commit 06fc5a7714621324b121fb3ee03ac15eb018cf99
Author: Manoj Gupta <manojgupta@google.com>
Date:   Tue Aug 9 21:17:05 2022 -0700

    Driver: Refactor and support per target dirs in baremetal
    
    Refactor baremetal driver code to reduce the bespoke
    additions and base class overrides.
    This lets us use the per target runtimes like other clang
    targets. E.g. clang -target armv7m-cros-none-eabi will now
    be able to use the runtimes installed at
    <resource_dir>/lib/armv7m-cros-none-eabi instead of the hardcoded
    path <resource_dir>/lib/baremetal.
    The older code paths should still continue to work as before if
    <resource_dir>/lib/<tuple> does not exist.
    
    Reviewed By: MaskRay, barannikov88
    
    Differential Revision: https://reviews.llvm.org/D131225

diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
index f20ab164531b..8915c3b80413 100644
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -532,7 +532,7 @@ public:
 
   /// Add an additional -fdebug-prefix-map entry.
   virtual std::string GetGlobalDebugPathRemapping() const { return {}; }
-  
+
   // Return the DWARF version to emit, in the absence of arguments
   // to the contrary.
   virtual unsigned GetDefaultDwarfVersion() const { return 5; }
@@ -575,6 +575,9 @@ public:
   /// isThreadModelSupported() - Does this target support a thread model?
   virtual bool isThreadModelSupported(const StringRef Model) const;
 
+  /// isBareMetal - Is this a bare metal target.
+  virtual bool isBareMetal() const { return false; }
+
   virtual std::string getMultiarchTriple(const Driver &D,
                                          const llvm::Triple &TargetTriple,
                                          StringRef SysRoot) const {
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 7a4319ea680f..bc86e5be655f 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -422,6 +422,9 @@ static StringRef getArchNameForCompilerRTLib(const ToolChain &TC,
   const llvm::Triple &Triple = TC.getTriple();
   bool IsWindows = Triple.isOSWindows();
 
+  if (TC.isBareMetal())
+    return Triple.getArchName();
+
   if (TC.getArch() == llvm::Triple::arm || TC.getArch() == llvm::Triple::armeb)
     return (arm::getARMFloatABI(TC, Args) == arm::FloatABI::Hard && !IsWindows)
                ? "armhf"
@@ -459,7 +462,10 @@ StringRef ToolChain::getOSLibName() const {
 
 std::string ToolChain::getCompilerRTPath() const {
   SmallString<128> Path(getDriver().ResourceDir);
-  if (Triple.isOSUnknown()) {
+  if (isBareMetal()) {
+    llvm::sys::path::append(Path, "lib", getOSLibName());
+    Path += SelectedMultilib.gccSuffix();
+  } else if (Triple.isOSUnknown()) {
     llvm::sys::path::append(Path, "lib");
   } else {
     llvm::sys::path::append(Path, "lib", getOSLibName());
diff --git a/clang/lib/Driver/ToolChains/BareMetal.cpp b/clang/lib/Driver/ToolChains/BareMetal.cpp
index 5f1638a159d5..75b06d5e7d0d 100644
--- a/clang/lib/Driver/ToolChains/BareMetal.cpp
+++ b/clang/lib/Driver/ToolChains/BareMetal.cpp
@@ -92,7 +92,7 @@ static bool findRISCVMultilibs(const Driver &D,
 }
 
 BareMetal::BareMetal(const Driver &D, const llvm::Triple &Triple,
-                           const ArgList &Args)
+                     const ArgList &Args)
     : ToolChain(D, Triple, Args) {
   getProgramPaths().push_back(getDriver().getInstalledDir());
   if (getDriver().getInstalledDir() != getDriver().Dir)
@@ -173,21 +173,6 @@ Tool *BareMetal::buildLinker() const {
   return new tools::baremetal::Linker(*this);
 }
 
-std::string BareMetal::getCompilerRTPath() const { return getRuntimesDir(); }
-
-std::string BareMetal::buildCompilerRTBasename(const llvm::opt::ArgList &,
-                                               StringRef, FileType,
-                                               bool) const {
-  return ("libclang_rt.builtins-" + getTriple().getArchName() + ".a").str();
-}
-
-std::string BareMetal::getRuntimesDir() const {
-  SmallString<128> Dir(getDriver().ResourceDir);
-  llvm::sys::path::append(Dir, "lib", "baremetal");
-  Dir += SelectedMultilib.gccSuffix();
-  return std::string(Dir.str());
-}
-
 std::string BareMetal::computeSysRoot() const {
   if (!getDriver().SysRoot.empty())
     return getDriver().SysRoot + SelectedMultilib.osSuffix();
@@ -226,8 +211,8 @@ void BareMetal::addClangTargetOptions(const ArgList &DriverArgs,
   CC1Args.push_back("-nostdsysteminc");
 }
 
-void BareMetal::AddClangCXXStdlibIncludeArgs(
-    const ArgList &DriverArgs, ArgStringList &CC1Args) const {
+void BareMetal::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
+                                             ArgStringList &CC1Args) const {
   if (DriverArgs.hasArg(options::OPT_nostdinc) ||
       DriverArgs.hasArg(options::OPT_nostdlibinc) ||
       DriverArgs.hasArg(options::OPT_nostdincxx))
@@ -292,10 +277,14 @@ void BareMetal::AddLinkRuntimeLib(const ArgList &Args,
                                   ArgStringList &CmdArgs) const {
   ToolChain::RuntimeLibType RLT = GetRuntimeLibType(Args);
   switch (RLT) {
-  case ToolChain::RLT_CompilerRT:
-    CmdArgs.push_back(
-        Args.MakeArgString("-lclang_rt.builtins-" + getTriple().getArchName()));
+  case ToolChain::RLT_CompilerRT: {
+    const std::string FileName = getCompilerRT(Args, "builtins");
+    llvm::StringRef BaseName = llvm::sys::path::filename(FileName);
+    BaseName.consume_front("lib");
+    BaseName.consume_back(".a");
+    CmdArgs.push_back(Args.MakeArgString("-l" + BaseName));
     return;
+  }
   case ToolChain::RLT_Libgcc:
     CmdArgs.push_back("-lgcc");
     return;
@@ -310,7 +299,7 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                      const char *LinkingOutput) const {
   ArgStringList CmdArgs;
 
-  auto &TC = static_cast<const toolchains::BareMetal&>(getToolChain());
+  auto &TC = static_cast<const toolchains::BareMetal &>(getToolChain());
 
   AddLinkerInputs(TC, Inputs, Args, CmdArgs, JA);
 
@@ -322,10 +311,17 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   TC.AddFilePathLibArgs(Args, CmdArgs);
 
-  CmdArgs.push_back(Args.MakeArgString("-L" + TC.getRuntimesDir()));
+  for (const auto &LibPath : TC.getLibraryPaths())
+    CmdArgs.push_back(Args.MakeArgString(llvm::Twine("-L", LibPath)));
+
+  const std::string FileName = TC.getCompilerRT(Args, "builtins");
+  llvm::SmallString<128> PathBuf{FileName};
+  llvm::sys::path::remove_filename(PathBuf);
+  CmdArgs.push_back(Args.MakeArgString("-L" + PathBuf));
 
   if (TC.ShouldLinkCXXStdlib(Args))
     TC.AddCXXStdlibLibArgs(Args, CmdArgs);
+
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
     CmdArgs.push_back("-lc");
     CmdArgs.push_back("-lm");
diff --git a/clang/lib/Driver/ToolChains/BareMetal.h b/clang/lib/Driver/ToolChains/BareMetal.h
index dc718e09ad43..2a16a5beb08d 100644
--- a/clang/lib/Driver/ToolChains/BareMetal.h
+++ b/clang/lib/Driver/ToolChains/BareMetal.h
@@ -1,4 +1,4 @@
-//===--- BareMetal.h - Bare Metal Tool and ToolChain -------------*- C++ -*-===//
+//===--- BareMetal.h - Bare Metal Tool and ToolChain ------------*- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -33,13 +33,9 @@ public:
 protected:
   Tool *buildLinker() const override;
 
-  std::string buildCompilerRTBasename(const llvm::opt::ArgList &Args,
-                                      StringRef Component,
-                                      FileType Type = ToolChain::FT_Static,
-                                      bool AddArch = true) const override;
-
 public:
   bool useIntegratedAs() const override { return true; }
+  bool isBareMetal() const override { return true; }
   bool isCrossCompiling() const override { return true; }
   bool isPICDefault() const override { return false; }
   bool isPIEDefault(const llvm::opt::ArgList &Args) const override {
@@ -50,8 +46,6 @@ public:
 
   StringRef getOSLibName() const override { return "baremetal"; }
 
-  std::string getCompilerRTPath() const override;
-
   RuntimeLibType GetDefaultRuntimeLibType() const override {
     return ToolChain::RLT_CompilerRT;
   }
@@ -61,12 +55,13 @@ public:
 
   const char *getDefaultLinker() const override { return "ld.lld"; }
 
-  std::string getRuntimesDir() const;
-  void AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                                 llvm::opt::ArgStringList &CC1Args) const override;
-  void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
-                             llvm::opt::ArgStringList &CC1Args,
-                             Action::OffloadKind DeviceOffloadKind) const override;
+  void
+  AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                            llvm::opt::ArgStringList &CC1Args) const override;
+  void
+  addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
+                        llvm::opt::ArgStringList &CC1Args,
+                        Action::OffloadKind DeviceOffloadKind) const override;
   void AddClangCXXStdlibIncludeArgs(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
diff --git a/clang/test/Driver/Inputs/resource_dir_with_per_target_subdir/lib/armv7m-vendor-none-eabi/libclang_rt.builtins.a b/clang/test/Driver/Inputs/resource_dir_with_per_target_subdir/lib/armv7m-vendor-none-eabi/libclang_rt.builtins.a
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/clang/test/Driver/baremetal.cpp b/clang/test/Driver/baremetal.cpp
index 7c11fe67155a..53c666d3a91a 100644
--- a/clang/test/Driver/baremetal.cpp
+++ b/clang/test/Driver/baremetal.cpp
@@ -31,6 +31,20 @@
 // RUN:   | FileCheck --check-prefix=CHECK-V6M-LIBINC %s
 // CHECK-V6M-LIBINC-NOT: "-internal-isystem"
 
+// RUN: %clang -no-canonical-prefixes -rtlib=compiler-rt %s -### -o %t.o 2>&1 \
+// RUN:     -target armv7m-vendor-none-eabi \
+// RUN:     --sysroot=%S/Inputs/baremetal_arm \
+// RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
+// RUN:   | FileCheck --check-prefix=CHECK-ARMV7M-PER-TARGET %s
+// CHECK-ARMV7M-PER-TARGET: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
+// CHECK-ARMV7M-PER-TARGET: "-isysroot" "[[SYSROOT:[^"]*]]"
+// CHECK-ARMV7M-PER-TARGET: "-x" "c++" "{{.*}}baremetal.cpp"
+// CHECK-ARMV7M-PER-TARGET: "{{[^"]*}}ld{{(\.(lld|bfd|gold))?}}{{(\.exe)?}}" "{{.*}}.o" "-Bstatic"
+// CHECK-ARMV7M-PER-TARGET: "-L[[SYSROOT:[^"]+]]{{[/\\]+}}lib"
+// CHECK-ARMV7M-PER-TARGET: "-L[[RESOURCE_DIR:[^"]+]]{{[/\\]+}}lib{{[/\\]+}}armv7m-vendor-none-eabi
+// CHECK-ARMV7M-PER-TARGET: "-lc" "-lm" "-lclang_rt.builtins"
+// CHECK-ARMV7M-PER-TARGET: "-o" "{{.*}}.o"
+
 // RUN: %clangxx -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target armv6m-none-eabi \
 // RUN:     --sysroot=%S/Inputs/baremetal_arm \
diff --git a/clang/test/Driver/print-libgcc-file-name-clangrt.c b/clang/test/Driver/print-libgcc-file-name-clangrt.c
index ac921ec38b12..5084c9966474 100644
--- a/clang/test/Driver/print-libgcc-file-name-clangrt.c
+++ b/clang/test/Driver/print-libgcc-file-name-clangrt.c
@@ -48,3 +48,9 @@
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_arch_subdir \
 // RUN:   | FileCheck --check-prefix=CHECK-CLANGRT-ARM-BAREMETAL %s
 // CHECK-CLANGRT-ARM-BAREMETAL: libclang_rt.builtins-armv7m.a
+
+// RUN: %clang -rtlib=compiler-rt -print-libgcc-file-name 2>&1 \
+// RUN:     --target=armv7m-vendor-none-eabi \
+// RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
+// RUN:   | FileCheck --check-prefix=CHECK-CLANGRT-ARM-BAREMETAL-PER-TARGET %s
+// CHECK-CLANGRT-ARM-BAREMETAL-PER-TARGET: libclang_rt.builtins.a