[ELF] Implement parsing `-l` prefixed items in the `GROUP` linker script command.

There are two forms of `-l` prefixed expression:

* -l<libname>
* -l:<filename>

In the first case a linker should construct a full library name
`lib + libname + .[so|a]` and search this library as usual. In the second case
a linker should use the `<filename>` as is and search this file through library
search directories.

The patch reviewed by Shankar Easwaran.

llvm-svn: 213077

1 files changed, 7 insertions, 2 deletions

diff --git a/lld/lib/ReaderWriter/ELF/ELFLinkingContext.cpp b/lld/lib/ReaderWriter/ELF/ELFLinkingContext.cpp
index 23036bca9f9..fe33d403d10 100644
--- a/lld/lib/ReaderWriter/ELF/ELFLinkingContext.cpp
+++ b/lld/lib/ReaderWriter/ELF/ELFLinkingContext.cpp
@@ -163,18 +163,23 @@ static void buildSearchPath(SmallString<128> &path, StringRef dir,
 }
 
 ErrorOr<StringRef> ELFLinkingContext::searchLibrary(StringRef libName) const {
+  bool hasColonPrefix = libName[0] == ':';
+  Twine soName =
+      hasColonPrefix ? libName.drop_front() : Twine("lib", libName) + ".so";
+  Twine archiveName =
+      hasColonPrefix ? libName.drop_front() : Twine("lib", libName) + ".a";
   SmallString<128> path;
   for (StringRef dir : _inputSearchPaths) {
     // Search for dynamic library
     if (!_isStaticExecutable) {
       buildSearchPath(path, dir, _sysrootPath);
-      llvm::sys::path::append(path, Twine("lib") + libName + ".so");
+      llvm::sys::path::append(path, soName);
       if (llvm::sys::fs::exists(path.str()))
         return StringRef(*new (_allocator) std::string(path.str()));
     }
     // Search for static libraries too
     buildSearchPath(path, dir, _sysrootPath);
-    llvm::sys::path::append(path, Twine("lib") + libName + ".a");
+    llvm::sys::path::append(path, archiveName);
     if (llvm::sys::fs::exists(path.str()))
       return StringRef(*new (_allocator) std::string(path.str()));
   }