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Revert "[vm] Switch datastream Write/WriteUnsigned to (S)LEB128."

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This reverts commit 80102c981b.

Reason for revert: b/186359854

Original change's description:
> [vm] Switch datastream Write/WriteUnsigned to (S)LEB128.
>
> This reduces the number of variable-length integer encodings in our
> database from 2 to 1, and chooses the more standard one.
>
> TEST=Existing tests, in particular any that involve snapshots.
>
> Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-asan-linux-release-x64-try,vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-msan-linux-release-x64-try,vm-kernel-precomp-ubsan-linux-release-x64-try,vm-kernel-precomp-tsan-linux-release-x64-try,vm-kernel-precomp-nnbd-linux-debug-x64-try,vm-kernel-precomp-nnbd-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-simarm64c-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try
> Change-Id: Ia700158ac873ad32ac28c1027a669895961bc715
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196321
> Commit-Queue: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: Idf32bdd879cf8bb7407f6dae764312140ad6eeb2
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-asan-linux-release-x64-try,vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-msan-linux-release-x64-try,vm-kernel-precomp-ubsan-linux-release-x64-try,vm-kernel-precomp-tsan-linux-release-x64-try,vm-kernel-precomp-nnbd-linux-debug-x64-try,vm-kernel-precomp-nnbd-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-simarm64c-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196920
Reviewed-by: Ivan Inozemtsev <iinozemtsev@google.com>
Commit-Queue: Ivan Inozemtsev <iinozemtsev@google.com>
This commit is contained in:
Ivan Inozemtsev
2021-04-26 07:52:47 +00:00
committed by commit-bot@chromium.org
parent 50de84a3fb
commit a5ff656da1
14 changed files with 251 additions and 187 deletions
Download Patch File Download Diff File Expand all files Collapse all files
runtime/vm/datastream.cc
-115
View File
@@ -4,126 +4,11 @@
#include "vm/datastream.h"
#include "platform/text_buffer.h"
#include "vm/compiler/runtime_api.h"
#include "vm/os.h"
#include "vm/zone.h"
namespace dart {
// Setting up needed variables for the unrolled loop sections below.
#define UNROLLED_INIT() \
using Unsigned = typename std::make_unsigned<T>::type; \
Unsigned b = ReadByte(); \
if ((b & C::kMoreDataMask) == 0) { \
if ((b & C::kSignMask) != 0) { \
b |= ~Utils::NBitMask<Unsigned>(C::kDataBitsPerByte); \
} \
return static_cast<T>(b); \
} \
T r = static_cast<T>(b & C::kDataByteMask);
// Part of the unrolled loop where the loop may stop, having read the last part,
// or continue reading.
#define UNROLLED_BODY(bit_start) \
static_assert(bit_start % C::kDataBitsPerByte == 0, \
"Bit start must be a multiple of the data bits per byte"); \
static_assert(bit_start >= 0 && bit_start < kBitsPerByte * sizeof(T), \
"Starting unrolled body at invalid bit position"); \
static_assert(bit_start + C::kDataBitsPerByte < kBitsPerByte * sizeof(T), \
"Unrolled body should not contain final bits in value"); \
b = ReadByte(); \
r |= static_cast<Unsigned>(b & C::kDataByteMask) << bit_start; \
if ((b & C::kMoreDataMask) == 0) { \
if ((b & C::kSignMask) != 0) { \
r |= ~Utils::NBitMask<T>(bit_start + C::kDataBitsPerByte); \
} \
return r; \
}
// The end of the unrolled loop. Does not need to handle sign extension, as the
// last bits fill the rest of the bitspace.
#define UNROLLED_END(bit_start) \
static_assert(bit_start % C::kDataBitsPerByte == 0, \
"Bit start must be a multiple of the data bits per byte"); \
static_assert(bit_start >= 0 && bit_start < kBitsPerByte * sizeof(T), \
"Starting unrolled end at invalid bit position"); \
static_assert(bit_start + C::kDataBitsPerByte >= kBitsPerByte * sizeof(T), \
"Unrolled end does not contain final bits in value"); \
b = ReadByte(); \
ASSERT_EQUAL((b & C::kMoreDataMask), 0); \
r |= static_cast<Unsigned>(b & C::kDataByteMask) << bit_start; \
return r;
uint16_t ReadStream::Read16() {
using T = uint16_t;
UNROLLED_INIT();
UNROLLED_BODY(7);
UNROLLED_END(14);
}
uint32_t ReadStream::Read32() {
using T = uint32_t;
UNROLLED_INIT();
UNROLLED_BODY(7);
UNROLLED_BODY(14);
UNROLLED_BODY(21);
UNROLLED_END(28);
}
uint64_t ReadStream::Read64() {
using T = uint64_t;
UNROLLED_INIT();
UNROLLED_BODY(7);
UNROLLED_BODY(14);
UNROLLED_BODY(21);
UNROLLED_BODY(28);
UNROLLED_BODY(35);
UNROLLED_BODY(42);
UNROLLED_BODY(49);
UNROLLED_BODY(56);
UNROLLED_END(63);
}
#undef UNROLLED_INIT
#undef UNROLLED_BODY
#undef UNROLLED_END
static constexpr intptr_t kRowSize = 16;
void ReadStream::WriteWindow(BaseTextBuffer* buffer,
intptr_t start,
intptr_t window_size) {
const intptr_t buffer_size = end_ - buffer_;
ASSERT(0 <= start && start <= buffer_size);
intptr_t window_start = start - (window_size / 2);
intptr_t window_end = start + (window_size / 2);
if (window_start < 0) window_start = 0;
if (buffer_size < window_start + window_end) window_end = buffer_size;
for (intptr_t i = window_start - (window_start % kRowSize); i < window_end;
i += kRowSize) {
buffer->Printf("%016" Px " ", i);
intptr_t j = i;
if (j < window_start) {
while (j < window_start) {
buffer->AddString(" ");
++j;
}
}
for (; j < Utils::Minimum(window_end, i + kRowSize); j++) {
buffer->AddChar(j == start ? '|' : ' ');
buffer->Printf("%02x", static_cast<uint8_t>(buffer_[j] % kMaxUint8));
buffer->AddChar(j == start ? '|' : ' ');
}
buffer->AddChar('\n');
}
}
void ReadStream::PrintWindow(intptr_t start, intptr_t window_size) {
TextBuffer buffer(1024);
WriteWindow(&buffer, start, window_size);
OS::Print("%s", buffer.buffer());
}
void BaseWriteStream::WriteTargetWord(word value) {
ASSERT(compiler::target::kBitsPerWord == kBitsPerWord ||
Utils::IsAbsoluteUint(compiler::target::kBitsPerWord, value));