[PATCH] D13117: [DarwinDriver] Use -lto_library to specify the path for libLTO.dylib

[Bruno Cardoso Lopes via cfe-commits]

bruno created this revision.
bruno added a reviewer: dexonsmith.
bruno added subscribers: cfe-commits, kledzik, bob.wilson.
bruno set the repository for this revision to rL LLVM.

Usually, when using LTO with a clang installation newer than the system one, there's a libLTO.dylib version mismatch and LTO fails. One solution to this is to make ld point to the right libLTO.dylib by changing DYLD_LIBRARY_PATH.

However, ld64 supports specifying the complete path to the desired libLTO.dylib through the -lto_library option. This patch adds support for the clang driver to use this option whenever it's capable of finding a libLTO.dylib in clang's installed library directory. This way, we don't need to rely on DYLD_LIBRARY_PATH nor get caught by version mismatches.

Repository:
  rL LLVM

http://reviews.llvm.org/D13117

Files:
  include/clang/Basic/DiagnosticDriverKinds.td
  lib/Driver/Tools.cpp

Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -6501,15 +6501,34 @@
                    options::OPT_fno_application_extension, false))
     CmdArgs.push_back("-application_extension");
 
-  // If we are using LTO, then automatically create a temporary file path for
-  // the linker to use, so that it's lifetime will extend past a possible
-  // dsymutil step.
-  if (Version[0] >= 116 && D.IsUsingLTO(Args) && NeedsTempPath(Inputs)) {
-    const char *TmpPath = C.getArgs().MakeArgString(
-        D.GetTemporaryPath("cc", types::getTypeTempSuffix(types::TY_Object)));
-    C.addTempFile(TmpPath);
-    CmdArgs.push_back("-object_path_lto");
-    CmdArgs.push_back(TmpPath);
+  if (D.IsUsingLTO(Args)) {
+    // If we are using LTO, then automatically create a temporary file path for
+    // the linker to use, so that it's lifetime will extend past a possible
+    // dsymutil step.
+    if (Version[0] >= 116 && NeedsTempPath(Inputs)) {
+      const char *TmpPath = C.getArgs().MakeArgString(
+          D.GetTemporaryPath("cc", types::getTypeTempSuffix(types::TY_Object)));
+      C.addTempFile(TmpPath);
+      CmdArgs.push_back("-object_path_lto");
+      CmdArgs.push_back(TmpPath);
+    }
+
+    // Use -lto_library option to specify the libLTO.dylib path. Try to find
+    // it in clang installed libraries. If not found, the option is not used
+    // and 'ld' will use its default mechanism to search for libLTO.dylib.
+    if (Version[0] >= 133) {
+      // Search for libLTO in <InstalledDir>/../lib/libLTO.dylib
+      StringRef P = llvm::sys::path::parent_path(D.getInstalledDir());
+      SmallString<128> LibLTOPath(P);
+      llvm::sys::path::append(LibLTOPath, "lib");
+      llvm::sys::path::append(LibLTOPath, "libLTO.dylib");
+      if (llvm::sys::fs::exists(LibLTOPath)) {
+        CmdArgs.push_back("-lto_library");
+        CmdArgs.push_back(C.getArgs().MakeArgString(LibLTOPath));
+      } else {
+        D.Diag(diag::warn_lto_libpath);
+      }
+    }
   }
 
   // Derived from the "link" spec.
Index: include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- include/clang/Basic/DiagnosticDriverKinds.td
+++ include/clang/Basic/DiagnosticDriverKinds.td
@@ -117,6 +117,7 @@
 def err_drv_no_neon_modifier : Error<"[no]neon is not accepted as modifier, please use [no]simd instead">;
 
 def warn_O4_is_O3 : Warning<"-O4 is equivalent to -O3">, InGroup<Deprecated>;
+def warn_lto_libpath : Warning<"libLTO.dylib relative to clang installed dir not found; using 'ld' default search path instead">;
 def warn_drv_optimization_value : Warning<"optimization level '%0' is not supported; using '%1%2' instead">,
   InGroup<InvalidCommandLineArgument>;
 def warn_ignored_gcc_optimization : Warning<"optimization flag '%0' is not supported">,


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D13117.35547.patch
Type: text/x-patch
Size: 2926 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20150923/78faa5f3/attachment-0001.bin>