================ @@ -114,6 +114,44 @@ not re-targetable, we want to share the Clang CodeGen implementation for HLSL with other GPU graphics targets like SPIR-V and possibly other GPU and even CPU targets. +hlsl.h +------ + +HLSL has an extensive library of functionality. This is similar to OpenCL and +CUDA. The implementation approach for the HLSL library functionality draws from +patterns in use by OpenCL and other Clang resource headers. + +Similar to OpenCL, the HLSL library functionality is implicitly declared in +translation units without needing to include a header to provide declarations. +In Clang this is handled by making ``hlsl.h`` an implicitly included header +distributed as part of the Clang resource directory. + +Similar to OpenCL, HLSL's implicit header will explicitly declare all overloads, +and each overload will map to a corresponding ``__builtin_*`` compiler intrinsic +that is handled in ClangCodeGen. CUDA uses a similar pattern although many CUDA +functions have full definitions in the included headers which in turn call +corresponding ``__builtin*`` compiler intrinsics. By not having bodies HLSL +avoids the need for the inliner to clean up and inline large numbers of small +library functions. + +HLSL's implicit headers also define some of HLSL's typedefs. This is consistent +with how the AVX vector header is implemented. + +Concerns have been expressed that this approach may result in slower compile +times than the approach DXC uses where library functions are treated more like +Clang ``__builtin*`` intrinsics. No real world use cases have been identified +where parsing is a significant compile-time overhead, but the HLSL implicit +headers can be compiled into a module for performance if needed. + +Further, by treating these functions as functions rather than ``__builtin*`` +compiler intrinsics the language behaviors are more consistent and aligned with ---------------- bharadwajy wrote:
```suggestion compiler intrinsics, the language behaviors are more consistent and aligned with ``` https://github.com/llvm/llvm-project/pull/84081 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
