Commit 4ed3a4c1 authored by Joel E. Denny's avatar Joel E. Denny
Browse files

[Clacc][OpenACC] Document -fopenacc-ast-print/acc_on_device caveat

parent a59e21d4

clang/README-OpenACC-status.md

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@@ -452,8 +452,8 @@ OpenACC Runtime Library API and Preprocessor 
      cannot be linked.  This implementation facilitates Clacc's

      source-to-source mode together with OpenACC's requirement that

      `acc_on_device` evaluate to a constant when its argument is a

      constant.  See the comments on `acc_on_device` in Clacc's

      `openacc.h` for related limitations for source-to-source mode.

      constant.  See the section "Source-to-Source Mode Limitations"

      below for caveats for source-to-source mode.

* Data and memory management routines supported on the host are:

    * `acc_malloc`, `acc_free`

        * OpenACC 3.1 is unclear about handling of a `bytes` argument
@@ -550,8 +550,10 @@ Source-to-Source Mode Limitations 
  OpenMP at compile time:

    * `acc_on_device` is implemented in terms of OpenMP fully within

      Clacc's `openacc.h`.  However, support for an OpenMP 5.1

      extension, enum variants, is required for full support.  See the

      comments on `acc_on_device` in Clacc's `openacc.h` for details.

      extension, enum variants, is required for full support.

      Moreover, it can malfunction when enabling source-to-source mode

      using `-fopenacc-ast-print`.  See the comments on

      `acc_on_device` in Clacc's `openacc.h` for details.

    * Other routines are implemented as wrappers around the OpenMP

      Runtime Library Routines and require Clacc's OpenACC runtime

      library to be linked.  See the section "Linking" in

openmp/libacc2omp/src/include/openacc.h.var

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@@ -95,7 +95,8 @@ int acc_get_device_num(acc_device_t dev_type); 
//     compile-time constant argument, it evaluates at compile time to a

//     constant."

//   - OpenMP 5.1 doesn't specify enum variants.  Currently, Clang supports this

//     extension as required here.

//     extension as required here except when using -fopenacc-ast-print, as

//     described below.

//   - If an OpenMP compiler doesn't support enum variants, the preprocessor

//     macro ACC2OMP_ENUM_VARIANTS_SUPPORTED should be set to 0 before including

//     this header.  Otherwise, the acc_on_device definition below may fail to
@@ -109,6 +110,10 @@ int acc_get_device_num(acc_device_t dev_type); 
//     not permit acc_on_device calls in contexts where constant expressions are

//     required.  Even so, compilers might still be able to optimize

//     acc_on_device calls as constant expressions in other contexts.

// - When Clang's OpenACC source-to-source mode is enabled by

//   -fopenacc-ast-print instead of -fopenacc-print, acc_on_device currently

//   behaves as if always called on the host because Clang's AST printing

//   facility currently does not print OpenMP variants correctly.

//----------------------------------------------------------------------------



#ifndef ACC2OMP_ENUM_VARIANTS_SUPPORTED