This only calls `noteStep()` on jump opcodes, so this works for loops.
It does not prevent "hangs" when a function is just _very_ long (could
be interesting how this interfaces with expand statements?).
Fixes https://github.com/llvm/llvm-project/issues/165951
The current interpreter does _not_ evaluate function calls when checking
for a potential constant expression.
However, it _does_ evaluate the initializers of constructors. In the
bytecode interpreter, this is harder because we compile the initializers
and the body of a constructor all in the same function.
Add a special opcode that we emit after the constructor initializers and
that aborts when we're checking for a potential constant expression.
Previously, we had two very similar diagnostics, "read of object outside
its lifetime" and "read of variable whose lifetime has ended".
The difference, as far as I can tell, is that the latter was used when
the variable was created in a function frame that has since vanished,
i.e. in this case:
```c++
constexpr const int& return_local() { return 5; }
static_assert(return_local() == 5);
```
so the output used to be:
```console
array.cpp:602:15: error: static assertion expression is not an integral constant expression
602 | static_assert(return_local() == 5);
| ^~~~~~~~~~~~~~~~~~~
array.cpp:602:15: note: read of temporary whose lifetime has ended
array.cpp:601:46: note: temporary created here
601 | constexpr const int& return_local() { return 5; }
| ^
```
But then this scenario gets the other diagnostic:
```c++
constexpr int b = b;
```
```console
array.cpp:603:15: error: constexpr variable 'b' must be initialized by a constant expression
603 | constexpr int b = b;
| ^ ~
array.cpp:603:19: note: read of object outside its lifetime is not allowed in a constant expression
603 | constexpr int b = b;
| ^
```
With this patch, we diagnose both cases similarly:
```c++
constexpr const int& return_local() { return 5; }
static_assert(return_local() == 5);
constexpr int b = b;
```
```console
array.cpp:602:15: error: static assertion expression is not an integral constant expression
602 | static_assert(return_local() == 5);
| ^~~~~~~~~~~~~~~~~~~
array.cpp:602:15: note: read of object outside its lifetime is not allowed in a constant expression
602 | static_assert(return_local() == 5);
| ^~~~~~~~~~~~~~
array.cpp:601:46: note: temporary created here
601 | constexpr const int& return_local() { return 5; }
| ^
array.cpp:603:15: error: constexpr variable 'b' must be initialized by a constant expression
603 | constexpr int b = b;
| ^ ~
array.cpp:603:19: note: read of object outside its lifetime is not allowed in a constant expression
603 | constexpr int b = b;
| ^
```
We do lose the "object" vs. "temporary" distinction in the note and only
mention it in the "created here" note. That can be added back if it's
important enough. I wasn't sure.
Clang will make the instance pointer be of type 'int' if it is invalid,
which trips up later logic. Mark functions as invalid if any of their
parameters is and compile + check them early in CallPtr.
Fixes https://github.com/llvm/llvm-project/issues/175425
When activating a union member, none of the unions in that path can have
a non-trivial constructor. Unfortunately, this is something we have to
do when evaluating the bytecode, not while compiling it.
Save them as a pointer intead of using a shared_ptr. This we we can use
the pointer integer value to differentiate the "no initmap yet" and "all
values initialzed" cases.
This regresses one test case in const-eval.c, but as it turns out, that
only worked coincidentally before.
Instead of checking the initial callee, check the callee after the
virtual dispatch. This means we need to check whether we're in a ctor to
not regress existing tests.
Fixes https://github.com/llvm/llvm-project/issues/165234
We used to do this the other way around to work around an awkwardness
with CheckStore, namely that we shouldn't check pointers for being
activated when activating them.
Add a parameter to CheckStore instead and call CheckStore() _before_
activating and initializing the pointers in the respective opcode
implementations.
Fixes https://github.com/llvm/llvm-project/issues/164975
Fixes#152893.
An assert was raised when a constexpr virtual function was called from
an constexpr array element with -fexperimental-new-constant-interpreter
set.
In the attached test case, the global variable later only points to
gargbage, because the MaterializeTemporaryExpr used to initialize it is
a local variable, which is gone by the time we try to evaluate the
store.
Fixes#156223
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
