diff options
Diffstat (limited to 'absl/base')
-rw-r--r-- | absl/base/BUILD.bazel | 14 | ||||
-rw-r--r-- | absl/base/internal/unique_small_name_test.cc | 77 | ||||
-rw-r--r-- | absl/base/optimization.h | 26 |
3 files changed, 117 insertions, 0 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel index 816e592b..76122dab 100644 --- a/absl/base/BUILD.bazel +++ b/absl/base/BUILD.bazel @@ -777,3 +777,17 @@ cc_test( "@com_google_googletest//:gtest_main", ], ) + +cc_test( + name = "unique_small_name_test", + size = "small", + srcs = ["internal/unique_small_name_test.cc"], + copts = ABSL_TEST_COPTS, + linkopts = ABSL_DEFAULT_LINKOPTS, + linkstatic = 1, + deps = [ + ":core_headers", + "//absl/strings", + "@com_google_googletest//:gtest_main", + ], +) diff --git a/absl/base/internal/unique_small_name_test.cc b/absl/base/internal/unique_small_name_test.cc new file mode 100644 index 00000000..ff8c2b3f --- /dev/null +++ b/absl/base/internal/unique_small_name_test.cc @@ -0,0 +1,77 @@ +// Copyright 2020 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "gtest/gtest.h" +#include "absl/base/optimization.h" +#include "absl/strings/string_view.h" + +// This test by itself does not do anything fancy, but it serves as binary I can +// query in shell test. + +namespace { + +template <class T> +void DoNotOptimize(const T& var) { +#ifdef __GNUC__ + asm volatile("" : "+m"(const_cast<T&>(var))); +#else + std::cout << (void*)&var; +#endif +} + +int very_long_int_variable_name ABSL_INTERNAL_UNIQUE_SMALL_NAME() = 0; +char very_long_str_variable_name[] ABSL_INTERNAL_UNIQUE_SMALL_NAME() = "abc"; + +TEST(UniqueSmallName, NonAutomaticVar) { + EXPECT_EQ(very_long_int_variable_name, 0); + EXPECT_EQ(absl::string_view(very_long_str_variable_name), "abc"); +} + +int VeryLongFreeFunctionName() ABSL_INTERNAL_UNIQUE_SMALL_NAME(); + +TEST(UniqueSmallName, FreeFunction) { + DoNotOptimize(&VeryLongFreeFunctionName); + + EXPECT_EQ(VeryLongFreeFunctionName(), 456); +} + +int VeryLongFreeFunctionName() { return 456; } + +struct VeryLongStructName { + explicit VeryLongStructName(int i); + + int VeryLongMethodName() ABSL_INTERNAL_UNIQUE_SMALL_NAME(); + + static int VeryLongStaticMethodName() ABSL_INTERNAL_UNIQUE_SMALL_NAME(); + + private: + int fld; +}; + +TEST(UniqueSmallName, Struct) { + VeryLongStructName var(10); + + DoNotOptimize(var); + DoNotOptimize(&VeryLongStructName::VeryLongMethodName); + DoNotOptimize(&VeryLongStructName::VeryLongStaticMethodName); + + EXPECT_EQ(var.VeryLongMethodName(), 10); + EXPECT_EQ(VeryLongStructName::VeryLongStaticMethodName(), 123); +} + +VeryLongStructName::VeryLongStructName(int i) : fld(i) {} +int VeryLongStructName::VeryLongMethodName() { return fld; } +int VeryLongStructName::VeryLongStaticMethodName() { return 123; } + +} // namespace diff --git a/absl/base/optimization.h b/absl/base/optimization.h index 1541d7a8..92bf9cd3 100644 --- a/absl/base/optimization.h +++ b/absl/base/optimization.h @@ -212,4 +212,30 @@ } while (0) #endif +// ABSL_INTERNAL_UNIQUE_SMALL_NAME(cond) +// This macro forces small unique name on a static file level symbols like +// static local variables or static functions. This is intended to be used in +// macro definitions to optimize the cost of generated code. Do NOT use it on +// symbols exported from translation unit since it may casue a link time +// conflict. +// +// Example: +// +// #define MY_MACRO(txt) +// namespace { +// char VeryVeryLongVarName[] ABSL_INTERNAL_UNIQUE_SMALL_NAME() = txt; +// const char* VeryVeryLongFuncName() ABSL_INTERNAL_UNIQUE_SMALL_NAME(); +// const char* VeryVeryLongFuncName() { return txt; } +// } +// + +#if defined(__GNUC__) +#define ABSL_INTERNAL_UNIQUE_SMALL_NAME2(x) #x +#define ABSL_INTERNAL_UNIQUE_SMALL_NAME1(x) ABSL_INTERNAL_UNIQUE_SMALL_NAME2(x) +#define ABSL_INTERNAL_UNIQUE_SMALL_NAME() \ + asm(ABSL_INTERNAL_UNIQUE_SMALL_NAME1(.absl.__COUNTER__)) +#else +#define ABSL_INTERNAL_UNIQUE_SMALL_NAME() +#endif + #endif // ABSL_BASE_OPTIMIZATION_H_ |