Add support for -L and -l command line switches.

Patch by Igor Kudrin!

llvm-svn: 248708

lld/ELF/Config.h

@@ -19,6 +19,7 @@ struct Configuration {
   llvm::StringRef OutputFile;
   llvm::StringRef DynamicLinker;
   std::string RPath;
+  std::vector<llvm::StringRef> InputSearchPaths;
   bool Shared = false;
   bool DiscardAll = false;
   bool DiscardLocals = false;

lld/ELF/Driver.cpp

@@ -16,6 +16,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
 
 using namespace llvm;
 
@@ -59,6 +60,28 @@ static std::unique_ptr<InputFile> createFile(MemoryBufferRef MB) {
   return createELFFile<ObjectFile>(MB);
 }
 
+// Searches a given library from input search paths, which are filled
+// from -L command line switches. Returns a path to an existent library file.
+static std::string searchLibrary(StringRef Path) {
+  std::vector<std::string> Names;
+  if (Path[0] == ':') {
+    Names.push_back(Path.drop_front().str());
+  } else {
+    Names.push_back((Twine("lib") + Path + ".so").str());
+    Names.push_back((Twine("lib") + Path + ".a").str());
+  }
+  SmallString<128> FullPath;
+  for (StringRef Dir : Config->InputSearchPaths) {
+    for (const std::string &Name : Names) {
+      FullPath = Dir;
+      sys::path::append(FullPath, Name);
+      if (sys::fs::exists(FullPath.str()))
+        return FullPath.str().str();
+    }
+  }
+  error(Twine("Unable to find library -l") + Path);
+}
+
 void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   // Parse command line options.
   opt::InputArgList Args = Parser.parse(ArgsArr);
@@ -79,6 +102,9 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   if (!RPaths.empty())
     Config->RPath = llvm::join(RPaths.begin(), RPaths.end(), ":");
 
+  for (auto *Arg : Args.filtered(OPT_L))
+    Config->InputSearchPaths.push_back(Arg->getValue());
+
   if (Args.hasArg(OPT_shared))
     Config->Shared = true;
 
@@ -100,8 +126,12 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   // Create a list of input files.
   std::vector<MemoryBufferRef> Inputs;
 
-  for (auto *Arg : Args.filtered(OPT_INPUT)) {
+  for (auto *Arg : Args.filtered(OPT_l, OPT_INPUT)) {
     StringRef Path = Arg->getValue();
+    if (Arg->getOption().getID() == OPT_l) {
+      Inputs.push_back(openFile(searchLibrary(Path)));
+      continue;
+    }
     Inputs.push_back(openFile(Path));
   }
 

lld/ELF/Options.td

@@ -37,3 +37,15 @@ def discard_none : Flag<["-"], "discard-none">,
 
 def export_dynamic : Flag<["--"], "export-dynamic">,
      HelpText<"Put symbols in the dynamic symbol table">;
+
+def L : Joined<["-"], "L">, MetaVarName<"<dir>">,
+     HelpText<"Directory to search for libraries">;
+
+def alias_L : Joined<["--"], "library-path=">,
+     Alias<L>;
+
+def l : Joined<["-"], "l">, MetaVarName<"<libName>">,
+     HelpText<"Root name of library to use">;
+
+def alias_l : Joined<["--"], "library=">,
+     Alias<l>;

lld/test/elf2/Inputs/libsearch-dyn.s

@@ -0,0 +1,3 @@
+.globl _bar,_dynamic;
+_bar:
+_dynamic:

lld/test/elf2/Inputs/libsearch-st.s

@@ -0,0 +1,3 @@
+.globl _bar,_static;
+_bar:
+_static:

lld/test/elf2/libsearch.s

@@ -0,0 +1,46 @@
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
+// RUN:     %p/Inputs/libsearch-dyn.s -o %tdyn.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
+// RUN:     %p/Inputs/libsearch-st.s -o %tst.o
+// RUN: lld -flavor gnu2 -shared %tdyn.o -o %T/libls.so
+// RUN: rm -f %T/libls.a
+// RUN: llvm-ar rcs %T/libls.a %tst.o
+// REQUIRES: x86
+
+// Should not link because of undefined symbol _bar
+// RUN: not lld -flavor gnu2 -o %t3 %t.o 2>&1 \
+// RUN:     | FileCheck --check-prefix=UNDEFINED %s
+// UNDEFINED: undefined symbol: _bar
+
+// Should fail if cannot find specified library (without -L switch)
+// RUN: not lld -flavor gnu2 -o %t3 %t.o -lls 2>&1 \
+// RUN:     | FileCheck --check-prefix=NOLIB %s
+// NOLIB: Unable to find library -lls
+
+// Should use explicitly specified static library
+// RUN: lld -flavor gnu2 -o %t3 %t.o -L%T -l:libls.a
+// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=STATIC %s
+// STATIC: Symbols [
+// STATIC: Name: _static
+// STATIC: ]
+
+// Should use explicitly specified dynamic library
+// RUN: lld -flavor gnu2 -o %t3 %t.o -L%T -l:libls.so
+// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=DYNAMIC %s
+// DYNAMIC: Symbols [
+// DYNAMIC-NOT: Name: _static
+// DYNAMIC: ]
+
+// Should prefer dynamic to static
+// RUN: lld -flavor gnu2 -o %t3 %t.o -L%T -lls
+// RUN: llvm-readobj --symbols %t3 | FileCheck --check-prefix=DYNAMIC %s
+
+// -L can be placed after -l
+// RUN: lld -flavor gnu2 -o %t3 %t.o -lls -L%T
+
+// Check long forms as well
+// RUN: lld -flavor gnu2 -o %t3 %t.o --library-path=%T --library=ls
+
+.globl _start,_bar;
+_start: