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-rw-r--r--clang/lib/CodeGen/ItaniumCXXABI.cpp80
-rw-r--r--clang/test/CodeGenCXX/aarch64-cxxabi.cpp4
-rw-r--r--clang/test/CodeGenCXX/arm.cpp12
3 files changed, 47 insertions, 49 deletions
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 27825ab85d6..4b1c1c255af 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -1393,25 +1393,7 @@ void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
}
// Test whether the variable has completed initialization.
- llvm::Value *isInitialized;
-
- // ARM C++ ABI 3.2.3.1:
- // To support the potential use of initialization guard variables
- // as semaphores that are the target of ARM SWP and LDREX/STREX
- // synchronizing instructions we define a static initialization
- // guard variable to be a 4-byte aligned, 4- byte word with the
- // following inline access protocol.
- // #define INITIALIZED 1
- // if ((obj_guard & INITIALIZED) != INITIALIZED) {
- // if (__cxa_guard_acquire(&obj_guard))
- // ...
- // }
- if (UseARMGuardVarABI && !useInt8GuardVariable) {
- llvm::Value *V = Builder.CreateLoad(guard);
- llvm::Value *Test1 = llvm::ConstantInt::get(guardTy, 1);
- V = Builder.CreateAnd(V, Test1);
- isInitialized = Builder.CreateIsNull(V, "guard.uninitialized");
-
+ //
// Itanium C++ ABI 3.3.2:
// The following is pseudo-code showing how these functions can be used:
// if (obj_guard.first_byte == 0) {
@@ -1427,29 +1409,45 @@ void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
// }
// }
- // ARM64 C++ ABI 3.2.2:
- // This ABI instead only specifies the value bit 0 of the static guard
- // variable; all other bits are platform defined. Bit 0 shall be 0 when the
- // variable is not initialized and 1 when it is.
- // FIXME: Reading one bit is no more efficient than reading one byte so
- // the codegen is same as generic Itanium ABI.
- } else {
- // Load the first byte of the guard variable.
- llvm::LoadInst *LI =
+ // Load the first byte of the guard variable.
+ llvm::LoadInst *LI =
Builder.CreateLoad(Builder.CreateBitCast(guard, CGM.Int8PtrTy));
- LI->setAlignment(1);
-
- // Itanium ABI:
- // An implementation supporting thread-safety on multiprocessor
- // systems must also guarantee that references to the initialized
- // object do not occur before the load of the initialization flag.
- //
- // In LLVM, we do this by marking the load Acquire.
- if (threadsafe)
- LI->setAtomic(llvm::Acquire);
-
- isInitialized = Builder.CreateIsNull(LI, "guard.uninitialized");
- }
+ LI->setAlignment(1);
+
+ // Itanium ABI:
+ // An implementation supporting thread-safety on multiprocessor
+ // systems must also guarantee that references to the initialized
+ // object do not occur before the load of the initialization flag.
+ //
+ // In LLVM, we do this by marking the load Acquire.
+ if (threadsafe)
+ LI->setAtomic(llvm::Acquire);
+
+ // For ARM, we should only check the first bit, rather than the entire byte:
+ //
+ // ARM C++ ABI 3.2.3.1:
+ // To support the potential use of initialization guard variables
+ // as semaphores that are the target of ARM SWP and LDREX/STREX
+ // synchronizing instructions we define a static initialization
+ // guard variable to be a 4-byte aligned, 4-byte word with the
+ // following inline access protocol.
+ // #define INITIALIZED 1
+ // if ((obj_guard & INITIALIZED) != INITIALIZED) {
+ // if (__cxa_guard_acquire(&obj_guard))
+ // ...
+ // }
+ //
+ // and similarly for ARM64:
+ //
+ // ARM64 C++ ABI 3.2.2:
+ // This ABI instead only specifies the value bit 0 of the static guard
+ // variable; all other bits are platform defined. Bit 0 shall be 0 when the
+ // variable is not initialized and 1 when it is.
+ llvm::Value *V =
+ (UseARMGuardVarABI && !useInt8GuardVariable)
+ ? Builder.CreateAnd(LI, llvm::ConstantInt::get(CGM.Int8Ty, 1))
+ : LI;
+ llvm::Value *isInitialized = Builder.CreateIsNull(V, "guard.uninitialized");
llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check");
llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
diff --git a/clang/test/CodeGenCXX/aarch64-cxxabi.cpp b/clang/test/CodeGenCXX/aarch64-cxxabi.cpp
index 04d9493ae6b..c7d910d5f00 100644
--- a/clang/test/CodeGenCXX/aarch64-cxxabi.cpp
+++ b/clang/test/CodeGenCXX/aarch64-cxxabi.cpp
@@ -40,8 +40,8 @@ public:
void guard_variables(int a) {
static Guarded mine(a);
-// CHECK: [[GUARDBIT:%[0-9]+]] = and i64 {{%[0-9]+}}, 1
-// CHECK: icmp eq i64 [[GUARDBIT]], 0
+// CHECK: [[GUARDBIT:%[0-9]+]] = and i8 {{%[0-9]+}}, 1
+// CHECK: icmp eq i8 [[GUARDBIT]], 0
// As guards are 64-bit, these helpers should take 64-bit pointers.
// CHECK: call i32 @__cxa_guard_acquire(i64*
diff --git a/clang/test/CodeGenCXX/arm.cpp b/clang/test/CodeGenCXX/arm.cpp
index 2790199446d..b8d95991e2d 100644
--- a/clang/test/CodeGenCXX/arm.cpp
+++ b/clang/test/CodeGenCXX/arm.cpp
@@ -292,9 +292,9 @@ namespace test7 {
// CHECK-LABEL: define void @_ZN5test74testEv()
void test() {
- // CHECK: [[T0:%.*]] = load i32* @_ZGVZN5test74testEvE1x
- // CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], 1
- // CHECK-NEXT: [[T2:%.*]] = icmp eq i32 [[T1]], 0
+ // CHECK: [[T0:%.*]] = load atomic i8* bitcast (i32* @_ZGVZN5test74testEvE1x to i8*) acquire, align 1
+ // CHECK-NEXT: [[T1:%.*]] = and i8 [[T0]], 1
+ // CHECK-NEXT: [[T2:%.*]] = icmp eq i8 [[T1]], 0
// CHECK-NEXT: br i1 [[T2]]
// -> fallthrough, end
// CHECK: [[T3:%.*]] = call i32 @__cxa_guard_acquire(i32* @_ZGVZN5test74testEvE1x)
@@ -327,9 +327,9 @@ namespace test8 {
// CHECK-LABEL: define void @_ZN5test84testEv()
void test() {
- // CHECK: [[T0:%.*]] = load i32* @_ZGVZN5test84testEvE1x
- // CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], 1
- // CHECK-NEXT: [[T2:%.*]] = icmp eq i32 [[T1]], 0
+ // CHECK: [[T0:%.*]] = load atomic i8* bitcast (i32* @_ZGVZN5test84testEvE1x to i8*) acquire, align 1
+ // CHECK-NEXT: [[T1:%.*]] = and i8 [[T0]], 1
+ // CHECK-NEXT: [[T2:%.*]] = icmp eq i8 [[T1]], 0
// CHECK-NEXT: br i1 [[T2]]
// -> fallthrough, end
// CHECK: [[T3:%.*]] = call i32 @__cxa_guard_acquire(i32* @_ZGVZN5test84testEvE1x)
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