r248932 - [DarwinDriver] Use -lto_library to specify the path for libLTO.dylib

[Bruno Cardoso Lopes via cfe-commits]

Author: bruno
Date: Wed Sep 30 14:55:07 2015
New Revision: 248932

URL: http://llvm.org/viewvc/llvm-project?rev=248932&view=rev
Log:
[DarwinDriver] Use -lto_library to specify the path for libLTO.dylib

Usually, when using LTO with a clang installation newer than the
system's 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 commit 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.

Differential Revision: http://reviews.llvm.org/D13117

rdar://problem/7363476

Modified:
    cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
    cfe/trunk/lib/Driver/Tools.cpp
    cfe/trunk/test/Driver/darwin-ld.c

Modified: cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td?rev=248932&r1=248931&r2=248932&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td Wed Sep 30 14:55:07 2015
@@ -117,6 +117,7 @@ def err_drv_optimization_remark_pattern
 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">,

Modified: cfe/trunk/lib/Driver/Tools.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=248932&r1=248931&r2=248932&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/Tools.cpp (original)
+++ cfe/trunk/lib/Driver/Tools.cpp Wed Sep 30 14:55:07 2015
@@ -6551,15 +6551,34 @@ void darwin::Linker::AddLinkArgs(Compila
                    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.

Modified: cfe/trunk/test/Driver/darwin-ld.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/darwin-ld.c?rev=248932&r1=248931&r2=248932&view=diff
==============================================================================
--- cfe/trunk/test/Driver/darwin-ld.c (original)
+++ cfe/trunk/test/Driver/darwin-ld.c Wed Sep 30 14:55:07 2015
@@ -110,6 +110,21 @@
 // LINK_OBJECT_LTO_PATH: {{ld(.exe)?"}}
 // LINK_OBJECT_LTO_PATH: "-object_path_lto"
 
+// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN:   -mlinker-version=133 -flto 2> %t.log
+// RUN: cat %t.log
+// RUN: FileCheck -check-prefix=LINK_LTOLIB_PATH %s < %t.log
+//
+// LINK_LTOLIB_PATH: {{ld(.exe)?"}}
+// LINK_LTOLIB_PATH: "-lto_library"
+
+// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN:   -ccc-install-dir %S/dummytestdir -mlinker-version=133 -flto 2> %t.log
+// RUN: cat %t.log
+// RUN: FileCheck -check-prefix=LINK_LTOLIB_PATH_WRN %s < %t.log
+//
+// LINK_LTOLIB_PATH_WRN: warning: libLTO.dylib relative to clang installed dir not found; using 'ld' default search path instead
+
 // RUN: %clang -target x86_64-apple-darwin10 -### %t.o \
 // RUN:   -force_load a -force_load b 2> %t.log
 // RUN: cat %t.log