gdb/fortran: array stride support

Currently GDB supports a byte or bit stride on arrays, in DWARF this
would be DW_AT_bit_stride or DW_AT_byte_stride on DW_TAG_array_type.
However, DWARF can also support DW_AT_byte_stride or DW_AT_bit_stride
on DW_TAG_subrange_type, the tag used to describe each dimension of an
array.

Strides on subranges are used by gFortran to represent Fortran arrays,
and this commit adds support for this to GDB.

I've extended the range_bounds struct to include the stride
information.  The name is possibly a little inaccurate now, but this
still sort of makes sense, the structure represents information about
the bounds of the range, and also how to move from the lower to the
upper bound (the stride).

I've added initial support for bit strides, but I've never actually
seen an example of this being generated.  Further, I don't really see
right now how GDB would currently handle a bit stride that was not a
multiple of the byte size as the code in, for example,
valarith.c:value_subscripted_rvalue seems geared around byte
addressing.  As a consequence if we see a bit stride that is not a
multiple of 8 then GDB will give an error.

gdb/ChangeLog:

	* dwarf2read.c (read_subrange_type): Read bit and byte stride and
	create a range with stride where appropriate.
	* f-valprint.c: Include 'gdbarch.h'.
	(f77_print_array_1): Take the stride into account when walking the
	array.  Also convert the stride into addressable units.
	* gdbtypes.c (create_range_type): Initialise the stride to
	constant zero.
	(create_range_type_with_stride): New function, initialise the
	range as normal, and then setup the stride.
	(has_static_range): Include the stride here.  Also change the
	return type to bool.
	(create_array_type_with_stride): Consider the range stride if the
	array isn't given its own stride.
	(resolve_dynamic_range): Resolve the stride if needed.
	* gdbtypes.h (struct range_bounds) <stride>: New member variable.
	(struct range_bounds) <flag_is_byte_stride>: New member variable.
	(TYPE_BIT_STRIDE): Define.
	(TYPE_ARRAY_BIT_STRIDE): Define.
	(create_range_type_with_stride): Declare.
	* valarith.c (value_subscripted_rvalue): Take range stride into
	account when walking the array.

gdb/testsuite/ChangeLog:

	* gdb.fortran/derived-type-striding.exp: New file.
	* gdb.fortran/derived-type-striding.f90: New file.
	* gdb.fortran/array-slices.exp: New file.
	* gdb.fortran/array-slices.f90: New file.

Change-Id: I9af2bcd1f2d4c56f76f5f3f9f89d8f06bef10d9a

4 files changed, 208 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.fortran/array-slices.exp b/gdb/testsuite/gdb.fortran/array-slices.exp
new file mode 100644
index 0000000..db07ace
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/array-slices.exp
@@ -0,0 +1,58 @@
+# Copyright 2019 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/> .
+
+# Print a 2 dimensional assumed shape array.  We pass different slices
+# of the array to a subroutine and print the array as recieved within
+# the subroutine.  This should exercise GDB's ability to handle
+# different strides for the different dimensions.
+
+if {[skip_fortran_tests]} { return -1 }
+
+standard_testfile ".f90"
+
+if {[prepare_for_testing ${testfile}.exp ${testfile} ${srcfile} \
+	 {debug f90}]} {
+    return -1
+}
+
+if ![runto_main] {
+    untested "could not run to main"
+    return -1
+}
+
+gdb_breakpoint "show"
+gdb_breakpoint [gdb_get_line_number "Final Breakpoint"]
+
+set array_contents \
+    [list \
+	 " = \\(\\( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10\\) \\( 11, 12, 13, 14, 15, 16, 17, 18, 19, 20\\) \\( 21, 22, 23, 24, 25, 26, 27, 28, 29, 30\\) \\( 31, 32, 33, 34, 35, 36, 37, 38, 39, 40\\) \\( 41, 42, 43, 44, 45, 46, 47, 48, 49, 50\\) \\( 51, 52, 53, 54, 55, 56, 57, 58, 59, 60\\) \\( 61, 62, 63, 64, 65, 66, 67, 68, 69, 70\\) \\( 71, 72, 73, 74, 75, 76, 77, 78, 79, 80\\) \\( 81, 82, 83, 84, 85, 86, 87, 88, 89, 90\\) \\( 91, 92, 93, 94, 95, 96, 97, 98, 99, 100\\) \\)" \
+	 " = \\(\\( 1, 2, 3, 4, 5\\) \\( 11, 12, 13, 14, 15\\) \\( 21, 22, 23, 24, 25\\) \\( 31, 32, 33, 34, 35\\) \\( 41, 42, 43, 44, 45\\) \\)" \
+	 " = \\(\\( 1, 3, 5, 7, 9\\) \\( 21, 23, 25, 27, 29\\) \\( 41, 43, 45, 47, 49\\) \\( 61, 63, 65, 67, 69\\) \\( 81, 83, 85, 87, 89\\) \\)" \
+	 " = \\(\\( 1, 4, 7, 10\\) \\( 21, 24, 27, 30\\) \\( 41, 44, 47, 50\\) \\( 61, 64, 67, 70\\) \\( 81, 84, 87, 90\\) \\)" \
+	 " = \\(\\( 1, 5, 9\\) \\( 31, 35, 39\\) \\( 61, 65, 69\\) \\( 91, 95, 99\\) \\)" \
+	 " = \\(\\( -26, -25, -24, -23, -22, -21, -20, -19, -18, -17\\) \\( -19, -18, -17, -16, -15, -14, -13, -12, -11, -10\\) \\( -12, -11, -10, -9, -8, -7, -6, -5, -4, -3\\) \\( -5, -4, -3, -2, -1, 0, 1, 2, 3, 4\\) \\( 2, 3, 4, 5, 6, 7, 8, 9, 10, 11\\) \\( 9, 10, 11, 12, 13, 14, 15, 16, 17, 18\\) \\( 16, 17, 18, 19, 20, 21, 22, 23, 24, 25\\) \\( 23, 24, 25, 26, 27, 28, 29, 30, 31, 32\\) \\( 30, 31, 32, 33, 34, 35, 36, 37, 38, 39\\) \\( 37, 38, 39, 40, 41, 42, 43, 44, 45, 46\\) \\)" \
+	 " = \\(\\( -26, -25, -24, -23, -22, -21\\) \\( -19, -18, -17, -16, -15, -14\\) \\( -12, -11, -10, -9, -8, -7\\) \\)" \
+	 " = \\(\\( -26, -24, -22, -20, -18\\) \\( -5, -3, -1, 1, 3\\) \\( 16, 18, 20, 22, 24\\) \\( 37, 39, 41, 43, 45\\) \\)" ]
+
+set i 0
+foreach result $array_contents {
+    incr i
+    with_test_prefix "test $i" {
+	gdb_continue_to_breakpoint "show"
+	gdb_test "p array" $result
+    }
+}
+
+gdb_continue_to_breakpoint "continue to Final Breakpoint"
diff --git a/gdb/testsuite/gdb.fortran/array-slices.f90 b/gdb/testsuite/gdb.fortran/array-slices.f90
new file mode 100644
index 0000000..ec4e1eb
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/array-slices.f90
@@ -0,0 +1,70 @@
+! Copyright 2019 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/>.
+
+subroutine show (message, array)
+  character (len=*) :: message
+  integer, dimension (:,:) :: array
+
+  print *, message
+  do i=LBOUND (array, 2), UBOUND (array, 2), 1
+     do j=LBOUND (array, 1), UBOUND (array, 1), 1
+        write(*, fmt="(i4)", advance="no") array (j, i)
+     end do
+     print *, ""
+ end do
+ print *, array
+ print *, ""
+
+end subroutine show
+
+program test
+
+  interface
+     subroutine show (message, array)
+       character (len=*) :: message
+       integer, dimension(:,:) :: array
+     end subroutine show
+  end interface
+
+  integer, dimension (1:10,1:10) :: array
+  integer, allocatable :: other (:, :)
+
+  allocate (other (-5:4, -2:7))
+
+  do i=LBOUND (array, 2), UBOUND (array, 2), 1
+     do j=LBOUND (array, 1), UBOUND (array, 1), 1
+        array (j,i) = ((i - 1) * UBOUND (array, 2)) + j
+     end do
+  end do
+
+  do i=LBOUND (other, 2), UBOUND (other, 2), 1
+     do j=LBOUND (other, 1), UBOUND (other, 1), 1
+        other (j,i) = ((i - 1) * UBOUND (other, 2)) + j
+     end do
+  end do
+
+  call show ("array", array)
+  call show ("array (1:5,1:5)", array (1:5,1:5))
+  call show ("array (1:10:2,1:10:2)", array (1:10:2,1:10:2))
+  call show ("array (1:10:3,1:10:2)", array (1:10:3,1:10:2))
+  call show ("array (1:10:5,1:10:3)", array (1:10:4,1:10:3))
+
+  call show ("other", other)
+  call show ("other (-5:0, -2:0)", other (-5:0, -2:0))
+  call show ("other (-5:4:2, -2:7:3)", other (-5:4:2, -2:7:3))
+
+  deallocate (other)
+  print *, "" ! Final Breakpoint.
+end program test
diff --git a/gdb/testsuite/gdb.fortran/derived-type-striding.exp b/gdb/testsuite/gdb.fortran/derived-type-striding.exp
new file mode 100644
index 0000000..a2590a9
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/derived-type-striding.exp
@@ -0,0 +1,37 @@
+# Copyright 2019 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/> .
+
+# Print some single dimensional integer arrays that will have a byte
+# stride in the debug information.
+
+if {[skip_fortran_tests]} { return -1 }
+
+standard_testfile ".f90"
+
+if {[prepare_for_testing ${testfile}.exp ${testfile} ${srcfile} \
+	 {debug f90}]} {
+    return -1
+}
+
+if {![runto [gdb_get_line_number "post_init"]]} then {
+    perror "couldn't run to breakpoint post_init"
+    continue
+}
+
+# Test homogeneous derived type.
+gdb_test "p point_dimension" "= \\\(2, 2, 2, 2, 2, 2, 2, 2, 2\\\)"
+
+# Test mixed type derived type.
+gdb_test "p point_mixed_dimension" "= \\\(3, 3, 3, 3\\\)"
diff --git a/gdb/testsuite/gdb.fortran/derived-type-striding.f90 b/gdb/testsuite/gdb.fortran/derived-type-striding.f90
new file mode 100644
index 0000000..8189ad3
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/derived-type-striding.f90
@@ -0,0 +1,43 @@
+! Copyright 2019 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/>.
+
+program derived_type_member_stride
+    type cartesian
+        integer(kind=8) :: x
+        integer(kind=8) :: y
+        integer(kind=8) :: z
+    end type
+    type mixed_cartesian
+        integer(kind=8) :: x
+        integer(kind=4) :: y
+        integer(kind=8) :: z
+    end type
+    type(cartesian), dimension(10), target :: cloud
+    type(mixed_cartesian), dimension(10), target :: mixed_cloud
+    integer(kind=8), dimension(:), pointer :: point_dimension => null()
+    integer(kind=8), dimension(:), pointer :: point_mixed_dimension => null()
+    cloud(:)%x = 1
+    cloud(:)%y = 2
+    cloud(:)%z = 3
+    point_dimension => cloud(1:9)%y
+    mixed_cloud(:)%x = 1
+    mixed_cloud(:)%y = 2
+    mixed_cloud(:)%z = 3
+    point_mixed_dimension => mixed_cloud(1:4)%z
+    ! Prevent the compiler from optimising the work out.
+    print *, cloud(:)%x ! post_init
+    print *, point_dimension
+    print *, point_mixed_dimension
+end program