[Triple][Driver] Add muslx32 environment and use /lib/ld-musl-x32.so.1 for -dynamic-linker

[raj.khem]

once you fix the clang-format issue reported this looks good to me.

[MaskRay]

In D99308#2649636, @raj.khem wrote:

once you fix the clang-format issue reported this looks good to me.

I'll ignore it... The first block does not directly touch the formatted part and the second block would need a larger formatting... Such formatting changes should be done separately, if done at all, not mixed in this functionality patch.
Personally I deem the formatting less useful, so I'll ignore it.

[MaskRay]

Fix test

clang/lib/Driver/ToolChains/Linux.cpp

if (Triple.isMusl()) {
     case llvm::Triple::armeb:
     case llvm::Triple::thumbeb:
       ArchName = "armeb";
       IsArm = true;
       break;
     case llvm::Triple::x86:
       ArchName = "i386";
       break;
+    case llvm::Triple::x86_64:
+      ArchName = Triple.getEnvironment() == llvm::Triple::MuslX32
+                     ? "x32"
+                     : Triple.getArchName().str();
+      break;
     default:
       ArchName = Triple.getArchName().str();
     }
     if (IsArm &&
         (Triple.getEnvironment() == llvm::Triple::MuslEABIHF ||
          tools::arm::getARMFloatABI(*this, Args) == tools::arm::FloatABI::Hard))
       ArchName += "hf";
 

clang/test/Driver/linux-cross.cpp

 // DEBIAN_AARCH64-SAME: {{^}} "-L[[SYSROOT]]/usr/lib/gcc-cross/aarch64-linux-gnu/10/../../.."
 // DEBIAN_AARCH64-SAME: {{^}} "-L[[SYSROOT]]/lib"
 // DEBIAN_AARCH64-SAME: {{^}} "-L[[SYSROOT]]/usr/lib"
 
 /// LDSO_ARCH is i386 for all x86-32 variants.
 // RUN: %clang -### %s --target=i686-linux-musl --sysroot= \
 // RUN:   --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=MUSL_I686
 // MUSL_I686: "-dynamic-linker" "/lib/ld-musl-i386.so.1"
+
+// RUN: %clang -### %s --target=x86_64-linux-muslx32 --sysroot= \
+// RUN:   --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=MUSL_X32
+// MUSL_X32: "-dynamic-linker" "/lib/ld-musl-x32.so.1"

llvm/include/llvm/ADT/Triple.h

enum EnvironmentType {
     GNUILP32,
     CODE16,
     EABI,
     EABIHF,
     Android,
     Musl,
     MuslEABI,
     MuslEABIHF,
+    MuslX32,
 
     MSVC,
     Itanium,
     Cygnus,
     CoreCLR,
     Simulator, // Simulator variants of other systems, e.g., Apple's iOS
     MacABI, // Mac Catalyst variant of Apple's iOS deployment target.
     LastEnvironmentType = MacABI
bool isAndroidVersionLT(unsigned Major) const {
 
     return Env[0] < Major;
   }
 
   /// Tests whether the environment is musl-libc
   bool isMusl() const {
     return getEnvironment() == Triple::Musl ||
            getEnvironment() == Triple::MuslEABI ||
-           getEnvironment() == Triple::MuslEABIHF;
+           getEnvironment() == Triple::MuslEABIHF ||
+           getEnvironment() == Triple::MuslX32;
   }
 
   /// Tests whether the target is SPIR (32- or 64-bit).
   bool isSPIR() const {
     return getArch() == Triple::spir || getArch() == Triple::spir64;
   }
 
   /// Tests whether the target is NVPTX (32- or 64-bit).

llvm/lib/Support/Triple.cpp

StringRef Triple::getEnvironmentTypeName(EnvironmentType Kind) {
   case GNUX32: return "gnux32";
   case GNUILP32: return "gnu_ilp32";
   case Itanium: return "itanium";
   case MSVC: return "msvc";
   case MacABI: return "macabi";
   case Musl: return "musl";
   case MuslEABI: return "musleabi";
   case MuslEABIHF: return "musleabihf";
+  case MuslX32: return "muslx32";
   case Simulator: return "simulator";
   }
 
   llvm_unreachable("Invalid EnvironmentType!");
 }
 
 static Triple::ArchType parseBPFArch(StringRef ArchName) {
   if (ArchName.equals("bpf")) {
return StringSwitch<Triple::EnvironmentType>(EnvironmentName)
       .StartsWith("gnueabi", Triple::GNUEABI)
       .StartsWith("gnux32", Triple::GNUX32)
       .StartsWith("gnu_ilp32", Triple::GNUILP32)
       .StartsWith("code16", Triple::CODE16)
       .StartsWith("gnu", Triple::GNU)
       .StartsWith("android", Triple::Android)
       .StartsWith("musleabihf", Triple::MuslEABIHF)
       .StartsWith("musleabi", Triple::MuslEABI)
+      .StartsWith("muslx32", Triple::MuslX32)
       .StartsWith("musl", Triple::Musl)
       .StartsWith("msvc", Triple::MSVC)
       .StartsWith("itanium", Triple::Itanium)
       .StartsWith("cygnus", Triple::Cygnus)
       .StartsWith("coreclr", Triple::CoreCLR)
       .StartsWith("simulator", Triple::Simulator)
       .StartsWith("macabi", Triple::MacABI)
       .Default(Triple::UnknownEnvironment);

llvm/unittests/ADT/TripleTest.cpp

TEST(TripleTest, ParsedIDs) {
   EXPECT_EQ(Triple::GNU, T.getEnvironment());
 
   T = Triple("x86_64-pc-linux-musl");
   EXPECT_EQ(Triple::x86_64, T.getArch());
   EXPECT_EQ(Triple::PC, T.getVendor());
   EXPECT_EQ(Triple::Linux, T.getOS());
   EXPECT_EQ(Triple::Musl, T.getEnvironment());
 
+  T = Triple("x86_64-pc-linux-muslx32");
+  EXPECT_EQ(Triple::x86_64, T.getArch());
+  EXPECT_EQ(Triple::PC, T.getVendor());
+  EXPECT_EQ(Triple::Linux, T.getOS());
+  EXPECT_EQ(Triple::MuslX32, T.getEnvironment());
+
   // PS4 has two spellings for the vendor.
   T = Triple("x86_64-scei-ps4");
   EXPECT_EQ(Triple::x86_64, T.getArch());
   EXPECT_EQ(Triple::SCEI, T.getVendor());
   EXPECT_EQ(Triple::PS4, T.getOS());
 
   T = Triple("x86_64-sie-ps4");
   EXPECT_EQ(Triple::x86_64, T.getArch());