[wasm] Move memory-related methods to wasm-memory.(cc|h).

R=gdeepti@chromium.org

Bug: 
Change-Id: Ic2e519d24354b3327a92daa0d4d6e06c9ca4605e
Reviewed-on: https://chromium-review.googlesource.com/687056
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48256}

BUILD.gn

@@ -2069,6 +2069,8 @@ v8_source_set("v8_base") {
     "src/wasm/wasm-js.cc",
     "src/wasm/wasm-js.h",
     "src/wasm/wasm-limits.h",
+    "src/wasm/wasm-memory.cc",
+    "src/wasm/wasm-memory.h",
     "src/wasm/wasm-module-builder.cc",
     "src/wasm/wasm-module-builder.h",
     "src/wasm/wasm-module.cc",

src/v8.gyp

@@ -1456,6 +1456,8 @@
         'wasm/wasm-js.cc',
         'wasm/wasm-js.h',
         'wasm/wasm-limits.h',
+        'wasm/wasm-memory.cc',
+        'wasm/wasm-memory.h',
         'wasm/wasm-module.cc',
         'wasm/wasm-module.h',
         'wasm/wasm-module-builder.cc',

src/wasm/module-compiler.cc

@@ -19,6 +19,7 @@
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-code-specialization.h"
 #include "src/wasm/wasm-js.h"
+#include "src/wasm/wasm-memory.h"
 #include "src/wasm/wasm-objects-inl.h"
 #include "src/wasm/wasm-result.h"
 

src/wasm/wasm-js.cc

@@ -19,6 +19,7 @@
 #include "src/wasm/wasm-api.h"
 #include "src/wasm/wasm-js.h"
 #include "src/wasm/wasm-limits.h"
+#include "src/wasm/wasm-memory.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-objects-inl.h"
 #include "src/wasm/wasm-result.h"
@@ -780,7 +781,7 @@ void WebAssemblyMemoryGrow(const v8::FunctionCallbackInfo<v8::Value>& args) {
       i::WasmMemoryObject::SetupNewBufferWithSameBackingStore(
           i_isolate, receiver, static_cast<uint32_t>(new_size64));
     }
-    i::wasm::DetachWebAssemblyMemoryBuffer(i_isolate, old_buffer, free_memory);
+    i::wasm::DetachMemoryBuffer(i_isolate, old_buffer, free_memory);
   }
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(ret);

src/wasm/wasm-memory.cc

@@ -0,0 +1,136 @@
+// 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/wasm-memory.h"
+#include "src/objects-inl.h"
+#include "src/wasm/wasm-limits.h"
+#include "src/wasm/wasm-module.h"
+
+namespace v8 {
+namespace internal {
+namespace wasm {
+
+void* TryAllocateBackingStore(Isolate* isolate, size_t size,
+                              bool enable_guard_regions, void*& allocation_base,
+                              size_t& allocation_length) {
+  // TODO(eholk): Right now enable_guard_regions has no effect on 32-bit
+  // systems. It may be safer to fail instead, given that other code might do
+  // things that would be unsafe if they expected guard pages where there
+  // weren't any.
+  if (enable_guard_regions && kGuardRegionsSupported) {
+    // TODO(eholk): On Windows we want to make sure we don't commit the guard
+    // pages yet.
+
+    // We always allocate the largest possible offset into the heap, so the
+    // addressable memory after the guard page can be made inaccessible.
+    allocation_length = RoundUp(kWasmMaxHeapOffset, base::OS::CommitPageSize());
+    DCHECK_EQ(0, size % base::OS::CommitPageSize());
+
+    // AllocateGuarded makes the whole region inaccessible by default.
+    allocation_base =
+        isolate->array_buffer_allocator()->Reserve(allocation_length);
+    if (allocation_base == nullptr) {
+      return nullptr;
+    }
+
+    void* memory = allocation_base;
+
+    // Make the part we care about accessible.
+    isolate->array_buffer_allocator()->SetProtection(
+        memory, size, v8::ArrayBuffer::Allocator::Protection::kReadWrite);
+
+    reinterpret_cast<v8::Isolate*>(isolate)
+        ->AdjustAmountOfExternalAllocatedMemory(size);
+
+    return memory;
+  } else {
+    void* memory =
+        size == 0 ? nullptr : isolate->array_buffer_allocator()->Allocate(size);
+    allocation_base = memory;
+    allocation_length = size;
+    return memory;
+  }
+}
+
+Handle<JSArrayBuffer> SetupArrayBuffer(Isolate* isolate, void* allocation_base,
+                                       size_t allocation_length,
+                                       void* backing_store, size_t size,
+                                       bool is_external,
+                                       bool enable_guard_regions,
+                                       SharedFlag shared) {
+  Handle<JSArrayBuffer> buffer =
+      isolate->factory()->NewJSArrayBuffer(shared, TENURED);
+  DCHECK_GE(kMaxInt, size);
+  if (shared == SharedFlag::kShared) DCHECK(FLAG_experimental_wasm_threads);
+  JSArrayBuffer::Setup(buffer, isolate, is_external, allocation_base,
+                       allocation_length, backing_store, static_cast<int>(size),
+                       shared);
+  buffer->set_is_neuterable(false);
+  buffer->set_is_wasm_buffer(true);
+  buffer->set_has_guard_region(enable_guard_regions);
+  return buffer;
+}
+
+Handle<JSArrayBuffer> NewArrayBuffer(Isolate* isolate, size_t size,
+                                     bool enable_guard_regions,
+                                     SharedFlag shared) {
+  // Check against kMaxInt, since the byte length is stored as int in the
+  // JSArrayBuffer. Note that wasm_max_mem_pages can be raised from the command
+  // line, and we don't want to fail a CHECK then.
+  if (size > FLAG_wasm_max_mem_pages * WasmModule::kPageSize ||
+      size > kMaxInt) {
+    // TODO(titzer): lift restriction on maximum memory allocated here.
+    return Handle<JSArrayBuffer>::null();
+  }
+
+  enable_guard_regions = enable_guard_regions && kGuardRegionsSupported;
+
+  void* allocation_base = nullptr;  // Set by TryAllocateBackingStore
+  size_t allocation_length = 0;     // Set by TryAllocateBackingStore
+  // Do not reserve memory till non zero memory is encountered.
+  void* memory =
+      (size == 0) ? nullptr
+                  : TryAllocateBackingStore(isolate, size, enable_guard_regions,
+                                            allocation_base, allocation_length);
+
+  if (size > 0 && memory == nullptr) {
+    return Handle<JSArrayBuffer>::null();
+  }
+
+#if DEBUG
+  // Double check the API allocator actually zero-initialized the memory.
+  const byte* bytes = reinterpret_cast<const byte*>(memory);
+  for (size_t i = 0; i < size; ++i) {
+    DCHECK_EQ(0, bytes[i]);
+  }
+#endif
+
+  constexpr bool is_external = false;
+  return SetupArrayBuffer(isolate, allocation_base, allocation_length, memory,
+                          size, is_external, enable_guard_regions, shared);
+}
+
+void DetachMemoryBuffer(Isolate* isolate, Handle<JSArrayBuffer> buffer,
+                        bool free_memory) {
+  const bool is_external = buffer->is_external();
+  DCHECK(!buffer->is_neuterable());
+  if (!is_external) {
+    buffer->set_is_external(true);
+    isolate->heap()->UnregisterArrayBuffer(*buffer);
+    if (free_memory) {
+      // We need to free the memory before neutering the buffer because
+      // FreeBackingStore reads buffer->allocation_base(), which is nulled out
+      // by Neuter. This means there is a dangling pointer until we neuter the
+      // buffer. Since there is no way for the user to directly call
+      // FreeBackingStore, we can ensure this is safe.
+      buffer->FreeBackingStore();
+    }
+  }
+  buffer->set_is_neuterable(true);
+  buffer->Neuter();
+}
+
+}  // namespace wasm
+}  // namespace internal
+}  // namespace v8

src/wasm/wasm-memory.h

@@ -0,0 +1,43 @@
+// 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_MEMORY_H_
+#define V8_WASM_MEMORY_H_
+
+#include "src/flags.h"
+#include "src/handles.h"
+#include "src/objects.h"
+
+namespace v8 {
+namespace internal {
+namespace wasm {
+
+#if V8_TARGET_ARCH_64_BIT
+const bool kGuardRegionsSupported = true;
+#else
+const bool kGuardRegionsSupported = false;
+#endif
+
+inline bool EnableGuardRegions() {
+  return FLAG_wasm_guard_pages && kGuardRegionsSupported &&
+         !FLAG_experimental_wasm_threads;
+}
+
+Handle<JSArrayBuffer> NewArrayBuffer(
+    Isolate*, size_t size, bool enable_guard_regions,
+    SharedFlag shared = SharedFlag::kNotShared);
+
+Handle<JSArrayBuffer> SetupArrayBuffer(
+    Isolate*, void* allocation_base, size_t allocation_length,
+    void* backing_store, size_t size, bool is_external,
+    bool enable_guard_regions, SharedFlag shared = SharedFlag::kNotShared);
+
+void DetachMemoryBuffer(Isolate* isolate, Handle<JSArrayBuffer> buffer,
+                        bool free_memory);
+
+}  // namespace wasm
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_WASM_MODULE_H_

src/wasm/wasm-module.cc

@@ -22,7 +22,6 @@
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-code-specialization.h"
 #include "src/wasm/wasm-js.h"
-#include "src/wasm/wasm-limits.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-objects-inl.h"
 #include "src/wasm/wasm-result.h"
@@ -46,54 +45,6 @@ namespace wasm {
     if (FLAG_trace_wasm_compiler) PrintF(__VA_ARGS__); \
   } while (false)
 
-namespace {
-
-
-void* TryAllocateBackingStore(Isolate* isolate, size_t size,
-                              bool enable_guard_regions, void*& allocation_base,
-                              size_t& allocation_length) {
-  // TODO(eholk): Right now enable_guard_regions has no effect on 32-bit
-  // systems. It may be safer to fail instead, given that other code might do
-  // things that would be unsafe if they expected guard pages where there
-  // weren't any.
-  if (enable_guard_regions && kGuardRegionsSupported) {
-    // TODO(eholk): On Windows we want to make sure we don't commit the guard
-    // pages yet.
-
-    // We always allocate the largest possible offset into the heap, so the
-    // addressable memory after the guard page can be made inaccessible.
-    allocation_length = RoundUp(kWasmMaxHeapOffset, base::OS::CommitPageSize());
-    DCHECK_EQ(0, size % base::OS::CommitPageSize());
-
-    // AllocateGuarded makes the whole region inaccessible by default.
-    allocation_base =
-        isolate->array_buffer_allocator()->Reserve(allocation_length);
-    if (allocation_base == nullptr) {
-      return nullptr;
-    }
-
-    void* memory = allocation_base;
-
-    // Make the part we care about accessible.
-    isolate->array_buffer_allocator()->SetProtection(
-        memory, size, v8::ArrayBuffer::Allocator::Protection::kReadWrite);
-
-    reinterpret_cast<v8::Isolate*>(isolate)
-        ->AdjustAmountOfExternalAllocatedMemory(size);
-
-    return memory;
-  } else {
-    void* memory =
-        size == 0 ? nullptr : isolate->array_buffer_allocator()->Allocate(size);
-    allocation_base = memory;
-    allocation_length = size;
-    return memory;
-  }
-}
-
-
-}  // namespace
-
 // static
 const WasmExceptionSig WasmException::empty_sig_(0, 0, nullptr);
 
@@ -103,64 +54,6 @@ constexpr const char* WasmException::kRuntimeIdStr;
 // static
 constexpr const char* WasmException::kRuntimeValuesStr;
 
-Handle<JSArrayBuffer> SetupArrayBuffer(Isolate* isolate, void* allocation_base,
-                                       size_t allocation_length,
-                                       void* backing_store, size_t size,
-                                       bool is_external,
-                                       bool enable_guard_regions,
-                                       SharedFlag shared) {
-  Handle<JSArrayBuffer> buffer =
-      isolate->factory()->NewJSArrayBuffer(shared, TENURED);
-  DCHECK_GE(kMaxInt, size);
-  if (shared == SharedFlag::kShared) DCHECK(FLAG_experimental_wasm_threads);
-  JSArrayBuffer::Setup(buffer, isolate, is_external, allocation_base,
-                       allocation_length, backing_store, static_cast<int>(size),
-                       shared);
-  buffer->set_is_neuterable(false);
-  buffer->set_is_wasm_buffer(true);
-  buffer->set_has_guard_region(enable_guard_regions);
-  return buffer;
-}
-
-Handle<JSArrayBuffer> NewArrayBuffer(Isolate* isolate, size_t size,
-                                     bool enable_guard_regions,
-                                     SharedFlag shared) {
-  // Check against kMaxInt, since the byte length is stored as int in the
-  // JSArrayBuffer. Note that wasm_max_mem_pages can be raised from the command
-  // line, and we don't want to fail a CHECK then.
-  if (size > FLAG_wasm_max_mem_pages * WasmModule::kPageSize ||
-      size > kMaxInt) {
-    // TODO(titzer): lift restriction on maximum memory allocated here.
-    return Handle<JSArrayBuffer>::null();
-  }
-
-  enable_guard_regions = enable_guard_regions && kGuardRegionsSupported;
-
-  void* allocation_base = nullptr;  // Set by TryAllocateBackingStore
-  size_t allocation_length = 0;     // Set by TryAllocateBackingStore
-  // Do not reserve memory till non zero memory is encountered.
-  void* memory =
-      (size == 0) ? nullptr
-                  : TryAllocateBackingStore(isolate, size, enable_guard_regions,
-                                            allocation_base, allocation_length);
-
-  if (size > 0 && memory == nullptr) {
-    return Handle<JSArrayBuffer>::null();
-  }
-
-#if DEBUG
-  // Double check the API allocator actually zero-initialized the memory.
-  const byte* bytes = reinterpret_cast<const byte*>(memory);
-  for (size_t i = 0; i < size; ++i) {
-    DCHECK_EQ(0, bytes[i]);
-  }
-#endif
-
-  constexpr bool is_external = false;
-  return SetupArrayBuffer(isolate, allocation_base, allocation_length, memory,
-                          size, is_external, enable_guard_regions, shared);
-}
-
 void UnpackAndRegisterProtectedInstructions(Isolate* isolate,
                                             Handle<FixedArray> code_table) {
   DisallowHeapAllocation no_gc;
@@ -298,27 +191,6 @@ bool IsWasmCodegenAllowed(Isolate* isolate, Handle<Context> context) {
              v8::Utils::ToLocal(isolate->factory()->empty_string()));
 }
 
-void DetachWebAssemblyMemoryBuffer(Isolate* isolate,
-                                   Handle<JSArrayBuffer> buffer,
-                                   bool free_memory) {
-  const bool is_external = buffer->is_external();
-  DCHECK(!buffer->is_neuterable());
-  if (!is_external) {
-    buffer->set_is_external(true);
-    isolate->heap()->UnregisterArrayBuffer(*buffer);
-    if (free_memory) {
-      // We need to free the memory before neutering the buffer because
-      // FreeBackingStore reads buffer->allocation_base(), which is nulled out
-      // by Neuter. This means there is a dangling pointer until we neuter the
-      // buffer. Since there is no way for the user to directly call
-      // FreeBackingStore, we can ensure this is safe.
-      buffer->FreeBackingStore();
-    }
-  }
-  buffer->set_is_neuterable(true);
-  buffer->Neuter();
-}
-
 namespace testing {
 void ValidateInstancesChain(Isolate* isolate,
                             Handle<WasmModuleObject> module_obj,

src/wasm/wasm-module.h

@@ -275,19 +275,6 @@ V8_EXPORT_PRIVATE Handle<JSArray> GetCustomSections(
 // function index, the inner one by the local index.
 Handle<FixedArray> DecodeLocalNames(Isolate*, Handle<WasmCompiledModule>);
 
-Handle<JSArrayBuffer> NewArrayBuffer(
-    Isolate*, size_t size, bool enable_guard_regions,
-    SharedFlag shared = SharedFlag::kNotShared);
-
-Handle<JSArrayBuffer> SetupArrayBuffer(
-    Isolate*, void* allocation_base, size_t allocation_length,
-    void* backing_store, size_t size, bool is_external,
-    bool enable_guard_regions, SharedFlag shared = SharedFlag::kNotShared);
-
-void DetachWebAssemblyMemoryBuffer(Isolate* isolate,
-                                   Handle<JSArrayBuffer> buffer,
-                                   bool free_memory);
-
 // If the target is an export wrapper, return the {WasmFunction*} corresponding
 // to the wrapped wasm function; in all other cases, return nullptr.
 // The returned pointer is owned by the wasm instance target belongs to. The
@@ -300,17 +287,6 @@ Handle<Code> UnwrapExportWrapper(Handle<JSFunction> export_wrapper);
 void UpdateDispatchTables(Isolate* isolate, Handle<FixedArray> dispatch_tables,
                           int index, WasmFunction* function, Handle<Code> code);
 
-#if V8_TARGET_ARCH_64_BIT
-const bool kGuardRegionsSupported = true;
-#else
-const bool kGuardRegionsSupported = false;
-#endif
-
-inline bool EnableGuardRegions() {
-  return FLAG_wasm_guard_pages && kGuardRegionsSupported &&
-         !FLAG_experimental_wasm_threads;
-}
-
 void UnpackAndRegisterProtectedInstructions(Isolate* isolate,
                                             Handle<FixedArray> code_table);
 

src/wasm/wasm-objects.cc

@@ -14,6 +14,7 @@
 #include "src/wasm/module-compiler.h"
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-code-specialization.h"
+#include "src/wasm/wasm-memory.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-objects-inl.h"
 #include "src/wasm/wasm-text.h"

test/cctest/wasm/test-run-wasm-module.cc

@@ -11,6 +11,7 @@
 #include "src/version.h"
 #include "src/wasm/module-compiler.h"
 #include "src/wasm/module-decoder.h"
+#include "src/wasm/wasm-memory.h"
 #include "src/wasm/wasm-module-builder.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-objects-inl.h"
@@ -1111,7 +1112,7 @@ TEST(Run_WasmModule_Buffer_Externalized_GrowMem) {
       i::WasmMemoryObject::SetupNewBufferWithSameBackingStore(isolate, mem_obj,
                                                               current_pages);
     }
-    wasm::DetachWebAssemblyMemoryBuffer(isolate, memory, free_memory);
+    wasm::DetachMemoryBuffer(isolate, memory, free_memory);
     CHECK_EQ(16, result);
     memory = handle(mem_obj->array_buffer());
     instance->set_memory_buffer(*memory);
@@ -1152,7 +1153,7 @@ TEST(Run_WasmModule_Buffer_Externalized_GrowMemMemSize) {
         WasmMemoryObject::New(isolate, buffer, 100);
     v8::Utils::ToLocal(buffer)->Externalize();
     int32_t result = WasmMemoryObject::Grow(isolate, mem_obj, 0);
-    wasm::DetachWebAssemblyMemoryBuffer(isolate, buffer, false);
+    wasm::DetachMemoryBuffer(isolate, buffer, false);
     CHECK_EQ(16, result);
 
     isolate->array_buffer_allocator()->Free(backing_store,
@@ -1173,7 +1174,7 @@ TEST(Run_WasmModule_Buffer_Externalized_Detach) {
         isolate, backing_store, 16 * WasmModule::kPageSize, backing_store,
         16 * WasmModule::kPageSize, false, false);
     v8::Utils::ToLocal(buffer)->Externalize();
-    wasm::DetachWebAssemblyMemoryBuffer(isolate, buffer, true);
+    wasm::DetachMemoryBuffer(isolate, buffer, true);
     isolate->array_buffer_allocator()->Free(backing_store,
                                             16 * WasmModule::kPageSize);
   }

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

@@ -6,6 +6,7 @@
 
 #include "src/api.h"
 #include "src/assembler-inl.h"
+#include "src/wasm/wasm-memory.h"
 #include "src/wasm/wasm-objects-inl.h"
 
 namespace v8 {