[webkit-changes] [WebKit/WebKit] 6006aa: Generated IPC decoders check the decode success twice

[Kimmo Kinnunen]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 6006aa6aa0f6985b11051239c449ec95571ddecd
      https://github.com/WebKit/WebKit/commit/6006aa6aa0f6985b11051239c449ec95571ddecd
  Author: Kimmo Kinnunen <kkinnunen at apple.com>
  Date:   2023-07-03 (Mon, 03 Jul 2023)

  Changed paths:
    M Source/WebKit/Scripts/generate-serializers.py
    M Source/WebKit/Scripts/webkit/tests/GeneratedSerializers.cpp

  Log Message:
  -----------
  Generated IPC decoders check the decode success twice
https://bugs.webkit.org/show_bug.cgi?id=258604
rdar://problem/111434133

Reviewed by Alex Christensen.

The check would be like:
  decode property
  check success
  decode property
  check success

On first decode error, the subsequent decodes will fail as per design.
Thus we can omit the redundant caller checks and check only once after
series of decodes, before using the decoded properties.

Instead of checking each decode operation result, check as follows:

  decode properties
  if (!decoder.isValid())
    return std::nullopt;
  use properties
  decode more properties
  if (!decoder.isValid())
    return std::nullopt;
  use properties

This should, very slightly, optimize for the standard case of all
decodes succeeding.

* Source/WebKit/Scripts/generate-serializers.py:
(decode_type):
(generate_impl):
* Source/WebKit/Scripts/webkit/tests/GeneratedSerializers.cpp:
(IPC::ArgumentCoder<Namespace::Subnamespace::StructName>::decode):
(IPC::ArgumentCoder<Namespace::OtherClass>::decode):
(IPC::ArgumentCoder<Namespace::ReturnRefClass>::decode):
(IPC::ArgumentCoder<Namespace::EmptyConstructorStruct>::decode):
(IPC::ArgumentCoder<Namespace::EmptyConstructorNullable>::decode):
(IPC::ArgumentCoder<WithoutNamespace>::decode):
(IPC::ArgumentCoder<WithoutNamespaceWithAttributes>::decode):
(IPC::ArgumentCoder<WebCore::InheritsFrom>::decode):
(IPC::ArgumentCoder<WebCore::InheritanceGrandchild>::decode):
(IPC::ArgumentCoder<WTF::Seconds>::decode):
(IPC::ArgumentCoder<WTF::CreateUsingClass>::decode):
(IPC::ArgumentCoder<WebCore::FloatBoxExtent>::decode):
(IPC::ArgumentCoder<NullableSoftLinkedMember>::decode):
(IPC::ArgumentCoder<WebCore::TimingFunction>::decode):
(IPC::ArgumentCoder<Namespace::ConditionalCommonClass>::decode):
(IPC::ArgumentCoder<Namespace::CommonClass>::decode):
(IPC::ArgumentCoder<Namespace::AnotherCommonClass>::decode):
(IPC::ArgumentCoder<WebCore::MoveOnlyBaseClass>::decode):
(IPC::ArgumentCoder<WebCore::MoveOnlyDerivedClass>::decode):

Canonical link: https://commits.webkit.org/265717@main