CFE Knob for: Add a thread-model knob for lowering atomics on baremetal & single threaded systems

http://reviews.llvm.org/D4985

llvm-svn: 219027

5 files changed, 43 insertions, 5 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index e28f504020e..6db952613d2 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -425,6 +425,11 @@ TargetMachine *EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
 
   llvm::TargetOptions Options;
 
+  Options.ThreadModel =
+    llvm::StringSwitch<llvm::ThreadModel::Model>(CodeGenOpts.ThreadModel)
+      .Case("posix", llvm::ThreadModel::POSIX)
+      .Case("single", llvm::ThreadModel::Single);
+
   if (CodeGenOpts.DisableIntegratedAS)
     Options.DisableIntegratedAS = true;
 
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 8b097755064..89713f59ea6 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -684,9 +684,13 @@ void Driver::PrintVersion(const Compilation &C, raw_ostream &OS) const {
   OS << "Target: " << TC.getTripleString() << '\n';
 
   // Print the threading model.
-  //
-  // FIXME: Implement correctly.
-  OS << "Thread model: " << "posix" << '\n';
+  if (Arg *A = C.getArgs().getLastArg(options::OPT_mthread_model)) {
+    // Don't print if the ToolChain would have barfed on it already
+    if (TC.isThreadModelSupported(A->getValue()))
+      OS << "Thread model: " << A->getValue();
+  } else
+    OS << "Thread model: " << TC.getThreadModel();
+  OS << '\n';
 }
 
 /// PrintDiagnosticCategories - Implement the --print-diagnostic-categories
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 65dd4d4e2d8..6734ce7d709 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -27,8 +27,13 @@ using namespace clang;
 using namespace llvm::opt;
 
 ToolChain::ToolChain(const Driver &D, const llvm::Triple &T,
-                     const ArgList &A)
-  : D(D), Triple(T), Args(A) {
+                     const ArgList &Args)
+  : D(D), Triple(T), Args(Args) {
+  if (Arg *A = Args.getLastArg(options::OPT_mthread_model))
+    if (!isThreadModelSupported(A->getValue()))
+      D.Diag(diag::err_drv_invalid_thread_model_for_target)
+          << A->getValue()
+          << A->getAsString(Args);
 }
 
 ToolChain::~ToolChain() {
@@ -201,6 +206,19 @@ ObjCRuntime ToolChain::getDefaultObjCRuntime(bool isNonFragile) const {
                      VersionTuple());
 }
 
+bool ToolChain::isThreadModelSupported(const StringRef Model) const {
+  if (Model == "single") {
+    // FIXME: 'single' is only supported on ARM so far.
+    return Triple.getArch() == llvm::Triple::arm ||
+           Triple.getArch() == llvm::Triple::armeb ||
+           Triple.getArch() == llvm::Triple::thumb ||
+           Triple.getArch() == llvm::Triple::thumbeb;
+  } else if (Model == "posix")
+    return true;
+
+  return false;
+}
+
 std::string ToolChain::ComputeLLVMTriple(const ArgList &Args,
                                          types::ID InputType) const {
   switch (getTriple().getArch()) {
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 99e34e4be0c..c09d48906e5 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2753,6 +2753,12 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
+  CmdArgs.push_back("-mthread-model");
+  if (Arg *A = Args.getLastArg(options::OPT_mthread_model))
+    CmdArgs.push_back(A->getValue());
+  else
+    CmdArgs.push_back(Args.MakeArgString(getToolChain().getThreadModel()));
+
   if (!Args.hasFlag(options::OPT_fmerge_all_constants,
                     options::OPT_fno_merge_all_constants))
     CmdArgs.push_back("-fno-merge-all-constants");
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 0dde41acf2e..043141ad673 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -440,6 +440,11 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
                       Args.hasArg(OPT_cl_fast_relaxed_math);
   Opts.UnwindTables = Args.hasArg(OPT_munwind_tables);
   Opts.RelocationModel = Args.getLastArgValue(OPT_mrelocation_model, "pic");
+  Opts.ThreadModel = Args.getLastArgValue(OPT_mthread_model, "posix");
+  if (Opts.ThreadModel != "posix" && Opts.ThreadModel != "single")
+    Diags.Report(diag::err_drv_invalid_value)
+        << Args.getLastArg(OPT_mthread_model)->getAsString(Args)
+        << Opts.ThreadModel;
   Opts.TrapFuncName = Args.getLastArgValue(OPT_ftrap_function_EQ);
   Opts.UseInitArray = Args.hasArg(OPT_fuse_init_array);