[llvm] [llvm-c] Add EmulatedTLS and EnableTLSDESC to LLVMTargetMachineOptions (PR #161155)

[Julien Portalier via llvm-commits]

https://github.com/ysbaddaden created https://github.com/llvm/llvm-project/pull/161155

Adds a couple functions to LLVM-C to expose the Thread Local Storage options that are only available though the C++ API for now:

- `LLVMTargetMachineOptionsSetEmulatedTLS`
- `LLVMTargetMachineOptionsSetEnableTLSDESC`

We plan to use these options in @crystal-lang to reliably compile and cross compile to some targets regardless of downstream patches in OpenBSD or MingGW for example.

>From f052645ad7310f50ee5a99d6d5835d0c8a7305f0 Mon Sep 17 00:00:00 2001
From: Julien Portalier <julien at portalier.com>
Date: Sun, 28 Sep 2025 22:28:20 +0200
Subject: [PATCH] [llvm-c] Add LLVMTargetMachineOptionsSetEmulatedTLS and
 LLVMTargetMachineOptionsSetEnableTLSDESC

---
 llvm/include/llvm-c/TargetMachine.h                |  8 ++++++++
 llvm/lib/Target/TargetMachineC.cpp                 | 14 ++++++++++++++
 llvm/unittests/Target/TargetMachineOptionsTest.cpp |  2 ++
 3 files changed, 24 insertions(+)

diff --git a/llvm/include/llvm-c/TargetMachine.h b/llvm/include/llvm-c/TargetMachine.h
index 1c2d1ed9bfff8..a5dbe33cbae1b 100644
--- a/llvm/include/llvm-c/TargetMachine.h
+++ b/llvm/include/llvm-c/TargetMachine.h
@@ -151,6 +151,14 @@ LLVM_C_ABI void
 LLVMTargetMachineOptionsSetCodeModel(LLVMTargetMachineOptionsRef Options,
                                      LLVMCodeModel CodeModel);
 
+LLVM_C_ABI void
+LLVMTargetMachineOptionsSetEmulatedTLS(LLVMTargetMachineOptionsRef Options,
+                                       LLVMBool EmulatedTLS);
+
+LLVM_C_ABI void
+LLVMTargetMachineOptionsSetEnableTLSDESC(LLVMTargetMachineOptionsRef Options,
+                                         LLVMBool EnableTLSDESC);
+
 /**
  * Create a new llvm::TargetMachine.
  *
diff --git a/llvm/lib/Target/TargetMachineC.cpp b/llvm/lib/Target/TargetMachineC.cpp
index aba6ea436e767..c696f43b2b391 100644
--- a/llvm/lib/Target/TargetMachineC.cpp
+++ b/llvm/lib/Target/TargetMachineC.cpp
@@ -40,6 +40,8 @@ struct LLVMTargetMachineOptions {
   std::optional<Reloc::Model> RM;
   std::optional<CodeModel::Model> CM;
   bool JIT;
+  bool EmulatedTLS;
+  bool EnableTLSDESC;
 };
 
 } // namespace llvm
@@ -197,12 +199,24 @@ void LLVMTargetMachineOptionsSetCodeModel(LLVMTargetMachineOptionsRef Options,
   unwrap(Options)->CM = CM;
 }
 
+void LLVMTargetMachineOptionsSetEmulatedTLS(LLVMTargetMachineOptionsRef Options,
+                                            LLVMBool EmulatedTLS) {
+  unwrap(Options)->EmulatedTLS = EmulatedTLS;
+}
+
+void LLVMTargetMachineOptionsSetEnableTLSDESC(
+    LLVMTargetMachineOptionsRef Options, LLVMBool EnableTLSDESC) {
+  unwrap(Options)->EnableTLSDESC = EnableTLSDESC;
+}
+
 LLVMTargetMachineRef
 LLVMCreateTargetMachineWithOptions(LLVMTargetRef T, const char *TripleStr,
                                    LLVMTargetMachineOptionsRef Options) {
   auto *Opt = unwrap(Options);
   TargetOptions TO;
   TO.MCOptions.ABIName = Opt->ABI;
+  TO.EmulatedTLS = Opt->EmulatedTLS;
+  TO.EnableTLSDESC = Opt->EnableTLSDESC;
   return wrap(unwrap(T)->createTargetMachine(Triple(TripleStr), Opt->CPU,
                                              Opt->Features, TO, Opt->RM,
                                              Opt->CM, Opt->OL, Opt->JIT));
diff --git a/llvm/unittests/Target/TargetMachineOptionsTest.cpp b/llvm/unittests/Target/TargetMachineOptionsTest.cpp
index 27f8855b47551..6daed5a550366 100644
--- a/llvm/unittests/Target/TargetMachineOptionsTest.cpp
+++ b/llvm/unittests/Target/TargetMachineOptionsTest.cpp
@@ -29,6 +29,8 @@ TEST(TargetMachineCTest, TargetMachineOptions) {
   LLVMTargetMachineOptionsSetCodeGenOptLevel(Options, LLVMCodeGenLevelNone);
   LLVMTargetMachineOptionsSetRelocMode(Options, LLVMRelocStatic);
   LLVMTargetMachineOptionsSetCodeModel(Options, LLVMCodeModelKernel);
+  LLVMTargetMachineOptionsSetEmulatedTLS(Options, true);
+  LLVMTargetMachineOptionsSetEnableTLSDESC(Options, true);
 
   LLVMDisposeTargetMachineOptions(Options);
 }