7 files changed, 52 insertions, 1 deletions
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 6a75b7c2c15..9855c7d54c1 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -641,7 +641,7 @@ def flat__namespace : Flag<["-"], "flat_namespace">;
 def flax_vector_conversions : Flag<["-"], "flax-vector-conversions">, Group<f_Group>;
 def flimited_precision_EQ : Joined<["-"], "flimited-precision=">, Group<f_Group>;
 def flto_EQ : Joined<["-"], "flto=">, Group<clang_ignored_gcc_optimization_f_Group>;
-def flto : Flag<["-"], "flto">, Group<f_Group>;
+def flto : Flag<["-"], "flto">, Flags<[CC1Option]>, Group<f_Group>;
 def fno_lto : Flag<["-"], "fno-lto">, Group<f_Group>;
 def fmacro_backtrace_limit_EQ : Joined<["-"], "fmacro-backtrace-limit=">,
                                 Group<f_Group>, Flags<[DriverOption, CoreOption]>;
diff --git a/clang/include/clang/Frontend/CodeGenOptions.def b/clang/include/clang/Frontend/CodeGenOptions.def
index d34cf0cad1c..d52496d0951 100644
--- a/clang/include/clang/Frontend/CodeGenOptions.def
+++ b/clang/include/clang/Frontend/CodeGenOptions.def
@@ -67,6 +67,8 @@ CODEGENOPT(InstrumentFunctions , 1, 0) ///< Set when -finstrument-functions is
 CODEGENOPT(InstrumentForProfiling , 1, 0) ///< Set when -pg is enabled.
 CODEGENOPT(LessPreciseFPMAD  , 1, 0) ///< Enable less precise MAD instructions to
                                      ///< be generated.
+CODEGENOPT(PrepareForLTO     , 1, 0) ///< Set when -flto is enabled on the
+                                     ///< compile step.
 CODEGENOPT(MergeAllConstants , 1, 1) ///< Merge identical constants.
 CODEGENOPT(MergeFunctions    , 1, 0) ///< Set when -fmerge-functions is enabled.
 CODEGENOPT(MSVolatile        , 1, 0) ///< Set when /volatile:ms is enabled.
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 0bccad0570d..5ff760ca874 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -292,6 +292,7 @@ void EmitAssemblyHelper::CreatePasses() {
   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
+  PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
   PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index a2955dbb9e7..3ea2b36cf52 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2805,6 +2805,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     assert((isa<CompileJobAction>(JA) || isa<BackendJobAction>(JA)) &&
            "Invalid action for clang tool.");
 
+    if (JA.getType() == types::TY_LTO_IR ||
+        JA.getType() == types::TY_LTO_BC) {
+      CmdArgs.push_back("-flto");
+    }
     if (JA.getType() == types::TY_Nothing) {
       CmdArgs.push_back("-fsyntax-only");
     } else if (JA.getType() == types::TY_LLVM_IR ||
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index dd664ca652f..49823be0a00 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -508,6 +508,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
 
   Opts.MergeFunctions = Args.hasArg(OPT_fmerge_functions);
 
+  Opts.PrepareForLTO = Args.hasArg(OPT_flto);
+
   Opts.MSVolatile = Args.hasArg(OPT_fms_volatile);
 
   Opts.VectorizeBB = Args.hasArg(OPT_vectorize_slp_aggressive);
diff --git a/clang/test/CodeGen/available-externally-hidden.cpp b/clang/test/CodeGen/available-externally-hidden.cpp
new file mode 100644
index 00000000000..dc13f26b752
--- /dev/null
+++ b/clang/test/CodeGen/available-externally-hidden.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -O2 -fvisibility hidden -std=c++11 -emit-llvm -o - -triple x86_64-apple-darwin10 %s | FileCheck %s
+
+// Ensure that available_externally functions eliminated at -O2 are now
+// declarations, and are not emitted as hidden with -fvisibility=hidden,
+// but rather with default visibility.
+struct Filter {
+  virtual void Foo();
+  int a;
+};
+
+class Message{};
+class Sender {
+ public:
+  virtual bool Send(Message* msg) = 0;
+
+ protected:
+  virtual ~Sender() {}
+};
+
+// CHECK: declare zeroext i1 @_ZThn16_N17SyncMessageFilter4SendEP7Message
+class SyncMessageFilter : public Filter, public Sender {
+ public:
+  bool Send(Message* message) override;
+};
+
+class TestSyncMessageFilter : public SyncMessageFilter {
+};
+
+int main() {
+TestSyncMessageFilter*  f = new TestSyncMessageFilter;
+  f->Send(new Message);
+}
diff --git a/clang/test/CodeGen/available-externally-suppress.c b/clang/test/CodeGen/available-externally-suppress.c
index 390d2017884..a25a2827127 100644
--- a/clang/test/CodeGen/available-externally-suppress.c
+++ b/clang/test/CodeGen/available-externally-suppress.c
@@ -1,12 +1,18 @@
 // RUN: %clang_cc1 -emit-llvm -o - -triple x86_64-apple-darwin10 %s | FileCheck %s
+// RUN: %clang_cc1 -O2 -fno-inline -emit-llvm -o - -triple x86_64-apple-darwin10 %s | FileCheck %s
+// RUN: %clang_cc1 -flto -O2 -fno-inline -emit-llvm -o - -triple x86_64-apple-darwin10 %s | FileCheck %s -check-prefix=LTO
 
 // Ensure that we don't emit available_externally functions at -O0.
+// Also should not emit them at -O2, unless -flto is present in which case
+// we should preserve them for link-time inlining decisions.
 int x;
 
 inline void f0(int y) { x = y; }
 
 // CHECK-LABEL: define void @test()
 // CHECK: declare void @f0(i32)
+// LTO-LABEL: define void @test()
+// LTO: define available_externally void @f0
 void test() {
   f0(17);
 }
@@ -19,9 +25,13 @@ inline int __attribute__((always_inline)) f1(int x) {
 }
 
 // CHECK: @test1
+// LTO: @test1
 int test1(int x) {
   // CHECK: br i1
   // CHECK-NOT: call {{.*}} @f1
   // CHECK: ret i32
+  // LTO: br i1
+  // LTO-NOT: call {{.*}} @f1
+  // LTO: ret i32
   return f1(x);
 }