This is a major change on how we represent nested name qualifications in
the AST.
* The nested name specifier itself and how it's stored is changed. The
prefixes for types are handled within the type hierarchy, which makes
canonicalization for them super cheap, no memory allocation required.
Also translating a type into nested name specifier form becomes a no-op.
An identifier is stored as a DependentNameType. The nested name
specifier gains a lightweight handle class, to be used instead of
passing around pointers, which is similar to what is implemented for
TemplateName. There is still one free bit available, and this handle can
be used within a PointerUnion and PointerIntPair, which should keep
bit-packing aficionados happy.
* The ElaboratedType node is removed, all type nodes in which it could
previously apply to can now store the elaborated keyword and name
qualifier, tail allocating when present.
* TagTypes can now point to the exact declaration found when producing
these, as opposed to the previous situation of there only existing one
TagType per entity. This increases the amount of type sugar retained,
and can have several applications, for example in tracking module
ownership, and other tools which care about source file origins, such as
IWYU. These TagTypes are lazily allocated, in order to limit the
increase in AST size.
This patch offers a great performance benefit.
It greatly improves compilation time for
[stdexec](https://github.com/NVIDIA/stdexec). For one datapoint, for
`test_on2.cpp` in that project, which is the slowest compiling test,
this patch improves `-c` compilation time by about 7.2%, with the
`-fsyntax-only` improvement being at ~12%.
This has great results on compile-time-tracker as well:
This patch also further enables other optimziations in the future, and
will reduce the performance impact of template specialization resugaring
when that lands.
It has some other miscelaneous drive-by fixes.
About the review: Yes the patch is huge, sorry about that. Part of the
reason is that I started by the nested name specifier part, before the
ElaboratedType part, but that had a huge performance downside, as
ElaboratedType is a big performance hog. I didn't have the steam to go
back and change the patch after the fact.
There is also a lot of internal API changes, and it made sense to remove
ElaboratedType in one go, versus removing it from one type at a time, as
that would present much more churn to the users. Also, the nested name
specifier having a different API avoids missing changes related to how
prefixes work now, which could make existing code compile but not work.
How to review: The important changes are all in
`clang/include/clang/AST` and `clang/lib/AST`, with also important
changes in `clang/lib/Sema/TreeTransform.h`.
The rest and bulk of the changes are mostly consequences of the changes
in API.
PS: TagType::getDecl is renamed to `getOriginalDecl` in this patch, just
for easier to rebasing. I plan to rename it back after this lands.
Fixes#136624
Fixes https://github.com/llvm/llvm-project/issues/43179
Fixes https://github.com/llvm/llvm-project/issues/68670
Fixes https://github.com/llvm/llvm-project/issues/92757
Note that PointerUnion::dyn_cast has been soft deprecated in
PointerUnion.h:
// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>
Literal migration would result in dyn_cast_if_present (see the
definition of PointerUnion::dyn_cast), but this patch uses dyn_cast
because we expect AP to be nonnull.
Note that PointerUnion::{is,get} have been soft deprecated in
PointerUnion.h:
// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>
I'm not touching PointerUnion::dyn_cast for now because it's a bit
complicated; we could blindly migrate it to dyn_cast_if_present, but
we should probably use dyn_cast when the operand is known to be
non-null.
This commit addresses several null pointer issues identified by static
analysis by replacing dyn_cast<> with cast<> and getAs<> with castAs<>
in various parts of the Clang codebase. The cast and castAs method is
used to ensure that the type is correctly cast, which helps prevent
potential null pointer dereferences.
Changes:
1. ASTContext.cpp:
Replaced dyn_cast with cast to ensure that the type is correctly cast to
AttributedType.
2. SemaFunctionEffects.cpp:
Replaced getAs with castAs to ensure that the type is correctly cast to
FunctionProtoType.
3. SemaHLSL.cpp:
Replaced getAs with castAs to ensure that the type is correctly cast to
VectorType.
This is one of the many PRs to fix errors with LLVM_ENABLE_WERROR=on.
Built by GCC 11.
Fix warnings:
clang/lib/Sema/SemaFunctionEffects.cpp:1531:5: error: this statement may
fall through [-Werror=implicit-fallthrough=]
1531 | switch (DiffKind) {
| ^~~~~~
Bug fix: `@autoreleasepool`, `@synchronized`, and `@finally` were not
being noticed and treated as function effect violations.
---------
Co-authored-by: Doug Wyatt <dwyatt@apple.com>
Correctly detect `(x ? a : b)` as nonblocking when `a` and `b` are. Use
`FunctionEffectsRef::get` to get to the actual effect set instead of trying
to retrieve it manually via the `FunctionProtoType` as we may have to
look through function pointers etc. in some cases.
---------
Co-authored-by: Doug Wyatt <dwyatt@apple.com>
- In Sema, when encountering Decls with function effects needing
verification, add them to a vector, DeclsWithEffectsToVerify.
- Update AST serialization to include DeclsWithEffectsToVerify.
- In AnalysisBasedWarnings, use DeclsWithEffectsToVerify as a work
queue, verifying functions with declared effects, and inferring (when
permitted and necessary) whether their callees have effects.
---------
Co-authored-by: Doug Wyatt <dwyatt@apple.com>
Co-authored-by: Sirraide <aeternalmail@gmail.com>
Co-authored-by: Erich Keane <ekeane@nvidia.com>
