This breaks a ton of libc++ tests otherwise, since calling
std::destroy_at will currently end the lifetime of the entire array not
just the given element.
See https://github.com/llvm/llvm-project/issues/147528
This way, we can check a single uint8_t for != 0 to know whether this
block is accessible or not. If not, we still need to figure out why not
and diagnose appropriately of course.
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
I forgot to call this here as well. It was only used in the EvalEmitter
implementation of the function. Also fix a problem where we didn't
diagnose out-of-lifetime reads here.
For mutable and const fields, we have two bits in InlineDescriptor,
which both get inherited down the hierarchy. When a field is both const
and mutable, we CAN read from it if it is a mutable-in-const field, but
we _can't_ read from it if it is a const-in-mutable field. We need
another bit to distinguish the two cases.
Only activate things if the syntactical structure suggests so. This adds
a bunch of new opcodes to control whether to activate in stores, etc.
Fixes#134789
…types usi… (#144676)"
This reverts commit 68471d29eed2c49f9b439e505b3f24d387d54f97.
IntegralAP contains a union:
union {
uint64_t *Memory = nullptr;
uint64_t Val;
};
On 64bit systems, both Memory and Val have the same size. However, on 32
bit system, Val is 64bit and Memory only 32bit. Which means the default
initializer for Memory will only zero half of Val. We fixed this by
zero-initializing Val explicitly in the IntegralAP(unsigned BitWidth)
constructor.
See also the discussion in
https://github.com/llvm/llvm-project/pull/144246
Both `APInt` and `APFloat` will heap-allocate memory themselves using
the system allocator when the size of their data exceeds 64 bits.
This is why clang has `APNumericStorage`, which allocates its memory
using an allocator (via `ASTContext`) instead. Calling `getValue()` on
an ast node like that will then create a new `APInt`/`APFloat` , which
will copy the data (in the `APFloat` case, we even copy it twice).
That's sad but whatever.
In the bytecode interpreter, we have a similar problem. Large integers
and floating-point values are placement-new allocated into the
`InterpStack` (or into the bytecode, which is a `vector<std::byte>`).
When we then later interrupt interpretation, we don't run the destructor
for all items on the stack, which means we leak the memory the
`APInt`/`APFloat` (which backs the `IntegralAP`/`Floating` the
interpreter uses).
Fix this by using an approach similar to the one used in the AST. Add an
allocator to `InterpState`, which is used for temporaries and local
values. Those values will be freed at the end of interpretation. For
global variables, we need to promote the values to global lifetime,
which we do via `InitGlobal` and `FinishInitGlobal` ops.
Interestingly, this results in a slight _improvement_ in compile times:
https://llvm-compile-time-tracker.com/compare.php?from=6bfcdda9b1ddf0900f82f7e30cb5e3253a791d50&to=88d1d899127b408f0fb0f385c2c58e6283195049&stat=instructions:u
(but don't ask me why).
Fixes https://github.com/llvm/llvm-project/issues/139012
Rename isConstexpr to isValid, the former was always a bad name. Save a
constexpr bit in Function so we don't have to access the decl in
CheckCallable.
CheckStore is for assignments, but we're constructing something here, so
pass AK_Construct instead. We already diagnosed the test case, but as an
assignment.
