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[gdb/Ada] slices of arrays with dynamic strides 

Consider the following Ada code:

       procedure Nested (L, U : Integer) is
          subtype Small_Type is Integer range L .. U;
          type Record_Type (I : Small_Type := L) is record
             S : String (1 .. I);
          end record;
          type Array_Type is array (Integer range <>) of Record_Type;

          A1 : Array_Type :=
            (1 => (I => 0, S => <>),
             2 => (I => 1, S => "A"),
             3 => (I => 2, S => "AB"));

          procedure Discard (R : Record_Type) is
          begin
             null;
          end Discard;

       begin
          Discard (A1 (1));  -- STOP
       end;

Trying to print a slice of that array currently yields:

    (gdb) p a1(1..3)
    $1 = ((i => 0, s => ""), (i => 0, s => ""), (i => 0, s => ""))

We expected instead:

    (gdb) p a1(1..3)
    $1 = ((i => 0, s => ""), (i => 1, s => "A"), (i => 2, s => "AB"))

This is because the functions we use in ada-lang.c to create the type
of the array slice (ada_value_slice and ada_value_slice_from_ptr) was
not taking into account the stride of the array. This patch fixes this.

gdb/ChangeLog:

        * ada-lang.c (ada_value_slice_from_ptr): Take array stride into
        account when creating the array type of the slice.
        (ada_value_slice): Likewise.

gdb/testsuite/ChangeLog:

        * gdb.ada/dyn_stride.exp: Add slice test.

Note that, with the current use of ada_value_slice, the enhancement
to handle dynamic array strides seems unnecessary, because I do not
see how an array with a dynamic stride can be referenced by either
by reference or pointer. Since references are coerced to array pointers,
in both cases, the slice is performed by ada_value_slice_from_ptr.
But ada_value_slice is enhanced nonetheless, in the spirit of making
the code more robust, in case we missed something, and also as similar
as possible with its from_ptr counterpart.

tested on x86_64-linux.
This commit is contained in:
Joel Brobecker 2018-01-01 22:53:55 -05:00
parent a405673cc5
commit 9fe561ab7f
4 changed files with 21 additions and 4 deletions
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6
gdb/ChangeLog
View File

@ -1,3 +1,9 @@
2018-01-02 Joel Brobecker <brobecker@adacore.com>
* ada-lang.c (ada_value_slice_from_ptr): Take array stride into
account when creating the array type of the slice.
(ada_value_slice): Likewise.
2018-01-02 Joel Brobecker <brobecker@adacore.com>
* gdbtypes.h (enum dynamic_prop_node_kind) <DYN_PROP_BYTE_STRIDE>:

12
gdb/ada-lang.c
View File

@ -2910,8 +2910,10 @@ ada_value_slice_from_ptr (struct value *array_ptr, struct type *type,
struct type *base_index_type = TYPE_TARGET_TYPE (TYPE_INDEX_TYPE (type0));
struct type *index_type
= create_static_range_type (NULL, base_index_type, low, high);
struct type *slice_type =
create_array_type (NULL, TYPE_TARGET_TYPE (type0), index_type);
struct type *slice_type = create_array_type_with_stride
(NULL, TYPE_TARGET_TYPE (type0), index_type,
get_dyn_prop (DYN_PROP_BYTE_STRIDE, type0),
TYPE_FIELD_BITSIZE (type0, 0));
int base_low = ada_discrete_type_low_bound (TYPE_INDEX_TYPE (type0));
LONGEST base_low_pos, low_pos;
CORE_ADDR base;
@ -2938,8 +2940,10 @@ ada_value_slice (struct value *array, int low, int high)
struct type *base_index_type = TYPE_TARGET_TYPE (TYPE_INDEX_TYPE (type));
struct type *index_type
= create_static_range_type (NULL, TYPE_INDEX_TYPE (type), low, high);
struct type *slice_type =
create_array_type (NULL, TYPE_TARGET_TYPE (type), index_type);
struct type *slice_type = create_array_type_with_stride
(NULL, TYPE_TARGET_TYPE (type), index_type,
get_dyn_prop (DYN_PROP_BYTE_STRIDE, type),
TYPE_FIELD_BITSIZE (type, 0));
LONGEST low_pos, high_pos;
if (!discrete_position (base_index_type, low, &low_pos)

4
gdb/testsuite/ChangeLog
View File

@ -1,3 +1,7 @@
2018-01-02 Joel Brobecker <brobecker@adacore.com>
* gdb.ada/dyn_stride.exp: Add slice test.
2018-01-02 Joel Brobecker <brobecker@adacore.com>
* gdb.ada/dyn_stride: New testcase.

3
gdb/testsuite/gdb.ada/dyn_stride.exp
View File

@ -36,3 +36,6 @@ gdb_test "print A1(2)" \
gdb_test "print A1(3)" \
"\\(i => 2, s => \"AB\"\\)"
gdb_test "print A1(1..3)" \
"\\(\\(i => 0, s => \"\"\\), \\(i => 1, s => \"A\"\\), \\(i => 2, s => \"AB\"\\)\\)"