[gcc r14-4650] libgomp.texi: Improve "OpenACC Environment Variables"

[Tobias Burnus <burnus@gcc.gnu.org>]

https://gcc.gnu.org/g:67f5d368a5b0b63025e7f92b1936d80d4ea2b234

commit r14-4650-g67f5d368a5b0b63025e7f92b1936d80d4ea2b234
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Sun Oct 15 22:36:18 2023 +0200

    libgomp.texi: Improve "OpenACC Environment Variables"
    
    None of the ACC_* env vars was documented; in particular, the valid valids
    for ACC_DEVICE_TYPE found to be lacking as those are not document in the
    OpenACC spec.
    GCC_ACC_NOTIFY was removed as I failed to find any traces of it but the
    addition to the documentation in commit r6-6185-gcdf6119dad04dd
    ("libgomp.texi: Updates for OpenACC.").  It seems to be planned as GCC
    version of the ACC_NOTIFY env var used by another compiler for offloading
    debugging.
    
    libgomp/
            * libgomp.texi (ACC_DEVICE_TYPE, ACC_DEVICE_NUM, ACC_PROFLIB):
            Actually document what the function does.
            (GCC_ACC_NOTIFY): Remove unused env var.

Diff:
---
 libgomp/libgomp.texi | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/libgomp/libgomp.texi b/libgomp/libgomp.texi
index 8813854d425..dfe96f5e812 100644
--- a/libgomp/libgomp.texi
+++ b/libgomp/libgomp.texi
@@ -4989,13 +4989,11 @@ The variables @env{ACC_DEVICE_TYPE} and @env{ACC_DEVICE_NUM}
 are defined by section 4 of the OpenACC specification in version 2.0.
 The variable @env{ACC_PROFLIB}
 is defined by section 4 of the OpenACC specification in version 2.6.
-The variable @env{GCC_ACC_NOTIFY} is used for diagnostic purposes.
 
 @menu
 * ACC_DEVICE_TYPE::
 * ACC_DEVICE_NUM::
 * ACC_PROFLIB::
-* GCC_ACC_NOTIFY::
 @end menu
 
 
@@ -5003,6 +5001,17 @@ The variable @env{GCC_ACC_NOTIFY} is used for diagnostic purposes.
 @node ACC_DEVICE_TYPE
 @section @code{ACC_DEVICE_TYPE}
 @table @asis
+@item @emph{Description}:
+Control the default device type to use when executing compute regions.
+If unset, the code can be run on any device type, favoring a non-host
+device type.
+
+Supported values in GCC (if compiled in) are
+@itemize
+@item @code{host}
+@item @code{nvidia}
+@item @code{radeon}
+@end itemize
 @item @emph{Reference}:
 @uref{https://www.openacc.org, OpenACC specification v2.6}, section
 4.1.
@@ -5013,6 +5022,10 @@ The variable @env{GCC_ACC_NOTIFY} is used for diagnostic purposes.
 @node ACC_DEVICE_NUM
 @section @code{ACC_DEVICE_NUM}
 @table @asis
+@item @emph{Description}:
+Control which device, identified by device number, is the default device.
+The value must be a nonnegative integer less than the number of devices.
+If unset, device number zero is used.
 @item @emph{Reference}:
 @uref{https://www.openacc.org, OpenACC specification v2.6}, section
 4.2.
@@ -5023,6 +5036,11 @@ The variable @env{GCC_ACC_NOTIFY} is used for diagnostic purposes.
 @node ACC_PROFLIB
 @section @code{ACC_PROFLIB}
 @table @asis
+@item @emph{Description}:
+Semicolon-separated list of dynamic libraries that are loaded as profiling
+libraries.  Each library must provide at least the @code{acc_register_library}
+routine.  Each library file is found as described by the documentation of
+@code{dlopen} of your operating system.
 @item @emph{See also}:
 @ref{acc_register_library}, @ref{OpenACC Profiling Interface}
 
@@ -5033,15 +5051,6 @@ The variable @env{GCC_ACC_NOTIFY} is used for diagnostic purposes.
 
 
 
-@node GCC_ACC_NOTIFY
-@section @code{GCC_ACC_NOTIFY}
-@table @asis
-@item @emph{Description}:
-Print debug information pertaining to the accelerator.
-@end table
-
-
-
 @c ---------------------------------------------------------------------
 @c CUDA Streams Usage
 @c ---------------------------------------------------------------------