4 files changed, 56 insertions, 1 deletions
diff --git a/flang/lib/Frontend/CodeGenOptions.cpp b/flang/lib/Frontend/CodeGenOptions.cpp
index a794718..8a9d3c2 100644
--- a/flang/lib/Frontend/CodeGenOptions.cpp
+++ b/flang/lib/Frontend/CodeGenOptions.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Frontend/CodeGenOptions.h"
+#include <optional>
 #include <string.h>
 
 namespace Fortran::frontend {
@@ -21,4 +22,14 @@ CodeGenOptions::CodeGenOptions() {
 #include "flang/Frontend/CodeGenOptions.def"
 }
 
+std::optional<llvm::CodeModel::Model> getCodeModel(llvm::StringRef string) {
+  return llvm::StringSwitch<std::optional<llvm::CodeModel::Model>>(string)
+      .Case("tiny", llvm::CodeModel::Model::Tiny)
+      .Case("small", llvm::CodeModel::Model::Small)
+      .Case("kernel", llvm::CodeModel::Model::Kernel)
+      .Case("medium", llvm::CodeModel::Model::Medium)
+      .Case("large", llvm::CodeModel::Model::Large)
+      .Default(std::nullopt);
+}
+
 } // end namespace Fortran::frontend
diff --git a/flang/lib/Frontend/CompilerInstance.cpp b/flang/lib/Frontend/CompilerInstance.cpp
index c781373..27c36b7 100644
--- a/flang/lib/Frontend/CompilerInstance.cpp
+++ b/flang/lib/Frontend/CompilerInstance.cpp
@@ -321,11 +321,19 @@ bool CompilerInstance::setUpTargetMachine() {
   assert(OptLevelOrNone && "Invalid optimization level!");
   llvm::CodeGenOptLevel OptLevel = *OptLevelOrNone;
   std::string featuresStr = getTargetFeatures();
+  std::optional<llvm::CodeModel::Model> cm = getCodeModel(CGOpts.CodeModel);
   targetMachine.reset(theTarget->createTargetMachine(
       theTriple, /*CPU=*/targetOpts.cpu,
       /*Features=*/featuresStr, llvm::TargetOptions(),
       /*Reloc::Model=*/CGOpts.getRelocationModel(),
-      /*CodeModel::Model=*/std::nullopt, OptLevel));
+      /*CodeModel::Model=*/cm, OptLevel));
   assert(targetMachine && "Failed to create TargetMachine");
+  if (cm.has_value()) {
+    const llvm::Triple triple(theTriple);
+    if ((cm == llvm::CodeModel::Medium || cm == llvm::CodeModel::Large) &&
+        triple.getArch() == llvm::Triple::x86_64) {
+      targetMachine->setLargeDataThreshold(CGOpts.LargeDataThreshold);
+    }
+  }
   return true;
 }
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index f96d72f..e2d60ad 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -32,6 +32,7 @@
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/OptTable.h"
+#include "llvm/Support/CodeGen.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/Path.h"
@@ -386,6 +387,29 @@ static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
       opts.IsPIE = 1;
   }
 
+  // -mcmodel option.
+  if (const llvm::opt::Arg *a =
+          args.getLastArg(clang::driver::options::OPT_mcmodel_EQ)) {
+    llvm::StringRef modelName = a->getValue();
+    std::optional<llvm::CodeModel::Model> codeModel = getCodeModel(modelName);
+
+    if (codeModel.has_value())
+      opts.CodeModel = modelName;
+    else
+      diags.Report(clang::diag::err_drv_invalid_value)
+          << a->getAsString(args) << modelName;
+  }
+
+  if (const llvm::opt::Arg *arg = args.getLastArg(
+          clang::driver::options::OPT_mlarge_data_threshold_EQ)) {
+    uint64_t LDT;
+    if (llvm::StringRef(arg->getValue()).getAsInteger(/*Radix=*/10, LDT)) {
+      diags.Report(clang::diag::err_drv_invalid_value)
+          << arg->getSpelling() << arg->getValue();
+    }
+    opts.LargeDataThreshold = LDT;
+  }
+
   // This option is compatible with -f[no-]underscoring in gfortran.
   if (args.hasFlag(clang::driver::options::OPT_fno_underscoring,
                    clang::driver::options::OPT_funderscoring, false)) {
diff --git a/flang/lib/Frontend/FrontendActions.cpp b/flang/lib/Frontend/FrontendActions.cpp
index 24db4df..a85ecd1 100644
--- a/flang/lib/Frontend/FrontendActions.cpp
+++ b/flang/lib/Frontend/FrontendActions.cpp
@@ -866,6 +866,17 @@ void CodeGenAction::generateLLVMIR() {
       llvmModule->setPIELevel(
           static_cast<llvm::PIELevel::Level>(opts.PICLevel));
   }
+
+  // Set mcmodel level LLVM module flags
+  std::optional<llvm::CodeModel::Model> cm = getCodeModel(opts.CodeModel);
+  if (cm.has_value()) {
+    const llvm::Triple triple(ci.getInvocation().getTargetOpts().triple);
+    llvmModule->setCodeModel(*cm);
+    if ((cm == llvm::CodeModel::Medium || cm == llvm::CodeModel::Large) &&
+        triple.getArch() == llvm::Triple::x86_64) {
+      llvmModule->setLargeDataThreshold(opts.LargeDataThreshold);
+    }
+  }
 }
 
 static std::unique_ptr<llvm::raw_pwrite_stream>
@@ -1280,6 +1291,7 @@ void CodeGenAction::executeAction() {
   // and the command-line target option if specified, or the default if not
   // given on the command-line).
   llvm::TargetMachine &targetMachine = ci.getTargetMachine();
+
   const std::string &theTriple = targetMachine.getTargetTriple().str();
 
   if (llvmModule->getTargetTriple() != theTriple) {