Revert "Reland [Driver] Add support for GCC installation detection in… (#144684)

… Baremetal toolchain (#144640)"

This reverts commit 45ea46c.

Author: Garvit Gupta

clang/docs/Toolchain.rst

@@ -347,8 +347,3 @@ workarounds for issues discovered in libstdc++, and these are removed
 as fixed libstdc++ becomes sufficiently old.
 
 You can instruct Clang to use libstdc++ with the ``-stdlib=libstdc++`` flag.
-
-GCC Installation
-=================
-Users can point to their GCC installation by using the ``-gcc-toolchain`` or by
-using ``-gcc-install-dir`` flag.

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -847,9 +847,6 @@ def note_drv_available_multilibs : Note<
   "available multilibs are:%0">;
 def err_drv_multilib_custom_error : Error<
   "multilib configuration error: %0">;
-def warn_drv_multilib_not_available_for_target: Warning<
-  "no multilib structure encoded for Arm, Aarch64 and PPC targets">,
-  InGroup<DiagGroup<"multilib-not-found">>;
 
 def err_drv_experimental_crel : Error<
   "-Wa,--allow-experimental-crel must be specified to use -Wa,--crel. "

clang/lib/Driver/ToolChains/BareMetal.cpp

@@ -31,40 +31,6 @@ using namespace clang::driver;
 using namespace clang::driver::tools;
 using namespace clang::driver::toolchains;
 
-/// Is the triple {aarch64.aarch64_be}-none-elf?
-static bool isAArch64BareMetal(const llvm::Triple &Triple) {
-  if (Triple.getArch() != llvm::Triple::aarch64 &&
-      Triple.getArch() != llvm::Triple::aarch64_be)
-    return false;
-
-  if (Triple.getVendor() != llvm::Triple::UnknownVendor)
-    return false;
-
-  if (Triple.getOS() != llvm::Triple::UnknownOS)
-    return false;
-
-  return Triple.getEnvironmentName() == "elf";
-}
-
-static bool isRISCVBareMetal(const llvm::Triple &Triple) {
-  if (!Triple.isRISCV())
-    return false;
-
-  if (Triple.getVendor() != llvm::Triple::UnknownVendor)
-    return false;
-
-  if (Triple.getOS() != llvm::Triple::UnknownOS)
-    return false;
-
-  return Triple.getEnvironmentName() == "elf";
-}
-
-/// Is the triple powerpc[64][le]-*-none-eabi?
-static bool isPPCBareMetal(const llvm::Triple &Triple) {
-  return Triple.isPPC() && Triple.getOS() == llvm::Triple::UnknownOS &&
-         Triple.getEnvironment() == llvm::Triple::EABI;
-}
-
 static bool findRISCVMultilibs(const Driver &D,
                                const llvm::Triple &TargetTriple,
                                const ArgList &Args, DetectedMultilibs &Result) {
@@ -129,8 +95,7 @@ static bool findRISCVMultilibs(const Driver &D,
   return false;
 }
 
-static std::string computeClangRuntimesSysRoot(const Driver &D,
-                                               bool IncludeTriple) {
+static std::string computeBaseSysRoot(const Driver &D, bool IncludeTriple) {
   if (!D.SysRoot.empty())
     return D.SysRoot;
 
@@ -143,123 +108,56 @@ static std::string computeClangRuntimesSysRoot(const Driver &D,
   return std::string(SysRootDir);
 }
 
-// Only consider the GCC toolchain based on the values provided through the
-// `--gcc-toolchain` and `--gcc-install-dir` flags. The function below returns
-// whether the GCC toolchain was initialized successfully.
-bool BareMetal::initGCCInstallation(const llvm::Triple &Triple,
-                                    const llvm::opt::ArgList &Args) {
-  if (Args.getLastArg(options::OPT_gcc_toolchain) ||
-      Args.getLastArg(clang::driver::options::OPT_gcc_install_dir_EQ)) {
-    GCCInstallation.init(Triple, Args);
-    return GCCInstallation.isValid();
+BareMetal::BareMetal(const Driver &D, const llvm::Triple &Triple,
+                     const ArgList &Args)
+    : ToolChain(D, Triple, Args),
+      SysRoot(computeBaseSysRoot(D, /*IncludeTriple=*/true)) {
+  getProgramPaths().push_back(getDriver().Dir);
+
+  findMultilibs(D, Triple, Args);
+  SmallString<128> SysRoot(computeSysRoot());
+  if (!SysRoot.empty()) {
+    for (const Multilib &M : getOrderedMultilibs()) {
+      SmallString<128> Dir(SysRoot);
+      llvm::sys::path::append(Dir, M.osSuffix(), "lib");
+      getFilePaths().push_back(std::string(Dir));
+      getLibraryPaths().push_back(std::string(Dir));
+    }
   }
-  return false;
 }
 
-// This logic is adapted from RISCVToolChain.cpp as part of the ongoing effort
-// to merge RISCVToolChain into the Baremetal toolchain. It infers the presence
-// of a valid GCC toolchain by checking whether the `crt0.o` file exists in the
-// `bin/../<target-triple>/lib` directory.
-static bool detectGCCToolchainAdjacent(const Driver &D) {
-  SmallString<128> GCCDir;
-  llvm::sys::path::append(GCCDir, D.Dir, "..", D.getTargetTriple(),
-                          "lib/crt0.o");
-  return llvm::sys::fs::exists(GCCDir);
-}
+/// Is the triple {aarch64.aarch64_be}-none-elf?
+static bool isAArch64BareMetal(const llvm::Triple &Triple) {
+  if (Triple.getArch() != llvm::Triple::aarch64 &&
+      Triple.getArch() != llvm::Triple::aarch64_be)
+    return false;
 
-// If no sysroot is provided the driver will first attempt to infer it from the
-// values of `--gcc-install-dir` or `--gcc-toolchain`, which specify the
-// location of a GCC toolchain.
-// If neither flag is used, the sysroot defaults to either:
-//    - `bin/../<target-triple>`
-//    - `bin/../lib/clang-runtimes/<target-triple>`
-//
-// To use the `clang-runtimes` path, ensure that `../<target-triple>/lib/crt0.o`
-// does not exist relative to the driver.
-std::string BareMetal::computeSysRoot() const {
-  // Use Baremetal::sysroot if it has already been set.
-  if (!SysRoot.empty())
-    return SysRoot;
-
-  // Use the sysroot specified via the `--sysroot` command-line flag, if
-  // provided.
-  const Driver &D = getDriver();
-  if (!D.SysRoot.empty())
-    return D.SysRoot;
+  if (Triple.getVendor() != llvm::Triple::UnknownVendor)
+    return false;
 
-  // Attempt to infer sysroot from a valid GCC installation.
-  // If no valid GCC installation, check for a GCC toolchain alongside Clang.
-  SmallString<128> inferredSysRoot;
-  if (IsGCCInstallationValid) {
-    llvm::sys::path::append(inferredSysRoot, GCCInstallation.getParentLibPath(),
-                            "..", GCCInstallation.getTriple().str());
-  } else if (detectGCCToolchainAdjacent(D)) {
-    // Use the triple as provided to the driver. Unlike the parsed triple
-    // this has not been normalized to always contain every field.
-    llvm::sys::path::append(inferredSysRoot, D.Dir, "..", D.getTargetTriple());
-  }
-  // If a valid sysroot was inferred and exists, use it
-  if (!inferredSysRoot.empty() && llvm::sys::fs::exists(inferredSysRoot))
-    return std::string(inferredSysRoot);
+  if (Triple.getOS() != llvm::Triple::UnknownOS)
+    return false;
 
-  // Use the clang-runtimes path.
-  return computeClangRuntimesSysRoot(D, /*IncludeTriple*/ true);
+  return Triple.getEnvironmentName() == "elf";
 }
 
-static void addMultilibsFilePaths(const Driver &D, const MultilibSet &Multilibs,
-                                  const Multilib &Multilib,
-                                  StringRef InstallPath,
-                                  ToolChain::path_list &Paths) {
-  if (const auto &PathsCallback = Multilibs.filePathsCallback())
-    for (const auto &Path : PathsCallback(Multilib))
-      addPathIfExists(D, InstallPath + Path, Paths);
+static bool isRISCVBareMetal(const llvm::Triple &Triple) {
+  if (!Triple.isRISCV())
+    return false;
+
+  if (Triple.getVendor() != llvm::Triple::UnknownVendor)
+    return false;
+
+  if (Triple.getOS() != llvm::Triple::UnknownOS)
+    return false;
+
+  return Triple.getEnvironmentName() == "elf";
 }
 
-// GCC mutltilibs will only work for those targets that have their multlib
-// structure encoded into GCCInstallation. Baremetal toolchain supports ARM,
-// AArch64, RISCV and PPC and of these only RISCV have GCC multilibs hardcoded
-// in GCCInstallation.
-BareMetal::BareMetal(const Driver &D, const llvm::Triple &Triple,
-                     const ArgList &Args)
-    : Generic_ELF(D, Triple, Args) {
-  IsGCCInstallationValid = initGCCInstallation(Triple, Args);
-  std::string ComputedSysRoot = computeSysRoot();
-  if (IsGCCInstallationValid) {
-    if (!isRISCVBareMetal(Triple))
-      D.Diag(clang::diag::warn_drv_multilib_not_available_for_target);
-
-    Multilibs = GCCInstallation.getMultilibs();
-    SelectedMultilibs.assign({GCCInstallation.getMultilib()});
-
-    path_list &Paths = getFilePaths();
-    // Add toolchain/multilib specific file paths.
-    addMultilibsFilePaths(D, Multilibs, SelectedMultilibs.back(),
-                          GCCInstallation.getInstallPath(), Paths);
-    // Adding filepath for locating crt{begin,end}.o files.
-    Paths.push_back(GCCInstallation.getInstallPath().str());
-    // Adding filepath for locating crt0.o file.
-    Paths.push_back(ComputedSysRoot + "/lib");
-
-    ToolChain::path_list &PPaths = getProgramPaths();
-    // Multilib cross-compiler GCC installations put ld in a triple-prefixed
-    // directory off of the parent of the GCC installation.
-    PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
-                           GCCInstallation.getTriple().str() + "/bin")
-                         .str());
-    PPaths.push_back((GCCInstallation.getParentLibPath() + "/../bin").str());
-  } else {
-    getProgramPaths().push_back(getDriver().Dir);
-    findMultilibs(D, Triple, Args);
-    const SmallString<128> SysRootDir(computeSysRoot());
-    if (!SysRootDir.empty()) {
-      for (const Multilib &M : getOrderedMultilibs()) {
-        SmallString<128> Dir(SysRootDir);
-        llvm::sys::path::append(Dir, M.osSuffix(), "lib");
-        getFilePaths().push_back(std::string(Dir));
-        getLibraryPaths().push_back(std::string(Dir));
-      }
-    }
-  }
+/// Is the triple powerpc[64][le]-*-none-eabi?
+static bool isPPCBareMetal(const llvm::Triple &Triple) {
+  return Triple.isPPC() && Triple.getOS() == llvm::Triple::UnknownOS &&
+         Triple.getEnvironment() == llvm::Triple::EABI;
 }
 
 static void
@@ -318,7 +216,7 @@ getMultilibConfigPath(const Driver &D, const llvm::Triple &Triple,
       return {};
     }
   } else {
-    MultilibPath = computeClangRuntimesSysRoot(D, /*IncludeTriple=*/false);
+    MultilibPath = computeBaseSysRoot(D, /*IncludeTriple=*/false);
     llvm::sys::path::append(MultilibPath, MultilibFilename);
   }
   return MultilibPath;
@@ -336,15 +234,15 @@ void BareMetal::findMultilibs(const Driver &D, const llvm::Triple &Triple,
   if (D.getVFS().exists(*MultilibPath)) {
     // If multilib.yaml is found, update sysroot so it doesn't use a target
     // specific suffix
-    SysRoot = computeClangRuntimesSysRoot(D, /*IncludeTriple=*/false);
+    SysRoot = computeBaseSysRoot(D, /*IncludeTriple=*/false);
     SmallVector<StringRef> CustomFlagMacroDefines;
     findMultilibsFromYAML(*this, D, *MultilibPath, Args, Result,
                           CustomFlagMacroDefines);
     SelectedMultilibs = Result.SelectedMultilibs;
     Multilibs = Result.Multilibs;
     MultilibMacroDefines.append(CustomFlagMacroDefines.begin(),
                                 CustomFlagMacroDefines.end());
-  } else if (isRISCVBareMetal(Triple) && !detectGCCToolchainAdjacent(D)) {
+  } else if (isRISCVBareMetal(Triple)) {
     if (findRISCVMultilibs(D, Triple, Args, Result)) {
       SelectedMultilibs = Result.SelectedMultilibs;
       Multilibs = Result.Multilibs;
@@ -365,6 +263,8 @@ Tool *BareMetal::buildStaticLibTool() const {
   return new tools::baremetal::StaticLibTool(*this);
 }
 
+std::string BareMetal::computeSysRoot() const { return SysRoot; }
+
 BareMetal::OrderedMultilibs BareMetal::getOrderedMultilibs() const {
   // Get multilibs in reverse order because they're ordered most-specific last.
   if (!SelectedMultilibs.empty())
@@ -392,10 +292,10 @@ void BareMetal::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   if (std::optional<std::string> Path = getStdlibIncludePath())
     addSystemInclude(DriverArgs, CC1Args, *Path);
 
-  const SmallString<128> SysRootDir(computeSysRoot());
-  if (!SysRootDir.empty()) {
+  const SmallString<128> SysRoot(computeSysRoot());
+  if (!SysRoot.empty()) {
     for (const Multilib &M : getOrderedMultilibs()) {
-      SmallString<128> Dir(SysRootDir);
+      SmallString<128> Dir(SysRoot);
       llvm::sys::path::append(Dir, M.includeSuffix());
       llvm::sys::path::append(Dir, "include");
       addSystemInclude(DriverArgs, CC1Args, Dir.str());
@@ -409,19 +309,6 @@ void BareMetal::addClangTargetOptions(const ArgList &DriverArgs,
   CC1Args.push_back("-nostdsysteminc");
 }
 
-void BareMetal::addLibStdCxxIncludePaths(
-    const llvm::opt::ArgList &DriverArgs,
-    llvm::opt::ArgStringList &CC1Args) const {
-  if (!IsGCCInstallationValid)
-    return;
-  const GCCVersion &Version = GCCInstallation.getVersion();
-  StringRef TripleStr = GCCInstallation.getTriple().str();
-  const Multilib &Multilib = GCCInstallation.getMultilib();
-  addLibStdCXXIncludePaths(computeSysRoot() + "/include/c++/" + Version.Text,
-                           TripleStr, Multilib.includeSuffix(), DriverArgs,
-                           CC1Args);
-}
-
 void BareMetal::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                              ArgStringList &CC1Args) const {
   if (DriverArgs.hasArg(options::OPT_nostdinc, options::OPT_nostdlibinc,
@@ -452,23 +339,23 @@ void BareMetal::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
   };
 
   switch (GetCXXStdlibType(DriverArgs)) {
-  case ToolChain::CST_Libcxx: {
-    SmallString<128> P(D.Dir);
-    llvm::sys::path::append(P, "..", "include");
-    AddCXXIncludePath(P);
-    break;
-  }
-  case ToolChain::CST_Libstdcxx:
-    addLibStdCxxIncludePaths(DriverArgs, CC1Args);
-    break;
+    case ToolChain::CST_Libcxx: {
+      SmallString<128> P(D.Dir);
+      llvm::sys::path::append(P, "..", "include");
+      AddCXXIncludePath(P);
+      break;
+    }
+    case ToolChain::CST_Libstdcxx:
+      // We only support libc++ toolchain installation.
+      break;
   }
 
-  std::string SysRootDir(computeSysRoot());
-  if (SysRootDir.empty())
+  std::string SysRoot(computeSysRoot());
+  if (SysRoot.empty())
     return;
 
   for (const Multilib &M : getOrderedMultilibs()) {
-    SmallString<128> Dir(SysRootDir);
+    SmallString<128> Dir(SysRoot);
     llvm::sys::path::append(Dir, M.gccSuffix());
     switch (GetCXXStdlibType(DriverArgs)) {
     case ToolChain::CST_Libcxx: {