Correctly initialise global blocks on Windows.
Summary:
Windows does not allow globals to be initialised to point to globals in
another DLL. Exported globals may be referenced only from code. Work
around this by creating an initialiser that runs in early library
initialisation and sets the isa pointer.
Reviewers: rjmccall
Reviewed By: rjmccall
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D50436
llvm-svn: 339317
diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 1643683..f8a7901 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -1213,9 +1213,13 @@
auto fields = builder.beginStruct();
bool IsOpenCL = CGM.getLangOpts().OpenCL;
+ bool IsWindows = CGM.getTarget().getTriple().isOSWindows();
if (!IsOpenCL) {
// isa
- fields.add(CGM.getNSConcreteGlobalBlock());
+ if (IsWindows)
+ fields.addNullPointer(CGM.Int8PtrPtrTy);
+ else
+ fields.add(CGM.getNSConcreteGlobalBlock());
// __flags
BlockFlags flags = BLOCK_IS_GLOBAL | BLOCK_HAS_SIGNATURE;
@@ -1250,7 +1254,27 @@
llvm::Constant *literal = fields.finishAndCreateGlobal(
"__block_literal_global", blockInfo.BlockAlign,
- /*constant*/ true, llvm::GlobalVariable::InternalLinkage, AddrSpace);
+ /*constant*/ !IsWindows, llvm::GlobalVariable::InternalLinkage, AddrSpace);
+
+ // Windows does not allow globals to be initialised to point to globals in
+ // different DLLs. Any such variables must run code to initialise them.
+ if (IsWindows) {
+ auto *Init = llvm::Function::Create(llvm::FunctionType::get(CGM.VoidTy,
+ {}), llvm::GlobalValue::InternalLinkage, ".block_isa_init",
+ &CGM.getModule());
+ llvm::IRBuilder<> b(llvm::BasicBlock::Create(CGM.getLLVMContext(), "entry",
+ Init));
+ b.CreateAlignedStore(CGM.getNSConcreteGlobalBlock(),
+ b.CreateStructGEP(literal, 0), CGM.getPointerAlign().getQuantity());
+ b.CreateRetVoid();
+ // We can't use the normal LLVM global initialisation array, because we
+ // need to specify that this runs early in library initialisation.
+ auto *InitVar = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
+ /*isConstant*/true, llvm::GlobalValue::InternalLinkage,
+ Init, ".block_isa_init_ptr");
+ InitVar->setSection(".CRT$XCLa");
+ CGM.addUsedGlobal(InitVar);
+ }
// Return a constant of the appropriately-casted type.
llvm::Type *RequiredType =