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Although GCC will silently accept larger alignments with __attribute__((aligned())), it warn on alignas() with an alignment larger than the target’s supported maximum. 8c35d92ae403 switched to alignas() where possible. The maxima are at least 128 on x86, x86_64, and arm64, and 64 on arm, in the common configurations, but may be even larger with certain features such as AVX enabled. These are ultimately derived from BIGGEST_ALIGNMENT in gcc/config/*/*.h. One alignment request in a test specified 1024 as a big alignment constraint, solely as a test that alignment worked correctly. For this, it’s perfectly reasonable to limit the alignment request to what GCC supports on the most constrained target we’ll encounter. Test: crashapd_util_test AlignedAllocator.AlignedVector Change-Id: I42af443f437e01228934ab34dc04983742f0ab3f Reviewed-on: https://chromium-review.googlesource.com/550236 Reviewed-by: Scott Graham <scottmg@chromium.org> Commit-Queue: Mark Mentovai <mark@chromium.org>
119 lines
3.8 KiB
C++
119 lines
3.8 KiB
C++
// Copyright 2015 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "util/stdlib/aligned_allocator.h"
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#include <stdint.h>
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#include "base/compiler_specific.h"
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#include "gtest/gtest.h"
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#if defined(OS_WIN)
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#include <crtdbg.h>
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#endif
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namespace crashpad {
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namespace test {
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namespace {
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bool IsAligned(void* pointer, size_t alignment) {
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uintptr_t address = reinterpret_cast<uintptr_t>(pointer);
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return (address & (alignment - 1)) == 0;
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}
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TEST(AlignedAllocator, AlignedVector) {
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// Test a structure with natural alignment.
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struct NaturalAlignedStruct {
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int i;
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};
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AlignedVector<NaturalAlignedStruct> natural_aligned_vector;
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natural_aligned_vector.push_back(NaturalAlignedStruct());
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EXPECT_TRUE(
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IsAligned(&natural_aligned_vector[0], alignof(NaturalAlignedStruct)));
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natural_aligned_vector.resize(3);
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EXPECT_TRUE(
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IsAligned(&natural_aligned_vector[0], alignof(NaturalAlignedStruct)));
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EXPECT_TRUE(
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IsAligned(&natural_aligned_vector[1], alignof(NaturalAlignedStruct)));
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EXPECT_TRUE(
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IsAligned(&natural_aligned_vector[2], alignof(NaturalAlignedStruct)));
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// Test a structure that declares its own alignment.
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struct alignas(16) AlignedStruct {
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int i;
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};
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ASSERT_EQ(alignof(AlignedStruct), 16u);
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AlignedVector<AlignedStruct> aligned_vector;
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aligned_vector.push_back(AlignedStruct());
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EXPECT_TRUE(IsAligned(&aligned_vector[0], alignof(AlignedStruct)));
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aligned_vector.resize(3);
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EXPECT_TRUE(IsAligned(&aligned_vector[0], alignof(AlignedStruct)));
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EXPECT_TRUE(IsAligned(&aligned_vector[1], alignof(AlignedStruct)));
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EXPECT_TRUE(IsAligned(&aligned_vector[2], alignof(AlignedStruct)));
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// Try a custom alignment. Since the structure itself doesn’t specify an
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// alignment constraint, only the base address will be aligned to the
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// requested boundary.
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AlignedVector<NaturalAlignedStruct, 32> custom_aligned_vector;
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custom_aligned_vector.push_back(NaturalAlignedStruct());
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EXPECT_TRUE(IsAligned(&custom_aligned_vector[0], 32));
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// Try a structure with a pretty big alignment request.
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struct alignas(64) BigAlignedStruct {
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int i;
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};
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ASSERT_EQ(alignof(BigAlignedStruct), 64u);
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AlignedVector<BigAlignedStruct> big_aligned_vector;
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big_aligned_vector.push_back(BigAlignedStruct());
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EXPECT_TRUE(IsAligned(&big_aligned_vector[0], alignof(BigAlignedStruct)));
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big_aligned_vector.resize(3);
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EXPECT_TRUE(IsAligned(&big_aligned_vector[0], alignof(BigAlignedStruct)));
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EXPECT_TRUE(IsAligned(&big_aligned_vector[1], alignof(BigAlignedStruct)));
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EXPECT_TRUE(IsAligned(&big_aligned_vector[2], alignof(BigAlignedStruct)));
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}
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void BadAlignmentTest() {
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#if defined(OS_WIN)
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// Suppress the assertion MessageBox() normally displayed by the CRT in debug
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// mode.
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int previous = _CrtSetReportMode(_CRT_ASSERT, _CRTDBG_MODE_DEBUG);
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// In release mode, _CrtSetReportMode() is #defined to ((int)0), so |previous|
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// would appear unused.
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ALLOW_UNUSED_LOCAL(previous);
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#endif
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// Alignment constraints must be powers of 2. 7 is not valid.
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AlignedVector<int, 7> bad_aligned_vector;
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bad_aligned_vector.push_back(0);
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#if defined(OS_WIN)
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_CrtSetReportMode(_CRT_ASSERT, previous);
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#endif
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}
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TEST(AlignedAllocatorDeathTest, BadAlignment) {
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ASSERT_DEATH(BadAlignmentTest(), "");
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}
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} // namespace
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} // namespace test
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} // namespace crashpad
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