[lld] r190585 - Do not hard code the leading underscore.

[Rui Ueyama]

Author: ruiu
Date: Wed Sep 11 23:42:31 2013
New Revision: 190585

URL: http://llvm.org/viewvc/llvm-project?rev=190585&view=rev
Log:
Do not hard code the leading underscore.

Mangling scheme varies on platform, and prepending an underscore is valid only
on 32-bit x86. Added a method to mangle name to PECOFFLinkingContext and use
it to avoid hard coding mangled names.

Modified:
    lld/trunk/include/lld/ReaderWriter/PECOFFLinkingContext.h
    lld/trunk/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h

Modified: lld/trunk/include/lld/ReaderWriter/PECOFFLinkingContext.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/include/lld/ReaderWriter/PECOFFLinkingContext.h?rev=190585&r1=190584&r2=190585&view=diff
==============================================================================
--- lld/trunk/include/lld/ReaderWriter/PECOFFLinkingContext.h (original)
+++ lld/trunk/include/lld/ReaderWriter/PECOFFLinkingContext.h Wed Sep 11 23:42:31 2013
@@ -69,6 +69,17 @@ public:
 
   StringRef searchLibraryFile(StringRef path) const;
 
+  /// Returns the decorated name of the given symbol name. On 32-bit x86, it
+  /// adds "_" at the beginning of the string. On other architectures, the
+  /// return value is the same as the argument.
+  StringRef decorateSymbol(StringRef name) const {
+    // Because we don't support architectures other than 32-bit x86, we'll
+    // prepend an underscore unconditionally.
+    std::string str = "_";
+    str.append(name);
+    return allocateString(str);
+  }
+
   void setBaseAddress(uint64_t addr) { _baseAddress = addr; }
   uint64_t getBaseAddress() const { return _baseAddress; }
 

Modified: lld/trunk/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h?rev=190585&r1=190584&r2=190585&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h (original)
+++ lld/trunk/lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.h Wed Sep 11 23:42:31 2013
@@ -31,18 +31,16 @@ namespace {
 // The symbol __ImageBase is a linker generated symbol. No standard library
 // files define it, but the linker is expected to prepare it as if it was read
 // from a file. The content of the atom is a 4-byte integer equal to the image
-// base address.
-//
-// Note that because the name is prefixed by an underscore on x86 Win32, the
-// actual symbol name becomes ___ImageBase (with three underscores). On other
-// architectures names are not mangled with an underscore. We need to handle
-// name mangling correctly when porting LLD Windows code to them.
+// base address. Note that because the name is prefixed by an underscore on x86
+// Win32, the actual symbol name will be ___ImageBase (three underscores).
 class ImageBaseAtom : public COFFLinkerInternalAtom {
 public:
-  ImageBaseAtom(const File &file, uint32_t imageBase)
-      : COFFLinkerInternalAtom(file, assembleRawContent(imageBase)) {}
+  ImageBaseAtom(const PECOFFLinkingContext &context, const File &file,
+                uint32_t imageBase)
+      : COFFLinkerInternalAtom(file, assembleRawContent(imageBase)),
+        _name(context.decorateSymbol("__ImageBase")) {}
 
-  virtual StringRef name() const { return "___ImageBase"; }
+  virtual StringRef name() const { return _name; }
   virtual uint64_t ordinal() const { return 0; }
   virtual ContentType contentType() const { return typeData; }
   virtual ContentPermissions permissions() const { return permRW_; }
@@ -54,6 +52,8 @@ private:
     *(reinterpret_cast<uint32_t *>(&data[0])) = imageBase;
     return data;
   }
+
+  StringRef _name;
 };
 
 // The file to wrap ImageBaseAtom. This is the only member file of
@@ -62,10 +62,14 @@ class MemberFile : public SimpleFile {
 public:
   MemberFile(const PECOFFLinkingContext &context)
       : SimpleFile(context, "Member of the Linker Internal File"),
-        _atom(*this, context.getBaseAddress()) {
+        _atom(context, *this, context.getBaseAddress()) {
     addAtom(_atom);
   };
 
+  bool contains(StringRef name) const {
+    return _atom.name() == name;
+  }
+
 private:
   ImageBaseAtom _atom;
 };
@@ -86,7 +90,7 @@ public:
         _memberFile(context) {};
 
   virtual const File *find(StringRef name, bool dataSymbolOnly) const {
-    if (name == "___ImageBase")
+    if (_memberFile.contains(name))
       return &_memberFile;
     return nullptr;
   }