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Squashed 'src/leveldb/' changes from 688561cba8..04b5790928

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04b5790928 Merge bitcoin-core/leveldb-subtree#46: Fix invalid pointer arithmetic in Hash (#1222)
59669817c5 Merge bitcoin-core/leveldb-subtree#40: cherry-pick: Remove leveldb::port::kLittleEndian.
73013d1a37 Merge bitcoin-core/leveldb-subtree#45: [jumbo] Add begin()/end() to Slice.
a8844b23ab Fix invalid pointer arithmetic in Hash (#1222)
be4dfc94b3 [jumbo] Add begin()/end() to Slice.
2e3c0131d3 Remove leveldb::port::kLittleEndian.

git-subtree-dir: src/leveldb
git-subtree-split: 04b57909285c7335c1908d53bcde9b90fe0439be
This commit is contained in:
fanquake
2025-01-16 11:09:56 +00:00
parent a37778d4d3
commit d336b7ab85
7 changed files with 8 additions and 62 deletions
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50
util/coding.h
View File

@@ -48,29 +48,13 @@ int VarintLength(uint64_t v);
char* EncodeVarint32(char* dst, uint32_t value);
char* EncodeVarint64(char* dst, uint64_t value);
// TODO(costan): Remove port::kLittleEndian and the fast paths based on
// std::memcpy when clang learns to optimize the generic code, as
// described in https://bugs.llvm.org/show_bug.cgi?id=41761
//
// The platform-independent code in DecodeFixed{32,64}() gets optimized to mov
// on x86 and ldr on ARM64, by both clang and gcc. However, only gcc optimizes
// the platform-independent code in EncodeFixed{32,64}() to mov / str.
// Lower-level versions of Put... that write directly into a character buffer
// REQUIRES: dst has enough space for the value being written
inline void EncodeFixed32(char* dst, uint32_t value) {
uint8_t* const buffer = reinterpret_cast<uint8_t*>(dst);
if (port::kLittleEndian) {
// Fast path for little-endian CPUs. All major compilers optimize this to a
// single mov (x86_64) / str (ARM) instruction.
std::memcpy(buffer, &value, sizeof(uint32_t));
return;
}
// Platform-independent code.
// Currently, only gcc optimizes this to a single mov / str instruction.
// Recent clang and gcc optimize this to a single mov / str instruction.
buffer[0] = static_cast<uint8_t>(value);
buffer[1] = static_cast<uint8_t>(value >> 8);
buffer[2] = static_cast<uint8_t>(value >> 16);
@@ -80,15 +64,7 @@ inline void EncodeFixed32(char* dst, uint32_t value) {
inline void EncodeFixed64(char* dst, uint64_t value) {
uint8_t* const buffer = reinterpret_cast<uint8_t*>(dst);
if (port::kLittleEndian) {
// Fast path for little-endian CPUs. All major compilers optimize this to a
// single mov (x86_64) / str (ARM) instruction.
std::memcpy(buffer, &value, sizeof(uint64_t));
return;
}
// Platform-independent code.
// Currently, only gcc optimizes this to a single mov / str instruction.
// Recent clang and gcc optimize this to a single mov / str instruction.
buffer[0] = static_cast<uint8_t>(value);
buffer[1] = static_cast<uint8_t>(value >> 8);
buffer[2] = static_cast<uint8_t>(value >> 16);
@@ -105,16 +81,7 @@ inline void EncodeFixed64(char* dst, uint64_t value) {
inline uint32_t DecodeFixed32(const char* ptr) {
const uint8_t* const buffer = reinterpret_cast<const uint8_t*>(ptr);
if (port::kLittleEndian) {
// Fast path for little-endian CPUs. All major compilers optimize this to a
// single mov (x86_64) / ldr (ARM) instruction.
uint32_t result;
std::memcpy(&result, buffer, sizeof(uint32_t));
return result;
}
// Platform-independent code.
// Clang and gcc optimize this to a single mov / ldr instruction.
// Recent clang and gcc optimize this to a single mov / ldr instruction.
return (static_cast<uint32_t>(buffer[0])) |
(static_cast<uint32_t>(buffer[1]) << 8) |
(static_cast<uint32_t>(buffer[2]) << 16) |
@@ -124,16 +91,7 @@ inline uint32_t DecodeFixed32(const char* ptr) {
inline uint64_t DecodeFixed64(const char* ptr) {
const uint8_t* const buffer = reinterpret_cast<const uint8_t*>(ptr);
if (port::kLittleEndian) {
// Fast path for little-endian CPUs. All major compilers optimize this to a
// single mov (x86_64) / ldr (ARM) instruction.
uint64_t result;
std::memcpy(&result, buffer, sizeof(uint64_t));
return result;
}
// Platform-independent code.
// Clang and gcc optimize this to a single mov / ldr instruction.
// Recent clang and gcc optimize this to a single mov / ldr instruction.
return (static_cast<uint64_t>(buffer[0])) |
(static_cast<uint64_t>(buffer[1]) << 8) |
(static_cast<uint64_t>(buffer[2]) << 16) |

2
util/hash.cc
View File

@@ -27,7 +27,7 @@ uint32_t Hash(const char* data, size_t n, uint32_t seed) {
uint32_t h = seed ^ (n * m);
// Pick up four bytes at a time
while (data + 4 <= limit) {
while (limit - data >= 4) {
uint32_t w = DecodeFixed32(data);
data += 4;
h += w;