jfb updated this revision to Diff 145858.
jfb added a comment.
- Assert on zero alignment, instead of making it always byte-aligned.
Repository:
rC Clang
https://reviews.llvm.org/D46613
Files:
lib/AST/ASTContext.cpp
test/CodeGen/c11atomics-ios.c
test/CodeGen/c11atomics.c
Index: test/CodeGen/c11atomics.c
===================================================================
--- test/CodeGen/c11atomics.c
+++ test/CodeGen/c11atomics.c
@@ -474,3 +474,17 @@
// CHECK: ret i1 [[RES]]
return __c11_atomic_compare_exchange_strong(addr, desired, *new, 5, 5);
}
+
+struct Empty {};
+
+struct Empty test_empty_struct_load(_Atomic(struct Empty)* empty) {
+ // CHECK-LABEL: @test_empty_struct_load(
+ // CHECK: call arm_aapcscc zeroext i8 @__atomic_load_1(i8* %{{.*}}, i32 5)
+ return __c11_atomic_load(empty, 5);
+}
+
+void test_empty_struct_store(_Atomic(struct Empty)* empty, struct Empty value)
{
+ // CHECK-LABEL: @test_empty_struct_store(
+ // CHECK: call arm_aapcscc void @__atomic_store_1(i8* %{{.*}}, i8 zeroext
%{{.*}}, i32 5)
+ __c11_atomic_store(empty, value, 5);
+}
Index: test/CodeGen/c11atomics-ios.c
===================================================================
--- test/CodeGen/c11atomics-ios.c
+++ test/CodeGen/c11atomics-ios.c
@@ -319,3 +319,19 @@
return __c11_atomic_compare_exchange_strong(addr, desired, *new, 5, 5);
}
+
+struct Empty {};
+
+struct Empty testEmptyStructLoad(_Atomic(struct Empty)* empty) {
+ // CHECK-LABEL: @testEmptyStructLoad(
+ // CHECK-NOT: @__atomic_load
+ // CHECK: load atomic i8, i8* %{{.*}} seq_cst, align 1
+ return *empty;
+}
+
+void testEmptyStructStore(_Atomic(struct Empty)* empty, struct Empty value) {
+ // CHECK-LABEL: @testEmptyStructStore(
+ // CHECK-NOT: @__atomic_store
+ // CHECK: store atomic i8 %{{.*}}, i8* %{{.*}} seq_cst, align 1
+ *empty = value;
+}
Index: lib/AST/ASTContext.cpp
===================================================================
--- lib/AST/ASTContext.cpp
+++ lib/AST/ASTContext.cpp
@@ -1958,10 +1958,16 @@
Width = Info.Width;
Align = Info.Align;
- // If the size of the type doesn't exceed the platform's max
- // atomic promotion width, make the size and alignment more
- // favorable to atomic operations:
- if (Width != 0 && Width <= Target->getMaxAtomicPromoteWidth()) {
+ if (!Width) {
+ // An otherwise zero-sized type should still generate an
+ // atomic operation.
+ Width = Target->getCharWidth();
+ assert(Align);
+ } else if (Width <= Target->getMaxAtomicPromoteWidth()) {
+ // If the size of the type doesn't exceed the platform's max
+ // atomic promotion width, make the size and alignment more
+ // favorable to atomic operations:
+
// Round the size up to a power of 2.
if (!llvm::isPowerOf2_64(Width))
Width = llvm::NextPowerOf2(Width);
Index: test/CodeGen/c11atomics.c
===================================================================
--- test/CodeGen/c11atomics.c
+++ test/CodeGen/c11atomics.c
@@ -474,3 +474,17 @@
// CHECK: ret i1 [[RES]]
return __c11_atomic_compare_exchange_strong(addr, desired, *new, 5, 5);
}
+
+struct Empty {};
+
+struct Empty test_empty_struct_load(_Atomic(struct Empty)* empty) {
+ // CHECK-LABEL: @test_empty_struct_load(
+ // CHECK: call arm_aapcscc zeroext i8 @__atomic_load_1(i8* %{{.*}}, i32 5)
+ return __c11_atomic_load(empty, 5);
+}
+
+void test_empty_struct_store(_Atomic(struct Empty)* empty, struct Empty value) {
+ // CHECK-LABEL: @test_empty_struct_store(
+ // CHECK: call arm_aapcscc void @__atomic_store_1(i8* %{{.*}}, i8 zeroext %{{.*}}, i32 5)
+ __c11_atomic_store(empty, value, 5);
+}
Index: test/CodeGen/c11atomics-ios.c
===================================================================
--- test/CodeGen/c11atomics-ios.c
+++ test/CodeGen/c11atomics-ios.c
@@ -319,3 +319,19 @@
return __c11_atomic_compare_exchange_strong(addr, desired, *new, 5, 5);
}
+
+struct Empty {};
+
+struct Empty testEmptyStructLoad(_Atomic(struct Empty)* empty) {
+ // CHECK-LABEL: @testEmptyStructLoad(
+ // CHECK-NOT: @__atomic_load
+ // CHECK: load atomic i8, i8* %{{.*}} seq_cst, align 1
+ return *empty;
+}
+
+void testEmptyStructStore(_Atomic(struct Empty)* empty, struct Empty value) {
+ // CHECK-LABEL: @testEmptyStructStore(
+ // CHECK-NOT: @__atomic_store
+ // CHECK: store atomic i8 %{{.*}}, i8* %{{.*}} seq_cst, align 1
+ *empty = value;
+}
Index: lib/AST/ASTContext.cpp
===================================================================
--- lib/AST/ASTContext.cpp
+++ lib/AST/ASTContext.cpp
@@ -1958,10 +1958,16 @@
Width = Info.Width;
Align = Info.Align;
- // If the size of the type doesn't exceed the platform's max
- // atomic promotion width, make the size and alignment more
- // favorable to atomic operations:
- if (Width != 0 && Width <= Target->getMaxAtomicPromoteWidth()) {
+ if (!Width) {
+ // An otherwise zero-sized type should still generate an
+ // atomic operation.
+ Width = Target->getCharWidth();
+ assert(Align);
+ } else if (Width <= Target->getMaxAtomicPromoteWidth()) {
+ // If the size of the type doesn't exceed the platform's max
+ // atomic promotion width, make the size and alignment more
+ // favorable to atomic operations:
+
// Round the size up to a power of 2.
if (!llvm::isPowerOf2_64(Width))
Width = llvm::NextPowerOf2(Width);
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