1919204 - Remove some global constructors

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P2)

Description

[André Bargull [:anba]]

Remove some global constructors according to -Wglobal-constructors. Not necessarily still global constructors after compiler optimisations, see bug 74803, comment #99. But no harm also removing global constructors from -Wglobal-constructors, too. The proposed patches do remove the effective number of global constructors per nm libmozjs-132a1.so | grep -c _GLOBAL__sub_, but I haven't spent time investigating which patch removed which constructor.

Comment 1

[André Bargull [:anba]]

Attachment: Bug 1919204 - Part 1: Add more constexpr to mozilla::EnumSet. r=glandium!

Add more constexpr in preparation for part 2.

Part 2 only requires constexpr operator+, but there shouldn't be harm
adding constexpr to the other methods, too.

Comment 2

[André Bargull [:anba]]

Attachment: Bug 1919204 - Part 2: Avoid global constructors when creating EnumSet objects. r=#spidermonkey-reviewers!

Requires the previous part.

Comment 3

[André Bargull [:anba]]

Attachment: Bug 1919204 - Part 1: Avoid global constructors for ModuleNamespaceObject::ProxyHandler. r=#spidermonkey-reviewers!

Comment 4

[André Bargull [:anba]]

Attachment: Bug 1919204 - Part 3: Make PackedTypeCode and PackedType constructors constexpr. r=#spidermonkey-reviewers!

Required for the next part.

PackedTypeCode:

• Add separate PackedTypeCode::pack() for non-ref type case, because
  reinterpret_cast isn't allowed in constexpr functions. (There's an
  implicit reinterpret_cast in (uint64_t)(uintptr_t)typeDef.)
• Add private constructors to PackedTypeCode to fully initialise all parts of
  the union. constexpr functions can't change the active member of an union
  and the initialisation through PackedTypeCode ptc = {}; activates the
  PackedTypeCode::bits_ member.
• The default constructor is needed for the std::is_pod_v<LitValPOD> static
  assertion in "js/src/wasm/AsmJS.cpp".

Comment 5

[André Bargull [:anba]]

Attachment: Bug 1919204 - Part 4: Make SymbolicAddressSignature globals constexpr. r=#spidermonkey-reviewers!

The preprocessor generated SymbolicAddressSignature SASig##sa_name globals needed
global constructors, because when calling ValType::toMIRType(), cf. specTypeToMIRType
in "GenerateBuiltinModules.py".

The previous part made ValType::toMIRType() constexpr, also add constexpr here to
avoid regressions. Also add constexpr to all other SymbolicAddressSignature globals
for consistency.

Comment 6

[André Bargull [:anba]]

Attachment: Bug 1919204 - Part 2: Avoid global constructor for protoTable. r=#spidermonkey-reviewers!

TypedArrayObject::{fixedLength,resizable}Classes were defined out-of-line,
which caused protoTable to generate a global constructor. Change the
definition to be inline and then make protoTable constexpr to ensure we
don't regress this.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9cda912ff9b9
Part 1: Avoid global constructors for ModuleNamespaceObject::ProxyHandler. r=spidermonkey-reviewers,mgaudet
https://hg.mozilla.org/integration/autoland/rev/973011a914fc
Part 2: Avoid global constructor for protoTable. r=spidermonkey-reviewers,mgaudet

Comment 8

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/9cda912ff9b9
https://hg.mozilla.org/mozilla-central/rev/973011a914fc

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/378c7b45cb5d
Part 3: Make PackedTypeCode and PackedType constructors constexpr. r=yury
https://hg.mozilla.org/integration/autoland/rev/75900af5f9c7
Part 4: Make SymbolicAddressSignature globals constexpr. r=yury

Comment 10

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/378c7b45cb5d
https://hg.mozilla.org/mozilla-central/rev/75900af5f9c7