Frontend: Add a more explicit -backend-option flag for passing backend command

line options, instead of leveraging the blanket -mllvm option.
 - This allows using the frontend itself without requiring the backend have
   those options available (i.e., if the target wasn't built).

llvm-svn: 128087

clang/include/clang/Driver/CC1Options.td

@@ -155,6 +155,8 @@ def momit_leaf_frame_pointer : Flag<"-momit-leaf-frame-pointer">,
   HelpText<"Omit frame pointer setup for leaf functions.">;
 def msoft_float : Flag<"-msoft-float">,
   HelpText<"Use software floating point">;
+def backend_option : Separate<"-backend-option">,
+  HelpText<"Additional arguments to forward to LLVM backend (during code gen)">;
 def mregparm : Separate<"-mregparm">,
   HelpText<"Limit the number of registers available for integer arguments">;
 def mrelax_all : Flag<"-mrelax-all">,

clang/include/clang/Frontend/CodeGenOptions.h

@@ -15,6 +15,7 @@
 #define LLVM_CLANG_FRONTEND_CODEGENOPTIONS_H
 
 #include <string>
+#include <vector>
 
 namespace clang {
 
@@ -114,6 +115,9 @@ public:
   /// The name of the relocation model to use.
   std::string RelocationModel;
 
+  /// A list of command-line options to forward to the LLVM backend.
+  std::vector<std::string> BackendOptions;
+
   /// The user specified number of registers to be used for integral arguments,
   /// or 0 if unspecified.
   unsigned NumRegisterParameters;

clang/lib/CodeGen/BackendUtil.cpp

@@ -248,6 +248,8 @@ bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
   }
   if (llvm::TimePassesIsEnabled)
     BackendArgs.push_back("-time-passes");
+  for (unsigned i = 0, e = CodeGenOpts.BackendOptions.size(); i != e; ++i)
+    BackendArgs.push_back(CodeGenOpts.BackendOptions[i].c_str());
   BackendArgs.push_back(0);
   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
                                     const_cast<char **>(&BackendArgs[0]));

clang/lib/Driver/Tools.cpp

@@ -440,7 +440,7 @@ void Clang::AddARMTargetArgs(const ArgList &Args,
 
   // Disable movt generation, if requested.
 #ifdef DISABLE_ARM_DARWIN_USE_MOVT
-  CmdArgs.push_back("-mllvm");
+  CmdArgs.push_back("-backend-option");
   CmdArgs.push_back("-arm-darwin-use-movt=0");
 #endif
 
@@ -607,10 +607,10 @@ void Clang::AddARMTargetArgs(const ArgList &Args,
 
   // Kernel code has more strict alignment requirements.
   if (KernelOrKext) {
-    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("-backend-option");
     CmdArgs.push_back("-arm-long-calls");
 
-    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("-backend-option");
     CmdArgs.push_back("-arm-strict-align");
   }
 }

clang/lib/Frontend/CompilerInvocation.cpp

@@ -207,6 +207,10 @@ static void CodeGenOptsToArgs(const CodeGenOptions &Opts,
   }
   if (!Opts.VerifyModule)
     Res.push_back("-disable-llvm-verifier");
+  for (unsigned i = 0, e = Opts.BackendOptions.size(); i != e; ++i) {
+    Res.push_back("-backend-option");
+    Res.push_back(Opts.BackendOptions[i]);
+  }
 }
 
 static void DependencyOutputOptsToArgs(const DependencyOutputOptions &Opts,
@@ -927,6 +931,7 @@ static void ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.NoInfsFPMath = Opts.NoNaNsFPMath = Args.hasArg(OPT_cl_finite_math_only)||
                                           Args.hasArg(OPT_cl_fast_relaxed_math);
   Opts.NoZeroInitializedInBSS = Args.hasArg(OPT_mno_zero_initialized_in_bss);
+  Opts.BackendOptions = Args.getAllArgValues(OPT_backend_option);
   Opts.NumRegisterParameters = Args.getLastArgIntValue(OPT_mregparm, 0, Diags);
   Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
   Opts.OmitLeafFramePointer = Args.hasArg(OPT_momit_leaf_frame_pointer);

clang/test/Driver/apple-kext-mkernel.c

@@ -11,8 +11,8 @@
 // RUN:   -arch armv7 -mkernel -### -fsyntax-only %s 2> %t
 // RUN: FileCheck --check-prefix=CHECK-ARM < %t %s
 
-// CHECK-ARM: "-mllvm" "-arm-long-calls"
-// CHECK-ARM: "-mllvm" "-arm-strict-align"
+// CHECK-ARM: "-backend-option" "-arm-long-calls"
+// CHECK-ARM: "-backend-option" "-arm-strict-align"
 // CHECK-ARM: "-fno-builtin"
 // CHECK-ARM: "-fno-rtti"
 // CHECK-ARM: "-fno-common"