gfortran.texi: Add description in sections on TS 29113 and further in…

…teroperability with C.

2019-01-12  Paul Thomas  <pault@gcc.gnu.org>

	* gfortran.texi : Add description in sections on TS 29113 and
	further interoperability with C.
	* trans-array.c (gfc_conv_descriptor_attribute): New function.
	(gfc_get_dataptr_offset): Remove static function attribute.
	* trans-array.h : Add prototypes for above functions.
	* trans-decl.c : Add declarations for the library functions
	cfi_desc_to_gfc_desc and gfc_desc_to_cfi_desc.
	* trans-expr.c (gfc_conv_gfc_desc_to_cfi_desc): New function.
	(gfc_conv_procedure_call): Call it for scalar and array actual
	arguments, when the formal arguments are bind_c with assumed
	shape or assumed rank.
	* trans.h : External declarations for gfor_fndecl_cfi_to_gfc
	and gfor_fndecl_gfc_to_cfi.

2019-01-12  Paul Thomas  <pault@gcc.gnu.org>

	* gfortran.dg/ISO_Fortran_binding_1.f90 : New test.
	* gfortran.dg/ISO_Fortran_binding_1.c : Auxilliary file for test.
	* gfortran.dg/ISO_Fortran_binding_2.f90 : New test.
	* gfortran.dg/ISO_Fortran_binding_2.c : Auxilliary file for test.
	* gfortran.dg/bind_c_array_params_2.f90 : Change search string
	for dump tree scan.

2019-01-12  Paul Thomas  <pault@gcc.gnu.org>

	* ISO_Fortran_binding.h : New file.
	* Makefile.am : Include ISO_Fortran_binding.c in the list of
	files to compile.
	* Makefile.in : Regenerated.
	* gfortran.map : Add _gfortran_cfi_desc_to_gfc_desc,
	_gfortran_gfc_desc_to_cfi_desc and the CFI API functions.
	* runtime/ISO_Fortran_binding.c : New file containing the new
	functions added to the map.

From-SVN: r267881

gcc/fortran/ChangeLog

@@ -1,3 +1,19 @@
+2019-01-12  Paul Thomas  <pault@gcc.gnu.org>
+
+	* gfortran.texi : Add description in sections on TS 29113 and
+	further interoperability with C.
+	* trans-array.c (gfc_conv_descriptor_attribute): New function.
+	(gfc_get_dataptr_offset): Remove static function attribute.
+	* trans-array.h : Add prototypes for above functions.
+	* trans-decl.c : Add declarations for the library functions
+	cfi_desc_to_gfc_desc and gfc_desc_to_cfi_desc.
+	* trans-expr.c (gfc_conv_gfc_desc_to_cfi_desc): New function.
+	(gfc_conv_procedure_call): Call it for scalar and array actual
+	arguments, when the formal arguments are bind_c with assumed
+	shape or assumed rank.
+	* trans.h : External declarations for gfor_fndecl_cfi_to_gfc
+	and gfor_fndecl_gfc_to_cfi.
+
 2019-01-11  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/35031

gcc/fortran/gfortran.texi

@@ -384,7 +384,7 @@ extension are also run through preprocessing.
 This manual specifically documents the Fortran front end, which handles
 the programming language's syntax and semantics.  The aspects of GCC
 which relate to the optimization passes and the back-end code generation
-are documented in the GCC manual; see 
+are documented in the GCC manual; see
 @ref{Top,,Introduction,gcc,Using the GNU Compiler Collection (GCC)}.
 The two manuals together provide a complete reference for the GNU
 Fortran compiler.
@@ -446,11 +446,11 @@ to preprocess such files (@uref{http://www.daniellnagle.com/coco.html}).
 @cindex Fortran 77
 @cindex @command{g77}
 
-The GNU Fortran compiler is the successor to @command{g77}, the Fortran 
-77 front end included in GCC prior to version 4.  It is an entirely new 
-program that has been designed to provide Fortran 95 support and 
-extensibility for future Fortran language standards, as well as providing 
-backwards compatibility for Fortran 77 and nearly all of the GNU language 
+The GNU Fortran compiler is the successor to @command{g77}, the Fortran
+77 front end included in GCC prior to version 4.  It is an entirely new
+program that has been designed to provide Fortran 95 support and
+extensibility for future Fortran language standards, as well as providing
+backwards compatibility for Fortran 77 and nearly all of the GNU language
 extensions supported by @command{g77}.
 
 
@@ -490,10 +490,10 @@ change in future versions of GCC.  See
 @uref{https://gcc.gnu.org/wiki/OpenACC} for more information.
 
 At present, the GNU Fortran compiler passes the
-@uref{http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html, 
+@uref{http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html,
 NIST Fortran 77 Test Suite}, and produces acceptable results on the
 @uref{http://www.netlib.org/lapack/faq.html#1.21, LAPACK Test Suite}.
-It also provides respectable performance on 
+It also provides respectable performance on
 the @uref{http://www.polyhedron.com/fortran-compiler-comparisons/polyhedron-benchmark-suite,
 Polyhedron Fortran
 compiler benchmarks} and the
@@ -668,7 +668,7 @@ This is the default.
 @section @env{GFORTRAN_UNBUFFERED_PRECONNECTED}---Do not buffer I/O on preconnected units
 
 The environment variable named @env{GFORTRAN_UNBUFFERED_PRECONNECTED} controls
-whether I/O on a preconnected unit (i.e.@: STDOUT or STDERR) is unbuffered.  If 
+whether I/O on a preconnected unit (i.e.@: STDOUT or STDERR) is unbuffered.  If
 the first letter is @samp{y}, @samp{Y} or @samp{1}, I/O is unbuffered.  This
 will slow down small sequential reads and writes.  If the first letter
 is @samp{n}, @samp{N} or @samp{0}, I/O is buffered.  This is the default.
@@ -733,7 +733,7 @@ A missing mode for an exception is taken to mean @code{BIG_ENDIAN}.
 Examples of values for @env{GFORTRAN_CONVERT_UNIT} are:
 @itemize @w{}
 @item @code{'big_endian'}  Do all unformatted I/O in big_endian mode.
-@item @code{'little_endian;native:10-20,25'}  Do all unformatted I/O 
+@item @code{'little_endian;native:10-20,25'}  Do all unformatted I/O
 in little_endian mode, except for units 10 to 20 and 25, which are in
 native format.
 @item @code{'10-20'}  Units 10 to 20 are big-endian, the rest is native.
@@ -834,7 +834,7 @@ initialization are available.
 
 @item The @code{ASSOCIATE} construct.
 
-@item Interoperability with C including enumerations, 
+@item Interoperability with C including enumerations,
 
 @item In structure constructors the components with default values may be
 omitted.
@@ -999,7 +999,7 @@ about the current Fortran 2008 implementation status.  In particular, the
 following is implemented.
 
 @itemize
-@item The @option{-std=f2008} option and support for the file extensions 
+@item The @option{-std=f2008} option and support for the file extensions
 @file{.f08} and @file{.F08}.
 
 @item The @code{OPEN} statement now supports the @code{NEWUNIT=} option,
@@ -1103,8 +1103,6 @@ arrays are supported for named constants (@code{PARAMETER}).
 @node Fortran 2018 status
 @section Status of Fortran 2018 support
 
-So far very little work has been done to support Fortran 2018.
-
 @itemize
 @item ERROR STOP in a PURE procedure
 An @code{ERROR STOP} statement is permitted in a @code{PURE}
@@ -1143,8 +1141,12 @@ attribute is compatible with TS 29113.
 
 @item Assumed types (@code{TYPE(*)}).
 
-@item Assumed-rank (@code{DIMENSION(..)}). However, the array descriptor
-of the TS is not yet supported.
+@item Assumed-rank (@code{DIMENSION(..)}).
+
+@item ISO_Fortran_binding (now in Fortran 2018 18.4) is implemented such that
+conversion of the array descriptor for assumed type or assumed rank arrays is
+done in the library. The include file ISO_Fortran_binding.h is can be found in
+@code{~prefix/lib/gcc/$target/$version}.
 @end itemize
 
 
@@ -1300,7 +1302,7 @@ being called from a multi-threaded program.
 
 The GNU Fortran runtime library, (@code{libgfortran}), supports being
 called concurrently from multiple threads with the following
-exceptions. 
+exceptions.
 
 During library initialization, the C @code{getenv} function is used,
 which need not be thread-safe.  Similarly, the @code{getenv}
@@ -1430,7 +1432,7 @@ processor dependent.  GNU Fortran behaves as follows:
 @cindex file, symbolic link
 
 This section documents the behavior of GNU Fortran for file operations on
-symbolic links, on systems that support them. 
+symbolic links, on systems that support them.
 
 @itemize
 
@@ -1497,7 +1499,7 @@ record containing a single subrecord:
 program main
   use iso_fortran_env, only: int32
   implicit none
-  integer(int32) :: i 
+  integer(int32) :: i
   real, dimension(10) :: a, b
   call random_number(a)
   open (10,file='test.dat',form='unformatted',access='stream')
@@ -1725,7 +1727,7 @@ PROGRAM test_print
 END PROGRAM test_print
 @end smallexample
 
-Expanded namelist reads are permitted.  This causes an error if 
+Expanded namelist reads are permitted.  This causes an error if
 @option{-std=f95} is used.  In the following example, the first element
 of the array will be given the value 0.00 and the two succeeding
 elements will be given the values 1.00 and 2.00.
@@ -1988,7 +1990,7 @@ pointer in order to increment it.  Consider the following example:
         real pointee(10)
         pointer (ipt, pointee)
         ipt = loc (target)
-        ipt = ipt + 1       
+        ipt = ipt + 1
 @end smallexample
 The last statement does not set @code{ipt} to the address of
 @code{target(1)}, as it would in C pointer arithmetic.  Adding @code{1}
@@ -2120,13 +2122,13 @@ portable.
 @cindex OpenMP
 
 OpenMP (Open Multi-Processing) is an application programming
-interface (API) that supports multi-platform shared memory 
-multiprocessing programming in C/C++ and Fortran on many 
+interface (API) that supports multi-platform shared memory
+multiprocessing programming in C/C++ and Fortran on many
 architectures, including Unix and Microsoft Windows platforms.
 It consists of a set of compiler directives, library routines,
 and environment variables that influence run-time behavior.
 
-GNU Fortran strives to be compatible to the 
+GNU Fortran strives to be compatible to the
 @uref{http://openmp.org/wp/openmp-specifications/,
 OpenMP Application Program Interface v4.5}.
 
@@ -2169,7 +2171,7 @@ if the stacksize is limited.
 @item
 On glibc-based systems, OpenMP enabled applications cannot be statically
 linked due to limitations of the underlying pthreads-implementation.  It
-might be possible to get a working solution if 
+might be possible to get a working solution if
 @command{-Wl,--whole-archive -lpthread -Wl,--no-whole-archive} is added
 to the command line.  However, this is not supported by @command{gcc} and
 thus not recommended.
@@ -2213,20 +2215,20 @@ change in future versions of GCC.  See
 @cindex @code{%REF}
 @cindex @code{%LOC}
 
-GNU Fortran supports argument list functions @code{%VAL}, @code{%REF} 
-and @code{%LOC} statements, for backward compatibility with g77. 
-It is recommended that these should be used only for code that is 
-accessing facilities outside of GNU Fortran, such as operating system 
-or windowing facilities.  It is best to constrain such uses to isolated 
-portions of a program--portions that deal specifically and exclusively 
-with low-level, system-dependent facilities.  Such portions might well 
-provide a portable interface for use by the program as a whole, but are 
-themselves not portable, and should be thoroughly tested each time they 
+GNU Fortran supports argument list functions @code{%VAL}, @code{%REF}
+and @code{%LOC} statements, for backward compatibility with g77.
+It is recommended that these should be used only for code that is
+accessing facilities outside of GNU Fortran, such as operating system
+or windowing facilities.  It is best to constrain such uses to isolated
+portions of a program--portions that deal specifically and exclusively
+with low-level, system-dependent facilities.  Such portions might well
+provide a portable interface for use by the program as a whole, but are
+themselves not portable, and should be thoroughly tested each time they
 are rebuilt using a new compiler or version of a compiler.
 
-@code{%VAL} passes a scalar argument by value, @code{%REF} passes it by 
-reference and @code{%LOC} passes its memory location.  Since gfortran 
-already passes scalar arguments by reference, @code{%REF} is in effect 
+@code{%VAL} passes a scalar argument by value, @code{%REF} passes it by
+reference and @code{%LOC} passes its memory location.  Since gfortran
+already passes scalar arguments by reference, @code{%REF} is in effect
 a do-nothing.  @code{%LOC} has the same effect as a Fortran pointer.
 
 An example of passing an argument by value to a C subroutine foo.:
@@ -2384,7 +2386,7 @@ following shows some examples:
 @example
 structure /appointment/
   ! nested structure definition: app_time is an array of two 'time'
-  structure /time/ app_time (2) 
+  structure /time/ app_time (2)
     integer(1) hour, minute
   end structure
   character(10) memo
@@ -2970,7 +2972,7 @@ with the following:
 @smallexample
 c     Variable declaration
       CHARACTER(LEN=20) FMT
-c     
+c
 c     Other code here...
 c
       WRITE(FMT,'("(I", I0, ")")') N+1
@@ -2983,7 +2985,7 @@ or with:
 @smallexample
 c     Variable declaration
       CHARACTER(LEN=20) FMT
-c     
+c
 c     Other code here...
 c
       WRITE(FMT,*) N+1
@@ -3430,11 +3432,14 @@ and constraints, it adds assumed-type (@code{TYPE(*)}) and assumed-rank
 assumed-shape, assumed-rank and deferred-shape arrays, including
 allocatables and pointers.
 
-Note: Currently, GNU Fortran does not support the array descriptor
+Note: Currently, GNU Fortran does not use internally the array descriptor
 (dope vector) as specified in the Technical Specification, but uses
-an array descriptor with different fields. The Chasm Language
-Interoperability Tools, @url{http://chasm-interop.sourceforge.net/},
-provide an interface to GNU Fortran's array descriptor.
+an array descriptor with different fields. Assumed type and assumed rank
+formal arguments are converted in the library to the specified form. The
+ISO_Fortran_binding API functions (also Fortran 2018 18.4) are implemented
+in libgfortran. Alternatively, the Chasm Language Interoperability Tools,
+@url{http://chasm-interop.sourceforge.net/}, provide an interface to GNU
+Fortran's array descriptor.
 
 The Technical Specification adds the following new features, which
 are supported by GNU Fortran:
@@ -5735,7 +5740,7 @@ ideas and significant help to the GNU Fortran project
 The following people have contributed bug reports,
 smaller or larger patches,
 and much needed feedback and encouragement for the
-GNU Fortran project: 
+GNU Fortran project:
 
 @itemize @minus
 @item Bill Clodius

gcc/fortran/trans-array.c

@@ -292,6 +292,22 @@ gfc_conv_descriptor_rank (tree desc)
 }
 
 
+tree
+gfc_conv_descriptor_attribute (tree desc)
+{
+  tree tmp;
+  tree dtype;
+
+  dtype = gfc_conv_descriptor_dtype (desc);
+  tmp = gfc_advance_chain (TYPE_FIELDS (TREE_TYPE (dtype)),
+			   GFC_DTYPE_ATTRIBUTE);
+  gcc_assert (tmp!= NULL_TREE
+	      && TREE_TYPE (tmp) == short_integer_type_node);
+  return fold_build3_loc (input_location, COMPONENT_REF, TREE_TYPE (tmp),
+			  dtype, tmp, NULL_TREE);
+}
+
+
 tree
 gfc_get_descriptor_dimension (tree desc)
 {
@@ -6767,7 +6783,7 @@ gfc_trans_dummy_array_bias (gfc_symbol * sym, tree tmpdesc,
 
 
 /* Calculate the overall offset, including subreferences.  */
-static void
+void
 gfc_get_dataptr_offset (stmtblock_t *block, tree parm, tree desc, tree offset,
 			bool subref, gfc_expr *expr)
 {

gcc/fortran/trans-array.h

@@ -136,6 +136,8 @@ void gfc_conv_tmp_array_ref (gfc_se * se);
 /* Translate a reference to an array temporary.  */
 void gfc_conv_tmp_ref (gfc_se *);
 
+/* Calculate the overall offset, including subreferences.  */
+void gfc_get_dataptr_offset (stmtblock_t*, tree, tree, tree, bool, gfc_expr*);
 /* Obtain the span of an array.  */
 tree gfc_get_array_span (tree, gfc_expr *);
 /* Evaluate an array expression.  */
@@ -167,6 +169,7 @@ tree gfc_conv_descriptor_offset_get (tree);
 tree gfc_conv_descriptor_span_get (tree);
 tree gfc_conv_descriptor_dtype (tree);
 tree gfc_conv_descriptor_rank (tree);
+tree gfc_conv_descriptor_attribute (tree);
 tree gfc_get_descriptor_dimension (tree);
 tree gfc_conv_descriptor_stride_get (tree, tree);
 tree gfc_conv_descriptor_lbound_get (tree, tree);

gcc/fortran/trans-decl.c

@@ -114,6 +114,8 @@ tree gfor_fndecl_fdate;
 tree gfor_fndecl_ttynam;
 tree gfor_fndecl_in_pack;
 tree gfor_fndecl_in_unpack;
+tree gfor_fndecl_cfi_to_gfc;
+tree gfor_fndecl_gfc_to_cfi;
 tree gfor_fndecl_associated;
 tree gfor_fndecl_system_clock4;
 tree gfor_fndecl_system_clock8;
@@ -3619,6 +3621,14 @@ gfc_build_builtin_function_decls (void)
 	get_identifier (PREFIX("internal_unpack")), ".wR",
 	void_type_node, 2, pvoid_type_node, pvoid_type_node);
 
+  gfor_fndecl_cfi_to_gfc = gfc_build_library_function_decl_with_spec (
+	get_identifier (PREFIX("cfi_desc_to_gfc_desc")), ".ww",
+	void_type_node, 2, pvoid_type_node, ppvoid_type_node);
+
+  gfor_fndecl_gfc_to_cfi = gfc_build_library_function_decl_with_spec (
+	get_identifier (PREFIX("gfc_desc_to_cfi_desc")), ".wR",
+	void_type_node, 2, ppvoid_type_node, pvoid_type_node);
+
   gfor_fndecl_associated = gfc_build_library_function_decl_with_spec (
 	get_identifier (PREFIX("associated")), ".RR",
 	integer_type_node, 2, ppvoid_type_node, ppvoid_type_node);