[RISCV] Change linker job in Baremetal toolchain object to accomodate valid

GCCInstallation.(2/3)

This patch adds the defaults for CXXSstdlib type and other runtime libs.
Additionally, this patch also modifes the linker job and extend it to support
valid GCCInstallation.

This PR preserves the behavior of both toolchain objects in the linker job with
the only new change being that the presence of `--gcc-toolchain` or
`--gcc-install-dir` will imply that GNU linker is the default linker unless
otherwise a differnt linker is passed through `-fuse-ld` flag.

This is the second PR in the series of 3 PRs for merging and extending Baremetal
toolchain object. The division of the PRs is as follows:
- Teach Baremetal toolchain about GCC installation and make sysroot and
  assembler
  related changes.
- Changes related to linker job and defaults for CXXStdlib and other runtime
  libs.
- Finally removing the call to RISCVToolchain object.

RFC:
https://discourse.llvm.org/t/merging-riscvtoolchain-and-baremetal-toolchains/75524

Change-Id: I8fdb3490a3888001b1bb999e7ee8df90a187d18d

Author: Garvit Gupta

clang/lib/Driver/ToolChains/BareMetal.cpp

@@ -172,6 +172,8 @@ BareMetal::BareMetal(const Driver &D, const llvm::Triple &Triple,
     : Generic_ELF(D, Triple, Args) {
   GCCInstallation.init(Triple, Args);
   SysRoot = computeSysRoot();
+  UseLD =
+      Args.getLastArgValue(options::OPT_fuse_ld_EQ).equals_insensitive("ld");
   if (GCCInstallation.isValid()) {
     Multilibs = GCCInstallation.getMultilibs();
     SelectedMultilibs.assign({GCCInstallation.getMultilib()});
@@ -342,6 +344,32 @@ BareMetal::OrderedMultilibs BareMetal::getOrderedMultilibs() const {
   return llvm::reverse(Default);
 }
 
+ToolChain::CXXStdlibType BareMetal::GetDefaultCXXStdlibType() const {
+  if (getTriple().isRISCV() && GCCInstallation.isValid())
+    return ToolChain::CST_Libstdcxx;
+  return ToolChain::CST_Libcxx;
+}
+
+ToolChain::RuntimeLibType BareMetal::GetDefaultRuntimeLibType() const {
+  if (getTriple().isRISCV() && GCCInstallation.isValid())
+    return ToolChain::RLT_Libgcc;
+  return ToolChain::RLT_CompilerRT;
+}
+
+ToolChain::UnwindLibType
+BareMetal::GetUnwindLibType(const llvm::opt::ArgList &Args) const {
+  if (getTriple().isRISCV())
+    return ToolChain::UNW_None;
+
+  return ToolChain::GetUnwindLibType(Args);
+}
+
+const char *BareMetal::getDefaultLinker() const {
+  if (isUsingLD())
+    return "ld";
+  return "ld.lld";
+}
+
 void BareMetal::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                           ArgStringList &CC1Args) const {
   if (DriverArgs.hasArg(options::OPT_nostdinc))
@@ -535,12 +563,21 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   const llvm::Triple::ArchType Arch = TC.getArch();
   const llvm::Triple &Triple = getToolChain().getEffectiveTriple();
 
-  AddLinkerInputs(TC, Inputs, Args, CmdArgs, JA);
+  if (!D.SysRoot.empty())
+    CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
 
   CmdArgs.push_back("-Bstatic");
 
-  if (TC.getTriple().isRISCV() && Args.hasArg(options::OPT_mno_relax))
-    CmdArgs.push_back("--no-relax");
+  if (Triple.isRISCV()) {
+    if (Args.hasArg(options::OPT_mno_relax))
+      CmdArgs.push_back("--no-relax");
+    if (TC.isUsingLD()) {
+      CmdArgs.push_back("-m");
+      CmdArgs.push_back(Arch == llvm::Triple::riscv64 ? "elf64lriscv"
+                                                      : "elf32lriscv");
+    }
+    CmdArgs.push_back("-X");
+  }
 
   if (Triple.isARM() || Triple.isThumb()) {
     bool IsBigEndian = arm::isARMBigEndian(Triple, Args);
@@ -551,19 +588,54 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(Arch == llvm::Triple::aarch64_be ? "-EB" : "-EL");
   }
 
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles,
-                   options::OPT_r)) {
-    CmdArgs.push_back(Args.MakeArgString(TC.GetFilePath("crt0.o")));
+  bool WantCRTs =
+      !Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles);
+
+  const char *crtbegin, *crtend;
+  if (WantCRTs) {
+    if (!Args.hasArg(options::OPT_r))
+      CmdArgs.push_back(Args.MakeArgString(TC.GetFilePath("crt0.o")));
+    if (TC.isUsingLD()) {
+      auto RuntimeLib = TC.GetRuntimeLibType(Args);
+      if (RuntimeLib == ToolChain::RLT_Libgcc) {
+        crtbegin = "crtbegin.o";
+        crtend = "crtend.o";
+      } else {
+        assert(RuntimeLib == ToolChain::RLT_CompilerRT);
+        crtbegin =
+            TC.getCompilerRTArgString(Args, "crtbegin", ToolChain::FT_Object);
+        crtend =
+            TC.getCompilerRTArgString(Args, "crtend", ToolChain::FT_Object);
+      }
+      CmdArgs.push_back(Args.MakeArgString(TC.GetFilePath(crtbegin)));
+    }
   }
 
-  Args.addAllArgs(CmdArgs, {options::OPT_L, options::OPT_T_Group,
-                            options::OPT_s, options::OPT_t, options::OPT_r});
+  Args.addAllArgs(CmdArgs,
+                  {options::OPT_L, options::OPT_u, options::OPT_T_Group,
+                   options::OPT_s, options::OPT_t, options::OPT_r});
 
   TC.AddFilePathLibArgs(Args, CmdArgs);
 
   for (const auto &LibPath : TC.getLibraryPaths())
     CmdArgs.push_back(Args.MakeArgString(llvm::Twine("-L", LibPath)));
 
+  if (D.isUsingLTO()) {
+    assert(!Inputs.empty() && "Must have at least one input.");
+    // Find the first filename InputInfo object.
+    auto Input = llvm::find_if(
+        Inputs, [](const InputInfo &II) -> bool { return II.isFilename(); });
+    if (Input == Inputs.end())
+      // For a very rare case, all of the inputs to the linker are
+      // InputArg. If that happens, just use the first InputInfo.
+      Input = Inputs.begin();
+
+    addLTOOptions(TC, Args, CmdArgs, Output, *Input,
+                  D.getLTOMode() == LTOK_Thin);
+  }
+
+  AddLinkerInputs(TC, Inputs, Args, CmdArgs, JA);
+
   if (TC.ShouldLinkCXXStdlib(Args)) {
     bool OnlyLibstdcxxStatic = Args.hasArg(options::OPT_static_libstdcxx) &&
                                !Args.hasArg(options::OPT_static);
@@ -576,26 +648,16 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   }
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
+    CmdArgs.push_back("--start-group");
     AddRunTimeLibs(TC, D, CmdArgs, Args);
-
     CmdArgs.push_back("-lc");
+    if (TC.isUsingLD())
+      CmdArgs.push_back("-lgloss");
+    CmdArgs.push_back("--end-group");
   }
 
-  if (D.isUsingLTO()) {
-    assert(!Inputs.empty() && "Must have at least one input.");
-    // Find the first filename InputInfo object.
-    auto Input = llvm::find_if(
-        Inputs, [](const InputInfo &II) -> bool { return II.isFilename(); });
-    if (Input == Inputs.end())
-      // For a very rare case, all of the inputs to the linker are
-      // InputArg. If that happens, just use the first InputInfo.
-      Input = Inputs.begin();
-
-    addLTOOptions(TC, Args, CmdArgs, Output, *Input,
-                  D.getLTOMode() == LTOK_Thin);
-  }
-  if (TC.getTriple().isRISCV())
-    CmdArgs.push_back("-X");
+  if (TC.isUsingLD() && WantCRTs)
+    CmdArgs.push_back(Args.MakeArgString(TC.GetFilePath(crtend)));
 
   // The R_ARM_TARGET2 relocation must be treated as R_ARM_REL32 on arm*-*-elf
   // and arm*-*-eabi (the default is R_ARM_GOT_PREL, used on arm*-*-linux and

clang/lib/Driver/ToolChains/BareMetal.h

@@ -36,6 +36,7 @@ class LLVM_LIBRARY_VISIBILITY BareMetal : public Generic_ELF {
   Tool *buildStaticLibTool() const override;
 
 public:
+  virtual bool isUsingLD() const { return UseLD || GCCInstallation.isValid(); }
   bool isBareMetal() const override { return true; }
   bool isCrossCompiling() const override { return true; }
   bool HasNativeLLVMSupport() const override { return true; }
@@ -48,19 +49,18 @@ class LLVM_LIBRARY_VISIBILITY BareMetal : public Generic_ELF {
 
   StringRef getOSLibName() const override { return "baremetal"; }
 
-  RuntimeLibType GetDefaultRuntimeLibType() const override {
-    return ToolChain::RLT_CompilerRT;
-  }
-  CXXStdlibType GetDefaultCXXStdlibType() const override {
-    return ToolChain::CST_Libcxx;
-  }
-
   UnwindTableLevel
   getDefaultUnwindTableLevel(const llvm::opt::ArgList &Args) const override {
     return UnwindTableLevel::None;
   }
 
-  const char *getDefaultLinker() const override { return "ld.lld"; }
+  CXXStdlibType GetDefaultCXXStdlibType() const override;
+
+  RuntimeLibType GetDefaultRuntimeLibType() const override;
+
+  UnwindLibType GetUnwindLibType(const llvm::opt::ArgList &Args) const override;
+
+  const char *getDefaultLinker() const override;
 
   void
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
@@ -82,7 +82,7 @@ class LLVM_LIBRARY_VISIBILITY BareMetal : public Generic_ELF {
   using OrderedMultilibs =
       llvm::iterator_range<llvm::SmallVector<Multilib>::const_reverse_iterator>;
   OrderedMultilibs getOrderedMultilibs() const;
-
+  bool UseLD;
   std::string SysRoot;
   std::string computeGCCSysRoot() const;
 };
@@ -108,7 +108,7 @@ class LLVM_LIBRARY_VISIBILITY StaticLibTool : public Tool {
 
 class LLVM_LIBRARY_VISIBILITY Linker final : public Tool {
 public:
-  Linker(const ToolChain &TC) : Tool("baremetal::Linker", "ld.lld", TC) {}
+  Linker(const ToolChain &TC) : Tool("baremetal::Linker", "linker", TC) {}
   bool isLinkJob() const override { return true; }
   bool hasIntegratedCPP() const override { return false; }
   void ConstructJob(Compilation &C, const JobAction &JA,

clang/test/Driver/aarch64-toolchain-extra.c

@@ -26,3 +26,9 @@
 // RUN:    | FileCheck -check-prefix=C-ARM-BAREMETAL-NOGCC %s
 
 // C-ARM-BAREMETAL-NOGCC: "-internal-isystem" "{{.*}}/aarch64-nogcc/bin/../aarch64-none-elf/include"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/ld"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/aarch64-nogcc/bin/../aarch64-none-elf/lib/crt0.o"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/aarch64-nogcc/{{.*}}/aarch64-none-elf/lib/crtbegin.o"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/aarch64-nogcc/bin/../aarch64-none-elf/lib"
+// C-ARM-BAREMETAL-NOGCC: "--start-group" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgloss" "--end-group"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/aarch64-nogcc/{{.*}}/aarch64-none-elf/lib/crtend.o"

clang/test/Driver/aarch64-toolchain.c

@@ -9,6 +9,14 @@
 // C-AARCH64-BAREMETAL: "-cc1" "-triple" "aarch64-unknown-none-elf"
 // C-AARCH64-BAREMETAL: "-isysroot" "{{.*}}Inputs/basic_aarch64_gcc_tree/aarch64-none-elf"
 // C-AARCH64-BAREMETAL: "-internal-isystem" "{{.*}}Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/include"
+// C-AARCH64-BAREMETAL: "{{.*}}/ld" "--sysroot={{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf"
+// C-AARCH64-BAREMETAL: "-Bstatic" "-EL"
+// C-AARCH64-BAREMETAL: "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/lib/crt0.o"
+// C-AARCH64-BAREMETAL: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtbegin.o"
+// C-AARCH64-BAREMETAL: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1"
+// C-AARCH64-BAREMETAL: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/lib"
+// C-AARCH64-BAREMETAL: "--start-group" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgloss" "--end-group"
+// C-AARCH64-BAREMETAL: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtend.o"
 
 // RUN: %clang -### %s -fuse-ld= \
 // RUN:   --target=aarch64-none-elf --rtlib=libgcc \
@@ -18,6 +26,13 @@
 
 // C-AARCH64-BAREMETAL-NOSYSROOT: "-cc1" "-triple" "aarch64-unknown-none-elf"
 // C-AARCH64-BAREMETAL-NOSYSROOT: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include"
+// C-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/ld" "-Bstatic" "-EL"
+// C-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib/crt0.o"
+// C-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtbegin.o"
+// C-AARCH64-BAREMETAL-NOSYSROOT: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1"
+// C-AARCH64-BAREMETAL-NOSYSROOT: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib"
+// C-AARCH64-BAREMETAL-NOSYSROOT: "--start-group" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgloss" "--end-group"
+// C-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtend.o"
 
 // RUN: %clangxx -### %s -fuse-ld= \
 // RUN:   --target=aarch64-none-elf -stdlib=libstdc++ --rtlib=libgcc \
@@ -29,6 +44,14 @@
 // CXX-AARCH64-BAREMETAL: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/include/c++/8.2.1/backward"
 // CXX-AARCH64-BAREMETAL: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/include/c++/8.2.1"
 // CXX-AARCH64-BAREMETAL: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/include"
+// CXX-AARCH64-BAREMETAL: "{{.*}}/ld" "--sysroot={{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf"
+// CXX-AARCH64-BAREMETAL: "-Bstatic" "-EL"
+// CXX-AARCH64-BAREMETAL: "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/lib/crt0.o"
+// CXX-AARCH64-BAREMETAL: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtbegin.o"
+// CXX-AARCH64-BAREMETAL: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1"
+// CXX-AARCH64-BAREMETAL: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/lib"
+// CXX-AARCH64-BAREMETAL: "-lstdc++" "-lm" "--start-group" "-lgcc_s" "-lgcc" "-lc" "-lgloss" "--end-group"
+// CXX-AARCH64-BAREMETAL: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtend.o"
 
 // RUN: %clangxx -### %s -fuse-ld= \
 // RUN:   --target=aarch64-none-elf -stdlib=libstdc++ --rtlib=libgcc \
@@ -40,6 +63,13 @@
 // CXX-AARCH64-BAREMETAL-NOSYSROOT: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include/c++/8.2.1/backward"
 // CXX-AARCH64-BAREMETAL-NOSYSROOT: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include/c++/8.2.1"
 // CXX-AARCH64-BAREMETAL-NOSYSROOT: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/ld" "-Bstatic" "-EL"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib/crt0.o"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtbegin.o"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT: "-lstdc++" "-lm" "--start-group" "-lgcc_s" "-lgcc" "-lc" "-lgloss" "--end-group"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtend.o"
 
 // RUN: %clangxx -### %s -fuse-ld= \
 // RUN:   --target=aarch64-none-elf -stdlib=libc++ --rtlib=libgcc \
@@ -50,6 +80,14 @@
 // CXX-AARCH64-BAREMETAL-LIBCXX: "-isysroot" "{{.*}}Inputs/basic_aarch64_gcc_tree/aarch64-none-elf"
 // CXX-AARCH64-BAREMETAL-LIBCXX: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/include/c++/v1"
 // CXX-AARCH64-BAREMETAL-LIBCXX: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/include"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "{{.*}}/ld" "--sysroot={{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "-Bstatic" "-EL"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/lib/crt0.o"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtbegin.o"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf/lib"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "-lc++" "-lm" "--start-group" "-lgcc_s" "-lgcc" "-lc" "-lgloss" "--end-group"
+// CXX-AARCH64-BAREMETAL-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtend.o"
 
 // RUN: %clangxx -### %s -fuse-ld= \
 // RUN:   --target=aarch64-none-elf -stdlib=libc++ --rtlib=libgcc \
@@ -59,3 +97,38 @@
 
 // CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include/c++/v1"
 // CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/ld" "-Bstatic" "-EL"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib/crt0.o"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtbegin.o"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-lc++" "-lm" "--start-group" "-lgcc_s" "-lgcc" "-lc" "-lgloss" "--end-group"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtend.o"
+
+// RUN: %clang -### %s -fuse-ld= \
+// RUN:   --target=aarch64-none-elf --rtlib=compiler-rt \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_aarch64_gcc_tree \
+// RUN:   --sysroot=%S/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf 2>&1 \
+// RUN:   | FileCheck -check-prefix=AARCH64-BAREMETAL-COMPILER-RT %s
+
+// AARCH64-BAREMETAL-COMPILER-RT: "{{.*}}crt0.o"
+// AARCH64-BAREMETAL-COMPILER-RT: "{{.*}}clang_rt.crtbegin.o"
+// AARCH64-BAREMETAL-COMPILER-RT: "--start-group" "{{.*}}libclang_rt.builtins.a" "-lc" "-lgloss" "--end-group"
+// AARCH64-BAREMETAL-COMPILER-RT: "{{.*}}clang_rt.crtend.o"
+
+// RUN: %clang -### %s -fuse-ld= \
+// RUN:   --target=aarch64-none-elf --unwindlib=libunwind \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_aarch64_gcc_tree \
+// RUN:   --sysroot=%S/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf 2>&1 \
+// RUN:   | FileCheck -check-prefix=AARCH64-BAREMETAL-UNWINDLIB %s
+
+// RUN: %clang -### %s -fuse-ld= \
+// RUN:   --target=aarch64-none-elf --rtlib=compiler-rt --unwindlib=libunwind \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_aarch64_gcc_tree \
+// RUN:   --sysroot=%S/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf 2>&1 \
+// RUN:   | FileCheck -check-prefix=AARCH64-BAREMETAL-UNWINDLIB %s
+
+// AARCH64-BAREMETAL-UNWINDLIB: "{{.*}}crt0.o"
+// AARCH64-BAREMETAL-UNWINDLIB: "{{.*}}clang_rt.crtbegin.o"
+// AARCH64-BAREMETAL-UNWINDLIB: "--start-group" "{{.*}}libclang_rt.builtins.a" "--as-needed" "-lunwind" "--no-as-needed" "-lc" "-lgloss" "--end-group"
+// AARCH64-BAREMETAL-UNWINDLIB: "{{.*}}clang_rt.crtend.o"

clang/test/Driver/arm-toolchain-extra.c

@@ -26,4 +26,9 @@
 // RUN:    | FileCheck -check-prefix=C-ARM-BAREMETAL-NOGCC %s
 
 // C-ARM-BAREMETAL-NOGCC: "-internal-isystem" "{{.*}}/arm-nogcc/bin/../armv6m-none-eabi/include"
-
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/ld"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/arm-nogcc/bin/../armv6m-none-eabi/lib/crt0.o"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/arm-nogcc/{{.*}}/armv6m-none-eabi/lib/crtbegin.o"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/arm-nogcc/bin/../armv6m-none-eabi/lib"
+// C-ARM-BAREMETAL-NOGCC: "--start-group" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgloss" "--end-group"
+// C-ARM-BAREMETAL-NOGCC: "{{.*}}/arm-nogcc/{{.*}}/armv6m-none-eabi/lib/crtend.o