Re: [Patch][v5] OpenMP: Move omp requires checks to libgomp

[Thomas Schwinge <thomas@codesourcery.com>]

Hi!

On 2022-07-01T15:06:05+0200, Tobias Burnus <tobias@codesourcery.com> wrote:
> OpenMP: Move omp requires checks to libgomp

This became commit r13-1458-g683f11843974f0bdf42f79cdcbb0c2b43c7b81b0
"OpenMP: Move omp requires checks to libgomp".


As of this, when I need to debug an offloading-compilation ICE, for
example, and start with 'gcc -save-temps -v', I can no longer just re-run
the offloading-compilation's 'lto1' invocation, because:

    $ [...]/gcc/lto1 [...] -foffload-abi=lp64 -fopenmp [...]
    [...]
    lto1: fatal error: GCC_OFFLOAD_OMP_REQUIRES_FILE unset
    compilation terminated.

That's because I missed setting the environment variable:

    GCC_OFFLOAD_OMP_REQUIRES_FILE=./declare-variant-1.xnvptx-none.mkoffload.omp_requires

..., which appears a number of lines earlier in the '-v' log.  Couldn't
we easily overcome this issue by turning the environment variable
'GCC_OFFLOAD_OMP_REQUIRES_FILE' into some new internal-use command-line
flag, like '-foffload-abi'?  That is, communication mechanics via
'[...].mkoffload.omp_requires' files would stay the same, just how we
communicate the file name changes: command-line flag instead of
environment variable.

For reference:

> --- a/gcc/config/gcn/mkoffload.cc
> +++ b/gcc/config/gcn/mkoffload.cc

> @@ -1077,9 +1080,27 @@ main (int argc, char **argv)
>        unsetenv ("COMPILER_PATH");
>        unsetenv ("LIBRARY_PATH");
>
> +      char *omp_requires_file;
> +      if (save_temps)
> +     omp_requires_file = concat (dumppfx, ".mkoffload.omp_requires", NULL);
> +      else
> +     omp_requires_file = make_temp_file (".mkoffload.omp_requires");
> +
>        /* Run the compiler pass.  */
> +      xputenv (concat ("GCC_OFFLOAD_OMP_REQUIRES_FILE=", omp_requires_file, NULL));
>        fork_execute (cc_argv[0], CONST_CAST (char **, cc_argv), true, ".gcc_args");
>        obstack_free (&cc_argv_obstack, NULL);
> +      unsetenv("GCC_OFFLOAD_OMP_REQUIRES_FILE");
> +
> +      in = fopen (omp_requires_file, "rb");
> +      if (!in)
> +     fatal_error (input_location, "cannot open omp_requires file %qs",
> +                  omp_requires_file);
> +      uint32_t omp_requires;
> +      if (fread (&omp_requires, sizeof (omp_requires), 1, in) != 1)
> +     fatal_error (input_location, "cannot read omp_requires file %qs",
> +                  omp_requires_file);
> +      fclose (in);

> --- a/gcc/config/nvptx/mkoffload.cc
> +++ b/gcc/config/nvptx/mkoffload.cc

> @@ -583,19 +586,37 @@ main (int argc, char **argv)
>        unsetenv ("COMPILER_PATH");
>        unsetenv ("LIBRARY_PATH");
>
> +      char *omp_requires_file;
> +      if (save_temps)
> +     omp_requires_file = concat (dumppfx, ".mkoffload.omp_requires", NULL);
> +      else
> +     omp_requires_file = make_temp_file (".mkoffload.omp_requires");
> +
> +      xputenv (concat ("GCC_OFFLOAD_OMP_REQUIRES_FILE=", omp_requires_file, NULL));
>        fork_execute (new_argv[0], CONST_CAST (char **, new_argv), true,
>                   ".gcc_args");
>        obstack_free (&argv_obstack, NULL);
> +      unsetenv("GCC_OFFLOAD_OMP_REQUIRES_FILE");
>
>        xputenv (concat ("GCC_EXEC_PREFIX=", execpath, NULL));
>        xputenv (concat ("COMPILER_PATH=", cpath, NULL));
>        xputenv (concat ("LIBRARY_PATH=", lpath, NULL));
>
> +      in = fopen (omp_requires_file, "rb");
> +      if (!in)
> +     fatal_error (input_location, "cannot open omp_requires file %qs",
> +                  omp_requires_file);
> +      uint32_t omp_requires;
> +      if (fread (&omp_requires, sizeof (omp_requires), 1, in) != 1)
> +     fatal_error (input_location, "cannot read omp_requires file %qs",
> +                  omp_requires_file);
> +      fclose (in);

> --- a/gcc/lto-cgraph.cc
> +++ b/gcc/lto-cgraph.cc

> @@ -1821,6 +1906,18 @@ input_offload_tables (bool do_force_output)
>        lto_destroy_simple_input_block (file_data, LTO_section_offload_table,
>                                     ib, data, len);
>      }
> +#ifdef ACCEL_COMPILER
> +  char *omp_requires_file = getenv ("GCC_OFFLOAD_OMP_REQUIRES_FILE");
> +  if (omp_requires_file == NULL || omp_requires_file[0] == '\0')
> +    fatal_error (input_location, "GCC_OFFLOAD_OMP_REQUIRES_FILE unset");
> +  FILE *f = fopen (omp_requires_file, "wb");
> +  if (!f)
> +    fatal_error (input_location, "Cannot open omp_requires file %qs",
> +              omp_requires_file);
> +  uint32_t req_mask = omp_requires_mask & ~OMP_REQUIRES_TARGET_USED;
> +  fwrite (&req_mask, sizeof (req_mask), 1, f);
> +  fclose (f);
> +#endif
>  }


Grüße
 Thomas
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