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[Linker] Drop support for IR-level extended linking support (archives, etc.).

Browse Source 
- This code is dead, and the "right" way to get this support is to use the
   platform-specific linker-integrated LTO mechanisms, or the forthcoming LLVM
   linker.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172749 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar 2013-01-17 19:52:25 +00:00
parent d69a43a88d
commit 634bd8512a
6 changed files with 3 additions and 577 deletions
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4
docs/ReleaseNotes.rst
View File

@ -500,7 +500,9 @@ LowerInvoke already use the new interface.
The ``TargetData`` structure has been renamed to ``DataLayout`` and moved to
``VMCore`` to remove a dependency on ``Target``.
#. ...
#. The IR-level extended linker APIs (for example, to link bitcode files out of
archives) have been removed. Any existing clients of these features should
move to using a linker with integrated LTO support.
Tools Changes
-------------

94
include/llvm/Linker.h
View File

@ -153,93 +153,6 @@ class Linker {
/// @brief Set control flags.
void setFlags(unsigned flags) { Flags = flags; }
/// This method is the main interface to the linker. It can be used to
/// link a set of linkage items into a module. A linkage item is either a
/// file name with fully qualified path, or a library for which the Linker's
/// LibraryPath will be utilized to locate the library. The bool value in
/// the LinkItemKind should be set to true for libraries. This function
/// allows linking to preserve the order of specification associated with
/// the command line, or for other purposes. Each item will be linked in
/// turn as it occurs in \p Items.
/// @returns true if an error occurred, false otherwise
/// @see LinkItemKind
/// @see getLastError
bool LinkInItems (
const ItemList& Items, ///< Set of libraries/files to link in
ItemList& NativeItems ///< Output list of native files/libs
);
/// This function links the bitcode \p Files into the composite module.
/// Note that this does not do any linking of unresolved symbols. The \p
/// Files are all completely linked into \p HeadModule regardless of
/// unresolved symbols. This function just loads each bitcode file and
/// calls LinkInModule on them.
/// @returns true if an error occurs, false otherwise
/// @see getLastError
/// @brief Link in multiple files.
bool LinkInFiles (
const std::vector<sys::Path> & Files ///< Files to link in
);
/// This function links a single bitcode file, \p File, into the composite
/// module. Note that this does not attempt to resolve symbols. This method
/// just loads the bitcode file and calls LinkInModule on it. If an error
/// occurs, the Linker's error string is set.
/// @returns true if an error occurs, false otherwise
/// @see getLastError
/// @brief Link in a single file.
bool LinkInFile(
const sys::Path& File, ///< File to link in.
bool &is_native ///< Indicates if the file is native object file
);
/// This function provides a way to selectively link in a set of modules,
/// found in libraries, based on the unresolved symbols in the composite
/// module. Each item in \p Libraries should be the base name of a library,
/// as if given with the -l option of a linker tool. The Linker's LibPaths
/// are searched for the \p Libraries and any found will be linked in with
/// LinkInArchive. If an error occurs, the Linker's error string is set.
/// @see LinkInArchive
/// @see getLastError
/// @returns true if an error occurs, false otherwise
/// @brief Link libraries into the module
bool LinkInLibraries (
const std::vector<std::string> & Libraries ///< Libraries to link in
);
/// This function provides a way to selectively link in a set of modules,
/// found in one library, based on the unresolved symbols in the composite
/// module.The \p Library should be the base name of a library, as if given
/// with the -l option of a linker tool. The Linker's LibPaths are searched
/// for the \p Library and if found, it will be linked in with via the
/// LinkInArchive method. If an error occurs, the Linker's error string is
/// set.
/// @see LinkInArchive
/// @see getLastError
/// @returns true if an error occurs, false otherwise
/// @brief Link one library into the module
bool LinkInLibrary (
StringRef Library, ///< The library to link in
bool& is_native ///< Indicates if lib a native library
);
/// This function links one bitcode archive, \p Filename, into the module.
/// The archive is searched to resolve outstanding symbols. Any modules in
/// the archive that resolve outstanding symbols will be linked in. The
/// library is searched repeatedly until no more modules that resolve
/// symbols can be found. If an error occurs, the error string is set.
/// To speed up this function, ensure the archive has been processed
/// llvm-ranlib or the S option was given to llvm-ar when the archive was
/// created. These tools add a symbol table to the archive which makes the
/// search for undefined symbols much faster.
/// @see getLastError
/// @returns true if an error occurs, otherwise false.
/// @brief Link in one archive.
bool LinkInArchive(
const sys::Path& Filename, ///< Filename of the archive to link
bool& is_native ///< Indicates if archive is a native archive
);
/// This method links the \p Src module into the Linker's Composite module
/// by calling LinkModules. All the other LinkIn* methods eventually
/// result in calling this method to link a Module into the Linker's
@ -268,13 +181,6 @@ class Linker {
static bool LinkModules(Module* Dest, Module* Src, unsigned Mode,
std::string* ErrorMsg);
/// This function looks through the Linker's LibPaths to find a library with
/// the name \p Filename. If the library cannot be found, the returned path
/// will be empty (i.e. sys::Path::isEmpty() will return true).
/// @returns A sys::Path to the found library
/// @brief Find a library from its short name.
sys::Path FindLib(StringRef Filename);
/// @}
/// @name Implementation
/// @{

2
lib/Linker/CMakeLists.txt
View File

@ -1,6 +1,4 @@
add_llvm_library(LLVMLinker
LinkArchives.cpp
LinkItems.cpp
LinkModules.cpp
Linker.cpp
)

197
lib/Linker/LinkArchives.cpp
View File

@ -1,197 +0,0 @@
//===- lib/Linker/LinkArchives.cpp - Link LLVM objects and libraries ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains routines to handle linking together LLVM bitcode files,
// and to handle annoying things like static libraries.
//
//===----------------------------------------------------------------------===//
#include "llvm/Linker.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/Bitcode/Archive.h"
#include "llvm/IR/Module.h"
#include <memory>
#include <set>
using namespace llvm;
/// GetAllUndefinedSymbols - calculates the set of undefined symbols that still
/// exist in an LLVM module. This is a bit tricky because there may be two
/// symbols with the same name but different LLVM types that will be resolved to
/// each other but aren't currently (thus we need to treat it as resolved).
///
/// Inputs:
/// M - The module in which to find undefined symbols.
///
/// Outputs:
/// UndefinedSymbols - A set of C++ strings containing the name of all
/// undefined symbols.
///
static void
GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols) {
std::set<std::string> DefinedSymbols;
UndefinedSymbols.clear();
// If the program doesn't define a main, try pulling one in from a .a file.
// This is needed for programs where the main function is defined in an
// archive, such f2c'd programs.
Function *Main = M->getFunction("main");
if (Main == 0 || Main->isDeclaration())
UndefinedSymbols.insert("main");
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (I->hasName()) {
if (I->isDeclaration())
UndefinedSymbols.insert(I->getName());
else if (!I->hasLocalLinkage()) {
assert(!I->hasDLLImportLinkage()
&& "Found dllimported non-external symbol!");
DefinedSymbols.insert(I->getName());
}
}
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
I != E; ++I)
if (I->hasName()) {
if (I->isDeclaration())
UndefinedSymbols.insert(I->getName());
else if (!I->hasLocalLinkage()) {
assert(!I->hasDLLImportLinkage()
&& "Found dllimported non-external symbol!");
DefinedSymbols.insert(I->getName());
}
}
for (Module::alias_iterator I = M->alias_begin(), E = M->alias_end();
I != E; ++I)
if (I->hasName())
DefinedSymbols.insert(I->getName());
// Prune out any defined symbols from the undefined symbols set...
for (std::set<std::string>::iterator I = UndefinedSymbols.begin();
I != UndefinedSymbols.end(); )
if (DefinedSymbols.count(*I))
UndefinedSymbols.erase(I++); // This symbol really is defined!
else
++I; // Keep this symbol in the undefined symbols list
}
/// LinkInArchive - opens an archive library and link in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
/// Filename - The pathname of the archive.
///
/// Return Value:
/// TRUE - An error occurred.
/// FALSE - No errors.
bool
Linker::LinkInArchive(const sys::Path &Filename, bool &is_native) {
// Make sure this is an archive file we're dealing with
if (!Filename.isArchive())
return error("File '" + Filename.str() + "' is not an archive.");
// Open the archive file
verbose("Linking archive file '" + Filename.str() + "'");
// Find all of the symbols currently undefined in the bitcode program.
// If all the symbols are defined, the program is complete, and there is
// no reason to link in any archive files.
std::set<std::string> UndefinedSymbols;
GetAllUndefinedSymbols(Composite, UndefinedSymbols);
if (UndefinedSymbols.empty()) {
verbose("No symbols undefined, skipping library '" + Filename.str() + "'");
return false; // No need to link anything in!
}
std::string ErrMsg;
std::auto_ptr<Archive> AutoArch (
Archive::OpenAndLoadSymbols(Filename, Context, &ErrMsg));
Archive* arch = AutoArch.get();
if (!arch)
return error("Cannot read archive '" + Filename.str() +
"': " + ErrMsg);
if (!arch->isBitcodeArchive()) {
is_native = true;
return false;
}
is_native = false;
// Save a set of symbols that are not defined by the archive. Since we're
// entering a loop, there's no point searching for these multiple times. This
// variable is used to "set_subtract" from the set of undefined symbols.
std::set<std::string> NotDefinedByArchive;
// Save the current set of undefined symbols, because we may have to make
// multiple passes over the archive:
std::set<std::string> CurrentlyUndefinedSymbols;
do {
CurrentlyUndefinedSymbols = UndefinedSymbols;
// Find the modules we need to link into the target module. Note that arch
// keeps ownership of these modules and may return the same Module* from a
// subsequent call.
SmallVector<Module*, 16> Modules;
if (!arch->findModulesDefiningSymbols(UndefinedSymbols, Modules, &ErrMsg))
return error("Cannot find symbols in '" + Filename.str() +
"': " + ErrMsg);
// If we didn't find any more modules to link this time, we are done
// searching this archive.
if (Modules.empty())
break;
// Any symbols remaining in UndefinedSymbols after
// findModulesDefiningSymbols are ones that the archive does not define. So
// we add them to the NotDefinedByArchive variable now.
NotDefinedByArchive.insert(UndefinedSymbols.begin(),
UndefinedSymbols.end());
// Loop over all the Modules that we got back from the archive
for (SmallVectorImpl<Module*>::iterator I=Modules.begin(), E=Modules.end();
I != E; ++I) {
// Get the module we must link in.
std::string moduleErrorMsg;
Module* aModule = *I;
if (aModule != NULL) {
if (aModule->MaterializeAll(&moduleErrorMsg))
return error("Could not load a module: " + moduleErrorMsg);
verbose(" Linking in module: " + aModule->getModuleIdentifier());
// Link it in
if (LinkInModule(aModule, &moduleErrorMsg))
return error("Cannot link in module '" +
aModule->getModuleIdentifier() + "': " + moduleErrorMsg);
}
}
// Get the undefined symbols from the aggregate module. This recomputes the
// symbols we still need after the new modules have been linked in.
GetAllUndefinedSymbols(Composite, UndefinedSymbols);
// At this point we have two sets of undefined symbols: UndefinedSymbols
// which holds the undefined symbols from all the modules, and
// NotDefinedByArchive which holds symbols we know the archive doesn't
// define. There's no point searching for symbols that we won't find in the
// archive so we subtract these sets.
set_subtract(UndefinedSymbols, NotDefinedByArchive);
// If there's no symbols left, no point in continuing to search the
// archive.
if (UndefinedSymbols.empty())
break;
} while (CurrentlyUndefinedSymbols != UndefinedSymbols);
return false;
}

216
lib/Linker/LinkItems.cpp
View File

@ -1,216 +0,0 @@
//===- lib/Linker/LinkItems.cpp - Link LLVM objects and libraries ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains routines to handle linking together LLVM bitcode files,
// and to handle annoying things like static libraries.
//
//===----------------------------------------------------------------------===//
#include "llvm/Linker.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/system_error.h"
using namespace llvm;
// LinkItems - This function is the main entry point into linking. It takes a
// list of LinkItem which indicates the order the files should be linked and
// how each file should be treated (plain file or with library search). The
// function only links bitcode and produces a result list of items that are
// native objects.
bool
Linker::LinkInItems(const ItemList& Items, ItemList& NativeItems) {
// Clear the NativeItems just in case
NativeItems.clear();
// For each linkage item ...
for (ItemList::const_iterator I = Items.begin(), E = Items.end();
I != E; ++I) {
if (I->second) {
// Link in the library suggested.
bool is_native = false;
if (LinkInLibrary(I->first, is_native))
return true;
if (is_native)
NativeItems.push_back(*I);
} else {
// Link in the file suggested
bool is_native = false;
if (LinkInFile(sys::Path(I->first), is_native))
return true;
if (is_native)
NativeItems.push_back(*I);
}
}
return false;
}
/// LinkInLibrary - links one library into the HeadModule.
///
bool Linker::LinkInLibrary(StringRef Lib, bool& is_native) {
is_native = false;
// Determine where this library lives.
sys::Path Pathname = FindLib(Lib);
if (Pathname.isEmpty())
return error("Cannot find library '" + Lib.str() + "'");
// If its an archive, try to link it in
std::string Magic;
Pathname.getMagicNumber(Magic, 64);
switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
default: llvm_unreachable("Bad file type identification");
case sys::Unknown_FileType:
return warning("Supposed library '" + Lib.str() + "' isn't a library.");
case sys::Bitcode_FileType:
// LLVM ".so" file.
if (LinkInFile(Pathname, is_native))
return true;
break;
case sys::Archive_FileType:
if (LinkInArchive(Pathname, is_native))
return error("Cannot link archive '" + Pathname.str() + "'");
break;
case sys::ELF_Relocatable_FileType:
case sys::ELF_SharedObject_FileType:
case sys::Mach_O_Object_FileType:
case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
case sys::COFF_FileType:
is_native = true;
break;
}
return false;
}
/// LinkLibraries - takes the specified library files and links them into the
/// main bitcode object file.
///
/// Inputs:
/// Libraries - The list of libraries to link into the module.
///
/// Return value:
/// FALSE - No error.
/// TRUE - Error.
///
bool Linker::LinkInLibraries(const std::vector<std::string> &Libraries) {
// Process the set of libraries we've been provided.
bool is_native = false;
for (unsigned i = 0; i < Libraries.size(); ++i)
if (LinkInLibrary(Libraries[i], is_native))
return true;
return false;
}
/// LinkInFile - opens a bitcode file and links in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
/// File - The pathname of the bitcode file.
///
/// Outputs:
/// ErrorMessage - A C++ string detailing what error occurred, if any.
///
/// Return Value:
/// TRUE - An error occurred.
/// FALSE - No errors.
///
bool Linker::LinkInFile(const sys::Path &File, bool &is_native) {
is_native = false;
// Check for a file of name "-", which means "read standard input"
if (File.str() == "-") {
std::auto_ptr<Module> M;
OwningPtr<MemoryBuffer> Buffer;
error_code ec;
if (!(ec = MemoryBuffer::getSTDIN(Buffer))) {
if (!Buffer->getBufferSize()) {
Error = "standard input is empty";
} else {
M.reset(ParseBitcodeFile(Buffer.get(), Context, &Error));
if (M.get())
if (!LinkInModule(M.get(), &Error))
return false;
}
}
return error("Cannot link stdin: " + ec.message());
}
// Determine what variety of file it is.
std::string Magic;
if (!File.getMagicNumber(Magic, 64))
return error("Cannot find linker input '" + File.str() + "'");
switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
default: llvm_unreachable("Bad file type identification");
case sys::Unknown_FileType:
return warning("Ignoring file '" + File.str() +
"' because does not contain bitcode.");
case sys::Archive_FileType:
// A user may specify an ar archive without -l, perhaps because it
// is not installed as a library. Detect that and link the archive.
if (LinkInArchive(File, is_native))
return true;
break;
case sys::Bitcode_FileType: {
verbose("Linking bitcode file '" + File.str() + "'");
std::auto_ptr<Module> M(LoadObject(File));
if (M.get() == 0)
return error("Cannot load file '" + File.str() + "': " + Error);
if (LinkInModule(M.get(), &Error))
return error("Cannot link file '" + File.str() + "': " + Error);
verbose("Linked in file '" + File.str() + "'");
break;
}
case sys::ELF_Relocatable_FileType:
case sys::ELF_SharedObject_FileType:
case sys::Mach_O_Object_FileType:
case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
case sys::COFF_FileType:
is_native = true;
break;
}
return false;
}
/// LinkFiles - takes a module and a list of files and links them all together.
/// It locates the file either in the current directory, as its absolute
/// or relative pathname, or as a file somewhere in LLVM_LIB_SEARCH_PATH.
///
/// Inputs:
/// Files - A vector of sys::Path indicating the LLVM bitcode filenames
/// to be linked. The names can refer to a mixture of pure LLVM
/// bitcode files and archive (ar) formatted files.
///
/// Return value:
/// FALSE - No errors.
/// TRUE - Some error occurred.
///
bool Linker::LinkInFiles(const std::vector<sys::Path> &Files) {
bool is_native;
for (unsigned i = 0; i < Files.size(); ++i)
if (LinkInFile(Files[i], is_native))
return true;
return false;
}

67
lib/Linker/Linker.cpp
View File

@ -112,70 +112,3 @@ Linker::LoadObject(const sys::Path &FN) {
Error += ": " + ParseErrorMessage;
return std::auto_ptr<Module>();
}
// IsLibrary - Determine if "Name" is a library in "Directory". Return
// a non-empty sys::Path if its found, an empty one otherwise.
static inline sys::Path IsLibrary(StringRef Name,
const sys::Path &Directory) {
sys::Path FullPath(Directory);
// Try the libX.a form
FullPath.appendComponent(("lib" + Name).str());
FullPath.appendSuffix("a");
if (FullPath.isArchive())
return FullPath;
// Try the libX.bca form
FullPath.eraseSuffix();
FullPath.appendSuffix("bca");
if (FullPath.isArchive())
return FullPath;
// Try the libX.so (or .dylib) form
FullPath.eraseSuffix();
FullPath.appendSuffix(sys::Path::GetDLLSuffix());
if (FullPath.isDynamicLibrary()) // Native shared library?
return FullPath;
if (FullPath.isBitcodeFile()) // .so file containing bitcode?
return FullPath;
// Try libX form, to make it possible to add dependency on the
// specific version of .so, like liblzma.so.1.0.0
FullPath.eraseSuffix();
if (FullPath.isDynamicLibrary()) // Native shared library?
return FullPath;
if (FullPath.isBitcodeFile()) // .so file containing bitcode?
return FullPath;
// Not found .. fall through
// Indicate that the library was not found in the directory.
FullPath.clear();
return FullPath;
}
/// FindLib - Try to convert Filename into the name of a file that we can open,
/// if it does not already name a file we can open, by first trying to open
/// Filename, then libFilename.[suffix] for each of a set of several common
/// library suffixes, in each of the directories in LibPaths. Returns an empty
/// Path if no matching file can be found.
///
sys::Path
Linker::FindLib(StringRef Filename) {
// Determine if the pathname can be found as it stands.
sys::Path FilePath(Filename);
if (FilePath.canRead() &&
(FilePath.isArchive() || FilePath.isDynamicLibrary()))
return FilePath;
// Iterate over the directories in Paths to see if we can find the library
// there.
for (unsigned Index = 0; Index != LibPaths.size(); ++Index) {
sys::Path Directory(LibPaths[Index]);
sys::Path FullPath = IsLibrary(Filename, Directory);
if (!FullPath.isEmpty())
return FullPath;
}
return sys::Path();
}