fix some cfstring related issues:

1) -fwritable-string does affect the non-utf16 version of cfstrings
   just not the utf16 ones.
2) utf16 strings should always be marked constant, as the __TEXT segment
   is readonly.
3) The name of the global doesn't matter, remove it from TargetInfo.
4) Trust the asmprinter to drop cstrings into the right section, like llvmgcc does now.

This fixes rdar://7115750

llvm-svn: 84077

clang/include/clang/Basic/TargetInfo.h

@@ -300,12 +300,6 @@ public:
 
   virtual bool useGlobalsForAutomaticVariables() const { return false; }
 
-  /// getUnicodeStringSymbolPrefix - Get the default symbol prefix to
-  /// use for string literals.
-  virtual const char *getUnicodeStringSymbolPrefix() const {
-    return ".str";
-  }
-
   /// getUnicodeStringSection - Return the section to use for unicode
   /// string literals, or 0 if no special section is used.
   virtual const char *getUnicodeStringSection() const {
@@ -318,14 +312,6 @@ public:
     return "__DATA,__cfstring";
   }
 
-  /// getCFStringDataSection - Return the section to use for the
-  /// constant string data associated with a CFString literal, or 0 if
-  /// no special section is used.
-  virtual const char *getCFStringDataSection() const {
-    return "__TEXT,__cstring,cstring_literals";
-  }
-
-
   /// isValidSectionSpecifier - This is an optional hook that targets can
   /// implement to perform semantic checking on attribute((section("foo")))
   /// specifiers.  In this case, "foo" is passed in to be checked.  If the

clang/lib/Basic/Targets.cpp

@@ -197,10 +197,6 @@ public:
       this->TLSSupported = false;
     }
 
-  virtual const char *getUnicodeStringSymbolPrefix() const {
-    return "__utf16_string_";
-  }
-
   virtual const char *getUnicodeStringSection() const {
     return "__TEXT,__ustring";
   }

clang/lib/CodeGen/CodeGenModule.cpp

@@ -1434,27 +1434,24 @@ CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
   // String pointer.
   llvm::Constant *C = llvm::ConstantArray::get(VMContext, Entry.getKey().str());
 
-  const char *Sect, *Prefix;
+  const char *Sect = 0;
-  bool isConstant;
   llvm::GlobalValue::LinkageTypes Linkage;
+  bool isConstant;
   if (isUTF16) {
-    Prefix = getContext().Target.getUnicodeStringSymbolPrefix();
     Sect = getContext().Target.getUnicodeStringSection();
-    // FIXME: why do utf strings get "l" labels instead of "L" labels?
+    // FIXME: why do utf strings get "_" labels instead of "L" labels?
     Linkage = llvm::GlobalValue::InternalLinkage;
-    // FIXME: Why does GCC not set constant here?
+    // Note: -fwritable-strings doesn't make unicode CFStrings writable, but
-    isConstant = false;
+    // does make plain ascii ones writable.
-  } else {
-    Prefix = ".str";
-    Sect = getContext().Target.getCFStringDataSection();
-    Linkage = llvm::GlobalValue::PrivateLinkage;
-    // FIXME: -fwritable-strings should probably affect this, but we
-    // are following gcc here.
     isConstant = true;
+  } else {
+    Linkage = llvm::GlobalValue::PrivateLinkage;
+    isConstant = !Features.WritableStrings;
   }
+  
   llvm::GlobalVariable *GV =
-    new llvm::GlobalVariable(getModule(), C->getType(), isConstant,
+    new llvm::GlobalVariable(getModule(), C->getType(), isConstant, Linkage, C,
-                             Linkage, C, Prefix);
+                             ".str");
   if (Sect)
     GV->setSection(Sect);
   if (isUTF16) {

clang/test/CodeGen/darwin-string-literals.c

@@ -1,14 +1,14 @@
 // RUN: clang-cc -triple i386-apple-darwin9 -emit-llvm %s -o - | FileCheck -check-prefix LSB %s &&
 
 // CHECK-LSB: @.str = private constant [8 x i8] c"string0\00"
-// CHECK-LSB: @.str1 = private constant [8 x i8] c"string1\00", section "__TEXT,__cstring,cstring_literals"
+// CHECK-LSB: @.str1 = private constant [8 x i8] c"string1\00"
-// CHECK-LSB: @__utf16_string_ = internal global [36 x i8] c"h\00e\00l\00l\00o\00 \00\92! \00\03& \00\90! \00w\00o\00r\00l\00d\00\00\00", section "__TEXT,__ustring", align 2
+// CHECK-LSB: @.str2 = internal constant [36 x i8] c"h\00e\00l\00l\00o\00 \00\92! \00\03& \00\90! \00w\00o\00r\00l\00d\00\00\00", section "__TEXT,__ustring", align 2
 
 // RUN: clang-cc -triple powerpc-apple-darwin9 -emit-llvm %s -o - | FileCheck -check-prefix MSB %s
 
 // CHECK-MSB: @.str = private constant [8 x i8] c"string0\00"
-// CHECK-MSB: @.str1 = private constant [8 x i8] c"string1\00", section "__TEXT,__cstring,cstring_literals"
+// CHECK-MSB: @.str1 = private constant [8 x i8] c"string1\00"
-// CHECK-MSB: @__utf16_string_ = internal global [36 x i8] c"\00h\00e\00l\00l\00o\00 !\92\00 &\03\00 !\90\00 \00w\00o\00r\00l\00d\00\00", section "__TEXT,__ustring", align 2
+// CHECK-MSB: @.str2 = internal constant [36 x i8] c"\00h\00e\00l\00l\00o\00 !\92\00 &\03\00 !\90\00 \00w\00o\00r\00l\00d\00\00", section "__TEXT,__ustring", align 2
 
 const char *g0 = "string0";
 const void *g1 = __builtin___CFStringMakeConstantString("string1");