[Driver] Clean up Debian multiarch /usr/include/<triplet> madness

Debian multiarch additionally adds /usr/include/<triplet> and somehow
Android borrowed the idea. (Note /usr/<triplet>/include is already an
include dir...). On Debian, we should just assume a GCC installation is
available and use its triple.

Author: MaskRay

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -2999,8 +2999,6 @@ Generic_GCC::addGCCLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
   const Multilib &Multilib = GCCInstallation.getMultilib();
   const std::string Triple = getMultiarchTriple(
       getDriver(), GCCInstallation.getTriple(), getDriver().SysRoot);
-  const std::string TargetMultiarchTriple =
-      getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
   const GCCVersion &Version = GCCInstallation.getVersion();
 
   // Try /../$triple/include/c++/$version then /../include/c++/$version.

clang/lib/Driver/ToolChains/Linux.cpp

@@ -604,172 +604,16 @@ void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
     return;
   }
 
-  // Implement generic Debian multiarch support.
-  const StringRef X86_64MultiarchIncludeDirs[] = {
-      "/usr/include/x86_64-linux-gnu",
-
-      // FIXME: These are older forms of multiarch. It's not clear that they're
-      // in use in any released version of Debian, so we should consider
-      // removing them.
-      "/usr/include/i686-linux-gnu/64", "/usr/include/i486-linux-gnu/64"};
-  const StringRef X86MultiarchIncludeDirs[] = {
-      "/usr/include/i386-linux-gnu",
-
-      // FIXME: These are older forms of multiarch. It's not clear that they're
-      // in use in any released version of Debian, so we should consider
-      // removing them.
-      "/usr/include/x86_64-linux-gnu/32", "/usr/include/i686-linux-gnu",
-      "/usr/include/i486-linux-gnu"};
-  const StringRef AArch64MultiarchIncludeDirs[] = {
-      "/usr/include/aarch64-linux-gnu"};
-  const StringRef ARMMultiarchIncludeDirs[] = {
-      "/usr/include/arm-linux-gnueabi"};
-  const StringRef ARMHFMultiarchIncludeDirs[] = {
-      "/usr/include/arm-linux-gnueabihf"};
-  const StringRef ARMEBMultiarchIncludeDirs[] = {
-      "/usr/include/armeb-linux-gnueabi"};
-  const StringRef ARMEBHFMultiarchIncludeDirs[] = {
-      "/usr/include/armeb-linux-gnueabihf"};
-  const StringRef M68kMultiarchIncludeDirs[] = {"/usr/include/m68k-linux-gnu"};
-  const StringRef MIPSMultiarchIncludeDirs[] = {"/usr/include/mips-linux-gnu"};
-  const StringRef MIPSELMultiarchIncludeDirs[] = {
-      "/usr/include/mipsel-linux-gnu"};
-  const StringRef MIPS64MultiarchIncludeDirs[] = {
-      "/usr/include/mips64-linux-gnuabi64"};
-  const StringRef MIPS64ELMultiarchIncludeDirs[] = {
-      "/usr/include/mips64el-linux-gnuabi64"};
-  const StringRef MIPSN32MultiarchIncludeDirs[] = {
-      "/usr/include/mips64-linux-gnuabin32"};
-  const StringRef MIPSN32ELMultiarchIncludeDirs[] = {
-      "/usr/include/mips64el-linux-gnuabin32"};
-  const StringRef MIPSR6MultiarchIncludeDirs[] = {
-      "/usr/include/mipsisa32-linux-gnu"};
-  const StringRef MIPSR6ELMultiarchIncludeDirs[] = {
-      "/usr/include/mipsisa32r6el-linux-gnu"};
-  const StringRef MIPS64R6MultiarchIncludeDirs[] = {
-      "/usr/include/mipsisa64r6-linux-gnuabi64"};
-  const StringRef MIPS64R6ELMultiarchIncludeDirs[] = {
-      "/usr/include/mipsisa64r6el-linux-gnuabi64"};
-  const StringRef MIPSN32R6MultiarchIncludeDirs[] = {
-      "/usr/include/mipsisa64r6-linux-gnuabin32"};
-  const StringRef MIPSN32R6ELMultiarchIncludeDirs[] = {
-      "/usr/include/mipsisa64r6el-linux-gnuabin32"};
-  const StringRef PPCMultiarchIncludeDirs[] = {
-      "/usr/include/powerpc-linux-gnu",
-      "/usr/include/powerpc-linux-gnuspe"};
-  const StringRef PPCLEMultiarchIncludeDirs[] = {
-      "/usr/include/powerpcle-linux-gnu"};
-  const StringRef PPC64MultiarchIncludeDirs[] = {
-      "/usr/include/powerpc64-linux-gnu"};
-  const StringRef PPC64LEMultiarchIncludeDirs[] = {
-      "/usr/include/powerpc64le-linux-gnu"};
-  const StringRef SparcMultiarchIncludeDirs[] = {
-      "/usr/include/sparc-linux-gnu"};
-  const StringRef Sparc64MultiarchIncludeDirs[] = {
-      "/usr/include/sparc64-linux-gnu"};
-  const StringRef SYSTEMZMultiarchIncludeDirs[] = {
-      "/usr/include/s390x-linux-gnu"};
-  ArrayRef<StringRef> MultiarchIncludeDirs;
-  switch (getTriple().getArch()) {
-  case llvm::Triple::x86_64:
-    MultiarchIncludeDirs = X86_64MultiarchIncludeDirs;
-    break;
-  case llvm::Triple::x86:
-    MultiarchIncludeDirs = X86MultiarchIncludeDirs;
-    break;
-  case llvm::Triple::aarch64:
-  case llvm::Triple::aarch64_be:
-    MultiarchIncludeDirs = AArch64MultiarchIncludeDirs;
-    break;
-  case llvm::Triple::arm:
-  case llvm::Triple::thumb:
-    if (getTriple().getEnvironment() == llvm::Triple::GNUEABIHF)
-      MultiarchIncludeDirs = ARMHFMultiarchIncludeDirs;
-    else
-      MultiarchIncludeDirs = ARMMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::armeb:
-  case llvm::Triple::thumbeb:
-    if (getTriple().getEnvironment() == llvm::Triple::GNUEABIHF)
-      MultiarchIncludeDirs = ARMEBHFMultiarchIncludeDirs;
-    else
-      MultiarchIncludeDirs = ARMEBMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::m68k:
-    MultiarchIncludeDirs = M68kMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::mips:
-    if (getTriple().getSubArch() == llvm::Triple::MipsSubArch_r6)
-      MultiarchIncludeDirs = MIPSR6MultiarchIncludeDirs;
-    else
-      MultiarchIncludeDirs = MIPSMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::mipsel:
-    if (getTriple().getSubArch() == llvm::Triple::MipsSubArch_r6)
-      MultiarchIncludeDirs = MIPSR6ELMultiarchIncludeDirs;
-    else
-      MultiarchIncludeDirs = MIPSELMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::mips64:
-    if (getTriple().getSubArch() == llvm::Triple::MipsSubArch_r6)
-      if (getTriple().getEnvironment() == llvm::Triple::GNUABIN32)
-        MultiarchIncludeDirs = MIPSN32R6MultiarchIncludeDirs;
-      else
-        MultiarchIncludeDirs = MIPS64R6MultiarchIncludeDirs;
-    else if (getTriple().getEnvironment() == llvm::Triple::GNUABIN32)
-      MultiarchIncludeDirs = MIPSN32MultiarchIncludeDirs;
-    else
-      MultiarchIncludeDirs = MIPS64MultiarchIncludeDirs;
-    break;
-  case llvm::Triple::mips64el:
-    if (getTriple().getSubArch() == llvm::Triple::MipsSubArch_r6)
-      if (getTriple().getEnvironment() == llvm::Triple::GNUABIN32)
-        MultiarchIncludeDirs = MIPSN32R6ELMultiarchIncludeDirs;
-      else
-        MultiarchIncludeDirs = MIPS64R6ELMultiarchIncludeDirs;
-    else if (getTriple().getEnvironment() == llvm::Triple::GNUABIN32)
-      MultiarchIncludeDirs = MIPSN32ELMultiarchIncludeDirs;
-    else
-      MultiarchIncludeDirs = MIPS64ELMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::ppc:
-    MultiarchIncludeDirs = PPCMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::ppcle:
-    MultiarchIncludeDirs = PPCLEMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::ppc64:
-    MultiarchIncludeDirs = PPC64MultiarchIncludeDirs;
-    break;
-  case llvm::Triple::ppc64le:
-    MultiarchIncludeDirs = PPC64LEMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::sparc:
-    MultiarchIncludeDirs = SparcMultiarchIncludeDirs;
-    break;
-  case llvm::Triple::sparcv9:
-    MultiarchIncludeDirs = Sparc64MultiarchIncludeDirs;
-    break;
-  case llvm::Triple::systemz:
-    MultiarchIncludeDirs = SYSTEMZMultiarchIncludeDirs;
-    break;
-  default:
-    break;
-  }
-
-  const std::string AndroidMultiarchIncludeDir =
-      std::string("/usr/include/") +
-      getMultiarchTriple(D, getTriple(), SysRoot);
-  const StringRef AndroidMultiarchIncludeDirs[] = {AndroidMultiarchIncludeDir};
+  // On Android and Debian, add /usr/include/$triple if exists. On Debian, we
+  // can assume a GCC installation is available.
+  std::string MultiarchIncludeDir;
   if (getTriple().isAndroid())
-    MultiarchIncludeDirs = AndroidMultiarchIncludeDirs;
-
-  for (StringRef Dir : MultiarchIncludeDirs) {
-    if (D.getVFS().exists(SysRoot + Dir)) {
-      addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + Dir);
-      break;
-    }
-  }
+    MultiarchIncludeDir = getMultiarchTriple(D, getTriple(), SysRoot);
+  else if (GCCInstallation.isValid())
+    MultiarchIncludeDir = GCCInstallation.getTriple().str();
+  if (!MultiarchIncludeDir.empty() &&
+      D.getVFS().exists(SysRoot + "/usr/include/" + MultiarchIncludeDir))
+    addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include/" + MultiarchIncludeDir);
 
   if (getTriple().getOS() == llvm::Triple::RTEMS)
     return;

clang/test/Driver/Inputs/multilib_armeb_linux_tree/usr/include/armeb-linux-gnueabi/.keep renamed to clang/test/Driver/Inputs/multilib_arm_linux_tree/lib/arm-linux-gnueabi/crt1.o

@@ -1,14 +1,14 @@
-// RUN: %clang -target armv7-linux-gnueabi --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARM %s
-// RUN: %clang -target thumbv7-linux-gnueabi --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARM %s
+// RUN: %clang --target=armv7-linux-gnueabi --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARM %s
+// RUN: %clang --target=thumbv7-linux-gnueabi --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARM %s
 
-// RUN: %clang -target armv7-linux-gnueabihf --sysroot=%S/Inputs/multilib_armhf_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARMHF %s
-// RUN: %clang -target thumbv7-linux-gnueabihf --sysroot=%S/Inputs/multilib_armhf_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARMHF %s
+// RUN: %clang --target=armv7-linux-gnueabihf --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARMHF %s
+// RUN: %clang --target=thumbv7-linux-gnueabihf --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARMHF %s
 
-// RUN: %clang -target armv7eb-linux-gnueabi --sysroot=%S/Inputs/multilib_armeb_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARMEB %s
-// RUN: %clang -target thumbv7eb-linux-gnueabi --sysroot=%S/Inputs/multilib_armeb_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARMEB %s
+// RUN: %clang --target=armv7eb-linux-gnueabi --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARMEB %s
+// RUN: %clang --target=thumbv7eb-linux-gnueabi --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARMEB %s
 
-// RUN: %clang -target armv7eb-linux-gnueabihf --sysroot=%S/Inputs/multilib_armebhf_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARMEBHF %s
-// RUN: %clang -target thumbv7eb-linux-gnueabihf --sysroot=%S/Inputs/multilib_armebhf_linux_tree -### -c %s -o /dev/null 2>&1 | FileCheck -check-prefix CHECK-ARMEBHF %s
+// RUN: %clang --target=armv7eb-linux-gnueabihf --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARMEBHF %s
+// RUN: %clang --target=thumbv7eb-linux-gnueabihf --sysroot=%S/Inputs/multilib_arm_linux_tree -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-ARMEBHF %s
 
 // CHECK-ARM: "-internal-externc-isystem" "{{.*}}/usr/include/arm-linux-gnueabi"
 // CHECK-ARMHF: "-internal-externc-isystem" "{{.*}}/usr/include/arm-linux-gnueabihf"