Driver: use new gold/ld64 plugin flags with LTO-requiring passes.

[pcc]

We went with r232769 instead.

lib/Driver/Tools.cpp

static void AddGoldPlugin(const ToolChain &ToolChain, const ArgList &Args,
 
   // Try to pass driver level flags relevant to LTO code generation down to
   // the plugin.
 
   // Handle flags for selecting CPU variants.
   std::string CPU = getCPUName(Args, ToolChain.getTriple());
   if (!CPU.empty())
     CmdArgs.push_back(Args.MakeArgString(Twine("-plugin-opt=mcpu=") + CPU));
+
+  // If a sanitizer needs LTO, turn on the relevant passes.
+  if (ToolChain.getSanitizerArgs().needsLTO()) {
+    CmdArgs.push_back("-plugin-opt=lowerbitsets");
+
+    // Disable most optimizations unless LTO was specifically requested.
+    if (!Args.hasFlag(options::OPT_flto, options::OPT_fno_lto, false))
+      CmdArgs.push_back("-plugin-opt=disable-opt");
+  }
 }
 
 static void getX86TargetFeatures(const Driver & D,
                                  const llvm::Triple &Triple,
                                  const ArgList &Args,
                                  std::vector<const char *> &Features) {
   if (Triple.getArchName() == "x86_64h") {
     // x86_64h implies quite a few of the more modern subtarget features
if (Version[0] >= 116 && D.IsUsingLTO(getToolChain(), 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 a sanitizer needs LTO, turn on the relevant passes.
+  if (getToolChain().getSanitizerArgs().needsLTO()) {
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("-lowerbitsets");
+
+    // Disable most optimizations unless LTO was specifically requested.
+    if (!Args.hasFlag(options::OPT_flto, options::OPT_fno_lto, false)) {
+      CmdArgs.push_back("-mllvm");
+      CmdArgs.push_back("-disable-opt");
+    }
+  }
+
   // Derived from the "link" spec.
   Args.AddAllArgs(CmdArgs, options::OPT_static);
   if (!Args.hasArg(options::OPT_static))
     CmdArgs.push_back("-dynamic");
   if (Args.hasArg(options::OPT_fgnu_runtime)) {
     // FIXME: gcc replaces -lobjc in forward args with -lobjc-gnu
     // here. How do we wish to handle such things?
   }

test/Driver/fsanitize.c

 // RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi-derived-cast -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-DCAST
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi-unrelated-cast -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-UCAST
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi-vptr -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-VPTR
 // CHECK-CFI: -emit-llvm-bc{{.*}}-fsanitize=cfi-derived-cast,cfi-unrelated-cast,cfi-vptr
 // CHECK-CFI-DCAST: -emit-llvm-bc{{.*}}-fsanitize=cfi-derived-cast
 // CHECK-CFI-UCAST: -emit-llvm-bc{{.*}}-fsanitize=cfi-unrelated-cast
 // CHECK-CFI-VPTR: -emit-llvm-bc{{.*}}-fsanitize=cfi-vptr
 
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-LINK-LINUX
+// RUN: %clang -target x86_64-apple-darwin10 -fsanitize=cfi %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-LINK-DARWIN
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi -flto %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-LINK-LINUX-LTO
+// RUN: %clang -target x86_64-apple-darwin10 -fsanitize=cfi -flto %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-LINK-DARWIN-LTO
+// CHECK-CFI-LINK-LINUX: "-plugin-opt=lowerbitsets" "-plugin-opt=disable-opt"
+// CHECK-CFI-LINK-DARWIN: "-mllvm" "-lowerbitsets" "-mllvm" "-disable-opt"
+// CHECK-CFI-LINK-LINUX-LTO-NOT: "-plugin-opt=disable-opt"
+// CHECK-CFI-LINK-DARWIN-LTO-NOT: "-mllvm" "-disable-opt"
+
 // RUN: %clang_cl -fsanitize=address -c -MDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -MTd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -LDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -MD -MDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -MT -MTd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // RUN: %clang_cl -fsanitize=address -c -LD -LDd -### -- %s 2>&1 | FileCheck %s -check-prefix=CHECK-ASAN-DEBUGRTL
 // CHECK-ASAN-DEBUGRTL: error: invalid argument
 // CHECK-ASAN-DEBUGRTL: not allowed with '-fsanitize=address'