[RISCV][Driver] Refactor riscv::getRISCVArch to return std::string. NFC.

clang/lib/Driver/Driver.cpp

@@ -681,7 +681,7 @@ static llvm::Triple computeTargetTriple(const Driver &D,
   if (Target.isRISCV()) {
     if (Args.hasArg(options::OPT_march_EQ) ||
         Args.hasArg(options::OPT_mcpu_EQ)) {
-      StringRef ArchName = tools::riscv::getRISCVArch(Args, Target);
+      std::string ArchName = tools::riscv::getRISCVArch(Args, Target);
       auto ISAInfo = llvm::RISCVISAInfo::parseArchString(
           ArchName, /*EnableExperimentalExtensions=*/true);
       if (!llvm::errorToBool(ISAInfo.takeError())) {

clang/lib/Driver/ToolChains/Arch/RISCV.cpp

@@ -72,7 +72,7 @@ static void getRISCFeaturesFromMcpu(const Driver &D, const Arg *A,
 void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
                                    const ArgList &Args,
                                    std::vector<StringRef> &Features) {
-  StringRef MArch = getRISCVArch(Args, Triple);
+  std::string MArch = getRISCVArch(Args, Triple);
 
   if (!getArchFeatures(D, MArch, Features, Args))
     return;
@@ -227,7 +227,7 @@ StringRef riscv::getRISCVABI(const ArgList &Args, const llvm::Triple &Triple) {
   // rv64g | rv64*d -> lp64d
   // rv64e -> lp64e
   // rv64* -> lp64
-  StringRef Arch = getRISCVArch(Args, Triple);
+  std::string Arch = getRISCVArch(Args, Triple);
 
   auto ParseResult = llvm::RISCVISAInfo::parseArchString(
       Arch, /* EnableExperimentalExtension */ true);
@@ -253,8 +253,8 @@ StringRef riscv::getRISCVABI(const ArgList &Args, const llvm::Triple &Triple) {
   }
 }
 
-StringRef riscv::getRISCVArch(const llvm::opt::ArgList &Args,
-                              const llvm::Triple &Triple) {
+std::string riscv::getRISCVArch(const llvm::opt::ArgList &Args,
+                                const llvm::Triple &Triple) {
   assert(Triple.isRISCV() && "Unexpected triple");
 
   // GCC's logic around choosing a default `-march=` is complex. If GCC is not
@@ -295,7 +295,7 @@ StringRef riscv::getRISCVArch(const llvm::opt::ArgList &Args,
     StringRef MArch = llvm::RISCV::getMArchFromMcpu(CPU);
     // Bypass if target cpu's default march is empty.
     if (MArch != "")
-      return MArch;
+      return MArch.str();
   }
 
   // 3. Choose a default based on `-mabi=`

clang/lib/Driver/ToolChains/Arch/RISCV.h

@@ -24,8 +24,8 @@ void getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
                             std::vector<llvm::StringRef> &Features);
 StringRef getRISCVABI(const llvm::opt::ArgList &Args,
                       const llvm::Triple &Triple);
-StringRef getRISCVArch(const llvm::opt::ArgList &Args,
-                       const llvm::Triple &Triple);
+std::string getRISCVArch(const llvm::opt::ArgList &Args,
+                         const llvm::Triple &Triple);
 std::string getRISCVTargetCPU(const llvm::opt::ArgList &Args,
                               const llvm::Triple &Triple);
 } // end namespace riscv

clang/lib/Driver/ToolChains/BareMetal.cpp

@@ -37,7 +37,7 @@ static bool findRISCVMultilibs(const Driver &D,
                                const llvm::Triple &TargetTriple,
                                const ArgList &Args, DetectedMultilibs &Result) {
   Multilib::flags_list Flags;
-  StringRef Arch = riscv::getRISCVArch(Args, TargetTriple);
+  std::string Arch = riscv::getRISCVArch(Args, TargetTriple);
   StringRef Abi = tools::riscv::getRISCVABI(Args, TargetTriple);
 
   if (TargetTriple.isRISCV64()) {

clang/lib/Driver/ToolChains/Clang.cpp

@@ -2107,7 +2107,7 @@ void Clang::AddRISCVTargetArgs(const ArgList &Args,
 
     // Get minimum VLen from march.
     unsigned MinVLen = 0;
-    StringRef Arch = riscv::getRISCVArch(Args, Triple);
+    std::string Arch = riscv::getRISCVArch(Args, Triple);
     auto ISAInfo = llvm::RISCVISAInfo::parseArchString(
         Arch, /*EnableExperimentalExtensions*/ true);
     // Ignore parsing error.

clang/lib/Driver/ToolChains/Flang.cpp

@@ -204,7 +204,7 @@ void Flang::AddRISCVTargetArgs(const ArgList &Args,
 
     // Get minimum VLen from march.
     unsigned MinVLen = 0;
-    StringRef Arch = riscv::getRISCVArch(Args, Triple);
+    std::string Arch = riscv::getRISCVArch(Args, Triple);
     auto ISAInfo = llvm::RISCVISAInfo::parseArchString(
         Arch, /*EnableExperimentalExtensions*/ true);
     // Ignore parsing error.

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -769,9 +769,10 @@ void tools::gnutools::Assembler::ConstructJob(Compilation &C,
     StringRef ABIName = riscv::getRISCVABI(Args, getToolChain().getTriple());
     CmdArgs.push_back("-mabi");
     CmdArgs.push_back(ABIName.data());
-    StringRef MArchName = riscv::getRISCVArch(Args, getToolChain().getTriple());
+    std::string MArchName =
+        riscv::getRISCVArch(Args, getToolChain().getTriple());
     CmdArgs.push_back("-march");
-    CmdArgs.push_back(MArchName.data());
+    CmdArgs.push_back(Args.MakeArgString(MArchName));
     if (!Args.hasFlag(options::OPT_mrelax, options::OPT_mno_relax, true))
       Args.addOptOutFlag(CmdArgs, options::OPT_mrelax, options::OPT_mno_relax);
     break;
@@ -1882,7 +1883,7 @@ static void findRISCVBareMetalMultilibs(const Driver &D,
   Multilib::flags_list Flags;
   llvm::StringSet<> Added_ABIs;
   StringRef ABIName = tools::riscv::getRISCVABI(Args, TargetTriple);
-  StringRef MArch = tools::riscv::getRISCVArch(Args, TargetTriple);
+  std::string MArch = tools::riscv::getRISCVArch(Args, TargetTriple);
   for (auto Element : RISCVMultilibSet) {
     addMultilibFlag(MArch == Element.march,
                     Twine("-march=", Element.march).str().c_str(), Flags);