binutils-gdb/gdb/p-lang.c
Peeter Joot 34877895ca Adjust byte order variable display/change if DW_AT_endianity is present.
- Rationale:
It is possible for compilers to indicate the desired byte order
interpretation of scalar variables using the DWARF attribute:
   DW_AT_endianity

A type flagged with this variable would typically use one of:
   DW_END_big
   DW_END_little
which instructs the debugger what the desired byte order interpretation
of the variable should be.

The GCC compiler (as of V6) has a mechanism for setting the desired byte
ordering of the fields within a structure or union.  For, example, on a
little endian target, a structure declared as:
   struct big {
       int v;
       short a[4];
   } __attribute__( ( scalar_storage_order( "big-endian" ) ) );
could be used to ensure all the structure members have a big-endian
interpretation (the compiler would automatically insert byte swap
instructions before and after respective store and load instructions).

- To reproduce
GCC V8 is required to correctly emit DW_AT_endianity DWARF attributes
in all situations when the scalar_storage_order attribute is used.

A fix for (dwarf endianity instrumentation) for GCC V6-V7 can be found
in the URL field of the following PR:
   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82509

- Test-case:
A new test case (testsuite/gdb.base/endianity.*) is included with this
patch.

Manual testing for mixed endianity code has also been done with GCC V8.
See:
   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82509#c4

- Observed vs. expected:

Without this change, using scalar_storage_order that doesn't match the
target, such as

struct otherendian
{
  int v;
} __attribute__( ( scalar_storage_order( "big-endian" ) ) );

would behave like the following on a little endian target:

   Breakpoint 1 at 0x401135: file endianity.c, line 41.
   (gdb) run
   Starting program: /home/pjoot/freeware/t/a.out
   Missing separate debuginfos, use: debuginfo-install glibc-2.17-292.el7.x86_64

   Breakpoint 1, main () at endianity.c:41
   41        struct otherendian o = {3};
   (gdb) n
   43        do_nothing (&o); /* START */
   (gdb) p o
   $1 = {v = 50331648}
   (gdb) p /x
   $2 = {v = 0x3000000}

whereas with this gdb enhancement we can access the variable with the user
specified endianity:

   Breakpoint 1, main () at endianity.c:41
   41        struct otherendian o = {3};
   (gdb) p o
   $1 = {v = 0}
   (gdb) n
   43        do_nothing (&o); /* START */
   (gdb) p o
   $2 = {v = 3}
   (gdb) p o.v = 4
   $3 = 4
   (gdb) p o.v
   $4 = 4
   (gdb) x/4xb &o.v
   0x7fffffffd90c: 0x00    0x00    0x00    0x04

(observe that the 4 byte int variable has a big endian representation in the
 hex dump.)

gdb/ChangeLog
2019-11-21  Peeter Joot  <peeter.joot@lzlabs.com>

	Byte reverse display of variables with DW_END_big, DW_END_little
	(DW_AT_endianity) dwarf attributes if different than the native
	byte order.
	* ada-lang.c (ada_value_binop):
	Use type_byte_order instead of gdbarch_byte_order.
	* ada-valprint.c (printstr):
	(ada_val_print_string):
	* ada-lang.c (value_pointer):
	(ada_value_binop):
	Use type_byte_order instead of gdbarch_byte_order.
	* c-lang.c (c_get_string):
	Use type_byte_order instead of gdbarch_byte_order.
	* c-valprint.c (c_val_print_array):
	Use type_byte_order instead of gdbarch_byte_order.
	* cp-valprint.c (cp_print_class_member):
	Use type_byte_order instead of gdbarch_byte_order.
	* dwarf2loc.c (rw_pieced_value):
	Use type_byte_order instead of gdbarch_byte_order.
	* dwarf2read.c (read_base_type): Handle DW_END_big,
	DW_END_little
	* f-lang.c (f_get_encoding):
	Use type_byte_order instead of gdbarch_byte_order.
	* findvar.c (default_read_var_value):
	Use type_byte_order instead of gdbarch_byte_order.
	* gdbtypes.c (check_types_equal):
	Require matching TYPE_ENDIANITY_NOT_DEFAULT if set.
	(recursive_dump_type): Print TYPE_ENDIANITY_BIG,
	and TYPE_ENDIANITY_LITTLE if set.
	(type_byte_order): new function.
	* gdbtypes.h (TYPE_ENDIANITY_NOT_DEFAULT): New macro.
	(struct main_type) <flag_endianity_not_default>:
	New field.
	(type_byte_order): New function.
	* infcmd.c (default_print_one_register_info):
	Use type_byte_order instead of gdbarch_byte_order.
	* p-lang.c (pascal_printstr):
	Use type_byte_order instead of gdbarch_byte_order.
	* p-valprint.c (pascal_val_print):
	Use type_byte_order instead of gdbarch_byte_order.
	* printcmd.c (print_scalar_formatted):
	Use type_byte_order instead of gdbarch_byte_order.
	* solib-darwin.c (darwin_current_sos):
	Use type_byte_order instead of gdbarch_byte_order.
	* solib-svr4.c (solib_svr4_r_ldsomap):
	Use type_byte_order instead of gdbarch_byte_order.
	* stap-probe.c (stap_modify_semaphore):
	Use type_byte_order instead of gdbarch_byte_order.
	* target-float.c (target_float_same_format_p):
	Use type_byte_order instead of gdbarch_byte_order.
	* valarith.c (scalar_binop):
	(value_bit_index):
	Use type_byte_order instead of gdbarch_byte_order.
	* valops.c (value_cast):
	Use type_byte_order instead of gdbarch_byte_order.
	* valprint.c (generic_emit_char):
	(generic_printstr):
	(val_print_string):
	Use type_byte_order instead of gdbarch_byte_order.
	* value.c (unpack_long):
	(unpack_bits_as_long):
	(unpack_value_bitfield):
	(modify_field):
	(pack_long):
	(pack_unsigned_long):
	Use type_byte_order instead of gdbarch_byte_order.
	* findvar.c (unsigned_pointer_to_address):
	(signed_pointer_to_address):
	(unsigned_address_to_pointer):
	(address_to_signed_pointer):
	(default_read_var_value):
	(default_value_from_register):
	Use type_byte_order instead of gdbarch_byte_order.
	* gnu-v3-abi.c (gnuv3_make_method_ptr):
	Use type_byte_order instead of gdbarch_byte_order.
	* riscv-tdep.c (riscv_print_one_register_info):
	Use type_byte_order instead of gdbarch_byte_order.

gdb/testsuite/ChangeLog
2019-11-21  Peeter Joot  <peeter.joot@lzlabs.com>

	* gdb.base/endianity.c: New test.
	* gdb.base/endianity.exp: New file.

Change-Id: I4bd98c1b4508c2d7c5a5dbb15d7b7b1cb4e667e2
2019-11-21 11:48:59 -07:00

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/* Pascal language support routines for GDB, the GNU debugger.
Copyright (C) 2000-2019 Free Software Foundation, Inc.
This file is part of GDB.
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/>. */
/* This file is derived from c-lang.c */
#include "defs.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "expression.h"
#include "parser-defs.h"
#include "language.h"
#include "varobj.h"
#include "p-lang.h"
#include "valprint.h"
#include "value.h"
#include <ctype.h>
#include "c-lang.h"
#include "gdbarch.h"
#include "cli/cli-style.h"
/* All GPC versions until now (2007-09-27) also define a symbol called
'_p_initialize'. Check for the presence of this symbol first. */
static const char GPC_P_INITIALIZE[] = "_p_initialize";
/* The name of the symbol that GPC uses as the name of the main
procedure (since version 20050212). */
static const char GPC_MAIN_PROGRAM_NAME_1[] = "_p__M0_main_program";
/* Older versions of GPC (versions older than 20050212) were using
a different name for the main procedure. */
static const char GPC_MAIN_PROGRAM_NAME_2[] = "pascal_main_program";
/* Function returning the special symbol name used
by GPC for the main procedure in the main program
if it is found in minimal symbol list.
This function tries to find minimal symbols generated by GPC
so that it finds the even if the program was compiled
without debugging information.
According to information supplied by Waldeck Hebisch,
this should work for all versions posterior to June 2000. */
const char *
pascal_main_name (void)
{
struct bound_minimal_symbol msym;
msym = lookup_minimal_symbol (GPC_P_INITIALIZE, NULL, NULL);
/* If '_p_initialize' was not found, the main program is likely not
written in Pascal. */
if (msym.minsym == NULL)
return NULL;
msym = lookup_minimal_symbol (GPC_MAIN_PROGRAM_NAME_1, NULL, NULL);
if (msym.minsym != NULL)
{
return GPC_MAIN_PROGRAM_NAME_1;
}
msym = lookup_minimal_symbol (GPC_MAIN_PROGRAM_NAME_2, NULL, NULL);
if (msym.minsym != NULL)
{
return GPC_MAIN_PROGRAM_NAME_2;
}
/* No known entry procedure found, the main program is probably
not compiled with GPC. */
return NULL;
}
/* Determines if type TYPE is a pascal string type.
Returns a positive value if the type is a known pascal string type.
This function is used by p-valprint.c code to allow better string display.
If it is a pascal string type, then it also sets info needed
to get the length and the data of the string
length_pos, length_size and string_pos are given in bytes.
char_size gives the element size in bytes.
FIXME: if the position or the size of these fields
are not multiple of TARGET_CHAR_BIT then the results are wrong
but this does not happen for Free Pascal nor for GPC. */
int
is_pascal_string_type (struct type *type,int *length_pos,
int *length_size, int *string_pos,
struct type **char_type,
const char **arrayname)
{
if (type != NULL && TYPE_CODE (type) == TYPE_CODE_STRUCT)
{
/* Old Borland type pascal strings from Free Pascal Compiler. */
/* Two fields: length and st. */
if (TYPE_NFIELDS (type) == 2
&& TYPE_FIELD_NAME (type, 0)
&& strcmp (TYPE_FIELD_NAME (type, 0), "length") == 0
&& TYPE_FIELD_NAME (type, 1)
&& strcmp (TYPE_FIELD_NAME (type, 1), "st") == 0)
{
if (length_pos)
*length_pos = TYPE_FIELD_BITPOS (type, 0) / TARGET_CHAR_BIT;
if (length_size)
*length_size = TYPE_LENGTH (TYPE_FIELD_TYPE (type, 0));
if (string_pos)
*string_pos = TYPE_FIELD_BITPOS (type, 1) / TARGET_CHAR_BIT;
if (char_type)
*char_type = TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (type, 1));
if (arrayname)
*arrayname = TYPE_FIELD_NAME (type, 1);
return 2;
};
/* GNU pascal strings. */
/* Three fields: Capacity, length and schema$ or _p_schema. */
if (TYPE_NFIELDS (type) == 3
&& TYPE_FIELD_NAME (type, 0)
&& strcmp (TYPE_FIELD_NAME (type, 0), "Capacity") == 0
&& TYPE_FIELD_NAME (type, 1)
&& strcmp (TYPE_FIELD_NAME (type, 1), "length") == 0)
{
if (length_pos)
*length_pos = TYPE_FIELD_BITPOS (type, 1) / TARGET_CHAR_BIT;
if (length_size)
*length_size = TYPE_LENGTH (TYPE_FIELD_TYPE (type, 1));
if (string_pos)
*string_pos = TYPE_FIELD_BITPOS (type, 2) / TARGET_CHAR_BIT;
/* FIXME: how can I detect wide chars in GPC ?? */
if (char_type)
{
*char_type = TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (type, 2));
if (TYPE_CODE (*char_type) == TYPE_CODE_ARRAY)
*char_type = TYPE_TARGET_TYPE (*char_type);
}
if (arrayname)
*arrayname = TYPE_FIELD_NAME (type, 2);
return 3;
};
}
return 0;
}
/* This is a wrapper around IS_PASCAL_STRING_TYPE that returns true if TYPE
is a string. */
static bool
pascal_is_string_type_p (struct type *type)
{
return is_pascal_string_type (type, nullptr, nullptr, nullptr,
nullptr, nullptr) > 0;
}
static void pascal_one_char (int, struct ui_file *, int *);
/* Print the character C on STREAM as part of the contents of a literal
string.
In_quotes is reset to 0 if a char is written with #4 notation. */
static void
pascal_one_char (int c, struct ui_file *stream, int *in_quotes)
{
if (c == '\'' || ((unsigned int) c <= 0xff && (PRINT_LITERAL_FORM (c))))
{
if (!(*in_quotes))
fputs_filtered ("'", stream);
*in_quotes = 1;
if (c == '\'')
{
fputs_filtered ("''", stream);
}
else
fprintf_filtered (stream, "%c", c);
}
else
{
if (*in_quotes)
fputs_filtered ("'", stream);
*in_quotes = 0;
fprintf_filtered (stream, "#%d", (unsigned int) c);
}
}
static void pascal_emit_char (int c, struct type *type,
struct ui_file *stream, int quoter);
/* Print the character C on STREAM as part of the contents of a literal
string whose delimiter is QUOTER. Note that that format for printing
characters and strings is language specific. */
static void
pascal_emit_char (int c, struct type *type, struct ui_file *stream, int quoter)
{
int in_quotes = 0;
pascal_one_char (c, stream, &in_quotes);
if (in_quotes)
fputs_filtered ("'", stream);
}
void
pascal_printchar (int c, struct type *type, struct ui_file *stream)
{
int in_quotes = 0;
pascal_one_char (c, stream, &in_quotes);
if (in_quotes)
fputs_filtered ("'", stream);
}
/* Print the character string STRING, printing at most LENGTH characters.
Printing stops early if the number hits print_max; repeat counts
are printed as appropriate. Print ellipses at the end if we
had to stop before printing LENGTH characters, or if FORCE_ELLIPSES. */
void
pascal_printstr (struct ui_file *stream, struct type *type,
const gdb_byte *string, unsigned int length,
const char *encoding, int force_ellipses,
const struct value_print_options *options)
{
enum bfd_endian byte_order = type_byte_order (type);
unsigned int i;
unsigned int things_printed = 0;
int in_quotes = 0;
int need_comma = 0;
int width;
/* Preserve TYPE's original type, just set its LENGTH. */
check_typedef (type);
width = TYPE_LENGTH (type);
/* If the string was not truncated due to `set print elements', and
the last byte of it is a null, we don't print that, in traditional C
style. */
if ((!force_ellipses) && length > 0
&& extract_unsigned_integer (string + (length - 1) * width, width,
byte_order) == 0)
length--;
if (length == 0)
{
fputs_filtered ("''", stream);
return;
}
for (i = 0; i < length && things_printed < options->print_max; ++i)
{
/* Position of the character we are examining
to see whether it is repeated. */
unsigned int rep1;
/* Number of repetitions we have detected so far. */
unsigned int reps;
unsigned long int current_char;
QUIT;
if (need_comma)
{
fputs_filtered (", ", stream);
need_comma = 0;
}
current_char = extract_unsigned_integer (string + i * width, width,
byte_order);
rep1 = i + 1;
reps = 1;
while (rep1 < length
&& extract_unsigned_integer (string + rep1 * width, width,
byte_order) == current_char)
{
++rep1;
++reps;
}
if (reps > options->repeat_count_threshold)
{
if (in_quotes)
{
fputs_filtered ("', ", stream);
in_quotes = 0;
}
pascal_printchar (current_char, type, stream);
fprintf_filtered (stream, " %p[<repeats %u times>%p]",
metadata_style.style ().ptr (),
reps, nullptr);
i = rep1 - 1;
things_printed += options->repeat_count_threshold;
need_comma = 1;
}
else
{
if ((!in_quotes) && (PRINT_LITERAL_FORM (current_char)))
{
fputs_filtered ("'", stream);
in_quotes = 1;
}
pascal_one_char (current_char, stream, &in_quotes);
++things_printed;
}
}
/* Terminate the quotes if necessary. */
if (in_quotes)
fputs_filtered ("'", stream);
if (force_ellipses || i < length)
fputs_filtered ("...", stream);
}
/* Table mapping opcodes into strings for printing operators
and precedences of the operators. */
const struct op_print pascal_op_print_tab[] =
{
{",", BINOP_COMMA, PREC_COMMA, 0},
{":=", BINOP_ASSIGN, PREC_ASSIGN, 1},
{"or", BINOP_BITWISE_IOR, PREC_BITWISE_IOR, 0},
{"xor", BINOP_BITWISE_XOR, PREC_BITWISE_XOR, 0},
{"and", BINOP_BITWISE_AND, PREC_BITWISE_AND, 0},
{"=", BINOP_EQUAL, PREC_EQUAL, 0},
{"<>", BINOP_NOTEQUAL, PREC_EQUAL, 0},
{"<=", BINOP_LEQ, PREC_ORDER, 0},
{">=", BINOP_GEQ, PREC_ORDER, 0},
{">", BINOP_GTR, PREC_ORDER, 0},
{"<", BINOP_LESS, PREC_ORDER, 0},
{"shr", BINOP_RSH, PREC_SHIFT, 0},
{"shl", BINOP_LSH, PREC_SHIFT, 0},
{"+", BINOP_ADD, PREC_ADD, 0},
{"-", BINOP_SUB, PREC_ADD, 0},
{"*", BINOP_MUL, PREC_MUL, 0},
{"/", BINOP_DIV, PREC_MUL, 0},
{"div", BINOP_INTDIV, PREC_MUL, 0},
{"mod", BINOP_REM, PREC_MUL, 0},
{"@", BINOP_REPEAT, PREC_REPEAT, 0},
{"-", UNOP_NEG, PREC_PREFIX, 0},
{"not", UNOP_LOGICAL_NOT, PREC_PREFIX, 0},
{"^", UNOP_IND, PREC_SUFFIX, 1},
{"@", UNOP_ADDR, PREC_PREFIX, 0},
{"sizeof", UNOP_SIZEOF, PREC_PREFIX, 0},
{NULL, OP_NULL, PREC_PREFIX, 0}
};
enum pascal_primitive_types {
pascal_primitive_type_int,
pascal_primitive_type_long,
pascal_primitive_type_short,
pascal_primitive_type_char,
pascal_primitive_type_float,
pascal_primitive_type_double,
pascal_primitive_type_void,
pascal_primitive_type_long_long,
pascal_primitive_type_signed_char,
pascal_primitive_type_unsigned_char,
pascal_primitive_type_unsigned_short,
pascal_primitive_type_unsigned_int,
pascal_primitive_type_unsigned_long,
pascal_primitive_type_unsigned_long_long,
pascal_primitive_type_long_double,
pascal_primitive_type_complex,
pascal_primitive_type_double_complex,
nr_pascal_primitive_types
};
static void
pascal_language_arch_info (struct gdbarch *gdbarch,
struct language_arch_info *lai)
{
const struct builtin_type *builtin = builtin_type (gdbarch);
lai->string_char_type = builtin->builtin_char;
lai->primitive_type_vector
= GDBARCH_OBSTACK_CALLOC (gdbarch, nr_pascal_primitive_types + 1,
struct type *);
lai->primitive_type_vector [pascal_primitive_type_int]
= builtin->builtin_int;
lai->primitive_type_vector [pascal_primitive_type_long]
= builtin->builtin_long;
lai->primitive_type_vector [pascal_primitive_type_short]
= builtin->builtin_short;
lai->primitive_type_vector [pascal_primitive_type_char]
= builtin->builtin_char;
lai->primitive_type_vector [pascal_primitive_type_float]
= builtin->builtin_float;
lai->primitive_type_vector [pascal_primitive_type_double]
= builtin->builtin_double;
lai->primitive_type_vector [pascal_primitive_type_void]
= builtin->builtin_void;
lai->primitive_type_vector [pascal_primitive_type_long_long]
= builtin->builtin_long_long;
lai->primitive_type_vector [pascal_primitive_type_signed_char]
= builtin->builtin_signed_char;
lai->primitive_type_vector [pascal_primitive_type_unsigned_char]
= builtin->builtin_unsigned_char;
lai->primitive_type_vector [pascal_primitive_type_unsigned_short]
= builtin->builtin_unsigned_short;
lai->primitive_type_vector [pascal_primitive_type_unsigned_int]
= builtin->builtin_unsigned_int;
lai->primitive_type_vector [pascal_primitive_type_unsigned_long]
= builtin->builtin_unsigned_long;
lai->primitive_type_vector [pascal_primitive_type_unsigned_long_long]
= builtin->builtin_unsigned_long_long;
lai->primitive_type_vector [pascal_primitive_type_long_double]
= builtin->builtin_long_double;
lai->primitive_type_vector [pascal_primitive_type_complex]
= builtin->builtin_complex;
lai->primitive_type_vector [pascal_primitive_type_double_complex]
= builtin->builtin_double_complex;
lai->bool_type_symbol = "boolean";
lai->bool_type_default = builtin->builtin_bool;
}
static const char *p_extensions[] =
{
".pas", ".p", ".pp", NULL
};
extern const struct language_defn pascal_language_defn =
{
"pascal", /* Language name */
"Pascal",
language_pascal,
range_check_on,
case_sensitive_on,
array_row_major,
macro_expansion_no,
p_extensions,
&exp_descriptor_standard,
pascal_parse,
null_post_parser,
pascal_printchar, /* Print a character constant */
pascal_printstr, /* Function to print string constant */
pascal_emit_char, /* Print a single char */
pascal_print_type, /* Print a type using appropriate syntax */
pascal_print_typedef, /* Print a typedef using appropriate syntax */
pascal_val_print, /* Print a value using appropriate syntax */
pascal_value_print, /* Print a top-level value */
default_read_var_value, /* la_read_var_value */
NULL, /* Language specific skip_trampoline */
"this", /* name_of_this */
false, /* la_store_sym_names_in_linkage_form_p */
basic_lookup_symbol_nonlocal, /* lookup_symbol_nonlocal */
basic_lookup_transparent_type,/* lookup_transparent_type */
NULL, /* Language specific symbol demangler */
NULL,
NULL, /* Language specific class_name_from_physname */
pascal_op_print_tab, /* expression operators for printing */
1, /* c-style arrays */
0, /* String lower bound */
default_word_break_characters,
default_collect_symbol_completion_matches,
pascal_language_arch_info,
default_print_array_index,
default_pass_by_reference,
c_watch_location_expression,
NULL, /* la_compare_symbol_for_completion */
iterate_over_symbols,
default_search_name_hash,
&default_varobj_ops,
NULL,
NULL,
pascal_is_string_type_p,
"{...}" /* la_struct_too_deep_ellipsis */
};