From 1bf7a3fcc4e2ad30688f7b0db464ad1ccabe77e2 Mon Sep 17 00:00:00 2001 From: Bill Wendling Date: Tue, 10 Jan 2012 08:46:39 +0000 Subject: [PATCH] The `-fwritable-strings' flag doesn't make the backing store strings of all CFStrings writable. The strings (both Unicode and ASCII) should reside in a read-only section. E.g., __TEXT,__cstring instead of __DATA,__data. This is done by making the global variable created for the strings constant despite the value of that flag. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147845 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/CodeGenModule.cpp | 16 ++++++---------- test/CodeGen/cfstring.c | 10 ++++++++++ 2 files changed, 16 insertions(+), 10 deletions(-) diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp index 9e772b40c4..76918dd448 100644 --- a/lib/CodeGen/CodeGenModule.cpp +++ b/lib/CodeGen/CodeGenModule.cpp @@ -1848,24 +1848,20 @@ CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) { llvm::Constant *C = llvm::ConstantArray::get(VMContext, Entry.getKey().str()); llvm::GlobalValue::LinkageTypes Linkage; - bool isConstant; - if (isUTF16) { + if (isUTF16) // FIXME: why do utf strings get "_" labels instead of "L" labels? Linkage = llvm::GlobalValue::InternalLinkage; - // Note: -fwritable-strings doesn't make unicode CFStrings writable, but - // does make plain ascii ones writable. - isConstant = true; - } else { + else // FIXME: With OS X ld 123.2 (xcode 4) and LTO we would get a linker error // when using private linkage. It is not clear if this is a bug in ld // or a reasonable new restriction. Linkage = llvm::GlobalValue::LinkerPrivateLinkage; - isConstant = !Features.WritableStrings; - } + // Note: -fwritable-strings doesn't make the backing store strings of + // CFStrings writable. (See ) llvm::GlobalVariable *GV = - new llvm::GlobalVariable(getModule(), C->getType(), isConstant, Linkage, C, - ".str"); + new llvm::GlobalVariable(getModule(), C->getType(), /*isConstant=*/true, + Linkage, C, ".str"); GV->setUnnamedAddr(true); if (isUTF16) { CharUnits Align = getContext().getTypeAlignInChars(getContext().ShortTy); diff --git a/test/CodeGen/cfstring.c b/test/CodeGen/cfstring.c index 1f0977f039..9d98b56e6b 100644 --- a/test/CodeGen/cfstring.c +++ b/test/CodeGen/cfstring.c @@ -1,4 +1,14 @@ // RUN: %clang_cc1 -emit-llvm %s -o %t + +// : Check that the backing store of CFStrings are +// constant with the -fwritable-strings flag. +// +// RUN: %clang_cc1 -fwritable-strings -emit-llvm %s -o - | FileCheck %s +// +// CHECK: @.str = linker_private unnamed_addr constant [14 x i8] c"Hello, World!\00", align 1 +// CHECK: @.str1 = linker_private unnamed_addr constant [7 x i8] c"yo joe\00", align 1 +// CHECK: @.str3 = linker_private unnamed_addr constant [16 x i8] c"Goodbye, World!\00", align 1 + #define CFSTR __builtin___CFStringMakeConstantString void f() { -- 2.40.0