Hurd: Add x86_64 support (#78065)

This adds Hurd toolchain support to Clang's driver in addition to
handling
translating the triple from GCC toolchain-compatible form (x86_64-gnu)
to
the actual triple registered in LLVM (x86_64-pc-hurd-gnu).

Author: sthibaul

clang/lib/Basic/Targets.cpp

@@ -644,6 +644,8 @@ std::unique_ptr<TargetInfo> AllocateTarget(const llvm::Triple &Triple,
       return std::make_unique<PS4OSTargetInfo<X86_64TargetInfo>>(Triple, Opts);
     case llvm::Triple::PS5:
       return std::make_unique<PS5OSTargetInfo<X86_64TargetInfo>>(Triple, Opts);
+    case llvm::Triple::Hurd:
+      return std::make_unique<HurdTargetInfo<X86_64TargetInfo>>(Triple, Opts);
     default:
       return std::make_unique<X86_64TargetInfo>(Triple, Opts);
     }

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -2485,7 +2485,7 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
   static const char *const X86Triples[] = {
       "i586-linux-gnu",      "i686-linux-gnu",        "i686-pc-linux-gnu",
       "i386-redhat-linux6E", "i686-redhat-linux",     "i386-redhat-linux",
-      "i586-suse-linux",     "i686-montavista-linux", "i686-gnu",
+      "i586-suse-linux",     "i686-montavista-linux",
   };
 
   static const char *const LoongArch64LibDirs[] = {"/lib64", "/lib"};
@@ -2652,6 +2652,23 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
     return;
   }
 
+  if (TargetTriple.isOSHurd()) {
+    switch (TargetTriple.getArch()) {
+    case llvm::Triple::x86_64:
+      LibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
+      TripleAliases.push_back("x86_64-gnu");
+      break;
+    case llvm::Triple::x86:
+      LibDirs.append(begin(X86LibDirs), end(X86LibDirs));
+      TripleAliases.push_back("i686-gnu");
+      break;
+    default:
+      break;
+    }
+
+    return;
+  }
+
   switch (TargetTriple.getArch()) {
   case llvm::Triple::aarch64:
     LibDirs.append(begin(AArch64LibDirs), end(AArch64LibDirs));

clang/lib/Driver/ToolChains/Hurd.cpp

@@ -30,13 +30,21 @@ using tools::addPathIfExists;
 std::string Hurd::getMultiarchTriple(const Driver &D,
                                      const llvm::Triple &TargetTriple,
                                      StringRef SysRoot) const {
-  if (TargetTriple.getArch() == llvm::Triple::x86) {
+  switch (TargetTriple.getArch()) {
+  default:
+    break;
+
+  case llvm::Triple::x86:
     // We use the existence of '/lib/<triple>' as a directory to detect some
     // common hurd triples that don't quite match the Clang triple for both
     // 32-bit and 64-bit targets. Multiarch fixes its install triples to these
     // regardless of what the actual target triple is.
     if (D.getVFS().exists(SysRoot + "/lib/i386-gnu"))
       return "i386-gnu";
+    break;
+
+  case llvm::Triple::x86_64:
+    return "x86_64-gnu";
   }
 
   // For most architectures, just use whatever we have rather than trying to be
@@ -126,8 +134,12 @@ Tool *Hurd::buildAssembler() const {
 }
 
 std::string Hurd::getDynamicLinker(const ArgList &Args) const {
-  if (getArch() == llvm::Triple::x86)
+  switch (getArch()) {
+  case llvm::Triple::x86:
     return "/lib/ld.so";
+  case llvm::Triple::x86_64:
+    return "/lib/ld-x86-64.so.1";
+  }
 
   llvm_unreachable("unsupported architecture");
 }