Summary:
It's extremely common to conditionally blend two vectors. Previously
this was done with mask registers, which is what the normal ternary code
generation does when used on a vector. However, since Clang 15 we have
supported boolean vector types in the compiler. These are useful in
general for checking the mask registers, but are currently limited
because they do not map to an LLVM-IR select instruction.
This patch simply relaxes these checks, which are technically forbidden
by
the OpenCL standard. However, general vector support should be able to
handle these. We already support this for Arm SVE types, so this should
be make more consistent with the clang vector type.
The changes from https://github.com/llvm/llvm-project/pull/136855 missed
a change with atomic assignment constraints. This fixes a bug where we'd
accidentally drop a non-atomic-to-atomic conversion step.
Fixes#154157
co-authored-by: @ahatanak
These warnings are reported on a per expression basis, however some
potential misaligned accesses are discarded before that happens. The
problem is when a new expression starts while processing another
expression. The new expression will end first and emit all potential
misaligned accesses collected up to that point. That includes candidates
that were found in the parent expression, even though they might have
gotten discarded later.
Fixed by checking if the candidate is located withing the currently
processed expression.
Fixes#144729
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
This is a first pass at implementing
[P2841R7](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p2841r7.pdf).
The implementation is far from complete; however, I'm aiming to do that
in chunks, to make our lives easier.
In particular, this does not implement
- Subsumption
- Mangling
- Satisfaction checking is minimal as we should focus on #141776 first
(note that I'm currently very stuck)
FTM, release notes, status page, etc, will be updated once the feature
is more mature. Given the state of the feature, it is not yet allowed in
older language modes.
Of note:
- Mismatches between template template arguments and template template
parameters are a bit wonky. This is addressed by #130603
- We use `UnresolvedLookupExpr` to model template-id. While this is
pre-existing, I have been wondering if we want to introduce a different
OverloadExpr subclass for that. I did not make the change in this patch.
The checks for the 'z' and 't' format specifiers added in the original
PR #143653 had some issues and were overly strict, causing some build
failures and were consequently reverted at
4c85bf2fe8.
In the latest commit
27c58629ec,
I relaxed the checks for the 'z' and 't' format specifiers, so warnings
are now only issued when they are used with mismatched types.
The original intent of these checks was to diagnose code that assumes
the underlying type of `size_t` is `unsigned` or `unsigned long`, for
example:
```c
printf("%zu", 1ul); // Not portable, but not an error when size_t is unsigned long
```
However, it produced a significant number of false positives. This was
partly because Clang does not treat the `typedef` `size_t` and
`__size_t` as having a common "sugar" type, and partly because a large
amount of existing code either assumes `unsigned` (or `unsigned long`)
is `size_t`, or they define the equivalent of size_t in their own way
(such as
sanitizer_internal_defs.h).2e67dcfdcd/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h (L203)
Including the results of `sizeof`, `sizeof...`, `__datasizeof`,
`__alignof`, `_Alignof`, `alignof`, `_Countof`, `size_t` literals, and
signed `size_t` literals, the results of pointer-pointer subtraction and
checks for standard library functions (and their calls).
The goal is to enable clang and downstream tools such as clangd and
clang-tidy to provide more portable hints and diagnostics.
The previous discussion can be found at #136542.
This PR implements this feature by introducing a new subtype of `Type`
called `PredefinedSugarType`, which was considered appropriate in
discussions. I tried to keep `PredefinedSugarType` simple enough yet not
limited to `size_t` and `ptrdiff_t` so that it can be used for other
purposes. `PredefinedSugarType` wraps a canonical `Type` and provides a
name, conceptually similar to a compiler internal `TypedefType` but
without depending on a `TypedefDecl` or a source file.
Additionally, checks for the `z` and `t` format specifiers in format
strings for `scanf` and `printf` were added. It will precisely match
expressions using `typedef`s or built-in expressions.
The affected tests indicates that it works very well.
Several code require that `SizeType` is canonical, so I kept `SizeType`
to its canonical form.
The failed tests in CI are allowed to fail. See the
[comment](https://github.com/llvm/llvm-project/pull/135386#issuecomment-3049426611)
in another PR #135386.
This PR addresses instances of compiler warning C4146 that can be
replaced with std::numeric_limits. Specifically, these are cases where a
literal such as '-1ULL' was used to assign a value to a uint64_t
variable. The intent is much cleaner if we use the appropriate
std::numeric_limits value<Type>::max() for these cases.
Addresses #147439
443377a9d1a8d4a69a317a1a892184c59dd0aec6 handled simple variable
definitions, but it didn't handle uninitialized variables with a
consteval constructor, and it didn't handle template instantiation.
Fixes#135281 .
Deal with the following scenario
```cpp
struct S {
char* c = new char;
constexpr ~S() {
delete c;
}
};
if constexpr((S{}, true)){};
```
There were two issues
- We need to produce a full expression _before_ evaluating the condition
(otherwise, automatic variables are never destroyed)
- We need to preserve the evaluation context of the condition while
doing the semantics analysis for it (lest it is evaluated in a
non-constant-evaluated context)
Fixes#120197Fixes#134820
Fixes 2 bugs reported in #146063
- The body of a lambda appearing in a discarded statement was sometimes
considered discarded itself
- A lambda conversion operator that was not odr-used was sometimes not
defined even if it was needed
Fixes#146063
---------
Co-authored-by: Timm Baeder <tbaeder@redhat.com>
The 'cache' construct is lowered as marking the acc.loop in ACC MLIR.
This results in any variable references that are not inside of the
acc.loop being invalid. This patch adds a warning to that effect, and
ensures that the variable references won't be added to the AST during
parsing so we don't try to lower them.
This results in loss of instantiation-diagnostics for these, however
that seems like an acceptable consequence to ignoring it.
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
ArrayRef has a constructor that accepts std::nullopt. This
constructor dates back to the days when we still had llvm::Optional.
Since the use of std::nullopt outside the context of std::optional is
kind of abuse and not intuitive to new comers, I would like to move
away from the constructor and eventually remove it.
This patch takes care of the clang side of the migration.
Remove `[expr.prim.req.nested]` check which restrict that local
parameters in constraint-expressions can only appear as unevaluated
operands. This change makes the treatment of examples like `requires`
expressions and other constant expression contexts uniform, consistent
with the adoption of P2280.
References: https://cplusplus.github.io/CWG/issues/2517.html
Fixes #132825
---------
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
Fix the logic in rewriteBuiltinFunctionDecl to work when the builtin
has a pointer parameter with an address space and one without a fixed
address space. A builtin fitting these criteria was recently added.
Change the attribute string to perform type checking on it, so without
the sema change compilation would fail with a wrong number of arguments
error.
This introduces the attribute discussed in
https://discourse.llvm.org/t/rfc-function-type-attribute-to-prevent-cfi-instrumentation/85458.
The proposed name has been changed from `no_cfi` to
`cfi_unchecked_callee` to help differentiate from `no_sanitize("cfi")`
more easily. The proposed attribute has the following semantics:
1. Indirect calls to a function type with this attribute will not be
instrumented with CFI. That is, the indirect call will not be checked.
Note that this only changes the behavior for indirect calls on pointers
to function types having this attribute. It does not prevent all
indirect function calls for a given type from being checked.
2. All direct references to a function whose type has this attribute
will always reference the true function definition rather than an entry
in the CFI jump table.
3. When a pointer to a function with this attribute is implicitly cast
to a pointer to a function without this attribute, the compiler will
give a warning saying this attribute is discarded. This warning can be
silenced with an explicit C-style cast or C++ static_cast.
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
The previous approach broke the instantiation convention for templated
substitutions, as we were attempting to instantiate the initializer
even when it was still dependent.
We deferred variable template instantiation until the end of the TU.
However, type deduction requires the initializer immediately,
similar to how constant evaluation does.
Fixes https://github.com/llvm/llvm-project/issues/140773Fixes#135032Fixes#134526
Reapplies https://github.com/llvm/llvm-project/pull/138122
This silences the diagnostic when the right-hand side is a null pointer
constant that comes from a macro expansion, such as NULL. However, we do
not limit to just NULL because other custom macros may expand to an
implicit void * cast in C while expanding to something else in C++.
Functions referenced in discarded statements could be treated as
odr-used
because we did not properly set the correct evaluation context in some
places.
Fixes https://github.com/llvm/llvm-project/issues/140449
Compound literals initializer-list should be a constant expression if it
is defined outside the body of a function.
Emit error instead of falling through tripping assertion error.
Fixes#139160
charN_t represent code units of different UTF encodings. Therefore the
values of 2 different charN_t objects do not represent the same
characters.
In order to avoid comparing apples and oranges, we add new warnings to
warn on:
- Implicit conversions
- Comparisons
- Other cases involving arithmetic conversions
We only produce the warning if we cannot establish the comparison would
be safe through constant evaluation.
The new `-Wimplicit-unicode-conversion` warning is enabled by default.
Note that this PR intentionally doesn;t touches char/wchar_t, but it
would be worth considering also warning on extending the new warnings to
these types (in a follow up)
Additionally most arithmetic operations on charN_t don't really make
sense (ie what does it mean to addition code units), so we could add
warnings for that.
Fixes#138526
A bunch of uses of IsFunctionConversion don't use the third argument and
just make a dummy QualType to pass. This splits IsFunctionConversion
into 2 functions, one that just takes 2 arguments and does the check,
and one that does the actual conversion using the 3rd argument. Both
functions can be const and replace current uses appropriately.
When a builtin function is passed a pointer with a different
address space, clang creates an overloaded
builtin function but does not copy the host/device attribute. This
causes
error when the builtin is called by device functions
since CUDA/HIP relies on the host/device attribute to treat
a builtin function as callable on both host and device
sides.
Fixed by copying the host/device attribute of the original
builtin function to the created overloaded builtin function.
When forming an invalid function type, we were not diagnosing it if the
call was dependent.
However, we later rely on the function type to be sensible during
argument deduction.
We now diagnose anything that is not a potential function type, to avoid
constructing bogus call expressions.
Fixes#138657Fixes#115725Fixes#68852
Transforming an expression to a potentially evaluated expression can
fail. If it does so, no longer attempt to make the type trait
expression, instead return an error expression. This ensures we don't
try to compute the dependence for an invalid type.
Fixes#138444
We were converting a CXXParenListInitExpr to a ParenListExpr in
TreeTransform.
However, ParenListExpr is typeless, so Clang could not rebuild the
correct initialization sequence in some contexts.
Fixes#72880
