This change fixes one of the failures in
https://github.com/llvm/llvm-project/pull/147321
Following code snippet:
`
for (const auto &[CategoryName, PropSet] : PSRegistry) {
J.attributeObject(CategoryName, [&] {
for (const auto &[PropName, PropVal] : PropSet) {
`
causes a build warning that is emitted as an error.
error: reference to local binding 'PropSet' declared in enclosing lambda
expression
This is resolved by capturing PropSet in a local variable.
Thanks
Signed-off-by: Arvind Sudarsanam <arvind.sudarsanam@intel.com>
This PR adds the `PropertySet` type, along with a pair of functions used
to serialize and deserialize into a JSON representation. A property set
is a key-value map, with values being one of 2 types - uint32 or byte
array. A property set registry is a collection of property sets, indexed
by a "category" name.
In SYCL offloading, property sets will be used to communicate metadata
about device images needed by the SYCL runtime. For example, there is a
property set which has a byte array containing the numeric ID, offset,
and size of each SYCL2020 spec constant. Another example is a property
set describing the optional kernel features used in the module: does it
use fp64? fp16? atomic64?
This metadata will be computed by `clang-sycl-linker` and the JSON
representation will be inserted in the string table of each
output `OffloadBinary`. This JSON will be consumed the SYCL offload
wrapper and will be lowered to the binary form SYCL runtime expects.
For example, consider this SYCL program that calls a kernel that uses
fp64:
```c++
#include <sycl/sycl.hpp>
using namespace sycl;
class MyKernel;
int main() {
queue q;
auto *p = malloc_shared<double>(1, q);
*p = .1;
q.single_task<MyKernel>([=]{ *p *= 2; }).wait();
std::cout << *p << "\n";
free(p, q);
}
```
The device code for this program would have the kernel marked with
`!sycl_used_aspects`:
```
define spir_kernel void @_ZTS8MyKernel([...]) !sycl_used_aspects !n { [...] }
!n = {i32 6}
```
`clang-sycl-linker` would recognize this metadata and then would output
the following JSON in the `OffloadBinary`'s key-value map:
```
{
"SYCL/device requirements": {
// aspects contains a list of sycl::aspect values used
// by the module; in this case just the value 6 encoded
// as a 4-byte little-endian integer
"aspects": "BjAwMA=="
}
}
```
The SYCL offload wrapper would lower those property sets to something
like this:
```c++
struct _sycl_device_binary_property_set_struct {
char *CategoryName;
_sycl_device_binary_property *PropertiesBegin;
_sycl_device_binary_property *PropertiesEnd;
};
struct _sycl_device_binary_property_struct {
char *PropertyName;
void *ValAddr;
uint64_t ValSize;
};
//
_sycl_device_binary_property_struct device_requirements[] = {
/* PropertyName */ "aspects",
/* ValAddr */ [pointer to the bytes 0x06 0x00 0x00 0x00],
/* ValSize */ 4,
};
_sycl_device_binary_property_set_struct properties[] = {
/* CategoryName */ "SYCL/device requirements",
/* PropertiesBegin */ device_requirements,
/* PropertiesEnd */ std::end(device_requirments),
}
```
---------
Co-authored-by: Arvind Sudarsanam <arvind.sudarsanam@intel.com>
