Driver: Defer computation of linker path until it is needed.

This allows us to construct Linux toolchains without a valid linker. This
is needed for example to build a CUDA device toolchain after r253385.

llvm-svn: 253707

clang/include/clang/Driver/ToolChain.h

@@ -92,6 +92,7 @@ private:
 
 protected:
   MultilibSet Multilibs;
+  const char *DefaultLinker = "ld";
 
   ToolChain(const Driver &D, const llvm::Triple &T,
             const llvm::opt::ArgList &Args);

clang/lib/Driver/ToolChain.cpp

@@ -359,7 +359,7 @@ std::string ToolChain::GetLinkerPath() const {
     return "";
   }
 
-  return GetProgramPath("ld");
+  return GetProgramPath(DefaultLinker);
 }
 
 types::ID ToolChain::LookupTypeForExtension(const char *Ext) const {

clang/lib/Driver/ToolChains.cpp

@@ -2455,8 +2455,7 @@ MipsLLVMToolChain::MipsLLVMToolChain(const Driver &D,
   getFilePaths().push_back(computeSysRoot() + "/usr/lib" + LibSuffix);
 
   // Use LLD by default.
-  if (!Args.getLastArg(options::OPT_fuse_ld_EQ))
-    Linker = GetProgramPath("lld");
+  DefaultLinker = "lld";
 }
 
 void MipsLLVMToolChain::AddClangSystemIncludeArgs(
@@ -2837,8 +2836,6 @@ NaClToolChain::NaClToolChain(const Driver &D, const llvm::Triple &Triple,
     break;
   }
 
-  // Use provided linker, not system linker
-  Linker = GetLinkerPath();
   NaClArmMacrosPath = GetFilePath("nacl-arm-macros.s");
 }
 
@@ -3693,8 +3690,6 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
                          GCCInstallation.getTriple().str() + "/bin")
                        .str());
 
-  Linker = GetLinkerPath();
-
   Distro Distro = DetectDistro(D, Arch);
 
   if (IsOpenSUSE(Distro) || IsUbuntu(Distro)) {

clang/lib/Driver/ToolChains.h

@@ -796,7 +796,6 @@ public:
                         llvm::opt::ArgStringList &CmdArgs) const override;
   virtual std::string computeSysRoot() const;
 
-  std::string Linker;
   std::vector<std::string> ExtraOpts;
 
 protected:
@@ -921,7 +920,6 @@ public:
 
   std::string ComputeEffectiveClangTriple(const llvm::opt::ArgList &Args,
                                           types::ID InputType) const override;
-  std::string Linker;
 
 protected:
   Tool *buildLinker() const override;

clang/lib/Driver/Tools.cpp

@@ -8500,7 +8500,8 @@ void gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   // handled somewhere else.
   Args.ClaimAllArgs(options::OPT_w);
 
-  if (llvm::sys::path::filename(ToolChain.Linker) == "lld") {
+  const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
+  if (llvm::sys::path::filename(Exec) == "lld") {
     CmdArgs.push_back("-flavor");
     CmdArgs.push_back("old-gnu");
     CmdArgs.push_back("-target");
@@ -8686,8 +8687,7 @@ void gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   } else if (Args.hasArg(options::OPT_rtlib_EQ))
     AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
 
-  C.addCommand(llvm::make_unique<Command>(JA, *this, ToolChain.Linker.c_str(),
-                                          CmdArgs, Inputs));
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
 }
 
 // NaCl ARM assembly (inline or standalone) can be written with a set of macros
@@ -8858,8 +8858,8 @@ void nacltools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
-  C.addCommand(llvm::make_unique<Command>(JA, *this, ToolChain.Linker.c_str(),
-                                          CmdArgs, Inputs));
+  const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
 }
 
 void minix::Assembler::ConstructJob(Compilation &C, const JobAction &JA,

clang/test/Driver/mingw-useld.c

@@ -1,16 +1,19 @@
 // RUN: %clang -### -target i686-pc-windows-gnu --sysroot=%S/Inputs/mingw_clang_tree/mingw32 %s 2>&1 | FileCheck -check-prefix=CHECK_LD_32 %s
 // CHECK_LD_32: {{ld|ld.exe}}"
 // CHECK_LD_32: "i386pe"
-// CHECK_LD_32_NOT: "-flavor" "old-gnu"
+// CHECK_LD_32-NOT: "-flavor" "old-gnu"
 
 // RUN: %clang -### -target i686-pc-windows-gnu --sysroot=%S/Inputs/mingw_clang_tree/mingw32 %s -fuse-ld=lld 2>&1 | FileCheck -check-prefix=CHECK_LLD_32 %s
+// CHECK_LLD_32-NOT: invalid linker name in argument
 // CHECK_LLD_32: lld" "-flavor" "old-gnu"
 // CHECK_LLD_32: "i386pe"
 
 // RUN: %clang -### -target x86_64-pc-windows-gnu --sysroot=%S/Inputs/mingw_clang_tree/mingw32 %s -fuse-ld=lld 2>&1 | FileCheck -check-prefix=CHECK_LLD_64 %s
+// CHECK_LLD_64-NOT: invalid linker name in argument
 // CHECK_LLD_64: lld" "-flavor" "old-gnu"
 // CHECK_LLD_64: "i386pep"
 
 // RUN: %clang -### -target arm-pc-windows-gnu --sysroot=%S/Inputs/mingw_clang_tree/mingw32 %s -fuse-ld=lld 2>&1 | FileCheck -check-prefix=CHECK_LLD_ARM %s
+// CHECK_LLD_ARM-NOT: invalid linker name in argument
 // CHECK_LLD_ARM: lld" "-flavor" "old-gnu"
 // CHECK_LLD_ARM: "thumb2pe"