Author: theraven Date: Thu Aug 9 01:02:42 2018 New Revision: 339317 URL: http://llvm.org/viewvc/llvm-project?rev=339317&view=rev Log: 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 Added: cfe/trunk/test/CodeGen/global-blocks-win32.c Modified: cfe/trunk/lib/CodeGen/CGBlocks.cpp Modified: cfe/trunk/lib/CodeGen/CGBlocks.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.cpp?rev=339317&r1=339316&r2=339317&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CGBlocks.cpp (original) +++ cfe/trunk/lib/CodeGen/CGBlocks.cpp Thu Aug 9 01:02:42 2018 @@ -1213,9 +1213,13 @@ static llvm::Constant *buildGlobalBlock( 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 @@ static llvm::Constant *buildGlobalBlock( 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$XCLa"); + CGM.addUsedGlobal(InitVar); + } // Return a constant of the appropriately-casted type. llvm::Type *RequiredType = Added: cfe/trunk/test/CodeGen/global-blocks-win32.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/global-blocks-win32.c?rev=339317&view=auto ============================================================================== --- cfe/trunk/test/CodeGen/global-blocks-win32.c (added) +++ cfe/trunk/test/CodeGen/global-blocks-win32.c Thu Aug 9 01:02:42 2018 @@ -0,0 +1,18 @@ +// RUN: %clang_cc1 -fblocks -triple i386-pc-windows-msvc %s -emit-llvm -o - -fblocks | FileCheck %s + + +int (^x)(void) = ^() { return 21; }; + + +// Check that the block literal is emitted with a null isa pointer +// CHECK: @__block_literal_global = internal global { i8**, i32, i32, i8*, %struct.__block_descriptor* } { i8** null, + +// Check that _NSConcreteGlobalBlock has the correct dllimport specifier. +// CHECK: @_NSConcreteGlobalBlock = external dllimport global i8* +// Check that we create an initialiser pointer in the correct section (early library initialisation). +// CHECK: @.block_isa_init_ptr = internal constant void ()* @.block_isa_init, section ".CRT$XCLa" + +// Check that we emit an initialiser for it. +// CHECK: define internal void @.block_isa_init() { +// CHECK: store i8** @_NSConcreteGlobalBlock, i8*** getelementptr inbounds ({ i8**, i32, i32, i8*, %struct.__block_descriptor* }, { i8**, i32, i32, i8*, %struct.__block_descriptor* }* @__block_literal_global, i32 0, i32 0), align 4 + _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
