Mercurial > hg > CbC > CbC_gcc
diff libsanitizer/sanitizer_common/sanitizer_allocator_size_class_map.h @ 111:04ced10e8804
gcc 7
author | kono |
---|---|
date | Fri, 27 Oct 2017 22:46:09 +0900 |
parents | |
children | 1830386684a0 |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/libsanitizer/sanitizer_common/sanitizer_allocator_size_class_map.h Fri Oct 27 22:46:09 2017 +0900 @@ -0,0 +1,231 @@ +//===-- sanitizer_allocator_size_class_map.h --------------------*- C++ -*-===// +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Part of the Sanitizer Allocator. +// +//===----------------------------------------------------------------------===// +#ifndef SANITIZER_ALLOCATOR_H +#error This file must be included inside sanitizer_allocator.h +#endif + +// SizeClassMap maps allocation sizes into size classes and back. +// Class 0 always corresponds to size 0. +// The other sizes are controlled by the template parameters: +// kMinSizeLog: defines the class 1 as 2^kMinSizeLog. +// kMaxSizeLog: defines the last class as 2^kMaxSizeLog. +// kMidSizeLog: the classes starting from 1 increase with step +// 2^kMinSizeLog until 2^kMidSizeLog. +// kNumBits: the number of non-zero bits in sizes after 2^kMidSizeLog. +// E.g. with kNumBits==3 all size classes after 2^kMidSizeLog +// look like 0b1xx0..0, where x is either 0 or 1. +// +// Example: kNumBits=3, kMidSizeLog=4, kMidSizeLog=8, kMaxSizeLog=17: +// +// Classes 1 - 16 correspond to sizes 16 to 256 (size = class_id * 16). +// Next 4 classes: 256 + i * 64 (i = 1 to 4). +// Next 4 classes: 512 + i * 128 (i = 1 to 4). +// ... +// Next 4 classes: 2^k + i * 2^(k-2) (i = 1 to 4). +// Last class corresponds to kMaxSize = 1 << kMaxSizeLog. +// +// This structure of the size class map gives us: +// - Efficient table-free class-to-size and size-to-class functions. +// - Difference between two consequent size classes is between 14% and 25% +// +// This class also gives a hint to a thread-caching allocator about the amount +// of chunks that need to be cached per-thread: +// - kMaxNumCachedHint is a hint for maximal number of chunks per size class. +// The actual number is computed in TransferBatch. +// - (1 << kMaxBytesCachedLog) is the maximal number of bytes per size class. +// +// Part of output of SizeClassMap::Print(): +// c00 => s: 0 diff: +0 00% l 0 cached: 0 0; id 0 +// c01 => s: 16 diff: +16 00% l 4 cached: 256 4096; id 1 +// c02 => s: 32 diff: +16 100% l 5 cached: 256 8192; id 2 +// c03 => s: 48 diff: +16 50% l 5 cached: 256 12288; id 3 +// c04 => s: 64 diff: +16 33% l 6 cached: 256 16384; id 4 +// c05 => s: 80 diff: +16 25% l 6 cached: 256 20480; id 5 +// c06 => s: 96 diff: +16 20% l 6 cached: 256 24576; id 6 +// c07 => s: 112 diff: +16 16% l 6 cached: 256 28672; id 7 +// +// c08 => s: 128 diff: +16 14% l 7 cached: 256 32768; id 8 +// c09 => s: 144 diff: +16 12% l 7 cached: 256 36864; id 9 +// c10 => s: 160 diff: +16 11% l 7 cached: 256 40960; id 10 +// c11 => s: 176 diff: +16 10% l 7 cached: 256 45056; id 11 +// c12 => s: 192 diff: +16 09% l 7 cached: 256 49152; id 12 +// c13 => s: 208 diff: +16 08% l 7 cached: 256 53248; id 13 +// c14 => s: 224 diff: +16 07% l 7 cached: 256 57344; id 14 +// c15 => s: 240 diff: +16 07% l 7 cached: 256 61440; id 15 +// +// c16 => s: 256 diff: +16 06% l 8 cached: 256 65536; id 16 +// c17 => s: 320 diff: +64 25% l 8 cached: 204 65280; id 17 +// c18 => s: 384 diff: +64 20% l 8 cached: 170 65280; id 18 +// c19 => s: 448 diff: +64 16% l 8 cached: 146 65408; id 19 +// +// c20 => s: 512 diff: +64 14% l 9 cached: 128 65536; id 20 +// c21 => s: 640 diff: +128 25% l 9 cached: 102 65280; id 21 +// c22 => s: 768 diff: +128 20% l 9 cached: 85 65280; id 22 +// c23 => s: 896 diff: +128 16% l 9 cached: 73 65408; id 23 +// +// c24 => s: 1024 diff: +128 14% l 10 cached: 64 65536; id 24 +// c25 => s: 1280 diff: +256 25% l 10 cached: 51 65280; id 25 +// c26 => s: 1536 diff: +256 20% l 10 cached: 42 64512; id 26 +// c27 => s: 1792 diff: +256 16% l 10 cached: 36 64512; id 27 +// +// ... +// +// c48 => s: 65536 diff: +8192 14% l 16 cached: 1 65536; id 48 +// c49 => s: 81920 diff: +16384 25% l 16 cached: 1 81920; id 49 +// c50 => s: 98304 diff: +16384 20% l 16 cached: 1 98304; id 50 +// c51 => s: 114688 diff: +16384 16% l 16 cached: 1 114688; id 51 +// +// c52 => s: 131072 diff: +16384 14% l 17 cached: 1 131072; id 52 +// +// +// Another example (kNumBits=2): +// c00 => s: 0 diff: +0 00% l 0 cached: 0 0; id 0 +// c01 => s: 32 diff: +32 00% l 5 cached: 64 2048; id 1 +// c02 => s: 64 diff: +32 100% l 6 cached: 64 4096; id 2 +// c03 => s: 96 diff: +32 50% l 6 cached: 64 6144; id 3 +// c04 => s: 128 diff: +32 33% l 7 cached: 64 8192; id 4 +// c05 => s: 160 diff: +32 25% l 7 cached: 64 10240; id 5 +// c06 => s: 192 diff: +32 20% l 7 cached: 64 12288; id 6 +// c07 => s: 224 diff: +32 16% l 7 cached: 64 14336; id 7 +// c08 => s: 256 diff: +32 14% l 8 cached: 64 16384; id 8 +// c09 => s: 384 diff: +128 50% l 8 cached: 42 16128; id 9 +// c10 => s: 512 diff: +128 33% l 9 cached: 32 16384; id 10 +// c11 => s: 768 diff: +256 50% l 9 cached: 21 16128; id 11 +// c12 => s: 1024 diff: +256 33% l 10 cached: 16 16384; id 12 +// c13 => s: 1536 diff: +512 50% l 10 cached: 10 15360; id 13 +// c14 => s: 2048 diff: +512 33% l 11 cached: 8 16384; id 14 +// c15 => s: 3072 diff: +1024 50% l 11 cached: 5 15360; id 15 +// c16 => s: 4096 diff: +1024 33% l 12 cached: 4 16384; id 16 +// c17 => s: 6144 diff: +2048 50% l 12 cached: 2 12288; id 17 +// c18 => s: 8192 diff: +2048 33% l 13 cached: 2 16384; id 18 +// c19 => s: 12288 diff: +4096 50% l 13 cached: 1 12288; id 19 +// c20 => s: 16384 diff: +4096 33% l 14 cached: 1 16384; id 20 +// c21 => s: 24576 diff: +8192 50% l 14 cached: 1 24576; id 21 +// c22 => s: 32768 diff: +8192 33% l 15 cached: 1 32768; id 22 +// c23 => s: 49152 diff: +16384 50% l 15 cached: 1 49152; id 23 +// c24 => s: 65536 diff: +16384 33% l 16 cached: 1 65536; id 24 +// c25 => s: 98304 diff: +32768 50% l 16 cached: 1 98304; id 25 +// c26 => s: 131072 diff: +32768 33% l 17 cached: 1 131072; id 26 + +template <uptr kNumBits, uptr kMinSizeLog, uptr kMidSizeLog, uptr kMaxSizeLog, + uptr kMaxNumCachedHintT, uptr kMaxBytesCachedLog> +class SizeClassMap { + static const uptr kMinSize = 1 << kMinSizeLog; + static const uptr kMidSize = 1 << kMidSizeLog; + static const uptr kMidClass = kMidSize / kMinSize; + static const uptr S = kNumBits - 1; + static const uptr M = (1 << S) - 1; + + public: + // kMaxNumCachedHintT is a power of two. It serves as a hint + // for the size of TransferBatch, the actual size could be a bit smaller. + static const uptr kMaxNumCachedHint = kMaxNumCachedHintT; + COMPILER_CHECK((kMaxNumCachedHint & (kMaxNumCachedHint - 1)) == 0); + + static const uptr kMaxSize = 1UL << kMaxSizeLog; + static const uptr kNumClasses = + kMidClass + ((kMaxSizeLog - kMidSizeLog) << S) + 1 + 1; + static const uptr kLargestClassID = kNumClasses - 2; + static const uptr kBatchClassID = kNumClasses - 1; + COMPILER_CHECK(kNumClasses >= 16 && kNumClasses <= 256); + static const uptr kNumClassesRounded = + kNumClasses <= 32 ? 32 : + kNumClasses <= 64 ? 64 : + kNumClasses <= 128 ? 128 : 256; + + static uptr Size(uptr class_id) { + // Estimate the result for kBatchClassID because this class does not know + // the exact size of TransferBatch. It's OK since we are using the actual + // sizeof(TransferBatch) where it matters. + if (UNLIKELY(class_id == kBatchClassID)) + return kMaxNumCachedHint * sizeof(uptr); + if (class_id <= kMidClass) + return kMinSize * class_id; + class_id -= kMidClass; + uptr t = kMidSize << (class_id >> S); + return t + (t >> S) * (class_id & M); + } + + static uptr ClassID(uptr size) { + if (UNLIKELY(size > kMaxSize)) + return 0; + if (size <= kMidSize) + return (size + kMinSize - 1) >> kMinSizeLog; + uptr l = MostSignificantSetBitIndex(size); + uptr hbits = (size >> (l - S)) & M; + uptr lbits = size & ((1 << (l - S)) - 1); + uptr l1 = l - kMidSizeLog; + return kMidClass + (l1 << S) + hbits + (lbits > 0); + } + + static uptr MaxCachedHint(uptr class_id) { + // Estimate the result for kBatchClassID because this class does not know + // the exact size of TransferBatch. We need to cache fewer batches than user + // chunks, so this number can be small. + if (UNLIKELY(class_id == kBatchClassID)) + return 16; + if (UNLIKELY(class_id == 0)) + return 0; + uptr n = (1UL << kMaxBytesCachedLog) / Size(class_id); + return Max<uptr>(1, Min(kMaxNumCachedHint, n)); + } + + static void Print() { + uptr prev_s = 0; + uptr total_cached = 0; + for (uptr i = 0; i < kNumClasses; i++) { + uptr s = Size(i); + if (s >= kMidSize / 2 && (s & (s - 1)) == 0) + Printf("\n"); + uptr d = s - prev_s; + uptr p = prev_s ? (d * 100 / prev_s) : 0; + uptr l = s ? MostSignificantSetBitIndex(s) : 0; + uptr cached = MaxCachedHint(i) * s; + if (i == kBatchClassID) + d = p = l = 0; + Printf("c%02zd => s: %zd diff: +%zd %02zd%% l %zd " + "cached: %zd %zd; id %zd\n", + i, Size(i), d, p, l, MaxCachedHint(i), cached, ClassID(s)); + total_cached += cached; + prev_s = s; + } + Printf("Total cached: %zd\n", total_cached); + } + + static void Validate() { + for (uptr c = 1; c < kNumClasses; c++) { + // Printf("Validate: c%zd\n", c); + uptr s = Size(c); + CHECK_NE(s, 0U); + if (c == kBatchClassID) + continue; + CHECK_EQ(ClassID(s), c); + if (c < kLargestClassID) + CHECK_EQ(ClassID(s + 1), c + 1); + CHECK_EQ(ClassID(s - 1), c); + CHECK_GT(Size(c), Size(c - 1)); + } + CHECK_EQ(ClassID(kMaxSize + 1), 0); + + for (uptr s = 1; s <= kMaxSize; s++) { + uptr c = ClassID(s); + // Printf("s%zd => c%zd\n", s, c); + CHECK_LT(c, kNumClasses); + CHECK_GE(Size(c), s); + if (c > 0) + CHECK_LT(Size(c - 1), s); + } + } +}; + +typedef SizeClassMap<3, 4, 8, 17, 128, 16> DefaultSizeClassMap; +typedef SizeClassMap<3, 4, 8, 17, 64, 14> CompactSizeClassMap; +typedef SizeClassMap<2, 5, 9, 16, 64, 14> VeryCompactSizeClassMap;