[clang] Add -mlarge-data-threshold for x86_64 medium code model (#66839)

Error if not used with x86_64.
Warn if not used with the medium code model (can update if other code
models end up using this).

Set TargetMachine option and add module flag.

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 130cedcd4f2b..25945759e23f 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1146,6 +1146,12 @@ void CodeGenModule::Release() {
     if (CM != ~0u) {
       llvm::CodeModel::Model codeModel = static_cast<llvm::CodeModel::Model>(CM);
       getModule().setCodeModel(codeModel);
+
+      if (CM == llvm::CodeModel::Medium &&
+          Context.getTargetInfo().getTriple().getArch() ==
+              llvm::Triple::x86_64) {
+        getModule().setLargeDataThreshold(getCodeGenOpts().LargeDataThreshold);
+      }
     }
   }