From: LLVM Packaging Team <pkg-llvm-team@lists.alioth.debian.org>
Date: Sun, 18 Jun 2017 17:12:15 +0000 (+0100)
Subject: atomic_library_1
X-Git-Tag: archive/raspbian/1%3.9.1-10+rpi1^2~41
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=5c1c36568fd8d345c4cc03ec75e438a3c91237bb;p=llvm-toolchain-3.9.git

atomic_library_1

===================================================================

Gbp-Pq: Name atomic_library_1.diff
---

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index be5d4ad8..845a333c 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -4282,6 +4282,20 @@ protected:
     Builder.defineMacro("__ELF__");
   }
 
+  static bool shouldUseInlineAtomic(const llvm::Triple &T) {
+    // On linux, binaries targeting old cpus call functions in libgcc to
+    // perform atomic operations. The implementation in libgcc then calls into
+    // the kernel which on armv6 and newer uses ldrex and strex. The net result
+    // is that if we assume the kernel is at least as recent as the hardware,
+    // it is safe to use atomic instructions on armv6 and newer.
+    if (T.getOS() != llvm::Triple::Linux)
+     return false;
+    StringRef ArchName = T.getArchName();
+    if (ArchName.startswith("armv6") || ArchName.startswith("armv7"))
+      return true;
+    return false;
+  }
+
 public:
   RTEMSTargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : OSTargetInfo<Target>(Triple, Opts) {
diff --git a/clang/test/CodeGen/linux-arm-atomic.c b/clang/test/CodeGen/linux-arm-atomic.c
index 116925a5..0e0fa902 100644
--- a/clang/test/CodeGen/linux-arm-atomic.c
+++ b/clang/test/CodeGen/linux-arm-atomic.c
@@ -1,5 +1,15 @@
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=armv7-unknown-linux | FileCheck %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=armv6-unknown-linux | FileCheck %s
+
+typedef int _Atomic_word;
+_Atomic_word exchange_and_add(volatile _Atomic_word *__mem, int __val) {
+  return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL);
+}
+
+// CHECK: define {{.*}} @exchange_and_add
+// CHECK: atomicrmw {{.*}} add
+// RUN: %clang_cc1 %s -emit-llvm -o - -triple=armv7-unknown-linux | FileCheck %s
+// RUN: %clang_cc1 %s -emit-llvm -o - -triple=armv6-unknown-linux | FileCheck %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=thumbv7-unknown-linux | FileCheck %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=armv6-unknown-freebsd | FileCheck %s
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=armv6-unknown-bitrig | FileCheck %s