[𝘀𝗽𝗿] initial version

Created using spr 1.3.4
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index 2c4fb674..6b96764 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -359,6 +359,9 @@
 /// The default TLS model to use.
 ENUM_CODEGENOPT(DefaultTLSModel, TLSModel, 2, GeneralDynamicTLSModel)
 
+/// The default TLS model to use.
+ENUM_CODEGENOPT(DefaultTLSDialect, TLSDialect, 2, TraditionalTLSDialect)
+
 /// Bit size of immediate TLS offsets (0 == use the default).
 VALUE_CODEGENOPT(TLSSize, 8, 0)
 
diff --git a/clang/include/clang/Basic/CodeGenOptions.h b/clang/include/clang/Basic/CodeGenOptions.h
index 6952b48..23180ab 100644
--- a/clang/include/clang/Basic/CodeGenOptions.h
+++ b/clang/include/clang/Basic/CodeGenOptions.h
@@ -72,6 +72,11 @@
     LocalExecTLSModel
   };
 
+  enum TLSDialect {
+    TraditionalTLSDialect,
+    TLSDescTLSDialect,
+  };
+
   enum StructReturnConventionKind {
     SRCK_Default,  // No special option was passed.
     SRCK_OnStack,  // Small structs on the stack (-fpcc-struct-return).
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index d2e6c3ff..e0923dc 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4403,6 +4403,13 @@
   HelpText<"Specify bit size of immediate TLS offsets (AArch64 ELF only): "
            "12 (for 4KB) | 24 (for 16MB, default) | 32 (for 4GB) | 48 (for 256TB, needs -mcmodel=large)">,
   MarshallingInfoInt<CodeGenOpts<"TLSSize">>;
+def mtls_dialect_EQ : Joined<["-"], "mtls-dialect=">, Group<m_Group>,
+  Visibility<[ClangOption, CC1Option]>,
+  HelpText<"Use the given thread-local storage dialect">,
+  Values<"trad,desc">,
+  NormalizedValuesScope<"CodeGenOptions">,
+  NormalizedValues<["TraditionalTLSDialect", "TLSDescTLSDialect"]>,
+  MarshallingInfoEnum<CodeGenOpts<"DefaultTLSDialect">, "TraditionalTLSDialect">;
 def mimplicit_it_EQ : Joined<["-"], "mimplicit-it=">, Group<m_Group>;
 def mdefault_build_attributes : Joined<["-"], "mdefault-build-attributes">, Group<m_Group>;
 def mno_default_build_attributes : Joined<["-"], "mno-default-build-attributes">, Group<m_Group>;
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index a6142d9..0ab8156 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -401,6 +401,8 @@
   Options.UniqueBasicBlockSectionNames =
       CodeGenOpts.UniqueBasicBlockSectionNames;
   Options.TLSSize = CodeGenOpts.TLSSize;
+  // TODO: Add correct codegen options in LLVM
+  // Options.TLSDesc = CodeGenOpts.getDefaultTLSDialect();
   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index fead2e8..232b7c4 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5812,6 +5812,14 @@
     Args.AddLastArg(CmdArgs, options::OPT_mtls_size_EQ);
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_mtls_dialect_EQ)) {
+    // mlts-dialect= is ELF only
+    if (!Triple.isOSBinFormatELF())
+      D.Diag(diag::err_drv_unsupported_opt_for_target)
+          << A->getOption().getName() << TripleStr;
+    Args.AddLastArg(CmdArgs, options::OPT_mtls_dialect_EQ);
+  }
+
   // Add the target cpu
   std::string CPU = getCPUName(D, Args, Triple, /*FromAs*/ false);
   if (!CPU.empty()) {
diff --git a/clang/test/Driver/tls-dialect.c b/clang/test/Driver/tls-dialect.c
new file mode 100644
index 0000000..42bf9ef
--- /dev/null
+++ b/clang/test/Driver/tls-dialect.c
@@ -0,0 +1,15 @@
+/// Options for ELF
+// RUN: %clang -### -target aarch64-linux-gnu -mtls-dialect=trad %s 2>&1 | FileCheck -check-prefix=TRAD %s
+// RUN: %clang -### -target aarch64-linux-gnu -mtls-dialect=desc %s 2>&1 | FileCheck -check-prefix=DESC %s
+
+/// Unsupported target
+// RUN: not %clang -target aarch64-unknown-windows-msvc -mtls-dialect=trad %s 2>&1 | FileCheck -check-prefix=UNSUPPORTED-TARGET %s
+// RUN: not %clang -target aarch64-unknown-windows-msvc -mtls-dialect=desc %s 2>&1 | FileCheck -check-prefix=UNSUPPORTED-TARGET %s
+
+/// Invalid option value
+// RUN: not %clang -target x86_64-linux-gnu -mtls-dialect=foo %s 2>&1 | FileCheck -check-prefix=INVALID-VALUE %s
+
+// TRAD: "-cc1" {{.*}}"-mtls-dialect=trad"
+// DESC: "-cc1" {{.*}}"-mtls-dialect=desc"
+// UNSUPPORTED-TARGET: error: unsupported option
+// INVALID-VALUE: error: invalid value 'foo' in '-mtls-dialect=foo'