nvptx, libgfortran: Switch out of "minimal" mode

[Thomas Schwinge <thomas@codesourcery.com>]

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Hi!

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.)


Grüße
 Thomas


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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.
-- 
2.25.1