[wasm] Load module name during streaming compile

The streaming compilation pipeline did not parse the names section and
this is also not longer needed for getting function or local names.
However, the module name still needs to be set eagerly.

Change-Id: I1ac12e98b970ea0781302dc44ee684510bdf2d69
Reviewed-on: https://chromium-review.googlesource.com/962452Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Stephan Herhut <herhut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51979}

src/wasm/decoder.h

@@ -46,6 +46,8 @@ class Decoder {
 
   Decoder(const byte* start, const byte* end, uint32_t buffer_offset = 0)
       : Decoder(start, start, end, buffer_offset) {}
+  explicit Decoder(const Vector<const byte> bytes, uint32_t buffer_offset = 0)
+      : Decoder(bytes.start(), bytes.start() + bytes.length(), buffer_offset) {}
   Decoder(const byte* start, const byte* pc, const byte* end,
           uint32_t buffer_offset = 0)
       : start_(start), pc_(pc), end_(end), buffer_offset_(buffer_offset) {
@@ -248,6 +250,7 @@ class Decoder {
 
   const byte* start() const { return start_; }
   const byte* pc() const { return pc_; }
+  uint32_t position() const { return static_cast<uint32_t>(pc_ - start_); }
   uint32_t pc_offset() const {
     return static_cast<uint32_t>(pc_ - start_) + buffer_offset_;
   }

src/wasm/module-compiler.cc

@@ -3262,17 +3262,22 @@ bool AsyncStreamingProcessor::ProcessSection(SectionCode section_code,
                                              uint32_t offset) {
   TRACE_STREAMING("Process section %d ...\n", section_code);
   if (compilation_unit_builder_) {
-    // We reached a section after the code section, we do not need the the
+    // We reached a section after the code section, we do not need the
     // compilation_unit_builder_ anymore.
     CommitCompilationUnits();
     compilation_unit_builder_.reset();
   }
   if (section_code == SectionCode::kUnknownSectionCode) {
-    // No need to decode unknown sections, even the names section. If decoding
-    // of the unknown section fails, compilation should succeed anyways, and
-    // even decoding the names section is unnecessary because the result comes
-    // too late for streaming compilation.
-    return true;
+    Decoder decoder(bytes, offset);
+    section_code = ModuleDecoder::IdentifyUnknownSection(
+        decoder, bytes.start() + bytes.length());
+    if (section_code == SectionCode::kUnknownSectionCode) {
+      // Skip unknown sections that we do not know how to handle.
+      return true;
+    }
+    // Remove the unknown section tag from the payload bytes.
+    offset += decoder.position();
+    bytes = bytes.SubVector(decoder.position(), bytes.size());
   }
   constexpr bool verify_functions = false;
   decoder_.DecodeSection(section_code, bytes, offset, verify_functions);

src/wasm/module-decoder.cc

@@ -218,25 +218,11 @@ class WasmSectionIterator {
 
     if (section_code == kUnknownSectionCode) {
       // Check for the known "name" section.
-      WireBytesRef string =
-          wasm::consume_string(decoder_, true, "section name");
-      if (decoder_.failed() || decoder_.pc() > section_end_) {
-        section_code_ = kUnknownSectionCode;
-        return;
-      }
-      const byte* section_name_start =
-          decoder_.start() + decoder_.GetBufferRelativeOffset(string.offset());
+      section_code =
+          ModuleDecoder::IdentifyUnknownSection(decoder_, section_end_);
+      // As a side effect, the above function will forward the decoder to after
+      // the identifier string.
       payload_start_ = decoder_.pc();
-
-      TRACE("  +%d  section name        : \"%.*s\"\n",
-            static_cast<int>(section_name_start - decoder_.start()),
-            string.length() < 20 ? string.length() : 20, section_name_start);
-
-      if (string.length() == num_chars(kNameString) &&
-          strncmp(reinterpret_cast<const char*>(section_name_start),
-                  kNameString, num_chars(kNameString)) == 0) {
-        section_code = kNameSectionCode;
-      }
     } else if (!IsValidSectionCode(section_code)) {
       decoder_.errorf(decoder_.pc(), "unknown section code #0x%02x",
                       section_code);
@@ -1392,6 +1378,27 @@ ModuleResult ModuleDecoder::FinishDecoding(bool verify_functions) {
   return impl_->FinishDecoding(verify_functions);
 }
 
+SectionCode ModuleDecoder::IdentifyUnknownSection(Decoder& decoder,
+                                                  const byte* end) {
+  WireBytesRef string = wasm::consume_string(decoder, true, "section name");
+  if (decoder.failed() || decoder.pc() > end) {
+    return kUnknownSectionCode;
+  }
+  const byte* section_name_start =
+      decoder.start() + decoder.GetBufferRelativeOffset(string.offset());
+
+  TRACE("  +%d  section name        : \"%.*s\"\n",
+        static_cast<int>(section_name_start - decoder.start()),
+        string.length() < 20 ? string.length() : 20, section_name_start);
+
+  if (string.length() == num_chars(kNameString) &&
+      strncmp(reinterpret_cast<const char*>(section_name_start), kNameString,
+              num_chars(kNameString)) == 0) {
+    return kNameSectionCode;
+  }
+  return kUnknownSectionCode;
+}
+
 bool ModuleDecoder::ok() { return impl_->ok(); }
 
 ModuleResult SyncDecodeWasmModule(Isolate* isolate, const byte* module_start,

src/wasm/module-decoder.h

@@ -146,6 +146,16 @@ class ModuleDecoder {
 
   bool ok();
 
+  // Translates the unknown section that decoder is pointing to to an extended
+  // SectionCode if the unknown section is known to decoder. Currently this only
+  // handles the name section.
+  // The decoder is expected to point after the section lenght and just before
+  // the identifier string of the unknown section.
+  // If a SectionCode other than kUnknownSectionCode is returned, the decoder
+  // will point right after the identifier string. Otherwise, the position is
+  // undefined.
+  static SectionCode IdentifyUnknownSection(Decoder& decoder, const byte* end);
+
  private:
   std::unique_ptr<ModuleDecoderImpl> impl_;
 };

test/message/wasm-function-name-async.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --no-stress-opt
+
+load('test/mjsunit/mjsunit.js');
+load('test/mjsunit/wasm/wasm-constants.js');
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+var builder = new WasmModuleBuilder();
+builder.addFunction('main', kSig_i_v).addBody([kExprUnreachable]).exportFunc();
+let buffer = builder.toBuffer();
+assertPromiseResult(WebAssembly.instantiate(buffer), pair => {
+  try {
+    pair.instance.exports.main();
+  } catch (e) {
+    print(e.stack);
+  }
+});

test/message/wasm-function-name-async.out

+RuntimeError: unreachable
+    at main (wasm-function[0]:1)
+    at pair (*%(basename)s:16:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)

test/message/wasm-function-name-streaming.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --wasm-test-streaming --no-stress-opt
+
+load("test/message/wasm-function-name-async.js");

test/message/wasm-function-name-streaming.out

+RuntimeError: unreachable
+    at main (wasm-function[0]:1)
+    at pair (test/message/wasm-function-name-async.js:16:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)

test/message/wasm-module-and-function-name-async.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --no-stress-opt
+
+load('test/mjsunit/mjsunit.js');
+load('test/mjsunit/wasm/wasm-constants.js');
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+var builder = new WasmModuleBuilder();
+builder.setName('test-module');
+builder.addFunction('main', kSig_i_v).addBody([kExprUnreachable]).exportFunc();
+let buffer = builder.toBuffer();
+assertPromiseResult(WebAssembly.instantiate(buffer), pair => {
+  try {
+    pair.instance.exports.main();
+  } catch (e) {
+    print(e.stack);
+  }
+});

test/message/wasm-module-and-function-name-async.out

+RuntimeError: unreachable
+    at test-module.main (wasm-function[0]:1)
+    at pair (*%(basename)s:17:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)

test/message/wasm-module-and-function-name-streaming.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --wasm-test-streaming --no-stress-opt
+
+load("test/message/wasm-module-and-function-name-async.js");

test/message/wasm-module-and-function-name-streaming.out

+RuntimeError: unreachable
+    at test-module.main (wasm-function[0]:1)
+    at pair (test/message/wasm-module-and-function-name-async.js:17:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)

test/message/wasm-module-name-async.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --no-stress-opt
+
+load('test/mjsunit/mjsunit.js');
+load('test/mjsunit/wasm/wasm-constants.js');
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+var builder = new WasmModuleBuilder();
+builder.setName('test-module');
+builder.addFunction(undefined, kSig_i_v)
+    .addBody([kExprUnreachable])
+    .exportAs('main');
+let buffer = builder.toBuffer();
+assertPromiseResult(WebAssembly.instantiate(buffer), pair => {
+  try {
+    pair.instance.exports.main();
+  } catch (e) {
+    print(e.stack);
+  }
+});

test/message/wasm-module-name-async.out

+RuntimeError: unreachable
+    at test-module (wasm-function[0]:1)
+    at pair (*%(basename)s:19:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)

test/message/wasm-module-name-streaming.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --wasm-test-streaming --no-stress-opt
+
+load("test/message/wasm-module-name-async.js");

test/message/wasm-module-name-streaming.out

+RuntimeError: unreachable
+    at test-module (wasm-function[0]:1)
+    at pair (test/message/wasm-module-name-async.js:19:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)

test/message/wasm-no-name-async.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --no-stress-opt
+
+load('test/mjsunit/mjsunit.js');
+load('test/mjsunit/wasm/wasm-constants.js');
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+var builder = new WasmModuleBuilder();
+builder.addFunction(undefined, kSig_i_v)
+    .addBody([kExprUnreachable])
+    .exportAs('main');
+let buffer = builder.toBuffer();
+assertPromiseResult(WebAssembly.instantiate(buffer), pair => {
+  try {
+    pair.instance.exports.main();
+  } catch (e) {
+    print(e.stack);
+  }
+});

test/message/wasm-no-name-async.out

+RuntimeError: unreachable
+    at wasm-function[0]:1
+    at pair (*%(basename)s:18:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)

test/message/wasm-no-name-streaming.js

+// Copyright 2018 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.
+
+// Flags: --expose-wasm --wasm-test-streaming --no-stress-opt
+
+load("test/message/wasm-no-name-async.js");

test/message/wasm-no-name-streaming.out

+RuntimeError: unreachable
+    at wasm-function[0]:1
+    at pair (test/message/wasm-no-name-async.js:18:27)
+    at promise.then.result (test/mjsunit/mjsunit.js:576:15)