getContext().Char32Ty
   };
   llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass =
-      RD->hasAttr<DLLExportAttr>()
-      ? llvm::GlobalValue::DLLExportStorageClass
-      : llvm::GlobalValue::DefaultStorageClass;
+      RD->hasAttr<DLLExportAttr>() || CGM.shouldMapVisibilityToDLLExport(RD)
+          ? llvm::GlobalValue::DLLExportStorageClass
+          : llvm::GlobalValue::DefaultStorageClass;
   llvm::GlobalValue::VisibilityTypes Visibility =
       CodeGenModule::GetLLVMVisibility(RD->getVisibility());
   for (const QualType &FundamentalType : FundamentalTypes) {

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -47,7 +47,11 @@ class MicrosoftCXXABI : public CGCXXABI {
       : CGCXXABI(CGM), BaseClassDescriptorType(nullptr),
         ClassHierarchyDescriptorType(nullptr),
         CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),
-        ThrowInfoType(nullptr) {}
+        ThrowInfoType(nullptr) {
+    assert(!(CGM.getLangOpts().isExplicitDefaultVisibilityExportMapping() ||
+             CGM.getLangOpts().isAllDefaultVisibilityExportMapping()) &&
+           "visibility export mapping option unimplemented in this ABI");
+  }
 
   bool HasThisReturn(GlobalDecl GD) const override;
   bool hasMostDerivedReturn(GlobalDecl GD) const override;

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5982,6 +5982,14 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
           << A->getAsString(Args) << TripleStr;
   }
 
+  if (const Arg *A =
+          Args.getLastArg(options::OPT_mdefault_visibility_export_mapping_EQ)) {
+    if (Triple.isOSAIX())
+      A->render(Args, CmdArgs);
+    else
+      D.Diag(diag::err_drv_unsupported_opt_for_target)
+          << A->getAsString(Args) << TripleStr;
+  }
 
   if (Args.hasFlag(options::OPT_fvisibility_inlines_hidden,
                     options::OPT_fno_visibility_inlines_hidden, false))

diff --git a/clang/test/CodeGen/mdefault-visibility-export-mapping.c b/clang/test/CodeGen/mdefault-visibility-export-mapping.c
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-DEF,EXPLICIT-DEF %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -mdefault-visibility-export-mapping=none -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-DEF,EXPLICIT-DEF %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -mdefault-visibility-export-mapping=explicit -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-DEF,EXPLICIT-EXP %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -mdefault-visibility-export-mapping=all -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-EXP,EXPLICIT-EXP %s
+// RUN: %clang -target powerpc-ibm-aix %s -mdefault-visibility-export-mapping=all -fvisibility=hidden -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-HID,EXPLICIT-EXP %s
+
+// RUN: not %clang -mdefault-visibility-export-mapping=explicit -target powerpc-unknown-linux %s 2>&1 | \
+// RUN: FileCheck -check-prefix=ERROR %s
+// ERROR: unsupported option '-mdefault-visibility-export-mapping=explicit' for target 'powerpc-unknown-linux'
+
+// UNSPECIFIED-DEF: define void @func()
+// UNSPECIFIED-HID: define hidden void @func()
+// UNSPECIFIED-EXP: define dllexport void @func()
+void func() {}
+
+#pragma GCC visibility push(default)
+// EXPLICIT-DEF: define void @pragmafunc()
+// EXPLICIT-EXP: define dllexport void @pragmafunc()
+void pragmafunc() {}
+#pragma GCC visibility pop
+
+// EXPLICIT-DEF: define void @explicitfunc()
+// EXPLICIT-EXP: define dllexport void @explicitfunc()
+void __attribute__((visibility("default"))) explicitfunc() {}
diff --git a/clang/test/CodeGenCXX/mdefault-visibility-export-mapping-alias.cpp b/clang/test/CodeGenCXX/mdefault-visibility-export-mapping-alias.cpp
@@ -0,0 +1,41 @@
+// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -mdefault-visibility-export-mapping=none -mconstructor-aliases -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-DEF,EXPLICIT-DEF %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -mdefault-visibility-export-mapping=explicit -mconstructor-aliases -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-DEF,EXPLICIT-EXP %s
+// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -mdefault-visibility-export-mapping=all -mconstructor-aliases -S -emit-llvm -o - | \
+// RUN:   FileCheck -check-prefixes=UNSPECIFIED-EXP,EXPLICIT-EXP %s
+
+class A {
+public:
+  ~A();
+};
+
+A::~A() {}
+
+class __attribute__((visibility("default"))) B {
+public:
+  ~B();
+};
+
+B::~B() {}
+
+void func() {
+  A x;
+  B y;
+}
+
+// A::~A() (complete object destructor)
+// UNSPECIFIED-DEF:  @_ZN1AD1Ev = unnamed_addr alias
+// UNSPECIFIED-EXP:  @_ZN1AD1Ev = dllexport unnamed_addr alias
+
+// B::~B() (complete object destructor)
+// EXPLICIT-DEF:  @_ZN1BD1Ev = unnamed_addr alias
+// EXPLICIT-EXP:  @_ZN1BD1Ev = dllexport unnamed_addr alias
+
+// A::~A() (base object destructor)
+// UNSPECIFIED-DEF:  define void @_ZN1AD2Ev(
+// UNSPECIFIED-EXP:  define dllexport void @_ZN1AD2Ev(
+
+// B::~B() (base object destructor)
+// EXPLICIT-DEF:  define void @_ZN1BD2Ev(
+// EXPLICIT-EXP:  define dllexport void @_ZN1BD2Ev(