1// RUN: %clang_cc1 %s -emit-llvm -o - -triple=armv5-unknown-freebsd -std=c11 | FileCheck %s 2 3// Test that we are generating atomicrmw instructions, rather than 4// compare-exchange loops for common atomic ops. This makes a big difference 5// on RISC platforms, where the compare-exchange loop becomes a ll/sc pair for 6// the load and then another ll/sc in the loop, expanding to about 30 7// instructions when it should be only 4. It has a smaller, but still 8// noticeable, impact on platforms like x86 and RISC-V, where there are atomic 9// RMW instructions. 10// 11// We currently emit cmpxchg loops for most operations on _Bools, because 12// they're sufficiently rare that it's not worth making sure that the semantics 13// are correct. 14 15// CHECK: @testStructGlobal = global {{.*}} { i16 1, i16 2, i16 3, i16 4 } 16// CHECK: @testPromotedStructGlobal = global {{.*}} { %{{.*}} { i16 1, i16 2, i16 3 }, [2 x i8] zeroinitializer } 17 18typedef int __attribute__((vector_size(16))) vector; 19 20_Atomic(_Bool) b; 21_Atomic(int) i; 22_Atomic(long long) l; 23_Atomic(short) s; 24_Atomic(char*) p; 25_Atomic(float) f; 26_Atomic(vector) v; 27 28// CHECK: testinc 29void testinc(void) 30{ 31 // Special case for suffix bool++, sets to true and returns the old value. 32 // CHECK: atomicrmw xchg i8* @b, i8 1 seq_cst 33 b++; 34 // CHECK: atomicrmw add i32* @i, i32 1 seq_cst 35 i++; 36 // CHECK: atomicrmw add i64* @l, i64 1 seq_cst 37 l++; 38 // CHECK: atomicrmw add i16* @s, i16 1 seq_cst 39 s++; 40 // Prefix increment 41 // Special case for bool: set to true and return true 42 // CHECK: store atomic i8 1, i8* @b seq_cst, align 1 43 ++b; 44 // Currently, we have no variant of atomicrmw that returns the new value, so 45 // we have to generate an atomic add, which returns the old value, and then a 46 // non-atomic add. 47 // CHECK: atomicrmw add i32* @i, i32 1 seq_cst 48 // CHECK: add i32 49 ++i; 50 // CHECK: atomicrmw add i64* @l, i64 1 seq_cst 51 // CHECK: add i64 52 ++l; 53 // CHECK: atomicrmw add i16* @s, i16 1 seq_cst 54 // CHECK: add i16 55 ++s; 56} 57// CHECK: testdec 58void testdec(void) 59{ 60 // CHECK: call arm_aapcscc zeroext i1 @__atomic_compare_exchange(i32 1, i8* @b 61 b--; 62 // CHECK: atomicrmw sub i32* @i, i32 1 seq_cst 63 i--; 64 // CHECK: atomicrmw sub i64* @l, i64 1 seq_cst 65 l--; 66 // CHECK: atomicrmw sub i16* @s, i16 1 seq_cst 67 s--; 68 // CHECK: call arm_aapcscc zeroext i1 @__atomic_compare_exchange(i32 1, i8* @b 69 --b; 70 // CHECK: atomicrmw sub i32* @i, i32 1 seq_cst 71 // CHECK: sub i32 72 --i; 73 // CHECK: atomicrmw sub i64* @l, i64 1 seq_cst 74 // CHECK: sub i64 75 --l; 76 // CHECK: atomicrmw sub i16* @s, i16 1 seq_cst 77 // CHECK: sub i16 78 --s; 79} 80// CHECK: testaddeq 81void testaddeq(void) 82{ 83 // CHECK: call arm_aapcscc zeroext i1 @__atomic_compare_exchange(i32 1, i8* @b 84 // CHECK: atomicrmw add i32* @i, i32 42 seq_cst 85 // CHECK: atomicrmw add i64* @l, i64 42 seq_cst 86 // CHECK: atomicrmw add i16* @s, i16 42 seq_cst 87 b += 42; 88 i += 42; 89 l += 42; 90 s += 42; 91} 92// CHECK: testsubeq 93void testsubeq(void) 94{ 95 // CHECK: call arm_aapcscc zeroext i1 @__atomic_compare_exchange(i32 1, i8* @b 96 // CHECK: atomicrmw sub i32* @i, i32 42 seq_cst 97 // CHECK: atomicrmw sub i64* @l, i64 42 seq_cst 98 // CHECK: atomicrmw sub i16* @s, i16 42 seq_cst 99 b -= 42; 100 i -= 42; 101 l -= 42; 102 s -= 42; 103} 104// CHECK: testxoreq 105void testxoreq(void) 106{ 107 // CHECK: call arm_aapcscc zeroext i1 @__atomic_compare_exchange(i32 1, i8* @b 108 // CHECK: atomicrmw xor i32* @i, i32 42 seq_cst 109 // CHECK: atomicrmw xor i64* @l, i64 42 seq_cst 110 // CHECK: atomicrmw xor i16* @s, i16 42 seq_cst 111 b ^= 42; 112 i ^= 42; 113 l ^= 42; 114 s ^= 42; 115} 116// CHECK: testoreq 117void testoreq(void) 118{ 119 // CHECK: call arm_aapcscc zeroext i1 @__atomic_compare_exchange(i32 1, i8* @b 120 // CHECK: atomicrmw or i32* @i, i32 42 seq_cst 121 // CHECK: atomicrmw or i64* @l, i64 42 seq_cst 122 // CHECK: atomicrmw or i16* @s, i16 42 seq_cst 123 b |= 42; 124 i |= 42; 125 l |= 42; 126 s |= 42; 127} 128// CHECK: testandeq 129void testandeq(void) 130{ 131 // CHECK: call arm_aapcscc zeroext i1 @__atomic_compare_exchange(i32 1, i8* @b 132 // CHECK: atomicrmw and i32* @i, i32 42 seq_cst 133 // CHECK: atomicrmw and i64* @l, i64 42 seq_cst 134 // CHECK: atomicrmw and i16* @s, i16 42 seq_cst 135 b &= 42; 136 i &= 42; 137 l &= 42; 138 s &= 42; 139} 140 141// CHECK-LABEL: define arm_aapcscc void @testFloat(float* 142void testFloat(_Atomic(float) *fp) { 143// CHECK: [[FP:%.*]] = alloca float* 144// CHECK-NEXT: [[X:%.*]] = alloca float 145// CHECK-NEXT: [[F:%.*]] = alloca float 146// CHECK-NEXT: [[TMP0:%.*]] = alloca float 147// CHECK-NEXT: [[TMP1:%.*]] = alloca float 148// CHECK-NEXT: store float* {{%.*}}, float** [[FP]] 149 150// CHECK-NEXT: [[T0:%.*]] = load float*, float** [[FP]] 151// CHECK-NEXT: store float 1.000000e+00, float* [[T0]], align 4 152 __c11_atomic_init(fp, 1.0f); 153 154// CHECK-NEXT: store float 2.000000e+00, float* [[X]], align 4 155 _Atomic(float) x = 2.0f; 156 157// CHECK-NEXT: [[T0:%.*]] = load float*, float** [[FP]] 158// CHECK-NEXT: [[T1:%.*]] = bitcast float* [[T0]] to i8* 159// CHECK-NEXT: [[T2:%.*]] = bitcast float* [[TMP0]] to i8* 160// CHECK-NEXT: call arm_aapcscc void @__atomic_load(i32 4, i8* [[T1]], i8* [[T2]], i32 5) 161// CHECK-NEXT: [[T3:%.*]] = load float, float* [[TMP0]], align 4 162// CHECK-NEXT: store float [[T3]], float* [[F]] 163 float f = *fp; 164 165// CHECK-NEXT: [[T0:%.*]] = load float, float* [[F]], align 4 166// CHECK-NEXT: [[T1:%.*]] = load float*, float** [[FP]], align 4 167// CHECK-NEXT: store float [[T0]], float* [[TMP1]], align 4 168// CHECK-NEXT: [[T2:%.*]] = bitcast float* [[T1]] to i8* 169// CHECK-NEXT: [[T3:%.*]] = bitcast float* [[TMP1]] to i8* 170// CHECK-NEXT: call arm_aapcscc void @__atomic_store(i32 4, i8* [[T2]], i8* [[T3]], i32 5) 171 *fp = f; 172 173// CHECK-NEXT: ret void 174} 175 176// CHECK: define arm_aapcscc void @testComplexFloat([[CF:{ float, float }]]* 177void testComplexFloat(_Atomic(_Complex float) *fp) { 178// CHECK: [[FP:%.*]] = alloca [[CF]]*, align 4 179// CHECK-NEXT: [[X:%.*]] = alloca [[CF]], align 8 180// CHECK-NEXT: [[F:%.*]] = alloca [[CF]], align 4 181// CHECK-NEXT: [[TMP0:%.*]] = alloca [[CF]], align 8 182// CHECK-NEXT: [[TMP1:%.*]] = alloca [[CF]], align 8 183// CHECK-NEXT: store [[CF]]* 184 185// CHECK-NEXT: [[P:%.*]] = load [[CF]]*, [[CF]]** [[FP]] 186// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[P]], i32 0, i32 0 187// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[P]], i32 0, i32 1 188// CHECK-NEXT: store float 1.000000e+00, float* [[T0]] 189// CHECK-NEXT: store float 0.000000e+00, float* [[T1]] 190 __c11_atomic_init(fp, 1.0f); 191 192// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[X]], i32 0, i32 0 193// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[X]], i32 0, i32 1 194// CHECK-NEXT: store float 2.000000e+00, float* [[T0]] 195// CHECK-NEXT: store float 0.000000e+00, float* [[T1]] 196 _Atomic(_Complex float) x = 2.0f; 197 198// CHECK-NEXT: [[T0:%.*]] = load [[CF]]*, [[CF]]** [[FP]] 199// CHECK-NEXT: [[T1:%.*]] = bitcast [[CF]]* [[T0]] to i8* 200// CHECK-NEXT: [[T2:%.*]] = bitcast [[CF]]* [[TMP0]] to i8* 201// CHECK-NEXT: call arm_aapcscc void @__atomic_load(i32 8, i8* [[T1]], i8* [[T2]], i32 5) 202// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[TMP0]], i32 0, i32 0 203// CHECK-NEXT: [[R:%.*]] = load float, float* [[T0]] 204// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[TMP0]], i32 0, i32 1 205// CHECK-NEXT: [[I:%.*]] = load float, float* [[T0]] 206// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[F]], i32 0, i32 0 207// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[F]], i32 0, i32 1 208// CHECK-NEXT: store float [[R]], float* [[T0]] 209// CHECK-NEXT: store float [[I]], float* [[T1]] 210 _Complex float f = *fp; 211 212// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[F]], i32 0, i32 0 213// CHECK-NEXT: [[R:%.*]] = load float, float* [[T0]] 214// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[F]], i32 0, i32 1 215// CHECK-NEXT: [[I:%.*]] = load float, float* [[T0]] 216// CHECK-NEXT: [[DEST:%.*]] = load [[CF]]*, [[CF]]** [[FP]], align 4 217// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[TMP1]], i32 0, i32 0 218// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[CF]], [[CF]]* [[TMP1]], i32 0, i32 1 219// CHECK-NEXT: store float [[R]], float* [[T0]] 220// CHECK-NEXT: store float [[I]], float* [[T1]] 221// CHECK-NEXT: [[T0:%.*]] = bitcast [[CF]]* [[DEST]] to i8* 222// CHECK-NEXT: [[T1:%.*]] = bitcast [[CF]]* [[TMP1]] to i8* 223// CHECK-NEXT: call arm_aapcscc void @__atomic_store(i32 8, i8* [[T0]], i8* [[T1]], i32 5) 224 *fp = f; 225 226// CHECK-NEXT: ret void 227} 228 229typedef struct { short x, y, z, w; } S; 230_Atomic S testStructGlobal = (S){1, 2, 3, 4}; 231// CHECK: define arm_aapcscc void @testStruct([[S:.*]]* 232void testStruct(_Atomic(S) *fp) { 233// CHECK: [[FP:%.*]] = alloca [[S]]*, align 4 234// CHECK-NEXT: [[X:%.*]] = alloca [[S]], align 8 235// CHECK-NEXT: [[F:%.*]] = alloca [[S:%.*]], align 2 236// CHECK-NEXT: [[TMP0:%.*]] = alloca [[S]], align 8 237// CHECK-NEXT: store [[S]]* 238 239// CHECK-NEXT: [[P:%.*]] = load [[S]]*, [[S]]** [[FP]] 240// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[P]], i32 0, i32 0 241// CHECK-NEXT: store i16 1, i16* [[T0]], align 2 242// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[P]], i32 0, i32 1 243// CHECK-NEXT: store i16 2, i16* [[T0]], align 2 244// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[P]], i32 0, i32 2 245// CHECK-NEXT: store i16 3, i16* [[T0]], align 2 246// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[P]], i32 0, i32 3 247// CHECK-NEXT: store i16 4, i16* [[T0]], align 2 248 __c11_atomic_init(fp, (S){1,2,3,4}); 249 250// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[X]], i32 0, i32 0 251// CHECK-NEXT: store i16 1, i16* [[T0]], align 2 252// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[X]], i32 0, i32 1 253// CHECK-NEXT: store i16 2, i16* [[T0]], align 2 254// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[X]], i32 0, i32 2 255// CHECK-NEXT: store i16 3, i16* [[T0]], align 2 256// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[S]], [[S]]* [[X]], i32 0, i32 3 257// CHECK-NEXT: store i16 4, i16* [[T0]], align 2 258 _Atomic(S) x = (S){1,2,3,4}; 259 260// CHECK-NEXT: [[T0:%.*]] = load [[S]]*, [[S]]** [[FP]] 261// CHECK-NEXT: [[T1:%.*]] = bitcast [[S]]* [[T0]] to i8* 262// CHECK-NEXT: [[T2:%.*]] = bitcast [[S]]* [[F]] to i8* 263// CHECK-NEXT: call arm_aapcscc void @__atomic_load(i32 8, i8* [[T1]], i8* [[T2]], i32 5) 264 S f = *fp; 265 266// CHECK-NEXT: [[T0:%.*]] = load [[S]]*, [[S]]** [[FP]] 267// CHECK-NEXT: [[T1:%.*]] = bitcast [[S]]* [[TMP0]] to i8* 268// CHECK-NEXT: [[T2:%.*]] = bitcast [[S]]* [[F]] to i8* 269// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* [[T1]], i8* [[T2]], i32 8, i32 2, i1 false) 270// CHECK-NEXT: [[T3:%.*]] = bitcast [[S]]* [[T0]] to i8* 271// CHECK-NEXT: [[T4:%.*]] = bitcast [[S]]* [[TMP0]] to i8* 272// CHECK-NEXT: call arm_aapcscc void @__atomic_store(i32 8, i8* [[T3]], i8* [[T4]], i32 5) 273 *fp = f; 274 275// CHECK-NEXT: ret void 276} 277 278typedef struct { short x, y, z; } PS; 279_Atomic PS testPromotedStructGlobal = (PS){1, 2, 3}; 280// CHECK: define arm_aapcscc void @testPromotedStruct([[APS:.*]]* 281void testPromotedStruct(_Atomic(PS) *fp) { 282// CHECK: [[FP:%.*]] = alloca [[APS]]*, align 4 283// CHECK-NEXT: [[X:%.*]] = alloca [[APS]], align 8 284// CHECK-NEXT: [[F:%.*]] = alloca [[PS:%.*]], align 2 285// CHECK-NEXT: [[TMP0:%.*]] = alloca [[APS]], align 8 286// CHECK-NEXT: [[TMP1:%.*]] = alloca [[APS]], align 8 287// CHECK-NEXT: [[A:%.*]] = alloca i32, align 4 288// CHECK-NEXT: [[TMP2:%.*]] = alloca %struct.PS, align 2 289// CHECK-NEXT: [[TMP3:%.*]] = alloca [[APS]], align 8 290// CHECK-NEXT: store [[APS]]* 291 292// CHECK-NEXT: [[P:%.*]] = load [[APS]]*, [[APS]]** [[FP]] 293// CHECK-NEXT: [[T0:%.*]] = bitcast [[APS]]* [[P]] to i8* 294// CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[T0]], i8 0, i64 8, i32 8, i1 false) 295// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[APS]], [[APS]]* [[P]], i32 0, i32 0 296// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[PS]], [[PS]]* [[T0]], i32 0, i32 0 297// CHECK-NEXT: store i16 1, i16* [[T1]], align 2 298// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[PS]], [[PS]]* [[T0]], i32 0, i32 1 299// CHECK-NEXT: store i16 2, i16* [[T1]], align 2 300// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[PS]], [[PS]]* [[T0]], i32 0, i32 2 301// CHECK-NEXT: store i16 3, i16* [[T1]], align 2 302 __c11_atomic_init(fp, (PS){1,2,3}); 303 304// CHECK-NEXT: [[T0:%.*]] = bitcast [[APS]]* [[X]] to i8* 305// CHECK-NEXT: call void @llvm.memset.p0i8.i32(i8* [[T0]], i8 0, i32 8, i32 8, i1 false) 306// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[APS]], [[APS]]* [[X]], i32 0, i32 0 307// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[PS]], [[PS]]* [[T0]], i32 0, i32 0 308// CHECK-NEXT: store i16 1, i16* [[T1]], align 2 309// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[PS]], [[PS]]* [[T0]], i32 0, i32 1 310// CHECK-NEXT: store i16 2, i16* [[T1]], align 2 311// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[PS]], [[PS]]* [[T0]], i32 0, i32 2 312// CHECK-NEXT: store i16 3, i16* [[T1]], align 2 313 _Atomic(PS) x = (PS){1,2,3}; 314 315// CHECK-NEXT: [[T0:%.*]] = load [[APS]]*, [[APS]]** [[FP]] 316// CHECK-NEXT: [[T1:%.*]] = bitcast [[APS]]* [[T0]] to i8* 317// CHECK-NEXT: [[T2:%.*]] = bitcast [[APS]]* [[TMP0]] to i8* 318// CHECK-NEXT: call arm_aapcscc void @__atomic_load(i32 8, i8* [[T1]], i8* [[T2]], i32 5) 319// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[APS]], [[APS]]* [[TMP0]], i32 0, i32 0 320// CHECK-NEXT: [[T1:%.*]] = bitcast [[PS]]* [[F]] to i8* 321// CHECK-NEXT: [[T2:%.*]] = bitcast [[PS]]* [[T0]] to i8* 322// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* [[T1]], i8* [[T2]], i32 6, i32 2, i1 false) 323 PS f = *fp; 324 325// CHECK-NEXT: [[T0:%.*]] = load [[APS]]*, [[APS]]** [[FP]] 326// CHECK-NEXT: [[T1:%.*]] = bitcast { %struct.PS, [2 x i8] }* [[TMP1]] to i8* 327// CHECK-NEXT: call void @llvm.memset.p0i8.i32(i8* [[T1]], i8 0, i32 8, i32 8, i1 false) 328// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [[APS]], [[APS]]* [[TMP1]], i32 0, i32 0 329// CHECK-NEXT: [[T2:%.*]] = bitcast [[PS]]* [[T1]] to i8* 330// CHECK-NEXT: [[T3:%.*]] = bitcast [[PS]]* [[F]] to i8* 331// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* [[T2]], i8* [[T3]], i32 6, i32 2, i1 false) 332// CHECK-NEXT: [[T4:%.*]] = bitcast [[APS]]* [[T0]] to i8* 333// CHECK-NEXT: [[T5:%.*]] = bitcast [[APS]]* [[TMP1]] to i8* 334// CHECK-NEXT: call arm_aapcscc void @__atomic_store(i32 8, i8* [[T4]], i8* [[T5]], i32 5) 335 *fp = f; 336 337// CHECK-NEXT: [[T0:%.*]] = load [[APS]]*, [[APS]]** [[FP]], align 4 338// CHECK-NEXT: [[T1:%.*]] = bitcast [[APS]]* [[T0]] to i8* 339// CHECK-NEXT: [[T2:%.*]] = bitcast [[APS]]* [[TMP3]] to i8* 340// CHECK-NEXT: call arm_aapcscc void @__atomic_load(i32 8, i8* [[T1]], i8* [[T2]], i32 5) 341// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds [[APS]], [[APS]]* [[TMP3]], i32 0, i32 0 342// CHECK-NEXT: [[T1:%.*]] = bitcast %struct.PS* [[TMP2]] to i8* 343// CHECK-NEXT: [[T2:%.*]] = bitcast %struct.PS* [[T0]] to i8* 344// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32(i8* [[T1]], i8* [[T2]], i32 6, i32 2, i1 false) 345// CHECK-NEXT: [[T0:%.*]] = getelementptr inbounds %struct.PS, %struct.PS* [[TMP2]], i32 0, i32 0 346// CHECK-NEXT: [[T1:%.*]] = load i16, i16* [[T0]], align 2 347// CHECK-NEXT: [[T2:%.*]] = sext i16 [[T1]] to i32 348// CHECK-NEXT: store i32 [[T2]], i32* [[A]], align 4 349 int a = ((PS)*fp).x; 350 351// CHECK-NEXT: ret void 352} 353 354// CHECK: define arm_aapcscc void @testPromotedStructOps([[APS:.*]]* 355 356// FIXME: none of these look right, but we can leave the "test" here 357// to make sure they at least don't crash. 358void testPromotedStructOps(_Atomic(PS) *p) { 359 PS a = __c11_atomic_load(p, 5); 360 __c11_atomic_store(p, a, 5); 361 PS b = __c11_atomic_exchange(p, a, 5); 362 _Bool v = __c11_atomic_compare_exchange_strong(p, &b, a, 5, 5); 363 v = __c11_atomic_compare_exchange_weak(p, &b, a, 5, 5); 364} 365