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// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/wasm/local-decl-encoder.h"
#include "src/base/platform/wrappers.h"
#include "src/codegen/signature.h"
#include "src/wasm/leb-helper.h"
namespace v8 {
namespace internal {
namespace wasm {
// This struct is just a type tag for Zone::NewArray<T>(size_t) call.
struct LocalDeclEncoderBuffer {};
void LocalDeclEncoder::Prepend(Zone* zone, const byte** start,
const byte** end) const {
size_t size = (*end - *start);
byte* buffer = zone->NewArray<byte, LocalDeclEncoderBuffer>(Size() + size);
size_t pos = Emit(buffer);
if (size > 0) {
memcpy(buffer + pos, *start, size);
}
pos += size;
*start = buffer;
*end = buffer + pos;
}
size_t LocalDeclEncoder::Emit(byte* buffer) const {
byte* pos = buffer;
LEBHelper::write_u32v(&pos, static_cast<uint32_t>(local_decls.size()));
for (auto& local_decl : local_decls) {
uint32_t locals_count = local_decl.first;
ValueType locals_type = local_decl.second;
LEBHelper::write_u32v(&pos, locals_count);
*pos = locals_type.value_type_code();
++pos;
if (locals_type.has_depth()) {
*pos = locals_type.depth();
++pos;
}
if (locals_type.is_rtt()) {
LEBHelper::write_u32v(&pos, locals_type.ref_index());
}
if (locals_type.encoding_needs_heap_type()) {
LEBHelper::write_i32v(&pos, locals_type.heap_type().code());
}
}
DCHECK_EQ(Size(), pos - buffer);
return static_cast<size_t>(pos - buffer);
}
uint32_t LocalDeclEncoder::AddLocals(uint32_t count, ValueType type) {
uint32_t result =
static_cast<uint32_t>(total + (sig ? sig->parameter_count() : 0));
total += count;
if (local_decls.size() > 0 && local_decls.back().second == type) {
count += local_decls.back().first;
local_decls.pop_back();
}
local_decls.push_back(std::pair<uint32_t, ValueType>(count, type));
return result;
}
// Size = (size of locals count) +
// (for each local pair <reps, type>, (size of reps) + (size of type))
size_t LocalDeclEncoder::Size() const {
size_t size = LEBHelper::sizeof_u32v(local_decls.size());
for (auto p : local_decls) {
size +=
LEBHelper::sizeof_u32v(p.first) + // number of locals
1 + // Opcode
(p.second.has_depth() ? 1 : 0) + // Inheritance depth
(p.second.encoding_needs_heap_type()
? LEBHelper::sizeof_i32v(p.second.heap_type().code())
: 0) +
(p.second.is_rtt() ? LEBHelper::sizeof_u32v(p.second.ref_index()) : 0);
}
return size;
}
} // namespace wasm
} // namespace internal
} // namespace v8
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