[wasm] [cleanup] Move LocalDeclEncoder to own compilation unit

wasm-macro-gen.h is mainly used from tests, but LocalDeclEncoder is
also used from various other places.
This CL moves the LocalDeclEncoder to an own compilation unit. We want
to later move wasm-macro-gen.h to the tests folder.
It also refactors the LocalDeclEncoder to reuse the
LEBHelper::write_u32v and LEBHelper::sizeof_u32v methods instead of
reimplementing it.

R=ahaas@chromium.org

Change-Id: Ia4651436f0544578da7c1c43596d343571942e97
Reviewed-on: https://chromium-review.googlesource.com/486724Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44838}

BUILD.gn

@@ -1940,6 +1940,8 @@ v8_source_set("v8_base") {
     "src/wasm/function-body-decoder.cc",
     "src/wasm/function-body-decoder.h",
     "src/wasm/leb-helper.h",
+    "src/wasm/local-decl-encoder.cc",
+    "src/wasm/local-decl-encoder.h",
     "src/wasm/module-decoder.cc",
     "src/wasm/module-decoder.h",
     "src/wasm/signature-map.cc",

src/v8.gyp

@@ -1352,6 +1352,8 @@
         'wasm/function-body-decoder.h',
         'wasm/function-body-decoder-impl.h',
         'wasm/leb-helper.h',
+        'wasm/local-decl-encoder.cc',
+        'wasm/local-decl-encoder.h',
         'wasm/module-decoder.cc',
         'wasm/module-decoder.h',
         'wasm/signature-map.cc',

src/wasm/local-decl-encoder.cc

+// 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/wasm/leb-helper.h"
+
+using namespace v8::internal;
+using namespace v8::internal::wasm;
+
+void LocalDeclEncoder::Prepend(Zone* zone, const byte** start,
+                               const byte** end) const {
+  size_t size = (*end - *start);
+  byte* buffer = reinterpret_cast<byte*>(zone->New(Size() + size));
+  size_t pos = Emit(buffer);
+  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) {
+    LEBHelper::write_u32v(&pos, local_decl.first);
+    *pos = WasmOpcodes::ValueTypeCodeFor(local_decl.second);
+    ++pos;
+  }
+  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_t LocalDeclEncoder::Size() const {
+  size_t size = LEBHelper::sizeof_u32v(local_decls.size());
+  for (auto p : local_decls) size += 1 + LEBHelper::sizeof_u32v(p.first);
+  return size;
+}

src/wasm/local-decl-encoder.h

+// 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.
+
+#ifndef V8_WASM_LOCAL_DECL_ENCODER_H_
+#define V8_WASM_LOCAL_DECL_ENCODER_H_
+
+#include "src/wasm/wasm-opcodes.h"
+#include "src/zone/zone-containers.h"
+#include "src/zone/zone.h"
+
+namespace v8 {
+namespace internal {
+namespace wasm {
+
+// A helper for encoding local declarations prepended to the body of a
+// function.
+class LocalDeclEncoder {
+ public:
+  explicit LocalDeclEncoder(Zone* zone, FunctionSig* s = nullptr)
+      : sig(s), local_decls(zone), total(0) {}
+
+  // Prepend local declarations by creating a new buffer and copying data
+  // over. The new buffer must be delete[]'d by the caller.
+  void Prepend(Zone* zone, const byte** start, const byte** end) const;
+
+  size_t Emit(byte* buffer) const;
+
+  // Add locals declarations to this helper. Return the index of the newly added
+  // local(s), with an optional adjustment for the parameters.
+  uint32_t AddLocals(uint32_t count, ValueType type);
+
+  size_t Size() const;
+
+  bool has_sig() const { return sig != nullptr; }
+  FunctionSig* get_sig() const { return sig; }
+  void set_sig(FunctionSig* s) { sig = s; }
+
+ private:
+  FunctionSig* sig;
+  ZoneVector<std::pair<uint32_t, ValueType>> local_decls;
+  size_t total;
+};
+
+}  // namespace wasm
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_WASM_LOCAL_DECL_ENCODER_H_

src/wasm/wasm-macro-gen.h

@@ -170,90 +170,6 @@ inline void CheckI64v(int64_t value, int length) {
   DCHECK(length == 10 || I64V_IN_RANGE(value, length));
 }
 
-// A helper for encoding local declarations prepended to the body of a
-// function.
-// TODO(titzer): move this to an appropriate header.
-class LocalDeclEncoder {
- public:
-  explicit LocalDeclEncoder(Zone* zone, FunctionSig* s = nullptr)
-      : sig(s), local_decls(zone), total(0) {}
-
-  // Prepend local declarations by creating a new buffer and copying data
-  // over. The new buffer must be delete[]'d by the caller.
-  void Prepend(Zone* zone, const byte** start, const byte** end) const {
-    size_t size = (*end - *start);
-    byte* buffer = reinterpret_cast<byte*>(zone->New(Size() + size));
-    size_t pos = Emit(buffer);
-    memcpy(buffer + pos, *start, size);
-    pos += size;
-    *start = buffer;
-    *end = buffer + pos;
-  }
-
-  size_t Emit(byte* buffer) const {
-    size_t pos = 0;
-    pos = WriteUint32v(buffer, pos, static_cast<uint32_t>(local_decls.size()));
-    for (size_t i = 0; i < local_decls.size(); ++i) {
-      pos = WriteUint32v(buffer, pos, local_decls[i].first);
-      buffer[pos++] = WasmOpcodes::ValueTypeCodeFor(local_decls[i].second);
-    }
-    DCHECK_EQ(Size(), pos);
-    return pos;
-  }
-
-  // Add locals declarations to this helper. Return the index of the newly added
-  // local(s), with an optional adjustment for the parameters.
-  uint32_t 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_t Size() const {
-    size_t size = SizeofUint32v(static_cast<uint32_t>(local_decls.size()));
-    for (auto p : local_decls) size += 1 + SizeofUint32v(p.first);
-    return size;
-  }
-
-  bool has_sig() const { return sig != nullptr; }
-  FunctionSig* get_sig() const { return sig; }
-  void set_sig(FunctionSig* s) { sig = s; }
-
- private:
-  FunctionSig* sig;
-  ZoneVector<std::pair<uint32_t, ValueType>> local_decls;
-  size_t total;
-
-  size_t SizeofUint32v(uint32_t val) const {
-    size_t size = 1;
-    while (true) {
-      byte b = val & MASK_7;
-      if (b == val) return size;
-      size++;
-      val = val >> 7;
-    }
-  }
-
-  // TODO(titzer): lift encoding of u32v to a common place.
-  size_t WriteUint32v(byte* buffer, size_t pos, uint32_t val) const {
-    while (true) {
-      byte b = val & MASK_7;
-      if (b == val) {
-        buffer[pos++] = b;
-        break;
-      }
-      buffer[pos++] = 0x80 | b;
-      val = val >> 7;
-    }
-    return pos;
-  }
-};
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8

src/wasm/wasm-module-builder.h

@@ -9,6 +9,7 @@
 #include "src/zone/zone-containers.h"
 
 #include "src/wasm/leb-helper.h"
+#include "src/wasm/local-decl-encoder.h"
 #include "src/wasm/wasm-macro-gen.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-opcodes.h"

test/cctest/wasm/wasm-run-utils.h

@@ -25,6 +25,7 @@
 #include "src/compiler/zone-stats.h"
 #include "src/trap-handler/trap-handler.h"
 #include "src/wasm/function-body-decoder.h"
+#include "src/wasm/local-decl-encoder.h"
 #include "src/wasm/wasm-external-refs.h"
 #include "src/wasm/wasm-interpreter.h"
 #include "src/wasm/wasm-js.h"

test/unittests/wasm/function-body-decoder-unittest.cc

@@ -13,6 +13,7 @@
 
 #include "src/wasm/function-body-decoder-impl.h"
 #include "src/wasm/function-body-decoder.h"
+#include "src/wasm/local-decl-encoder.h"
 #include "src/wasm/signature-map.h"
 #include "src/wasm/wasm-limits.h"
 #include "src/wasm/wasm-macro-gen.h"