Add -Oz option and use it to set the inline threshold to 25.

Radar 9333566.  Patch by Chad Rosier!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130554 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/CC1Options.td

@@ -179,6 +179,7 @@ def mms_bitfields : Flag<"-mms-bitfields">,
   HelpText<"Set the default structure layout to be compatible with the Microsoft compiler standard.">;
 def O : Joined<"-O">, HelpText<"Optimization level">;
 def Os : Flag<"-Os">, HelpText<"Optimize for size">;
+def Oz : Flag<"-Oz">, HelpText<"Optimize for size, regardless of performance">;
 def pg : Flag<"-pg">, HelpText<"Enable mcount instrumentation">;
 
 //===----------------------------------------------------------------------===//

include/clang/Frontend/CodeGenOptions.h

@@ -76,7 +76,7 @@ public:
   unsigned OmitLeafFramePointer : 1; /// Set when -momit-leaf-frame-pointer is
                                      /// enabled.
   unsigned OptimizationLevel : 3; /// The -O[0-4] option specified.
-  unsigned OptimizeSize      : 1; /// If -Os is specified.
+  unsigned OptimizeSize      : 2; /// If -Os (==1) or -Oz (==2) is specified.
   unsigned RelaxAll          : 1; /// Relax all machine code instructions.
   unsigned RelaxedAliasing   : 1; /// Set when -fno-strict-aliasing is enabled.
   unsigned SaveTempLabels    : 1; /// Save temporary labels.

lib/CodeGen/BackendUtil.cpp

@@ -134,8 +134,10 @@ void EmitAssemblyHelper::CreatePasses() {
     //
     // FIXME: Derive these constants in a principled fashion.
     unsigned Threshold = 225;
-    if (CodeGenOpts.OptimizeSize)
+    if (CodeGenOpts.OptimizeSize == 1) //-Os
       Threshold = 75;
+    else if (CodeGenOpts.OptimizeSize == 2) //-Oz
+      Threshold = 25;
     else if (OptLevel > 2)
       Threshold = 275;
     InliningPass = createFunctionInliningPass(Threshold);

lib/Driver/Tools.cpp

@@ -1309,10 +1309,6 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     else if (A->getOption().matches(options::OPT_O) &&
              A->getValue(Args)[0] == '\0')
       CmdArgs.push_back("-O2");
-    else if (A->getOption().matches(options::OPT_O) &&
-             A->getValue(Args)[0] == 'z' &&
-             A->getValue(Args)[1] == '\0')
-      CmdArgs.push_back("-Os");
     else
       A->render(Args, CmdArgs);
   }

lib/Frontend/CompilerInvocation.cpp

@@ -139,7 +139,7 @@ static void CodeGenOptsToArgs(const CodeGenOptions &Opts,
     Res.push_back("-momit-leaf-frame-pointer");
   if (Opts.OptimizeSize) {
     assert(Opts.OptimizationLevel == 2 && "Invalid options!");
-    Res.push_back("-Os");
+    Opts.OptimizeSize == 1 ? Res.push_back("-Os") : Res.push_back("-Oz");
   } else if (Opts.OptimizationLevel != 0)
     Res.push_back("-O" + llvm::utostr(Opts.OptimizationLevel));
   if (!Opts.MainFileName.empty()) {
@@ -815,8 +815,8 @@ static unsigned getOptimizationLevel(ArgList &Args, InputKind IK,
   unsigned DefaultOpt = 0;
   if (IK == IK_OpenCL && !Args.hasArg(OPT_cl_opt_disable))
     DefaultOpt = 2;
-  // -Os implies -O2
-  return Args.hasArg(OPT_Os) ? 2 :
+  // -Os/-Oz implies -O2
+  return (Args.hasArg(OPT_Os) || Args.hasArg (OPT_Oz)) ? 2 :
     Args.getLastArgIntValue(OPT_O, DefaultOpt, Diags);
 }
 
@@ -931,6 +931,7 @@ static void ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.NoCommon = Args.hasArg(OPT_fno_common);
   Opts.NoImplicitFloat = Args.hasArg(OPT_no_implicit_float);
   Opts.OptimizeSize = Args.hasArg(OPT_Os);
+  Opts.OptimizeSize = Args.hasArg(OPT_Oz) ? 2 : Opts.OptimizeSize;
   Opts.SimplifyLibCalls = !(Args.hasArg(OPT_fno_builtin) ||
                             Args.hasArg(OPT_ffreestanding));
   Opts.UnrollLoops = Args.hasArg(OPT_funroll_loops) ||