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Index: llvm-toolchain-snapshot_3.5~svn205090/clang/lib/Basic/Targets.cpp
===================================================================
--- llvm-toolchain-snapshot_3.5~svn205090.orig/clang/lib/Basic/Targets.cpp 2014-03-29 12:14:58.543982773 +0100
+++ llvm-toolchain-snapshot_3.5~svn205090/clang/lib/Basic/Targets.cpp 2014-03-29 12:14:58.543982773 +0100
@@ -3843,6 +3843,20 @@
// FIXME: Override "preferred align" for double and long long.
}
+ 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:
ARMTargetInfo(const llvm::Triple &Triple, bool IsBigEndian)
: TargetInfo(Triple), CPU("arm1136j-s"), FPMath(FP_Default),
Index: llvm-toolchain-snapshot_3.5~svn205090/clang/test/CodeGen/linux-arm-atomic.c
===================================================================
--- llvm-toolchain-snapshot_3.5~svn205090.orig/clang/test/CodeGen/linux-arm-atomic.c 2014-03-29 12:14:58.543982773 +0100
+++ llvm-toolchain-snapshot_3.5~svn205090/clang/test/CodeGen/linux-arm-atomic.c 2014-03-29 12:14:58.543982773 +0100
@@ -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
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