summaryrefslogtreecommitdiff
path: root/absl/strings
diff options
context:
space:
mode:
authorGravatar Abseil Team <absl-team@google.com>2020-07-30 13:58:50 -0700
committerGravatar Mark Barolak <mbar@google.com>2020-07-31 11:30:59 -0400
commit184cf2524101310a0ba315c743e82cf45fccccf8 (patch)
tree61f5cb2de5da31efd024ce2a49f2d304352b33ba /absl/strings
parent82302f1e05d6daed93bdd77e8951b529b0ebfcf6 (diff)
Export of internal Abseil changes
-- 587e6db882749fa7faa12815e614afab04d218b9 by Derek Mauro <dmauro@google.com>: Use attribute detection for other sanitizer related attributes PiperOrigin-RevId: 324077073 -- 3ee55e4935b4235516b1fcac3c55945e510f7afc by Evan Brown <ezb@google.com>: Simplify CordRepExternal allocation/deallocation. I think this can save some memory when `Releaser` is empty and when on platforms where alignof(CordRepExternal) < (default `::operator new` alignment). We no longer need the API requirement that alignof(Releaser) <= (default `::operator new` alignment). Also remove another static_assert from a TODO in cord_internal.h and fix some warnings about calling std::move on a forwarding reference. PiperOrigin-RevId: 324053720 -- 9fc78436565eb3b204d4aa425ee3773354392f45 by Derek Mauro <dmauro@google.com>: Use auto-detected sanitizer attributes for ASAN, MSAN, and TSAN builds PiperOrigin-RevId: 323831461 GitOrigin-RevId: 587e6db882749fa7faa12815e614afab04d218b9 Change-Id: Ie0e4a2846d7f66988a2d81a5e50721b62fdb3d6d
Diffstat (limited to 'absl/strings')
-rw-r--r--absl/strings/BUILD.bazel3
-rw-r--r--absl/strings/CMakeLists.txt1
-rw-r--r--absl/strings/cord.cc74
-rw-r--r--absl/strings/cord.h57
-rw-r--r--absl/strings/internal/cord_internal.h65
-rw-r--r--absl/strings/string_view_test.cc4
6 files changed, 66 insertions, 138 deletions
diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index ef412639..64a13cef 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -258,6 +258,8 @@ cc_library(
visibility = ["//visibility:private"],
deps = [
":strings",
+ "//absl/base:base_internal",
+ "//absl/container:compressed_tuple",
"//absl/meta:type_traits",
],
)
@@ -277,7 +279,6 @@ cc_library(
":str_format",
":strings",
"//absl/base",
- "//absl/base:base_internal",
"//absl/base:core_headers",
"//absl/base:endian",
"//absl/base:raw_logging_internal",
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index d7237231..d6c2126d 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -548,6 +548,7 @@ absl_cc_library(
DEPS
absl::base
absl::base_internal
+ absl::compressed_tuple
absl::core_headers
absl::endian
absl::fixed_array
diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index 920dcc67..763dcc45 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -61,48 +61,6 @@ enum CordRepKind {
FLAT = 3,
};
-namespace {
-
-// Type used with std::allocator for allocating and deallocating
-// `CordRepExternal`. std::allocator is used because it opaquely handles the
-// different new / delete overloads available on a given platform.
-struct alignas(absl::cord_internal::ExternalRepAlignment()) ExternalAllocType {
- unsigned char value[absl::cord_internal::ExternalRepAlignment()];
-};
-
-// Returns the number of objects to pass in to std::allocator<ExternalAllocType>
-// allocate() and deallocate() to create enough room for `CordRepExternal` with
-// `releaser_size` bytes on the end.
-constexpr size_t GetExternalAllocNumObjects(size_t releaser_size) {
- // Be sure to round up since `releaser_size` could be smaller than
- // `sizeof(ExternalAllocType)`.
- return (sizeof(CordRepExternal) + releaser_size + sizeof(ExternalAllocType) -
- 1) /
- sizeof(ExternalAllocType);
-}
-
-// Allocates enough memory for `CordRepExternal` and a releaser with size
-// `releaser_size` bytes.
-void* AllocateExternal(size_t releaser_size) {
- return std::allocator<ExternalAllocType>().allocate(
- GetExternalAllocNumObjects(releaser_size));
-}
-
-// Deallocates the memory for a `CordRepExternal` assuming it was allocated with
-// a releaser of given size and alignment.
-void DeallocateExternal(CordRepExternal* p, size_t releaser_size) {
- std::allocator<ExternalAllocType>().deallocate(
- reinterpret_cast<ExternalAllocType*>(p),
- GetExternalAllocNumObjects(releaser_size));
-}
-
-// Returns a pointer to the type erased releaser for the given CordRepExternal.
-void* GetExternalReleaser(CordRepExternal* rep) {
- return rep + 1;
-}
-
-} // namespace
-
namespace cord_internal {
inline CordRepConcat* CordRep::concat() {
@@ -304,11 +262,7 @@ static void UnrefInternal(CordRep* rep) {
}
} else if (rep->tag == EXTERNAL) {
CordRepExternal* rep_external = rep->external();
- absl::string_view data(rep_external->base, rep->length);
- void* releaser = GetExternalReleaser(rep_external);
- size_t releaser_size = rep_external->releaser_invoker(releaser, data);
- rep_external->~CordRepExternal();
- DeallocateExternal(rep_external, releaser_size);
+ rep_external->releaser_invoker(rep_external);
rep = nullptr;
} else if (rep->tag == SUBSTRING) {
CordRepSubstring* rep_substring = rep->substring();
@@ -458,18 +412,12 @@ static CordRep* NewTree(const char* data,
namespace cord_internal {
-ExternalRepReleaserPair NewExternalWithUninitializedReleaser(
- absl::string_view data, ExternalReleaserInvoker invoker,
- size_t releaser_size) {
+void InitializeCordRepExternal(absl::string_view data, CordRepExternal* rep) {
assert(!data.empty());
-
- void* raw_rep = AllocateExternal(releaser_size);
- auto* rep = new (raw_rep) CordRepExternal();
rep->length = data.size();
rep->tag = EXTERNAL;
rep->base = data.data();
- rep->releaser_invoker = invoker;
- return {VerifyTree(rep), GetExternalReleaser(rep)};
+ VerifyTree(rep);
}
} // namespace cord_internal
@@ -721,12 +669,12 @@ Cord::Cord(T&& src) {
std::string data;
};
const absl::string_view original_data = src;
- CordRepExternal* rep =
- static_cast<CordRepExternal*>(absl::cord_internal::NewExternalRep(
- original_data, StringReleaser{std::move(src)}));
+ auto* rep = static_cast<
+ ::absl::cord_internal::CordRepExternalImpl<StringReleaser>*>(
+ absl::cord_internal::NewExternalRep(
+ original_data, StringReleaser{std::forward<T>(src)}));
// Moving src may have invalidated its data pointer, so adjust it.
- rep->base =
- static_cast<StringReleaser*>(GetExternalReleaser(rep))->data.data();
+ rep->base = rep->template get<0>().data.data();
contents_.set_tree(rep);
}
}
@@ -775,7 +723,7 @@ Cord& Cord::operator=(T&& src) {
if (src.size() <= kMaxBytesToCopy) {
*this = absl::string_view(src);
} else {
- *this = Cord(std::move(src));
+ *this = Cord(std::forward<T>(src));
}
return *this;
}
@@ -898,7 +846,7 @@ void Cord::Append(T&& src) {
if (src.size() <= kMaxBytesToCopy) {
Append(absl::string_view(src));
} else {
- Append(Cord(std::move(src)));
+ Append(Cord(std::forward<T>(src)));
}
}
@@ -938,7 +886,7 @@ inline void Cord::Prepend(T&& src) {
if (src.size() <= kMaxBytesToCopy) {
Prepend(absl::string_view(src));
} else {
- Prepend(Cord(std::move(src)));
+ Prepend(Cord(std::forward<T>(src)));
}
}
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index 8580d803..a0db2797 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -71,7 +71,6 @@
#include <type_traits>
#include "absl/base/internal/endian.h"
-#include "absl/base/internal/invoke.h"
#include "absl/base/internal/per_thread_tls.h"
#include "absl/base/macros.h"
#include "absl/base/port.h"
@@ -173,10 +172,6 @@ class Cord {
//
// * be move constructible
// * support `void operator()(absl::string_view) const` or `void operator()`
- // * not have alignment requirement greater than what is guaranteed by
- // `::operator new`. This alignment is dictated by
- // `alignof(std::max_align_t)` (pre-C++17 code) or
- // `__STDCPP_DEFAULT_NEW_ALIGNMENT__` (C++17 code).
//
// Example:
//
@@ -842,47 +837,15 @@ inline void SmallMemmove(char* dst, const char* src, size_t n,
}
}
-struct ExternalRepReleaserPair {
- CordRep* rep;
- void* releaser_address;
-};
-
-// Allocates a new external `CordRep` and returns a pointer to it and a pointer
-// to `releaser_size` bytes where the desired releaser can be constructed.
+// Does non-template-specific `CordRepExternal` initialization.
// Expects `data` to be non-empty.
-ExternalRepReleaserPair NewExternalWithUninitializedReleaser(
- absl::string_view data, ExternalReleaserInvoker invoker,
- size_t releaser_size);
-
-struct Rank1 {};
-struct Rank0 : Rank1 {};
-
-template <typename Releaser, typename = ::absl::base_internal::invoke_result_t<
- Releaser, absl::string_view>>
-void InvokeReleaser(Rank0, Releaser&& releaser, absl::string_view data) {
- ::absl::base_internal::invoke(std::forward<Releaser>(releaser), data);
-}
-
-template <typename Releaser,
- typename = ::absl::base_internal::invoke_result_t<Releaser>>
-void InvokeReleaser(Rank1, Releaser&& releaser, absl::string_view) {
- ::absl::base_internal::invoke(std::forward<Releaser>(releaser));
-}
+void InitializeCordRepExternal(absl::string_view data, CordRepExternal* rep);
// Creates a new `CordRep` that owns `data` and `releaser` and returns a pointer
// to it, or `nullptr` if `data` was empty.
template <typename Releaser>
// NOLINTNEXTLINE - suppress clang-tidy raw pointer return.
CordRep* NewExternalRep(absl::string_view data, Releaser&& releaser) {
- static_assert(
-#if defined(__STDCPP_DEFAULT_NEW_ALIGNMENT__)
- alignof(Releaser) <= __STDCPP_DEFAULT_NEW_ALIGNMENT__,
-#else
- alignof(Releaser) <= alignof(max_align_t),
-#endif
- "Releasers with alignment requirement greater than what is returned by "
- "default `::operator new()` are not supported.");
-
using ReleaserType = absl::decay_t<Releaser>;
if (data.empty()) {
// Never create empty external nodes.
@@ -891,18 +854,10 @@ CordRep* NewExternalRep(absl::string_view data, Releaser&& releaser) {
return nullptr;
}
- auto releaser_invoker = [](void* type_erased_releaser, absl::string_view d) {
- auto* my_releaser = static_cast<ReleaserType*>(type_erased_releaser);
- InvokeReleaser(Rank0{}, std::move(*my_releaser), d);
- my_releaser->~ReleaserType();
- return sizeof(Releaser);
- };
-
- ExternalRepReleaserPair external = NewExternalWithUninitializedReleaser(
- data, releaser_invoker, sizeof(releaser));
- ::new (external.releaser_address)
- ReleaserType(std::forward<Releaser>(releaser));
- return external.rep;
+ CordRepExternal* rep = new CordRepExternalImpl<ReleaserType>(
+ std::forward<Releaser>(releaser), 0);
+ InitializeCordRepExternal(data, rep);
+ return rep;
}
// Overload for function reference types that dispatches using a function
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 830ceaf4..d456eef8 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -21,6 +21,8 @@
#include <cstdint>
#include <type_traits>
+#include "absl/base/internal/invoke.h"
+#include "absl/container/internal/compressed_tuple.h"
#include "absl/meta/type_traits.h"
#include "absl/strings/string_view.h"
@@ -114,35 +116,56 @@ struct CordRepSubstring : public CordRep {
CordRep* child;
};
-// TODO(strel): replace the following logic (and related functions in cord.cc)
-// with container_internal::Layout.
-
-// Alignment requirement for CordRepExternal so that the type erased releaser
-// will be stored at a suitably aligned address.
-constexpr size_t ExternalRepAlignment() {
-#if defined(__STDCPP_DEFAULT_NEW_ALIGNMENT__)
- return __STDCPP_DEFAULT_NEW_ALIGNMENT__;
-#else
- return alignof(max_align_t);
-#endif
-}
-
-// Type for function pointer that will invoke and destroy the type-erased
-// releaser function object. Accepts a pointer to the releaser and the
-// `string_view` that were passed in to `NewExternalRep` below. The return value
-// is the size of the `Releaser` type.
-using ExternalReleaserInvoker = size_t (*)(void*, absl::string_view);
+// Type for function pointer that will invoke the releaser function and also
+// delete the `CordRepExternalImpl` corresponding to the passed in
+// `CordRepExternal`.
+using ExternalReleaserInvoker = void (*)(CordRepExternal*);
// External CordReps are allocated together with a type erased releaser. The
// releaser is stored in the memory directly following the CordRepExternal.
-struct alignas(ExternalRepAlignment()) CordRepExternal : public CordRep {
+struct CordRepExternal : public CordRep {
const char* base;
// Pointer to function that knows how to call and destroy the releaser.
ExternalReleaserInvoker releaser_invoker;
};
-// TODO(strel): look into removing, it doesn't seem like anything relies on this
-static_assert(sizeof(CordRepConcat) == sizeof(CordRepSubstring), "");
+struct Rank1 {};
+struct Rank0 : Rank1 {};
+
+template <typename Releaser, typename = ::absl::base_internal::invoke_result_t<
+ Releaser, absl::string_view>>
+void InvokeReleaser(Rank0, Releaser&& releaser, absl::string_view data) {
+ ::absl::base_internal::invoke(std::forward<Releaser>(releaser), data);
+}
+
+template <typename Releaser,
+ typename = ::absl::base_internal::invoke_result_t<Releaser>>
+void InvokeReleaser(Rank1, Releaser&& releaser, absl::string_view) {
+ ::absl::base_internal::invoke(std::forward<Releaser>(releaser));
+}
+
+// We use CompressedTuple so that we can benefit from EBCO.
+template <typename Releaser>
+struct CordRepExternalImpl
+ : public CordRepExternal,
+ public ::absl::container_internal::CompressedTuple<Releaser> {
+ // The extra int arg is so that we can avoid interfering with copy/move
+ // constructors while still benefitting from perfect forwarding.
+ template <typename T>
+ CordRepExternalImpl(T&& releaser, int)
+ : CordRepExternalImpl::CompressedTuple(std::forward<T>(releaser)) {
+ this->releaser_invoker = &Release;
+ }
+
+ ~CordRepExternalImpl() {
+ InvokeReleaser(Rank0{}, std::move(this->template get<0>()),
+ absl::string_view(base, length));
+ }
+
+ static void Release(CordRepExternal* rep) {
+ delete static_cast<CordRepExternalImpl*>(rep);
+ }
+};
} // namespace cord_internal
ABSL_NAMESPACE_END
diff --git a/absl/strings/string_view_test.cc b/absl/strings/string_view_test.cc
index 41dbc97b..dcebb150 100644
--- a/absl/strings/string_view_test.cc
+++ b/absl/strings/string_view_test.cc
@@ -1177,7 +1177,7 @@ TEST(FindOneCharTest, EdgeCases) {
EXPECT_EQ(absl::string_view::npos, a.rfind('x'));
}
-#ifndef THREAD_SANITIZER // Allocates too much memory for tsan.
+#ifndef ABSL_HAVE_THREAD_SANITIZER // Allocates too much memory for tsan.
TEST(HugeStringView, TwoPointTwoGB) {
if (sizeof(size_t) <= 4)
return;
@@ -1191,7 +1191,7 @@ TEST(HugeStringView, TwoPointTwoGB) {
sp.remove_suffix(2);
EXPECT_EQ(size - 1 - 2, sp.length());
}
-#endif // THREAD_SANITIZER
+#endif // ABSL_HAVE_THREAD_SANITIZER
#if !defined(NDEBUG) && !defined(ABSL_USES_STD_STRING_VIEW)
TEST(NonNegativeLenTest, NonNegativeLen) {