Handle biased types

In Ada, the programmer can request that a range type with a non-zero
base be stored in the minimal number of bits required for the range.
This is done by biasing the values; so, for example, a range of -7..-4
may be stored as two bits with a bias of -7.

This patch implements this for gdb.  It is done by adding a bias to
struct range_bounds and then adjusting a few spots to handle this.

The test case is written to use -fgnat-encodings=minimal, but a future
compiler patch will change the compiler to emit DW_AT_GNU_bias with
-fgnat-encodings=gdb.  It seemed good to get the gdb patch in first.

Tested on x86-64 Fedora 29; plus a variety of targets using AdaCore's
internal test suite.

gdb/ChangeLog
2019-09-03  Tom Tromey  <tromey@adacore.com>

	* ada-valprint.c (ada_val_print_num): Don't recurse for range
	types.
	(has_negatives): Unbias a range type bound.
	* dwarf2read.c (read_subrange_type): Handle DW_AT_GNU_bias.
	* gdbtypes.c (operator==): Handle new field.
	(create_range_type): Add "bias" parameter.
	(create_static_range_type, resolve_dynamic_range): Update.
	* gdbtypes.h (struct range_bounds) <bias>: New member.
	(create_range_type): Add bias parameter.
	* printcmd.c (print_scalar_formatted): Unbias range types.
	* value.c (unpack_long): Unbias range types.
	(pack_long): Bias range types.

gdb/testsuite/ChangeLog
2019-09-03  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/bias.exp: New file.
	* gdb.ada/bias/bias.adb: New file.
	* gdb.ada/print_chars.exp: Add regression test.
	* gdb.ada/print_chars/foo.adb (My_Character): New type.
	(MC): New variable.
This commit is contained in:
Tom Tromey 2019-05-13 13:21:48 -06:00
parent f44b758d31
commit 4e962e74e4
15 changed files with 250 additions and 33 deletions

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@ -1,3 +1,18 @@
2019-09-03 Tom Tromey <tromey@adacore.com>
* ada-valprint.c (ada_val_print_num): Don't recurse for range
types.
(has_negatives): Unbias a range type bound.
* dwarf2read.c (read_subrange_type): Handle DW_AT_GNU_bias.
* gdbtypes.c (operator==): Handle new field.
(create_range_type): Add "bias" parameter.
(create_static_range_type, resolve_dynamic_range): Update.
* gdbtypes.h (struct range_bounds) <bias>: New member.
(create_range_type): Add bias parameter.
* printcmd.c (print_scalar_formatted): Unbias range types.
* value.c (unpack_long): Unbias range types.
(pack_long): Bias range types.
2019-09-02 Alan Hayward <alan.hayward@arm.com>
* solib-svr4.c (svr4_find_and_create_probe_breakpoints): Check all

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@ -2361,7 +2361,7 @@ has_negatives (struct type *type)
case TYPE_CODE_INT:
return !TYPE_UNSIGNED (type);
case TYPE_CODE_RANGE:
return TYPE_LOW_BOUND (type) < 0;
return TYPE_LOW_BOUND (type) - TYPE_RANGE_DATA (type)->bias < 0;
}
}

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@ -841,8 +841,15 @@ ada_val_print_num (struct type *type, const gdb_byte *valaddr,
fputs_filtered (str.c_str (), stream);
return;
}
else if (TYPE_CODE (type) == TYPE_CODE_RANGE)
else if (TYPE_CODE (type) == TYPE_CODE_RANGE
&& (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_ENUM
|| TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_BOOL
|| TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_CHAR))
{
/* For enum-valued ranges, we want to recurse, because we'll end
up printing the constant's name rather than its numeric
value. Character and fixed-point types are also printed
differently, so recuse for those as well. */
struct type *target_type = TYPE_TARGET_TYPE (type);
if (TYPE_LENGTH (type) != TYPE_LENGTH (target_type))

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@ -17901,6 +17901,11 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
}
}
LONGEST bias = 0;
struct attribute *bias_attr = dwarf2_attr (die, DW_AT_GNU_bias, cu);
if (bias_attr != nullptr && attr_form_is_constant (bias_attr))
bias = dwarf2_get_attr_constant_value (bias_attr, 0);
/* Normally, the DWARF producers are expected to use a signed
constant form (Eg. DW_FORM_sdata) to express negative bounds.
But this is unfortunately not always the case, as witnessed
@ -17917,7 +17922,7 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
&& !TYPE_UNSIGNED (base_type) && (high.data.const_val & negative_mask))
high.data.const_val |= negative_mask;
range_type = create_range_type (NULL, orig_base_type, &low, &high);
range_type = create_range_type (NULL, orig_base_type, &low, &high, bias);
if (high_bound_is_count)
TYPE_RANGE_DATA (range_type)->flag_upper_bound_is_count = 1;

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@ -901,7 +901,8 @@ operator== (const range_bounds &l, const range_bounds &r)
return (FIELD_EQ (low)
&& FIELD_EQ (high)
&& FIELD_EQ (flag_upper_bound_is_count)
&& FIELD_EQ (flag_bound_evaluated));
&& FIELD_EQ (flag_bound_evaluated)
&& FIELD_EQ (bias));
#undef FIELD_EQ
}
@ -912,7 +913,8 @@ operator== (const range_bounds &l, const range_bounds &r)
struct type *
create_range_type (struct type *result_type, struct type *index_type,
const struct dynamic_prop *low_bound,
const struct dynamic_prop *high_bound)
const struct dynamic_prop *high_bound,
LONGEST bias)
{
/* The INDEX_TYPE should be a type capable of holding the upper and lower
bounds, as such a zero sized, or void type makes no sense. */
@ -932,6 +934,7 @@ create_range_type (struct type *result_type, struct type *index_type,
TYPE_ZALLOC (result_type, sizeof (struct range_bounds));
TYPE_RANGE_DATA (result_type)->low = *low_bound;
TYPE_RANGE_DATA (result_type)->high = *high_bound;
TYPE_RANGE_DATA (result_type)->bias = bias;
if (low_bound->kind == PROP_CONST && low_bound->data.const_val >= 0)
TYPE_UNSIGNED (result_type) = 1;
@ -968,7 +971,7 @@ create_static_range_type (struct type *result_type, struct type *index_type,
high.kind = PROP_CONST;
high.data.const_val = high_bound;
result_type = create_range_type (result_type, index_type, &low, &high);
result_type = create_range_type (result_type, index_type, &low, &high, 0);
return result_type;
}
@ -2015,9 +2018,10 @@ resolve_dynamic_range (struct type *dyn_range_type,
static_target_type
= resolve_dynamic_type_internal (TYPE_TARGET_TYPE (dyn_range_type),
addr_stack, 0);
LONGEST bias = TYPE_RANGE_DATA (dyn_range_type)->bias;
static_range_type = create_range_type (copy_type (dyn_range_type),
static_target_type,
&low_bound, &high_bound);
&low_bound, &high_bound, bias);
TYPE_RANGE_DATA (static_range_type)->flag_bound_evaluated = 1;
return static_range_type;
}

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@ -617,6 +617,11 @@ struct range_bounds
struct dynamic_prop high;
/* * The bias. Sometimes a range value is biased before storage.
The bias is added to the stored bits to form the true value. */
LONGEST bias;
/* True if HIGH range bound contains the number of elements in the
subrange. This affects how the final high bound is computed. */
@ -1951,7 +1956,8 @@ extern struct type *create_array_type_with_stride
extern struct type *create_range_type (struct type *, struct type *,
const struct dynamic_prop *,
const struct dynamic_prop *);
const struct dynamic_prop *,
LONGEST);
extern struct type *create_array_type (struct type *, struct type *,
struct type *);

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@ -405,21 +405,30 @@ print_scalar_formatted (const gdb_byte *valaddr, struct type *type,
/* Historically gdb has printed floats by first casting them to a
long, and then printing the long. PR cli/16242 suggests changing
this to using C-style hex float format. */
gdb::byte_vector converted_float_bytes;
if (TYPE_CODE (type) == TYPE_CODE_FLT
&& (options->format == 'o'
|| options->format == 'x'
|| options->format == 't'
|| options->format == 'z'
|| options->format == 'd'
|| options->format == 'u'))
this to using C-style hex float format.
Biased range types must also be unbiased here; the unbiasing is
done by unpack_long. */
gdb::byte_vector converted_bytes;
/* Some cases below will unpack the value again. In the biased
range case, we want to avoid this, so we store the unpacked value
here for possible use later. */
gdb::optional<LONGEST> val_long;
if ((TYPE_CODE (type) == TYPE_CODE_FLT
&& (options->format == 'o'
|| options->format == 'x'
|| options->format == 't'
|| options->format == 'z'
|| options->format == 'd'
|| options->format == 'u'))
|| (TYPE_CODE (type) == TYPE_CODE_RANGE
&& TYPE_RANGE_DATA (type)->bias != 0))
{
LONGEST val_long = unpack_long (type, valaddr);
converted_float_bytes.resize (TYPE_LENGTH (type));
store_signed_integer (converted_float_bytes.data (), TYPE_LENGTH (type),
byte_order, val_long);
valaddr = converted_float_bytes.data ();
val_long.emplace (unpack_long (type, valaddr));
converted_bytes.resize (TYPE_LENGTH (type));
store_signed_integer (converted_bytes.data (), TYPE_LENGTH (type),
byte_order, *val_long);
valaddr = converted_bytes.data ();
}
/* Printing a non-float type as 'f' will interpret the data as if it were
@ -469,7 +478,8 @@ print_scalar_formatted (const gdb_byte *valaddr, struct type *type,
{
struct value_print_options opts = *options;
LONGEST val_long = unpack_long (type, valaddr);
if (!val_long.has_value ())
val_long.emplace (unpack_long (type, valaddr));
opts.format = 0;
if (TYPE_UNSIGNED (type))
@ -477,15 +487,15 @@ print_scalar_formatted (const gdb_byte *valaddr, struct type *type,
else
type = builtin_type (gdbarch)->builtin_true_char;
value_print (value_from_longest (type, val_long), stream, &opts);
value_print (value_from_longest (type, *val_long), stream, &opts);
}
break;
case 'a':
{
CORE_ADDR addr = unpack_pointer (type, valaddr);
print_address (gdbarch, addr, stream);
if (!val_long.has_value ())
val_long.emplace (unpack_long (type, valaddr));
print_address (gdbarch, *val_long, stream);
}
break;

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@ -1,3 +1,11 @@
2019-09-03 Tom Tromey <tromey@adacore.com>
* gdb.ada/bias.exp: New file.
* gdb.ada/bias/bias.adb: New file.
* gdb.ada/print_chars.exp: Add regression test.
* gdb.ada/print_chars/foo.adb (My_Character): New type.
(MC): New variable.
2019-08-29 Sandra Loosemore <sandra@codesourcery.com>
* gdb.base/argv0-symlink.exp: Run only on native target

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@ -0,0 +1,56 @@
# 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/>.
load_lib "ada.exp"
standard_ada_testfile bias
if {[gdb_compile_ada "${srcfile}" "${binfile}" executable \
{debug additional_flags=-fgnat-encodings=minimal}] != "" } {
return -1
}
clean_restart ${testfile}
set bp_location [gdb_get_line_number "STOP" ${testdir}/bias.adb]
runto "bias.adb:$bp_location"
gdb_test "print x" " = 64"
gdb_test "print y" " = -5"
gdb_test "print cval" " = 65"
gdb_test "print/c cval" " = 65 'A'"
# Some binary arithmetic checks.
gdb_test "print y < y1" " = false"
gdb_test "print y <= y1" " = false"
gdb_test "print y > y1" " = true"
gdb_test "print y >= y1" " = true"
gdb_test "print y = y" " = true"
gdb_test "print y /= y" " = false"
gdb_test "print y /= y1" " = true"
gdb_test "print x + x1" " = 65"
gdb_test "ptype x + x1" "type = range 1 \\.\\. 64"
gdb_test "print x / x1" " = 64"
gdb_test "print x * x1" " = 64"
gdb_test "print x - x1" " = 63"
# Test that storing un-biases.
gdb_test "print x := 5" " = 5"
gdb_test "print x" " = 5" "re-read x after storing"
gdb_test "print spr" " = \\(r => -4, s => -5\\)"
gdb_test "print a" " = \\(-7, -5, -4\\)"

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@ -0,0 +1,52 @@
-- 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/>.
with Pck; use Pck;
procedure Bias is
type Small is range -7 .. -4;
for Small'Size use 2;
Y : Small := -5;
Y1 : Small := -7;
type Repeat_Count_T is range 1 .. 2 ** 6;
for Repeat_Count_T'Size use 6;
X : Repeat_Count_T := 64;
X1 : Repeat_Count_T := 1;
type Char_Range is range 65 .. 68;
for Char_Range'Size use 2;
Cval : Char_Range := 65;
type Some_Packed_Record is record
R: Small;
S: Small;
end record;
pragma Pack (Some_Packed_Record);
SPR : Some_Packed_Record := (R => -4, S => -5);
type Packed_Array is array (1 .. 3) of Small;
pragma pack (Packed_Array);
A : Packed_Array := (-7, -5, -4);
begin
Do_Nothing (Y'Address); -- STOP
Do_Nothing (Y1'Address);
Do_Nothing (X'Address);
Do_Nothing (X1'Address);
Do_Nothing (Cval'Address);
Do_Nothing (SPR'Address);
Do_Nothing (A'Address);
end Bias;

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@ -0,0 +1,23 @@
-- Copyright 2012-2019 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/>.
with System;
package body Pck is
procedure Do_Nothing (A : System.Address) is
begin
null;
end Do_Nothing;
end Pck;

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@ -0,0 +1,20 @@
-- Copyright 2012-2019 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/>.
with System;
package Pck is
procedure Do_Nothing (A : System.Address);
end Pck;

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@ -39,4 +39,4 @@ gdb_test "print WWC" \
"= 99 'c'" \
"print WWC"
gdb_test "print MC" " = 77 'M'"

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@ -19,6 +19,9 @@ procedure Foo is
C : Character := 'a';
WC : Wide_Character := 'b';
WWC : Wide_Wide_Character := 'c';
type My_Character is new Character;
MC : My_Character := 'M';
begin
Do_Nothing (C'Address); -- START
Do_Nothing (WC'Address);

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@ -2751,10 +2751,16 @@ unpack_long (struct type *type, const gdb_byte *valaddr)
case TYPE_CODE_CHAR:
case TYPE_CODE_RANGE:
case TYPE_CODE_MEMBERPTR:
if (nosign)
return extract_unsigned_integer (valaddr, len, byte_order);
else
return extract_signed_integer (valaddr, len, byte_order);
{
LONGEST result;
if (nosign)
result = extract_unsigned_integer (valaddr, len, byte_order);
else
result = extract_signed_integer (valaddr, len, byte_order);
if (code == TYPE_CODE_RANGE)
result += TYPE_RANGE_DATA (type)->bias;
return result;
}
case TYPE_CODE_FLT:
case TYPE_CODE_DECFLOAT:
@ -3315,12 +3321,14 @@ pack_long (gdb_byte *buf, struct type *type, LONGEST num)
switch (TYPE_CODE (type))
{
case TYPE_CODE_RANGE:
num -= TYPE_RANGE_DATA (type)->bias;
/* Fall through. */
case TYPE_CODE_INT:
case TYPE_CODE_CHAR:
case TYPE_CODE_ENUM:
case TYPE_CODE_FLAGS:
case TYPE_CODE_BOOL:
case TYPE_CODE_RANGE:
case TYPE_CODE_MEMBERPTR:
store_signed_integer (buf, len, byte_order, num);
break;