This patch is part of the upstreaming effort for supporting SYCL
language front end.
It makes the following changes:
1. Adds sycl_external attribute for functions with external linkage,
which is intended for use to implement the SYCL_EXTERNAL macro as
specified by the SYCL 2020 specification
2. Adds checks to avoid emitting device code when sycl_external and
sycl_kernel_entry_point attributes are not enabled
3. Fixes test failures caused by the above changes
This patch is missing diagnostics for the following diagnostics listed
in the SYCL 2020 specification's section 5.10.1, which will be addressed
in a subsequent PR:
Functions that are declared using SYCL_EXTERNAL have the following
additional restrictions beyond those imposed on other device functions:
1. If the SYCL backend does not support the generic address space then
the function cannot use raw pointers as parameter or return types.
Explicit pointer classes must be used instead;
2. The function cannot call group::parallel_for_work_item;
3. The function cannot be called from a parallel_for_work_group scope.
In addition to that, the subsequent PR will also implement diagnostics
for inline functions including virtual functions defined as inline.
---------
Co-authored-by: Mariya Podchishchaeva <mariya.podchishchaeva@intel.com>
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
Previously, the `sycl_kernel_entry_point` attribute could be specified
using either the GNU or C++11 spelling styles. Future SYCL attributes
are expected to support only the C++11 spelling style, so support for
the GNU style is being removed.
In order to ensure consistent presentation of the attribute in
diagnostic messages, diagnostics specific to this attribute now require
the attribute to be provided as an argument. This delegates formatting
of the attribute name to the diagnostic engine.
As an additional nicety, "the" is added to some diagnostic messages so
that they read more like proper sentences.
We have multiple different attributes in clang representing device
kernels for specific targets/languages. Refactor them into one attribute
with different spellings to make it more easily scalable for new
languages/targets.
---------
Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>
This patch replaces:
llvm::copy(Src, std::back_inserter(Dst));
with:
llvm::append_range(Dst, Src);
for breavity.
One side benefit is that llvm::append_range eventually calls
llvm::SmallVector::reserve if Dst is of llvm::SmallVector.
A SYCL kernel entry point function is a non-member function or a static
member function declared with the `sycl_kernel_entry_point` attribute.
Such functions define a pattern for an offload kernel entry point
function to be generated to enable execution of a SYCL kernel on a
device. A SYCL library implementation orchestrates the invocation of
these functions with corresponding SYCL kernel arguments in response to
calls to SYCL kernel invocation functions specified by the SYCL 2020
specification.
The offload kernel entry point function (sometimes referred to as the
SYCL kernel caller function) is generated from the SYCL kernel entry
point function by a transformation of the function parameters followed
by a transformation of the function body to replace references to the
original parameters with references to the transformed ones. Exactly how
parameters are transformed will be explained in a future change that
implements non-trivial transformations. For now, it suffices to state
that a given parameter of the SYCL kernel entry point function may be
transformed to multiple parameters of the offload kernel entry point as
needed to satisfy offload kernel argument passing requirements.
Parameters that are decomposed in this way are reconstituted as local
variables in the body of the generated offload kernel entry point
function.
For example, given the following SYCL kernel entry point function
definition:
```
template<typename KernelNameType, typename KernelType>
[[clang::sycl_kernel_entry_point(KernelNameType)]]
void sycl_kernel_entry_point(KernelType kernel) {
kernel();
}
```
and the following call:
```
struct Kernel {
int dm1;
int dm2;
void operator()() const;
};
Kernel k;
sycl_kernel_entry_point<class kernel_name>(k);
```
the corresponding offload kernel entry point function that is generated
might look as follows (assuming `Kernel` is a type that requires
decomposition):
```
void offload_kernel_entry_point_for_kernel_name(int dm1, int dm2) {
Kernel kernel{dm1, dm2};
kernel();
}
```
Other details of the generated offload kernel entry point function, such
as its name and calling convention, are implementation details that need
not be reflected in the AST and may differ across target devices. For
that reason, only the transformation described above is represented in
the AST; other details will be filled in during code generation.
These transformations are represented using new AST nodes introduced
with this change. `OutlinedFunctionDecl` holds a sequence of
`ImplicitParamDecl` nodes and a sequence of statement nodes that
correspond to the transformed parameters and function body.
`SYCLKernelCallStmt` wraps the original function body and associates it
with an `OutlinedFunctionDecl` instance. For the example above, the AST
generated for the `sycl_kernel_entry_point<kernel_name>` specialization
would look as follows:
```
FunctionDecl 'sycl_kernel_entry_point<kernel_name>(Kernel)'
TemplateArgument type 'kernel_name'
TemplateArgument type 'Kernel'
ParmVarDecl kernel 'Kernel'
SYCLKernelCallStmt
CompoundStmt
<original statements>
OutlinedFunctionDecl
ImplicitParamDecl 'dm1' 'int'
ImplicitParamDecl 'dm2' 'int'
CompoundStmt
VarDecl 'kernel' 'Kernel'
<initialization of 'kernel' with 'dm1' and 'dm2'>
<transformed statements with redirected references of 'kernel'>
```
Any ODR-use of the SYCL kernel entry point function will (with future
changes) suffice for the offload kernel entry point to be emitted. An
actual call to the SYCL kernel entry point function will result in a
call to the function. However, evaluation of a `SYCLKernelCallStmt`
statement is a no-op, so such calls will have no effect other than to
trigger emission of the offload kernel entry point.
Additionally, as a related change inspired by code review feedback,
these changes disallow use of the `sycl_kernel_entry_point` attribute
with functions defined with a _function-try-block_. The SYCL 2020
specification prohibits the use of C++ exceptions in device functions.
Even if exceptions were not prohibited, it is unclear what the semantics
would be for an exception that escapes the SYCL kernel entry point
function; the boundary between host and device code could be an implicit
noexcept boundary that results in program termination if violated, or
the exception could perhaps be propagated to host code via the SYCL
library. Pending support for C++ exceptions in device code and clear
semantics for handling them at the host-device boundary, this change
makes use of the `sycl_kernel_entry_point` attribute with a function
defined with a _function-try-block_ an error.
The `sycl_kernel_entry_point` attribute is used to declare a function that
defines a pattern for an offload kernel entry point. The attribute requires
a single type argument that specifies a class type that meets the requirements
for a SYCL kernel name as described in section 5.2, "Naming of kernels", of
the SYCL 2020 specification. A unique kernel name type is required for each
function declared with the attribute. The attribute may not first appear on a
declaration that follows a definition of the function. The function is
required to have a non-deduced `void` return type. The function must not be
a non-static member function, be deleted or defaulted, be declared with the
`constexpr` or `consteval` specifiers, be declared with the `[[noreturn]]`
attribute, be a coroutine, or accept variadic arguments.
Diagnostics are not yet provided for the following:
- Use of a type as a kernel name that does not satisfy the forward
declarability requirements specified in section 5.2, "Naming of kernels",
of the SYCL 2020 specification.
- Use of a type as a parameter of the attributed function that does not
satisfy the kernel parameter requirements specified in section 4.12.4,
"Rules for parameter passing to kernels", of the SYCL 2020 specification
(each such function parameter constitutes a kernel parameter).
- Use of language features that are not permitted in device functions as
specified in section 5.4, "Language restrictions for device functions",
of the SYCL 2020 specification.
There are several issues noted by various FIXME comments.
- The diagnostic generated for kernel name conflicts needs additional work
to better detail the relevant source locations; such as the location of
each declaration as well as the original source of each kernel name.
- A number of the tests illustrate spurious errors being produced due to
attributes that appertain to function templates being instantiated too
early (during overload resolution as opposed to after an overload is
selected).
Included changes allow the `SYCLKernelEntryPointAttr` attribute to be
marked as invalid if a `sycl_kernel_entry_point` attribute is used incorrectly.
This is intended to prevent trying to emit an offload kernel entry point
without having to mark the associated function as invalid since doing so
would affect overload resolution; which this attribute should not do.
Unfortunately, Clang eagerly instantiates attributes that appertain to
functions with the result that errors might be issued for function
declarations that are never selected by overload resolution. Tests have
been added to demonstrate this. Further work will be needed to address
these issues (for this and other attributes).
The `sycl_kernel_entry_point` attribute is used to declare a function that
defines a pattern for an offload kernel to be emitted. The attribute requires
a single type argument that specifies the type used as a SYCL kernel name as
described in section 5.2, "Naming of kernels", of the SYCL 2020 specification.
Properties of the offload kernel are collected when a function declared with
the `sycl_kernel_entry_point` attribute is parsed or instantiated. These
properties, such as the kernel name type, are stored in the AST context where
they are (or will be) used for diagnostic purposes and to facilitate reflection
to a SYCL run-time library. These properties are not serialized with the AST
but are recreated upon deserialization.
The `sycl_kernel_entry_point` attribute is intended to replace the existing
`sycl_kernel` attribute which is intended to be deprecated in a future change
and removed following an appropriate deprecation period. The new attribute
differs in that it is enabled for both SYCL host and device compilation, may
be used with non-template functions, explicitly indicates the type used as
the kernel name type, and will impact AST generation.
This change adds the basic infrastructure for the new attribute. Future
changes will add diagnostics and new AST support that will be used to drive
generation of the corresponding offload kernel.
When various `Sema*.h` and `Sema*.cpp` files were created, cleanup of
`Sema.h` includes and forward declarations was left for the later.
Now's the time. This commit touches `Sema.h` and Sema components:
1. Unused includes are removed.
2. Unused forward declarations are removed.
3. Missing includes are added (those files are largely IWYU-clean now).
4. Includes were converted into forward declarations where possible.
As this commit focuses on headers, all changes to `.cpp` files were
minimal, and were aiming at keeping everything buildable.
This patch moves language- and target-specific functions out of
`SemaDeclAttr.cpp`. As a consequence, `SemaAVR`, `SemaM68k`,
`SemaMSP430`, `SemaOpenCL`, `SemaSwift` were created (but they are not
the only languages and targets affected).
Notable things are that `Sema.h` actually grew a bit, because of
templated helpers that rely on `Sema` that I had to make available from
outside of `SemaDeclAttr.cpp`. I also had to left CUDA-related in
`SemaDeclAttr.cpp`, because it looks like HIP is building up on top of
CUDA attributes.
This is a follow-up to #93179 and continuation of efforts to split
`Sema` up. Additional context can be found in #84184 and #92682.
This patch moves SYCL-related `Sema` functions into new `SemaSYCL`
class, following the recent example of OpenACC and HLSL. This is a part
of the effort to split `Sema`. Additional context can be found in
#82217, #84184, #87634.
In PR #79382, I need to add a new type that derives from
ConstantArrayType. This means that ConstantArrayType can no longer use
`llvm::TrailingObjects` to store the trailing optional Expr*.
This change refactors ConstantArrayType to store a 60-bit integer and
4-bits for the integer size in bytes. This replaces the APInt field
previously in the type but preserves enough information to recreate it
where needed.
To reduce the number of places where the APInt is re-constructed I've
also added some helper methods to the ConstantArrayType to allow some
common use cases that operate on either the stored small integer or the
APInt as appropriate.
Resolves#85124.
Adds diagnosing on attempt to use zero length arrays, pointers, refs, arrays
of them and structs/classes containing all of it.
In case a struct/class with zero length array is used this emits a set
of notes pointing out how zero length array got into used struct, like
this:
```
struct ContainsArr {
int A[0]; // note: field of illegal type declared here
};
struct Wrapper {
ContainsArr F; // note: within field of type ContainsArr declared here
// ...
}
// Device code
Wrapper W;
W.use(); // error: zero-length arrays are not permitted
```
Total deep check of each used declaration may result in double
diagnosing at the same location.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D114080
After significant problems in our downstream with the previous
implementation, the SYCL standard has opted to make using macros/etc to
change kernel-naming-lambdas in any way UB (even passively). As a
result, we are able to just emit the itanium mangling.
However, this DOES require a little work in the CXXABI, as the microsoft
and itanium mangler use different numbering schemes for lambdas. This
patch adds a pair of mangling contexts that use the normal 'itanium'
mangling strategy to fill in the "DeviceManglingNumber" used previously
by CUDA.
Differential Revision: https://reviews.llvm.org/D110281
This reverts commit 5013131875402539a249dca47c58cca7c359baf8.
This patch didn't end up being the solution to the problem. It "fixed"
our issue but the actual correct solution is something else. Reverting
as this ends up being unnecessary/extra noise.
Discovered in our downstream, this function that is used to get the type
of the kernel parameter type needs to be unqualified, otherwise when our
downstream uses this function in a slightly different way, the kernel
types no longer match.
The original version of this was reverted, and @rjmcall provided some
advice to architect a new solution. This is that solution.
This implements a builtin to provide a unique name that is stable across
compilations of this TU for the purposes of implementing the library
component of the unnamed kernel feature of SYCL. It does this by
running the Itanium mangler with a few modifications.
Because it is somewhat common to wrap non-kernel-related lambdas in
macros that aren't present on the device (such as for logging), this
uniquely generates an ID for all lambdas involved in the naming of a
kernel. It uses the lambda-mangling number to do this, except replaces
this with its own number (starting at 10000 for readabililty reasons)
for lambdas used to name a kernel.
Additionally, this implements itself as constexpr with a slight catch:
if a name would be invalidated by the use of this lambda in a later
kernel invocation, it is diagnosed as an error (see the Sema tests).
Differential Revision: https://reviews.llvm.org/D103112
This recommits 7f1f89ec8d9944559042bb6d3b1132eabe3409de and
40df06cdafc010002fc9cfe1dda73d689b7d27a6 with bug fixes for
memory sanitizer failure and Tensile build failure.
In CUDA/HIP a function may become implicit host device function by
pragma or constexpr. A host device function is checked in both
host and device compilation. However it may be emitted only
on host or device side, therefore the diagnostics should be
deferred until it is known to be emitted.
Currently clang is only able to defer certain diagnostics. This causes
false alarms and limits the usefulness of host device functions.
This patch lets clang defer all overloading resolution diagnostics for host device functions.
An option -fgpu-defer-diag is added to control this behavior. By default
it is off.
It is NFC for other languages.
Differential Revision: https://reviews.llvm.org/D84364
Summary:
Diagnostic is emitted if some declaration of unsupported type
declaration is used inside device code.
Memcpy operations for structs containing member with unsupported type
are allowed. Fixed crash on attempt to emit diagnostic outside of the
functions.
The approach is generalized between SYCL and OpenMP.
CUDA/OMP deferred diagnostic interface is going to be used for SYCL device.
Reviewers: rsmith, rjmccall, ABataev, erichkeane, bader, jdoerfert, aaron.ballman
Reviewed By: jdoerfert
Subscribers: guansong, sstefan1, yaxunl, mgorny, bader, ebevhan, Anastasia, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D74387
