Driver/Darwin: When invoking the linker, automatically pass -object_p…

…ath_lto so

that the linker has a place to put the temporary object file and can leave it
around (for the driver to clean up). This is important so that the object file
references in the debug info are preserved for possible use by dsymutil.
 - <rdar://problem/8294279> executable has no debug symbols when compiled with LTO

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133543 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Driver/Tools.cpp

@@ -2907,6 +2907,17 @@ void darwin::Link::AddLinkArgs(Compilation &C,
       CmdArgs.push_back("-demangle");
   }
 
+  // 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] >= 100 && D.IsUsingLTO(Args)) {
+    const char *TmpPath = C.getArgs().MakeArgString(
+      D.GetTemporaryPath(types::getTypeTempSuffix(types::TY_Object)));
+    C.addTempFile(TmpPath);
+    CmdArgs.push_back("-object_path_lto");
+    CmdArgs.push_back(TmpPath);
+  }
+
   // Derived from the "link" spec.
   Args.AddAllArgs(CmdArgs, options::OPT_static);
   if (!Args.hasArg(options::OPT_static))

test/Driver/darwin-ld.c

@@ -92,3 +92,11 @@
 // LINK_OLDER_NODEMANGLE: {{ld(.exe)?"}}
 // LINK_OLDER_NODEMANGLE-NOT: "-demangle"
 // LINK_OLDER_NODEMANGLE: "-lSystem"
+
+// RUN: %clang -ccc-host-triple x86_64-apple-darwin10 -### %t.o \
+// RUN:   -mlinker-version=101 -flto 2> %t.log
+// RUN: cat %t.log
+// RUN: FileCheck -check-prefix=LINK_OBJECT_LTO_PATH %s < %t.log
+//
+// LINK_OBJECT_LTO_PATH: {{ld(.exe)?"}}
+// LINK_OBJECT_LTO_PATH: "-object_path_lto"