From 336e1f03d1bcda60cf02df09d2331a0ea9af3030 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Sun, 7 Jun 2020 12:27:11 -0700
Subject: [PATCH] [Driver] Omit -mthread-model posix which is the CC1 default

---
 clang/lib/Driver/ToolChains/Clang.cpp | 21 ++++++++++-------
 clang/test/Driver/thread-model.c      | 43 ++++++++++++-----------------------
 2 files changed, 27 insertions(+), 37 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 577733a..63b9d0e 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4444,15 +4444,20 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     if (RelocationModel != llvm::Reloc::Static && !IsPIE)
       A->render(Args, CmdArgs);
 
-  CmdArgs.push_back("-mthread-model");
-  if (Arg *A = Args.getLastArg(options::OPT_mthread_model)) {
-    if (!TC.isThreadModelSupported(A->getValue()))
-      D.Diag(diag::err_drv_invalid_thread_model_for_target)
-          << A->getValue() << A->getAsString(Args);
-    CmdArgs.push_back(A->getValue());
+  {
+    std::string Model;
+    if (Arg *A = Args.getLastArg(options::OPT_mthread_model)) {
+      if (!TC.isThreadModelSupported(A->getValue()))
+        D.Diag(diag::err_drv_invalid_thread_model_for_target)
+            << A->getValue() << A->getAsString(Args);
+      Model = A->getValue();
+    } else
+      Model = TC.getThreadModel();
+    if (Model != "posix") {
+      CmdArgs.push_back("-mthread-model");
+      CmdArgs.push_back(Args.MakeArgString(Model));
+    }
   }
-  else
-    CmdArgs.push_back(Args.MakeArgString(TC.getThreadModel()));
 
   Args.AddLastArg(CmdArgs, options::OPT_fveclib);
 
diff --git a/clang/test/Driver/thread-model.c b/clang/test/Driver/thread-model.c
index d01ef1c..5bc2be2 100644
--- a/clang/test/Driver/thread-model.c
+++ b/clang/test/Driver/thread-model.c
@@ -1,31 +1,16 @@
-// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -mthread-model posix -v 2>&1 | FileCheck -check-prefix=CHECK-POSIX %s
-// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -mthread-model single -v 2>&1 | FileCheck -check-prefix=CHECK-SINGLE %s
-// RUN: not %clang -target arm-unknown-linux-gnu -c %s -mthread-model silly -v 2>&1 | FileCheck -check-prefix=CHECK-INVALID %s
-// CHECK-POSIX: "-mthread-model" "posix"
-// CHECK-SINGLE: "-mthread-model" "single"
-// CHECK-INVALID: error: invalid thread model 'silly' in '-mthread-model silly' for this target
+// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -mthread-model posix -v 2>&1 | FileCheck %s
+// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -v 2>&1 | FileCheck %s
+// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -mthread-model single -v 2>&1 | FileCheck --check-prefix=SINGLE %s
+// RUN: not %clang -target arm-unknown-linux-gnu -c %s -mthread-model silly -v 2>&1 | FileCheck --check-prefix=INVALID %s
 
-// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-LINUX-POSIX %s
-// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -v -mthread-model single 2>&1 | FileCheck -check-prefix=CHECK-LINUX-SINGLE %s
-// RUN: %clang -### -target arm-unknown-linux-gnu -c %s -v -mthread-model silly 2>&1 | FileCheck -check-prefix=CHECK-LINUX-INVALID %s
-// CHECK-LINUX-POSIX: Thread model: posix
-// CHECK-LINUX-POSIX: "-mthread-model" "posix"
-// CHECK-LINUX-SINGLE: Thread model: single
-// CHECK-LINUX-SINGLE: "-mthread-model" "single"
-// CHECK-LINUX-INVALID-NOT: Thread model:
+// CHECK: Thread model: posix
+// CHECK-NOT: "-mthread-model"
+// SINGLE: Thread model: single
+// SINGLE: "-mthread-model" "single"
+// INVALID: error: invalid thread model 'silly' in '-mthread-model silly' for this target
 
-// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-DEFAULT %s
-// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v -mthread-model single 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-SINGLE %s
-// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v -mthread-model posix 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-POSIX %s
-// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v -mthread-model silly 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-INVALID %s
-// RUN: %clang -### -target wasm64-unknown-linux-gnu -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-DEFAULT %s
-// RUN: %clang -### -target wasm64-unknown-linux-gnu -c %s -v -mthread-model single 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-SINGLE %s
-// RUN: %clang -### -target wasm64-unknown-linux-gnu -c %s -v -mthread-model posix 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-POSIX %s
-// RUN: %clang -### -target wasm64-unknown-linux-gnu -c %s -v -mthread-model silly 2>&1 | FileCheck -check-prefix=CHECK-WEBASSEMBLY-INVALID %s
-// CHECK-WEBASSEMBLY-DEFAULT: Thread model: posix
-// CHECK-WEBASSEMBLY-DEFAULT: "-mthread-model" "posix"
-// CHECK-WEBASSEMBLY-SINGLE: Thread model: single
-// CHECK-WEBASSEMBLY-SINGLE: "-mthread-model" "single"
-// CHECK-WEBASSEMBLY-POSIX: Thread model: posix
-// CHECK-WEBASSEMBLY-POSIX: "-mthread-model" "posix"
-// CHECK-WEBASSEMBLY-INVALID-NOT: Thread model:
+// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v 2>&1 | FileCheck %s
+// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v -mthread-model single 2>&1 | FileCheck --check-prefix=SINGLE %s
+// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v -mthread-model posix 2>&1 | FileCheck %s
+// RUN: %clang -### -target wasm32-unknown-linux-gnu -c %s -v -mthread-model silly 2>&1 | FileCheck --check-prefix=INVALID %s
+// RUN: %clang -### -target wasm64-unknown-linux-gnu -c %s -v 2>&1 | FileCheck %s
-- 
2.7.4