Update 'libgomp/libgomp.texi' for 'nvptx, libgfortran: Switch out of "minimal" mode' (was: nvptx, libgfortran: Switch out of "minimal" mode)

[Thomas Schwinge <thomas@codesourcery.com>]

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Hi!

On 2023-01-20T22:16:00+0100, I wrote:
> On 2023-01-20T22:04:02+0100, I wrote:
>> We've been (t)asked to enable (portions of) GCC/Fortran I/O for nvptx
>> offloading, which means building a normal (non-'LIBGFOR_MINIMAL')
>> configuration of libgfortran.
>
> This is achieved by 'nvptx, libgfortran: Switch out of "minimal" mode',
> see attached, again based on WIP work by Andrew Stubbs.  This I've just
> pushed to devel/omp/gcc-12 branch in
> commit c7734c6fbb5513b4da6306de7bc85de9b8547988, and would like to push
> to master branch once other pending GCC patches have been accepted.
>
>
> The OpenACC XFAILs: "[...] overflows the stack for nvptx offloading"
> are unresolved at this point; see the discussion around
> "Handling of large stack objects in GPU code generation -- maybe transform into heap allocation?",
> and my "nvptx: '-mframe-malloc-threshold', '-Wframe-malloc-threshold'"
> experimenting.  (The latter works to some extent, but also has other
> issues that I shall detail at some later point in time.)

I had a note from Tobias to "update the the last but one bullet point at
https://gcc.gnu.org/onlinedocs/libgomp/nvptx.html".  Thus pushed to
devel/omp/gcc-12 branch commit 8c29332e98ca4669a059ebc0d90903b409ae049f
"Update 'libgomp/libgomp.texi' for 'nvptx, libgfortran: Switch out of "minimal" mode'",
see attached.  Please consider that one 'fixup'ed into the GCC master
branch submission.


Grüße
 Thomas


> From c7734c6fbb5513b4da6306de7bc85de9b8547988 Mon Sep 17 00:00:00 2001
> From: Thomas Schwinge <thomas@codesourcery.com>
> Date: Wed, 21 Sep 2022 18:58:34 +0200
> Subject: [PATCH] nvptx, libgfortran: Switch out of "minimal" mode
>
> ..., in order to enable (portions of) Fortran I/O, for example.
>
> libgfortran/ChangeLog:
>
>       * configure: Regenerate.
>       * configure.ac: No longer set LIBGFOR_MINIMAL for nvptx.
>
> libgomp/ChangeLog:
>
>       * testsuite/libgomp.fortran/target-print-1.f90: Adjust.
>       * testsuite/libgomp.fortran/target-print-1-nvptx.f90: Remove.
>       * testsuite/libgomp.oacc-fortran/print-1.f90: Adjust.
>       * testsuite/libgomp.oacc-fortran/print-1-nvptx.f90: Remove.
>       * testsuite/libgomp.oacc-fortran/error_stop-2.f: Adjust.
>       * testsuite/libgomp.oacc-fortran/stop-2.f: Likewise.
>
> Co-authored-by: Andrew Stubbs <ams@codesourcery.com>
> ---
>  libgfortran/ChangeLog.omp                       |  6 ++++++
>  libgfortran/configure                           | 17 ++++++-----------
>  libgfortran/configure.ac                        | 17 ++++++-----------
>  libgomp/ChangeLog.omp                           |  7 +++++++
>  .../libgomp.fortran/target-print-1-nvptx.f90    | 11 -----------
>  .../libgomp.fortran/target-print-1.f90          |  3 ---
>  .../libgomp.oacc-fortran/error_stop-2.f         |  4 +++-
>  .../libgomp.oacc-fortran/print-1-nvptx.f90      | 11 -----------
>  .../testsuite/libgomp.oacc-fortran/print-1.f90  |  5 ++---
>  libgomp/testsuite/libgomp.oacc-fortran/stop-2.f |  4 +++-
>  10 files changed, 33 insertions(+), 52 deletions(-)
>  delete mode 100644 libgomp/testsuite/libgomp.fortran/target-print-1-nvptx.f90
>  delete mode 100644 libgomp/testsuite/libgomp.oacc-fortran/print-1-nvptx.f90
>
> diff --git a/libgfortran/ChangeLog.omp b/libgfortran/ChangeLog.omp
> index b08c264daf9..925575e65fa 100644
> --- a/libgfortran/ChangeLog.omp
> +++ b/libgfortran/ChangeLog.omp
> @@ -1,3 +1,9 @@
> +2023-01-20  Thomas Schwinge  <thomas@codesourcery.com>
> +         Andrew Stubbs  <ams@codesourcery.com>
> +
> +     * configure: Regenerate.
> +     * configure.ac: No longer set LIBGFOR_MINIMAL for nvptx.
> +
>  2023-01-20  Thomas Schwinge  <thomas@codesourcery.com>
>
>       PR target/85463
> diff --git a/libgfortran/configure b/libgfortran/configure
> index ae64dca3114..3e5c931d4ad 100755
> --- a/libgfortran/configure
> +++ b/libgfortran/configure
> @@ -6230,17 +6230,12 @@ else
>  fi
>
>
> -# For GPU offloading, not everything in libfortran can be supported.
> -# Currently, the only target that has this problem is nvptx.  The
> -# following is a (partial) list of features that are unsupportable on
> -# this particular target:
> -# * Constructors
> -# * alloca
> -# * C library support for I/O, with printf as the one notable exception
> -# * C library support for other features such as signal, environment
> -#   variables, time functions
> -
> - if test "x${target_cpu}" = xnvptx; then
> +# "Minimal" mode is for targets that cannot (yet) support all features of
> +# libgfortran.  It avoids the need for working constructors, alloca, and C
> +# library support for I/O, signals, environment variables, time functions, etc.
> +# At present there are no targets that require this mode.
> +
> + if false; then
>    LIBGFOR_MINIMAL_TRUE=
>    LIBGFOR_MINIMAL_FALSE='#'
>  else
> diff --git a/libgfortran/configure.ac b/libgfortran/configure.ac
> index 97cc490cb5e..e5552949cc6 100644
> --- a/libgfortran/configure.ac
> +++ b/libgfortran/configure.ac
> @@ -222,17 +222,12 @@ AM_CONDITIONAL(LIBGFOR_USE_SYMVER, [test "x$gfortran_use_symver" != xno])
>  AM_CONDITIONAL(LIBGFOR_USE_SYMVER_GNU, [test "x$gfortran_use_symver" = xgnu])
>  AM_CONDITIONAL(LIBGFOR_USE_SYMVER_SUN, [test "x$gfortran_use_symver" = xsun])
>
> -# For GPU offloading, not everything in libfortran can be supported.
> -# Currently, the only target that has this problem is nvptx.  The
> -# following is a (partial) list of features that are unsupportable on
> -# this particular target:
> -# * Constructors
> -# * alloca
> -# * C library support for I/O, with printf as the one notable exception
> -# * C library support for other features such as signal, environment
> -#   variables, time functions
> -
> -AM_CONDITIONAL(LIBGFOR_MINIMAL, [test "x${target_cpu}" = xnvptx])
> +# "Minimal" mode is for targets that cannot (yet) support all features of
> +# libgfortran.  It avoids the need for working constructors, alloca, and C
> +# library support for I/O, signals, environment variables, time functions, etc.
> +# At present there are no targets that require this mode.
> +
> +AM_CONDITIONAL(LIBGFOR_MINIMAL, false)
>
>  # Some compiler target support may have limited support for integer
>  # or floating point numbers – or may want to reduce the libgfortran size
> diff --git a/libgomp/ChangeLog.omp b/libgomp/ChangeLog.omp
> index 32aa9705296..30b1e558ea3 100644
> --- a/libgomp/ChangeLog.omp
> +++ b/libgomp/ChangeLog.omp
> @@ -1,5 +1,12 @@
>  2023-01-20  Thomas Schwinge  <thomas@codesourcery.com>
>
> +     * testsuite/libgomp.fortran/target-print-1.f90: Adjust.
> +     * testsuite/libgomp.fortran/target-print-1-nvptx.f90: Remove.
> +     * testsuite/libgomp.oacc-fortran/print-1.f90: Adjust.
> +     * testsuite/libgomp.oacc-fortran/print-1-nvptx.f90: Remove.
> +     * testsuite/libgomp.oacc-fortran/error_stop-2.f: Adjust.
> +     * testsuite/libgomp.oacc-fortran/stop-2.f: Likewise.
> +
>       * plugin/plugin-nvptx.c (nvptx_do_global_cdtors): New.
>       (nvptx_close_device, GOMP_OFFLOAD_load_image)
>       (GOMP_OFFLOAD_unload_image): Call it.
> diff --git a/libgomp/testsuite/libgomp.fortran/target-print-1-nvptx.f90 b/libgomp/testsuite/libgomp.fortran/target-print-1-nvptx.f90
> deleted file mode 100644
> index a89c9c33484..00000000000
> --- a/libgomp/testsuite/libgomp.fortran/target-print-1-nvptx.f90
> +++ /dev/null
> @@ -1,11 +0,0 @@
> -! Ensure that write on the offload device works, nvptx offloading variant.
> -
> -! This doesn't compile: for nvptx offloading we're using a minimal libgfortran
> -! configuration.
> -! { dg-do link } ! ..., but still apply 'dg-do run' options.
> -! { dg-xfail-if "minimal libgfortran" { offload_target_nvptx } }
> -
> -! Skip duplicated testing.
> -! { dg-skip-if "separate file" { ! offload_target_nvptx } }
> -
> -include 'target-print-1.f90'
> diff --git a/libgomp/testsuite/libgomp.fortran/target-print-1.f90 b/libgomp/testsuite/libgomp.fortran/target-print-1.f90
> index 327bb22cb6d..9ac70e5a85f 100644
> --- a/libgomp/testsuite/libgomp.fortran/target-print-1.f90
> +++ b/libgomp/testsuite/libgomp.fortran/target-print-1.f90
> @@ -3,9 +3,6 @@
>  ! { dg-do run }
>  ! { dg-output "The answer is 42(\n|\r\n|\r)+" }
>
> -! Separate file 'target-print-1-nvptx.f90' for nvptx offloading.
> -! { dg-skip-if "separate file" { offload_target_nvptx } }
> -
>  program main
>    implicit none
>    integer :: var = 42
> diff --git a/libgomp/testsuite/libgomp.oacc-fortran/error_stop-2.f b/libgomp/testsuite/libgomp.oacc-fortran/error_stop-2.f
> index 5951e8cbe64..bbb4b55ef2c 100644
> --- a/libgomp/testsuite/libgomp.oacc-fortran/error_stop-2.f
> +++ b/libgomp/testsuite/libgomp.oacc-fortran/error_stop-2.f
> @@ -17,7 +17,9 @@
>
>  ! { dg-output "CheCKpOInT(\n|\r\n|\r)+" }
>
> -! { dg-output "ERROR STOP 35(\n|\r\n|\r)+" }
> +! '_gfortran_error_stop_numeric' -> '_gfortrani_st_printf' -> [...]
> +! overflows the stack for nvptx offloading, thus XFAILed.
> +! { dg-output "ERROR STOP 35(\n|\r\n|\r)+" { xfail openacc_nvidia_accel_selected } }
>  !
>  ! In gfortran's main program, libfortran's set_options is called - which sets
>  ! compiler_options.backtrace = 1 by default.  For an offload libgfortran, this
> diff --git a/libgomp/testsuite/libgomp.oacc-fortran/print-1-nvptx.f90 b/libgomp/testsuite/libgomp.oacc-fortran/print-1-nvptx.f90
> deleted file mode 100644
> index 866c8654355..00000000000
> --- a/libgomp/testsuite/libgomp.oacc-fortran/print-1-nvptx.f90
> +++ /dev/null
> @@ -1,11 +0,0 @@
> -! Ensure that write on the offload device works, nvptx offloading variant.
> -
> -! This doesn't compile: for nvptx offloading we're using a minimal libgfortran
> -! configuration.
> -! { dg-do link } ! ..., but still apply 'dg-do run' options.
> -! { dg-xfail-if "minimal libgfortran" { offload_target_nvptx } }
> -
> -! Skip duplicated testing.
> -! { dg-skip-if "separate file" { ! offload_target_nvptx } }
> -
> -include 'print-1.f90'
> diff --git a/libgomp/testsuite/libgomp.oacc-fortran/print-1.f90 b/libgomp/testsuite/libgomp.oacc-fortran/print-1.f90
> index d2f89d915f8..d04503a0249 100644
> --- a/libgomp/testsuite/libgomp.oacc-fortran/print-1.f90
> +++ b/libgomp/testsuite/libgomp.oacc-fortran/print-1.f90
> @@ -2,9 +2,8 @@
>
>  ! { dg-do run }
>  ! { dg-output "The answer is 42(\n|\r\n|\r)+" }
> -
> -! Separate file 'print-1-nvptx.f90' for nvptx offloading.
> -! { dg-skip-if "separate file" { offload_target_nvptx } }
> +! The 'write' overflows the stack for nvptx offloading, thus XFAILed.
> +! { dg-xfail-run-if TODO { openacc_nvidia_accel_selected } }
>
>  ! { dg-additional-options "-fopt-info-note-omp" }
>  ! { dg-additional-options "-foffload=-fopt-info-note-omp" }
> diff --git a/libgomp/testsuite/libgomp.oacc-fortran/stop-2.f b/libgomp/testsuite/libgomp.oacc-fortran/stop-2.f
> index fe7ee37813a..394de034b1f 100644
> --- a/libgomp/testsuite/libgomp.oacc-fortran/stop-2.f
> +++ b/libgomp/testsuite/libgomp.oacc-fortran/stop-2.f
> @@ -17,7 +17,9 @@
>
>  ! { dg-output "CheCKpOInT(\n|\r\n|\r)+" }
>
> -! { dg-output "STOP 35(\n|\r\n|\r)+" }
> +! '_gfortran_error_stop_numeric' -> '_gfortrani_st_printf' -> [...]
> +! overflows the stack for nvptx offloading, thus XFAILed.
> +! { dg-output "STOP 35(\n|\r\n|\r)+" { xfail openacc_nvidia_accel_selected } }
>  !
>  ! PR85463.  The 'exit' implementation used with nvptx
>  ! offloading is a little bit different.


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From 8c29332e98ca4669a059ebc0d90903b409ae049f Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Tue, 24 Jan 2023 10:29:01 +0100
Subject: [PATCH] Update 'libgomp/libgomp.texi' for 'nvptx, libgfortran: Switch
 out of "minimal" mode'

	libgomp/
	* libgomp.texi (nvptx): Update for
	'nvptx, libgfortran: Switch out of "minimal" mode'.
---
 libgomp/libgomp.texi | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/libgomp/libgomp.texi b/libgomp/libgomp.texi
index 896d187f1ff..17f1509343f 100644
--- a/libgomp/libgomp.texi
+++ b/libgomp/libgomp.texi
@@ -4448,7 +4448,7 @@ The used sizes are
 
 The implementation remark:
 @itemize
-@item I/O within OpenMP target regions and OpenACC parallel/kernels is supported
+@item I/O within OpenMP target regions and OpenACC compute regions is supported
       using the C library @code{printf} functions and the Fortran
       @code{print}/@code{write} statements.
 @end itemize
@@ -4496,9 +4496,11 @@ CUDA version and hardware.
 
 The implementation remark:
 @itemize
-@item I/O within OpenMP target regions and OpenACC parallel/kernels is supported
-      using the C library @code{printf} functions. Note that the Fortran
-      @code{print}/@code{write} statements are not supported, yet.
+@item I/O within OpenMP target regions and OpenACC compute regions is supported
+      using the C library @code{printf} functions.
+      Additionally, the Fortran @code{print}/@code{write} statements are
+      supported within OpenMP target regions, but not yet OpenACC compute
+      regions.
 @item Compilation OpenMP code that contains @code{requires reverse_offload}
       requires at least @code{-march=sm_35}, compiling for @code{-march=sm_30}
       is not supported.
-- 
2.25.1