gdb/fotran: add support for the 'shape' keyword

Add support for the SHAPE keyword to GDB's Fortran expression parser.

gdb/ChangeLog:

	* f-exp.h (eval_op_f_array_shape): Declare.
	(fortran_array_shape_operation): New type.
	* f-exp.y (exp): Handle UNOP_FORTRAN_SHAPE after parsing
	UNOP_INTRINSIC.
	(f77_keywords): Add "shape" keyword.
	* f-lang.c (fortran_array_shape): New function.
	(eval_op_f_array_shape): New function.
	* std-operator.def (UNOP_FORTRAN_SHAPE): New operator.

gdb/testsuite/ChangeLog:

	* gdb.fortran/shape.exp: New file.
	* gdb.fortran/shape.f90: New file.

8 files changed, 277 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 0a16353..6ed71c2 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,16 @@
 2021-03-09  Andrew Burgess  <andrew.burgess@embecosm.com>
 
+	* f-exp.h (eval_op_f_array_shape): Declare.
+	(fortran_array_shape_operation): New type.
+	* f-exp.y (exp): Handle UNOP_FORTRAN_SHAPE after parsing
+	UNOP_INTRINSIC.
+	(f77_keywords): Add "shape" keyword.
+	* f-lang.c (fortran_array_shape): New function.
+	(eval_op_f_array_shape): New function.
+	* std-operator.def (UNOP_FORTRAN_SHAPE): New operator.
+
+2021-03-09  Andrew Burgess  <andrew.burgess@embecosm.com>
+
 	* f-exp.y (eval_op_f_array_size): Declare 1 and 2 argument forms
 	of this function.
 	(expr::fortran_array_size_1arg): New type.
diff --git a/gdb/f-exp.h b/gdb/f-exp.h
index fc46c12..11f19af 100644
--- a/gdb/f-exp.h
+++ b/gdb/f-exp.h
@@ -108,6 +108,16 @@ extern struct value *eval_op_f_array_size (struct type *expect_type,
 					   struct value *arg1,
 					   struct value *arg2);
 
+/* Implement the evaluation of Fortran's SHAPE keyword.  EXPECTED_TYPE,
+   EXP, and NOSIDE are as for expression::evaluate (see expression.h).  OP
+   will always be UNOP_FORTRAN_SHAPE, and ARG1 is the argument being passed
+   to the expression.  */
+
+extern struct value *eval_op_f_array_shape (struct type *expect_type,
+					    struct expression *exp,
+					    enum noside noside,
+					    enum exp_opcode op,
+					    struct value *arg1);
 
 namespace expr
 {
@@ -135,6 +145,8 @@ using fortran_array_size_1arg = unop_operation<FORTRAN_ARRAY_SIZE,
 					       eval_op_f_array_size>;
 using fortran_array_size_2arg = binop_operation<FORTRAN_ARRAY_SIZE,
 						eval_op_f_array_size>;
+using fortran_array_shape_operation = unop_operation<UNOP_FORTRAN_SHAPE,
+						     eval_op_f_array_shape>;
 
 /* The Fortran "complex" operation.  */
 class fortran_cmplx_operation
diff --git a/gdb/f-exp.y b/gdb/f-exp.y
index e652bd9..dcc28b8 100644
--- a/gdb/f-exp.y
+++ b/gdb/f-exp.y
@@ -330,6 +330,9 @@ exp	:	UNOP_INTRINSIC '(' exp ')'
 			    case UNOP_FORTRAN_RANK:
 			      pstate->wrap<fortran_rank_operation> ();
 			      break;
+			    case UNOP_FORTRAN_SHAPE:
+			      pstate->wrap<fortran_array_shape_operation> ();
+			      break;
 			    default:
 			      gdb_assert_not_reached ("unhandled intrinsic");
 			    }
@@ -1151,6 +1154,7 @@ static const struct token f77_keywords[] =
   { "associated", UNOP_OR_BINOP_INTRINSIC, FORTRAN_ASSOCIATED, false },
   { "rank", UNOP_INTRINSIC, UNOP_FORTRAN_RANK, false },
   { "size", UNOP_OR_BINOP_INTRINSIC, FORTRAN_ARRAY_SIZE, false },
+  { "shape", UNOP_INTRINSIC, UNOP_FORTRAN_SHAPE, false },
 };
 
 /* Implementation of a dynamically expandable buffer for processing input
diff --git a/gdb/f-lang.c b/gdb/f-lang.c
index a33aef3..d79c458c 100644
--- a/gdb/f-lang.c
+++ b/gdb/f-lang.c
@@ -675,6 +675,87 @@ eval_op_f_array_size (struct type *expect_type,
   return fortran_array_size (exp->gdbarch, exp->language_defn, arg1, arg2);
 }
 
+/* Implement UNOP_FORTRAN_SHAPE expression.  Both GDBARCH and LANG are
+   extracted from the expression being evaluated.  VAL is the value on
+   which 'shape' was used, this can be any type.
+
+   Return an array of integers.  If VAL is not an array then the returned
+   array should have zero elements.  If VAL is an array then the returned
+   array should have one element per dimension, with the element
+   containing the extent of that dimension from VAL.  */
+
+static struct value *
+fortran_array_shape (struct gdbarch *gdbarch, const language_defn *lang,
+		     struct value *val)
+{
+  struct type *val_type = check_typedef (value_type (val));
+
+  /* If we are passed an array that is either not allocated, or not
+     associated, then this is explicitly not allowed according to the
+     Fortran specification.  */
+  if (val_type->code () == TYPE_CODE_ARRAY
+      && (type_not_associated (val_type) || type_not_allocated (val_type)))
+    error (_("The array passed to SHAPE must be allocated or associated"));
+
+  /* The Fortran specification allows non-array types to be passed to this
+     function, in which case we get back an empty array.
+
+     Calculate the number of dimensions for the resulting array.  */
+  int ndimensions = 0;
+  if (val_type->code () == TYPE_CODE_ARRAY)
+    ndimensions = calc_f77_array_dims (val_type);
+
+  /* Allocate a result value of the correct type.  */
+  struct type *range
+    = create_static_range_type (nullptr,
+				builtin_type (gdbarch)->builtin_int,
+				1, ndimensions);
+  struct type *elm_type = builtin_f_type (gdbarch)->builtin_integer;
+  struct type *result_type = create_array_type (nullptr, elm_type, range);
+  struct value *result = allocate_value (result_type);
+  LONGEST elm_len = TYPE_LENGTH (elm_type);
+
+  /* Walk the array dimensions backwards due to the way the array will be
+     laid out in memory, the first dimension will be the most inner.
+
+     If VAL was not an array then ndimensions will be 0, in which case we
+     will never go around this loop.  */
+  for (LONGEST dst_offset = elm_len * (ndimensions - 1);
+       dst_offset >= 0;
+       dst_offset -= elm_len)
+    {
+      LONGEST lbound, ubound;
+
+      if (!get_discrete_bounds (val_type->index_type (), &lbound, &ubound))
+	error (_("failed to find array bounds"));
+
+      LONGEST dim_size = (ubound - lbound + 1);
+
+      /* And copy the value into the result value.  */
+      struct value *v = value_from_longest (elm_type, dim_size);
+      gdb_assert (dst_offset + TYPE_LENGTH (value_type (v))
+		  <= TYPE_LENGTH (value_type (result)));
+      gdb_assert (TYPE_LENGTH (value_type (v)) == elm_len);
+      value_contents_copy (result, dst_offset, v, 0, elm_len);
+
+      /* Peel another dimension of the array.  */
+      val_type = TYPE_TARGET_TYPE (val_type);
+    }
+
+  return result;
+}
+
+/* See f-exp.h.  */
+
+struct value *
+eval_op_f_array_shape (struct type *expect_type, struct expression *exp,
+		       enum noside noside, enum exp_opcode opcode,
+		       struct value *arg1)
+{
+  gdb_assert (opcode == UNOP_FORTRAN_SHAPE);
+  return fortran_array_shape (exp->gdbarch, exp->language_defn, arg1);
+}
+
 /* A helper function for UNOP_ABS.  */
 
 struct value *
diff --git a/gdb/std-operator.def b/gdb/std-operator.def
index b67247f..1b8581f 100644
--- a/gdb/std-operator.def
+++ b/gdb/std-operator.def
@@ -379,6 +379,7 @@ OP (UNOP_FORTRAN_FLOOR)
 OP (UNOP_FORTRAN_CEILING)
 OP (UNOP_FORTRAN_ALLOCATED)
 OP (UNOP_FORTRAN_RANK)
+OP (UNOP_FORTRAN_SHAPE)
 
 /* Two operand builtins.  */
 OP (BINOP_FORTRAN_CMPLX)
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 00a7133..ea1401c 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2021-03-09  Andrew Burgess  <andrew.burgess@embecosm.com>
 
+	* gdb.fortran/shape.exp: New file.
+	* gdb.fortran/shape.f90: New file.
+
+2021-03-09  Andrew Burgess  <andrew.burgess@embecosm.com>
+
 	* gdb.fortran/size.exp: New file.
 	* gdb.fortran/size.f90: New file.
 
diff --git a/gdb/testsuite/gdb.fortran/shape.exp b/gdb/testsuite/gdb.fortran/shape.exp
new file mode 100644
index 0000000..0c41b7b
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/shape.exp
@@ -0,0 +1,86 @@
+# Copyright 2021 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/> .
+
+# Testing GDB's implementation of SHAPE keyword.
+
+if {[skip_fortran_tests]} { return -1 }
+
+standard_testfile ".f90"
+load_lib fortran.exp
+
+if {[prepare_for_testing ${testfile}.exp ${testfile} ${srcfile} \
+	 {debug f90}]} {
+    return -1
+}
+
+if ![fortran_runto_main] {
+    untested "could not run to main"
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Test Breakpoint"]
+gdb_breakpoint [gdb_get_line_number "Final Breakpoint"]
+
+# We place a limit on the number of tests that can be run, just in
+# case something goes wrong, and GDB gets stuck in an loop here.
+set found_final_breakpoint false
+set test_count 0
+while { $test_count < 500 } {
+    with_test_prefix "test $test_count" {
+	incr test_count
+
+	gdb_test_multiple "continue" "continue" {
+	    -re -wrap "! Test Breakpoint" {
+		# We can run a test from here.
+	    }
+	    -re -wrap "! Final Breakpoint" {
+		# We're done with the tests.
+		set found_final_breakpoint true
+	    }
+	}
+
+	if ($found_final_breakpoint) {
+	    break
+	}
+
+	# First grab the expected answer.
+	set answer [get_valueof "" "answer" "**unknown**"]
+
+	# Now move up a frame and figure out a command for us to run
+	# as a test.
+	set command ""
+	gdb_test_multiple "up" "up" {
+	    -re -wrap "\r\n\[0-9\]+\[ \t\]+call test_shape \\((\[^\r\n\]+)\\)" {
+		set command $expect_out(1,string)
+	    }
+	}
+
+	gdb_assert { ![string equal $command ""] } "found a command to run"
+
+	set answer [string_to_regexp $answer]
+	gdb_test "p $command" " = $answer"
+    }
+}
+
+# Ensure we reached the final breakpoint.  If more tests have been added
+# to the test script, and this starts failing, then the safety 'while'
+# loop above might need to be increased.
+gdb_assert {$found_final_breakpoint} "ran all compiled in tests"
+
+foreach var {array_1d_p array_2d_p allocatable_array_1d \
+		 allocatable_array_2d} {
+    gdb_test "p shape ($var)" \
+	"The array passed to SHAPE must be allocated or associated"
+}
diff --git a/gdb/testsuite/gdb.fortran/shape.f90 b/gdb/testsuite/gdb.fortran/shape.f90
new file mode 100644
index 0000000..1a1b3f0
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/shape.f90
@@ -0,0 +1,77 @@
+! Copyright 2021 Free Software Foundation, Inc.
+!
+! This program is free software; you can redistribute it and/or modify
+! it under the terms of the GNU General Public License as published by
+! the Free Software Foundation; either version 3 of the License, or
+! (at your option) any later version.
+!
+! This program is distributed in the hope that it will be useful,
+! but WITHOUT ANY WARRANTY; without even the implied warranty of
+! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+! GNU General Public License for more details.
+!
+! You should have received a copy of the GNU General Public License
+! along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+!
+! Start of test program.
+!
+program test
+
+  ! Things to perform tests on.
+  integer, target :: array_1d (1:10) = 0
+  integer, target :: array_2d (1:4, 1:3) = 0
+  integer :: an_integer = 0
+  real :: a_real = 0.0
+  integer, pointer :: array_1d_p (:) => null ()
+  integer, pointer :: array_2d_p (:,:) => null ()
+  integer, allocatable :: allocatable_array_1d (:)
+  integer, allocatable :: allocatable_array_2d (:,:)
+
+  call test_shape (shape (array_1d))
+  call test_shape (shape (array_2d))
+  call test_shape (shape (an_integer))
+  call test_shape (shape (a_real))
+
+  call test_shape (shape (array_1d (1:10:2)))
+  call test_shape (shape (array_1d (1:10:3)))
+
+  call test_shape (shape (array_2d (4:1:-1, 3:1:-1)))
+  call test_shape (shape (array_2d (4:1:-1, 1:3:2)))
+
+  allocate (allocatable_array_1d (-10:-5))
+  allocate (allocatable_array_2d (-3:3, 8:12))
+
+  call test_shape (shape (allocatable_array_1d))
+  call test_shape (shape (allocatable_array_2d))
+
+  call test_shape (shape (allocatable_array_2d (-2, 10:12)))
+
+  array_1d_p => array_1d
+  array_2d_p => array_2d
+
+  call test_shape (shape (array_1d_p))
+  call test_shape (shape (array_2d_p))
+
+  deallocate (allocatable_array_1d)
+  deallocate (allocatable_array_2d)
+  array_1d_p => null ()
+  array_2d_p => null ()
+
+  print *, "" ! Final Breakpoint
+  print *, an_integer
+  print *, a_real
+  print *, associated (array_1d_p)
+  print *, associated (array_2d_p)
+  print *, allocated (allocatable_array_1d)
+  print *, allocated (allocatable_array_2d)
+
+contains
+
+  subroutine test_shape (answer)
+    integer, dimension (:) :: answer
+
+    print *,answer	! Test Breakpoint
+  end subroutine test_shape
+
+end program test