Atomics: support __c11_* calls on _Atomic struct types.

When a struct's size is not a power of 2, the corresponding _Atomic() type is
promoted to the nearest. We already correctly handled normal C++ expressions of
this form, but direct calls to the __c11_atomic_whatever builtins ended up
performing dodgy operations on the smaller non-atomic types (e.g. memcpy too
much). Later optimisations removed this as undefined behaviour.

This patch converts EmitAtomicExpr to allocate its temporaries at the full
atomic width, sidestepping the issue.

llvm-svn: 252507

1 files changed, 12 insertions, 6 deletions

diff --git a/clang/test/CodeGen/atomic-ops.c b/clang/test/CodeGen/atomic-ops.c
index d8f7d28392a..353f77c37bd 100644
--- a/clang/test/CodeGen/atomic-ops.c
+++ b/clang/test/CodeGen/atomic-ops.c
@@ -179,8 +179,8 @@ struct S fd1(struct S *a) {
   // CHECK-LABEL: @fd1
   // CHECK: [[RETVAL:%.*]] = alloca %struct.S, align 4
   // CHECK: [[RET:%.*]]    = alloca %struct.S, align 4
-  // CHECK: [[CALL:%.*]]   = call i64 @__atomic_load_8(
   // CHECK: [[CAST:%.*]]   = bitcast %struct.S* [[RET]] to i64*
+  // CHECK: [[CALL:%.*]]   = call i64 @__atomic_load_8(
   // CHECK: store i64 [[CALL]], i64* [[CAST]], align 4
   struct S ret;
   __atomic_load(a, &ret, memory_order_seq_cst);
@@ -195,8 +195,9 @@ void fd2(struct S *a, struct S *b) {
   // CHECK-NEXT: store %struct.S* %b, %struct.S** [[B_ADDR]], align 4
   // CHECK-NEXT: [[LOAD_A_PTR:%.*]] = load %struct.S*, %struct.S** [[A_ADDR]], align 4
   // CHECK-NEXT: [[LOAD_B_PTR:%.*]] = load %struct.S*, %struct.S** [[B_ADDR]], align 4
-  // CHECK-NEXT: [[COERCED_A:%.*]] = bitcast %struct.S* [[LOAD_A_PTR]] to i8*
+  // CHECK-NEXT: [[COERCED_A_TMP:%.*]] = bitcast %struct.S* [[LOAD_A_PTR]] to i64*
   // CHECK-NEXT: [[COERCED_B:%.*]] = bitcast %struct.S* [[LOAD_B_PTR]] to i64*
+  // CHECK-NEXT: [[COERCED_A:%.*]] = bitcast i64* [[COERCED_A_TMP]] to i8*
   // CHECK-NEXT: [[LOAD_B:%.*]] = load i64, i64* [[COERCED_B]], align 4
   // CHECK-NEXT: call void @__atomic_store_8(i8* [[COERCED_A]], i64 [[LOAD_B]],
   // CHECK-NEXT: ret void
@@ -214,11 +215,12 @@ void fd3(struct S *a, struct S *b, struct S *c) {
   // CHECK-NEXT: [[LOAD_A_PTR:%.*]] = load %struct.S*, %struct.S** [[A_ADDR]], align 4
   // CHECK-NEXT: [[LOAD_B_PTR:%.*]] = load %struct.S*, %struct.S** [[B_ADDR]], align 4
   // CHECK-NEXT: [[LOAD_C_PTR:%.*]] = load %struct.S*, %struct.S** [[C_ADDR]], align 4
-  // CHECK-NEXT: [[COERCED_A:%.*]] = bitcast %struct.S* [[LOAD_A_PTR]] to i8*
+  // CHECK-NEXT: [[COERCED_A_TMP:%.*]] = bitcast %struct.S* [[LOAD_A_PTR]] to i64*
   // CHECK-NEXT: [[COERCED_B:%.*]] = bitcast %struct.S* [[LOAD_B_PTR]] to i64*
+  // CHECK-NEXT: [[COERCED_C:%.*]] = bitcast %struct.S* [[LOAD_C_PTR]] to i64*
+  // CHECK-NEXT: [[COERCED_A:%.*]] = bitcast i64* [[COERCED_A_TMP]] to i8*
   // CHECK-NEXT: [[LOAD_B:%.*]] = load i64, i64* [[COERCED_B]], align 4
   // CHECK-NEXT: [[CALL:%.*]] = call i64 @__atomic_exchange_8(i8* [[COERCED_A]], i64 [[LOAD_B]],
-  // CHECK-NEXT: [[COERCED_C:%.*]] = bitcast %struct.S* [[LOAD_C_PTR]] to i64*
   // CHECK-NEXT: store i64 [[CALL]], i64* [[COERCED_C]], align 4
 
   __atomic_exchange(a, b, c, memory_order_seq_cst);
@@ -235,9 +237,11 @@ _Bool fd4(struct S *a, struct S *b, struct S *c) {
   // CHECK-NEXT: [[LOAD_A_PTR:%.*]] = load %struct.S*, %struct.S** [[A_ADDR]], align 4
   // CHECK-NEXT: [[LOAD_B_PTR:%.*]] = load %struct.S*, %struct.S** [[B_ADDR]], align 4
   // CHECK-NEXT: [[LOAD_C_PTR:%.*]] = load %struct.S*, %struct.S** [[C_ADDR]], align 4
-  // CHECK-NEXT: [[COERCED_A:%.*]] = bitcast %struct.S* [[LOAD_A_PTR]] to i8*
-  // CHECK-NEXT: [[COERCED_B:%.*]] = bitcast %struct.S* [[LOAD_B_PTR]] to i8*
+  // CHECK-NEXT: [[COERCED_A_TMP:%.*]] = bitcast %struct.S* [[LOAD_A_PTR]] to i64*
+  // CHECK-NEXT: [[COERCED_B_TMP:%.*]] = bitcast %struct.S* [[LOAD_B_PTR]] to i64*
   // CHECK-NEXT: [[COERCED_C:%.*]] = bitcast %struct.S* [[LOAD_C_PTR]] to i64*
+  // CHECK-NEXT: [[COERCED_A:%.*]] = bitcast i64* [[COERCED_A_TMP]] to i8*
+  // CHECK-NEXT: [[COERCED_B:%.*]] = bitcast i64* [[COERCED_B_TMP]] to i8*
   // CHECK-NEXT: [[LOAD_C:%.*]] = load i64, i64* [[COERCED_C]], align 4
   // CHECK-NEXT: [[CALL:%.*]] = call zeroext i1 @__atomic_compare_exchange_8(i8* [[COERCED_A]], i8* [[COERCED_B]], i64 [[LOAD_C]]
   // CHECK-NEXT: ret i1 [[CALL]]
@@ -312,6 +316,8 @@ struct Seventeen {
   char c[17];
 } seventeen;
 
+struct Incomplete;
+
 int lock_free(struct Incomplete *incomplete) {
   // CHECK-LABEL: @lock_free