Make globals with mutable members non-constant, even in custom sections

Turned out we were making overly simple assumptions about which sections (& section flags) would be used when emitting a global into a custom section. This lead to sections with read-only flags being used for globals of struct types with mutable members.

Fixed by porting the codegen function with the more nuanced handling/checking for mutable members out of codegen for use in the sema code that does this initial checking/mapping to section flags.

Differential Revision: https://reviews.llvm.org/D156726

1 files changed, 6 insertions, 26 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 3a79dec53592..0d22713dbb31 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3377,7 +3377,7 @@ bool CodeGenModule::MayBeEmittedEagerly(const ValueDecl *Global) {
   // codegen for global variables, because they may be marked as threadprivate.
   if (LangOpts.OpenMP && LangOpts.OpenMPUseTLS &&
       getContext().getTargetInfo().isTLSSupported() && isa<VarDecl>(Global) &&
-      !isTypeConstant(Global->getType(), false, false) &&
+      !Global->getType().isConstantStorage(getContext(), false, false) &&
       !OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(Global))
     return false;
 
@@ -4581,27 +4581,6 @@ CodeGenModule::CreateRuntimeFunction(llvm::FunctionType *FTy, StringRef Name,
   return {FTy, C};
 }
 
-/// isTypeConstant - Determine whether an object of this type can be emitted
-/// as a constant.
-///
-/// If ExcludeCtor is true, the duration when the object's constructor runs
-/// will not be considered. The caller will need to verify that the object is
-/// not written to during its construction. ExcludeDtor works similarly.
-bool CodeGenModule::isTypeConstant(QualType Ty, bool ExcludeCtor,
-                                   bool ExcludeDtor) {
-  if (!Ty.isConstant(Context) && !Ty->isReferenceType())
-    return false;
-
-  if (Context.getLangOpts().CPlusPlus) {
-    if (const CXXRecordDecl *Record
-          = Context.getBaseElementType(Ty)->getAsCXXRecordDecl())
-      return ExcludeCtor && !Record->hasMutableFields() &&
-             (Record->hasTrivialDestructor() || ExcludeDtor);
-  }
-
-  return true;
-}
-
 /// GetOrCreateLLVMGlobal - If the specified mangled name is not in the module,
 /// create and return an llvm GlobalVariable with the specified type and address
 /// space. If there is something in the module with the specified name, return
@@ -4709,7 +4688,7 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName, llvm::Type *Ty,
 
     // FIXME: This code is overly simple and should be merged with other global
     // handling.
-    GV->setConstant(isTypeConstant(D->getType(), false, false));
+    GV->setConstant(D->getType().isConstantStorage(getContext(), false, false));
 
     GV->setAlignment(getContext().getDeclAlign(D).getAsAlign());
 
@@ -5270,7 +5249,7 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
 
   // If it is safe to mark the global 'constant', do so now.
   GV->setConstant(!NeedsGlobalCtor && !NeedsGlobalDtor &&
-                  isTypeConstant(D->getType(), true, true));
+                  D->getType().isConstantStorage(getContext(), true, true));
 
   // If it is in a read-only section, mark it 'constant'.
   if (const SectionAttr *SA = D->getAttr<SectionAttr>()) {
@@ -6344,8 +6323,9 @@ ConstantAddress CodeGenModule::GetAddrOfGlobalTemporary(
     emitter.emplace(*this);
     InitialValue = emitter->emitForInitializer(*Value, AddrSpace,
                                                MaterializedType);
-    Constant = isTypeConstant(MaterializedType, /*ExcludeCtor*/ Value,
-                              /*ExcludeDtor*/ false);
+    Constant =
+        MaterializedType.isConstantStorage(getContext(), /*ExcludeCtor*/ Value,
+                                           /*ExcludeDtor*/ false);
     Type = InitialValue->getType();
   } else {
     // No initializer, the initialization will be provided when we