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Unified Diff: base/lazy_instance.h

Issue 2932053002: Use C++11 alignment primitives (Closed)
Patch Set: Fixes Created 3 years, 6 months ago
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Index: base/lazy_instance.h
diff --git a/base/lazy_instance.h b/base/lazy_instance.h
index 070e436d1f0c5a74534ba8fb1a8535a29db789e0..4a8db924301449b40360b8454b47c88dc2473bdd 100644
--- a/base/lazy_instance.h
+++ b/base/lazy_instance.h
@@ -41,7 +41,6 @@
#include "base/base_export.h"
#include "base/debug/leak_annotations.h"
#include "base/logging.h"
-#include "base/memory/aligned_memory.h"
#include "base/threading/thread_restrictions.h"
// LazyInstance uses its own struct initializer-list style static
@@ -55,7 +54,7 @@ namespace base {
template <typename Type>
struct LazyInstanceTraitsBase {
static Type* New(void* instance) {
- DCHECK_EQ(reinterpret_cast<uintptr_t>(instance) & (ALIGNOF(Type) - 1), 0u);
+ DCHECK_EQ(reinterpret_cast<uintptr_t>(instance) & (alignof(Type) - 1), 0u);
// Use placement new to initialize our instance in our preallocated space.
// The parenthesis is very important here to force POD type initialization.
return new (instance) Type();
@@ -179,8 +178,7 @@ class LazyInstance {
if (!(value & kLazyInstanceCreatedMask) &&
internal::NeedsLazyInstance(&private_instance_)) {
// Create the instance in the space provided by |private_buf_|.
- value = reinterpret_cast<subtle::AtomicWord>(
- Traits::New(private_buf_.void_data()));
+ value = reinterpret_cast<subtle::AtomicWord>(Traits::New(private_buf_));
internal::CompleteLazyInstance(&private_instance_, value, this,
Traits::kRegisterOnExit ? OnExit : NULL);
}
@@ -192,19 +190,31 @@ class LazyInstance {
case 0:
return p == NULL;
case internal::kLazyInstanceStateCreating:
- return static_cast<void*>(p) == private_buf_.void_data();
+ return static_cast<void*>(p) == private_buf_;
default:
return p == instance();
}
}
+ // MSVC gives a warning that the alignment expands the size of the
+ // LazyInstance struct to make the size a multiple of the alignment. This
+ // is expected in this case.
+#if defined(OS_WIN)
+#pragma warning(push)
+#pragma warning(disable: 4324)
+#endif
+
// Effectively private: member data is only public to allow the linker to
// statically initialize it and to maintain a POD class. DO NOT USE FROM
// OUTSIDE THIS CLASS.
-
subtle::AtomicWord private_instance_;
+
// Preallocated space for the Type instance.
- base::AlignedMemory<sizeof(Type), ALIGNOF(Type)> private_buf_;
+ alignas(Type) char private_buf_[sizeof(Type)];
+
+#if defined(OS_WIN)
+#pragma warning(pop)
+#endif
private:
Type* instance() {

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