[4/6] Disassembly unit test: disassemble one instruction

  This patch adds one unit test, which disassemble one instruction for
every gdbarch if available.  The test needs one valid instruction of
each gdbarch, and most of them are got from breakpoint instruction.
For the rest gdbarch whose breakpoint instruction isn't a valid
instruction, I copy one instruction from the gas/testsuite/gas/
directory.

I get the valid instruction of most gdbarch except ia64, mep, mips,
tic6x, and xtensa.  People familiar with these arch should be easy
to extend the test.

In order to achieve "do the unit test for every gdbarch", I add
selftest-arch.[c,h], so that we can register a function pointer,
which has one argument gdbarch.  selftest.c will iterate over all
gdbarches to call the registered function pointer.

v2:
 - Add comments for getting breakpoint instructions for score and
   nios2,
 - Provide more contents in gdb_disassembler_test::read_memory if
   caller requests more than one instruction,
 - Stop using compound literal,
 - Use null_stream,
 - Split "selftest for each gdbarch" out of selftest.{c,h},

gdb:

2017-01-13  Yao Qi  <yao.qi@linaro.org>

	* Makefile.in (SFILES): Add disasm-selftests.c and
	selftest-arch.c.
	(COMMON_OBS): Add disasm-selftests.o and selftest-arch.o.
	* disasm-selftests.c: New file.
	* selftest-arch.c: New file.
	* selftest-arch.h: New file.
---
 gdb/Makefile.in        |   5 ++
 gdb/disasm-selftests.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/selftest-arch.c    | 103 ++++++++++++++++++++++++++++
 gdb/selftest-arch.h    |  26 ++++++++
 4 files changed, 312 insertions(+)
 create mode 100644 gdb/disasm-selftests.c
 create mode 100644 gdb/selftest-arch.c
 create mode 100644 gdb/selftest-arch.h
  

On 01/16/2017 04:02 AM, Yao Qi wrote:
> This patch adds one unit test, which disassemble one instruction for
> every gdbarch if available.  The test needs one valid instruction of
> each gdbarch, and most of them are got from breakpoint instruction.
> For the rest gdbarch whose breakpoint instruction isn't a valid
> instruction, I copy one instruction from the gas/testsuite/gas/
> directory.
>
> I get the valid instruction of most gdbarch except ia64, mep, mips,
> tic6x, and xtensa.  People familiar with these arch should be easy
> to extend the test.
>
> In order to achieve "do the unit test for every gdbarch", I add
> selftest-arch.[c,h], so that we can register a function pointer,
> which has one argument gdbarch.  selftest.c will iterate over all
> gdbarches to call the registered function pointer.
>
> v2:
>  - Add comments for getting breakpoint instructions for score and
>    nios2,
>  - Provide more contents in gdb_disassembler_test::read_memory if
>    caller requests more than one instruction,
>  - Stop using compound literal,
>  - Use null_stream,
>  - Split "selftest for each gdbarch" out of selftest.{c,h},
>
> gdb:
>
> 2017-01-13  Yao Qi  <yao.qi@linaro.org>
>
> 	* Makefile.in (SFILES): Add disasm-selftests.c and
> 	selftest-arch.c.
> 	(COMMON_OBS): Add disasm-selftests.o and selftest-arch.o.
> 	* disasm-selftests.c: New file.
> 	* selftest-arch.c: New file.
> 	* selftest-arch.h: New file.
> ---
>  gdb/Makefile.in        |   5 ++
>  gdb/disasm-selftests.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++
>  gdb/selftest-arch.c    | 103 ++++++++++++++++++++++++++++
>  gdb/selftest-arch.h    |  26 ++++++++
>  4 files changed, 312 insertions(+)
>  create mode 100644 gdb/disasm-selftests.c
>  create mode 100644 gdb/selftest-arch.c
>  create mode 100644 gdb/selftest-arch.h
>
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 3ce7d69..e0fe442 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -1039,6 +1039,7 @@ SFILES = \
>  	dfp.c \
>  	dictionary.c \
>  	disasm.c \
> +	disasm-selftests.c \
>  	doublest.c \
>  	dtrace-probe.c \
>  	dummy-frame.c \
> @@ -1140,6 +1141,7 @@ SFILES = \
>  	rust-exp.y \
>  	rust-lang.c \
>  	selftest.c \
> +	selftest-arch.c \
>  	sentinel-frame.c \
>  	ser-base.c \
>  	ser-event.c \
> @@ -1396,6 +1398,7 @@ HFILES_NO_SRCDIR = \
>  	rs6000-tdep.h \
>  	s390-linux-tdep.h \
>  	score-tdep.h \
> +	selftest-arch.h \
>  	sentinel-frame.h \
>  	ser-base.h \
>  	ser-event.h \
> @@ -1643,6 +1646,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
>  	dfp.o \
>  	dictionary.o \
>  	disasm.o \
> +	disasm-selftests.o \
>  	doublest.o \
>  	dummy-frame.o \
>  	dwarf2-frame.o \
> @@ -1744,6 +1748,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
>  	run-time-clock.o \
>  	rust-lang.o \
>  	selftest.o \
> +	selftest-arch.o \
>  	sentinel-frame.o \
>  	ser-event.o \
>  	serial.o \
> diff --git a/gdb/disasm-selftests.c b/gdb/disasm-selftests.c
> new file mode 100644
> index 0000000..46a0a21
> --- /dev/null
> +++ b/gdb/disasm-selftests.c
> @@ -0,0 +1,178 @@
> +/* Self tests for disassembler for GDB, the GNU debugger.
> +
> +   Copyright (C) 2017 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/>.  */
> +
> +#include "defs.h"
> +#include "disasm.h"
> +
> +#if GDB_SELF_TEST
> +#include "selftest.h"
> +#include "selftest-arch.h"
> +
> +namespace selftests {
> +
> +/* Test disassembly of one instruction.  */
> +
> +static void
> +gdb_disassembler_print_one_insn_test (struct gdbarch *gdbarch)

One suggestion. Do you think it is worth repeating the context of the 
test in the function names? We already know this is a gdb disassembler 
selftest from the name of the source file.

If we don't think it is worth it, we could significantly reduce the 
length of the name of these functions.

> +{
> +  size_t len = 0;
> +  const gdb_byte *insn = NULL;
> +
> +  switch (gdbarch_bfd_arch_info (gdbarch)->arch)
> +    {
> +    case bfd_arch_bfin:
> +      /* M3.L = 0xe117 */
> +      static const gdb_byte bfin_insn[] = {0x17, 0xe1, 0xff, 0xff};
> +
> +      insn = bfin_insn;
> +      len = sizeof (bfin_insn);
> +      break;
> +    case bfd_arch_arm:
> +      /* mov     r0, #0 */
> +      static const gdb_byte arm_insn[] = {0x0, 0x0, 0xa0, 0xe3};
> +
> +      insn = arm_insn;
> +      len = sizeof (arm_insn);
> +      break;
> +    case bfd_arch_ia64:
> +    case bfd_arch_mep:
> +    case bfd_arch_mips:
> +    case bfd_arch_tic6x:
> +    case bfd_arch_xtensa:
> +      return;
> +    case bfd_arch_s390:
> +      /* nopr %r7 */
> +      static const gdb_byte s390_insn[] = {0x07, 0x07};
> +
> +      insn = s390_insn;
> +      len = sizeof (s390_insn);
> +      break;
> +    case bfd_arch_xstormy16:
> +      /* nop */
> +      static const gdb_byte xstormy16_insn[] = {0x0, 0x0};
> +
> +      insn = xstormy16_insn;
> +      len = sizeof (xstormy16_insn);
> +      break;
> +    case bfd_arch_arc:
> +      {
> +	/* PR 21003 */
> +	if (gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_arc_arc601)
> +	  return;
> +      }
> +    case bfd_arch_nios2:
> +    case bfd_arch_score:
> +      /* nios2 and score need to know the current instruction to select
> +	 breakpoint instruction.  Give the breakpoint instruction kind
> +	 explicitly.  */
> +      insn = gdbarch_sw_breakpoint_from_kind (gdbarch, 4, (int *) &len);
> +      break;
> +    default:
> +      {
> +	/* Test disassemble breakpoint instruction.  */
> +	CORE_ADDR pc = 0;
> +	int kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
> +
> +	insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind,
> +						(int *) &len);
> +
> +	break;
> +      }
> +    }
> +  SELF_CHECK (len > 0);
> +
> +  /* Test gdb_disassembler for a given gdbarch by reading data from a
> +     pre-allocated buffer.  If you want to see the disassembled
> +     instruction printed to gdb_stdout, set DISASSEMBLER_TEST_VERBOSE
> +     to true.  */
> +
> +  class gdb_disassembler_test : public gdb_disassembler
> +  {
> +  public:
> +
> +    const bool DISASSEMBLER_TEST_VERBOSE = false;
> +
> +    explicit gdb_disassembler_test (struct gdbarch *gdbarch,
> +				    const gdb_byte *insn,
> +				    size_t len)
> +      : gdb_disassembler (gdbarch,
> +			  (DISASSEMBLER_TEST_VERBOSE
> +			   ? gdb_stdout : null_stream ()),
> +			  gdb_disassembler_test::read_memory),
> +	m_insn (insn), m_len (len)
> +    {
> +    }
> +
> +    int

Can this ever return negative? If not, then unsigned? This ties down 
with the comment on the other patch.

> +    print_insn (CORE_ADDR memaddr)
> +    {
> +      if (DISASSEMBLER_TEST_VERBOSE)
> +	{
> +	  fprintf_unfiltered (stream (), "%s ",
> +			      gdbarch_bfd_arch_info (arch ())->arch_name);
> +	}
> +
> +      int len = gdb_disassembler::print_insn (memaddr);
> +
> +      if (DISASSEMBLER_TEST_VERBOSE)
> +	fprintf_unfiltered (stream (), "\n");
> +
> +      return len;
> +    }
> +
> +  private:
> +    /* A buffer contain one instruction.  */

"A buffer containing..." or "A buffer contains ..."

> +    const gdb_byte *m_insn;
> +
> +    /* Length of the buffer.  */
> +    size_t m_len;
> +
> +    static int read_memory (bfd_vma memaddr, gdb_byte *myaddr,
> +			    unsigned int len, struct disassemble_info *info)
> +    {
> +      gdb_disassembler_test *self
> +	= static_cast<gdb_disassembler_test *>(info->application_data);
> +
> +      /* The disassembler in opcodes may read more data than one
> +	 instruction.  */
> +      for (unsigned int i = 0; i < len; i++)
> +	myaddr[i] = self->m_insn[(memaddr + i) % self->m_len];
> +
> +      return 0;
> +    }
> +  };
> +
> +  gdb_disassembler_test di (gdbarch, insn, len);
> +
> +  SELF_CHECK (di.print_insn (0) == len);
> +}
> +
> +} // namespace selftests
> +#endif /* GDB_SELF_TEST */
> +
> +/* Suppress warning from -Wmissing-prototypes.  */
> +extern initialize_file_ftype _initialize_disasm_test;
> +
> +void
> +_initialize_disasm_test (void)
> +{
> +#if GDB_SELF_TEST
> +  register_self_test (selftests::gdb_disassembler_print_one_insn_test);
> +#endif
> +}
> diff --git a/gdb/selftest-arch.c b/gdb/selftest-arch.c
> new file mode 100644
> index 0000000..aa716be
> --- /dev/null
> +++ b/gdb/selftest-arch.c
> @@ -0,0 +1,103 @@
> +/* GDB self-test for each gdbarch.
> +   Copyright (C) 2017 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/>.  */
> +
> +#include "defs.h"
> +
> +#if GDB_SELF_TEST
> +#include "selftest.h"
> +#include "selftest-arch.h"
> +#include "arch-utils.h"
> +
> +static std::vector<self_test_function_with_gdbarch *> gdbarch_tests;
> +
> +void
> +register_self_test (self_test_function_with_gdbarch *function)
> +{
> +  gdbarch_tests.push_back (function);
> +}
> +
> +namespace selftests {
> +
> +static void
> +tests_with_arch (void)
> +{
> +  int failed = 0;
> +
> +  for (const auto &f : gdbarch_tests)
> +    {
> +      const char **arches = gdbarch_printable_names ();
> +      int i;
> +
> +      for (i = 0; arches[i] != NULL; i++)
> +	{
> +	  if (strcmp ("fr300", arches[i]) == 0)
> +	    {
> +	      /* PR 20946 */
> +	      continue;
> +	    }
> +	  else if (strcmp ("powerpc:EC603e", arches[i]) == 0
> +		   || strcmp ("powerpc:e500mc", arches[i]) == 0
> +		   || strcmp ("powerpc:e500mc64", arches[i]) == 0
> +		   || strcmp ("powerpc:titan", arches[i]) == 0
> +		   || strcmp ("powerpc:vle", arches[i]) == 0
> +		   || strcmp ("powerpc:e5500", arches[i]) == 0
> +		   || strcmp ("powerpc:e6500", arches[i]) == 0)
> +	    {
> +	      /* PR 19797 */
> +	      continue;
> +	    }
> +
> +	  QUIT;
> +
> +	  TRY
> +	    {
> +	      struct gdbarch_info info;
> +
> +	      gdbarch_info_init (&info);
> +	      info.bfd_arch_info = bfd_scan_arch (arches[i]);
> +
> +	      struct gdbarch *gdbarch = gdbarch_find_by_info (info);
> +	      SELF_CHECK (gdbarch != NULL);
> +	      f (gdbarch);
> +	    }
> +	  CATCH (ex, RETURN_MASK_ERROR)
> +	    {
> +	      ++failed;
> +	      exception_fprintf (gdb_stderr, ex,
> +				 _("Self test failed: arch %s: "), arches[i]);
> +	    }
> +	  END_CATCH
> +	}
> +    }
> +
> +  SELF_CHECK (failed == 0);
> +}
> +
> +} // namespace selftests
> +#endif /* GDB_SELF_TEST */
> +
> +/* Suppress warning from -Wmissing-prototypes.  */
> +extern initialize_file_ftype _initialize_selftests_with_arch;
> +
> +void
> +_initialize_selftests_with_arch (void)
> +{
> +#if GDB_SELF_TEST
> +  register_self_test (selftests::tests_with_arch);
> +#endif
> +}
> diff --git a/gdb/selftest-arch.h b/gdb/selftest-arch.h
> new file mode 100644
> index 0000000..d63c2d2
> --- /dev/null
> +++ b/gdb/selftest-arch.h
> @@ -0,0 +1,26 @@
> +/* GDB self-test for each gdbarch.
> +   Copyright (C) 2017 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/>.  */
> +
> +#ifndef SELFTEST_ARCH_H
> +#define SELFTEST_ARCH_H
> +
> +typedef void self_test_function_with_gdbarch (struct gdbarch *);
> +
> +extern void register_self_test (self_test_function_with_gdbarch *function);
> +
> +#endif /* SELFTEST_ARCH_H */
>

Otherwise looks OK
  

On 01/16/2017 10:02 AM, Yao Qi wrote:

> +static void
> +gdb_disassembler_print_one_insn_test (struct gdbarch *gdbarch)
> +{
> +  size_t len = 0;
> +  const gdb_byte *insn = NULL;
> +

> +      insn = gdbarch_sw_breakpoint_from_kind (gdbarch, 4, (int *) &len);

That "(int *) &len" is invalid code.  It's an aliasing violation.
And even if that weren't a problem, consider what happens when
sizeof size_t != sizeof int, on big endian and little endian.

Use a temporary variable of the right type, like e.g.:

      int bplen;
      insn = gdbarch_sw_breakpoint_from_kind (gdbarch, 4, &bplen);
      len = bplen;

> +      break;
> +    default:
> +      {
> +	/* Test disassemble breakpoint instruction.  */
> +	CORE_ADDR pc = 0;
> +	int kind = gdbarch_breakpoint_kind_from_pc (gdbarch, &pc);
> +
> +	insn = gdbarch_sw_breakpoint_from_kind (gdbarch, kind,
> +						(int *) &len);

Ditto.


> +      len = sizeof (xstormy16_insn);
> +      break;
> +    case bfd_arch_arc:
> +      {
> +	/* PR 21003 */
> +	if (gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_arc_arc601)
> +	  return;
> +      }

Odd that this case got braces when it doesn't declare any variable,
and when other cases don't.  Also, is the fallthrough intended?
If so, add a comment otherwise we may get a warning with GCC 7.

> +    case bfd_arch_nios2:
> +    case bfd_arch_score:
> +      /* nios2 and score need to know the current instruction to select
> +	 breakpoint instruction.  Give the breakpoint instruction kind
> +	 explicitly.  */
> +      insn = gdbarch_sw_breakpoint_from_kind (gdbarch, 4, (int *) &len);
> +      break;
> +    default:


> +
> +	break;
> +      }
> +    }
> +  SELF_CHECK (len > 0);
> +
> +  /* Test gdb_disassembler for a given gdbarch by reading data from a
> +     pre-allocated buffer.  If you want to see the disassembled
> +     instruction printed to gdb_stdout, set DISASSEMBLER_TEST_VERBOSE
> +     to true.  */
> +
> +  class gdb_disassembler_test : public gdb_disassembler
> +  {
> +  public:
> +
> +    const bool DISASSEMBLER_TEST_VERBOSE = false;

static.  We give macros long unique names in order to
avoid naming conflicts, but if this is no longer a macro,
the name could be shortened, to e.g., just:

 static const bool verbose = false;

> +
> +    explicit gdb_disassembler_test (struct gdbarch *gdbarch,
> +				    const gdb_byte *insn,
> +				    size_t len)
> +      : gdb_disassembler (gdbarch,
> +			  (DISASSEMBLER_TEST_VERBOSE
> +			   ? gdb_stdout : null_stream ()),
> +			  gdb_disassembler_test::read_memory),
> +	m_insn (insn), m_len (len)
> +    {
> +    }
> +
> +    int
> +    print_insn (CORE_ADDR memaddr)
> +    {
> +      if (DISASSEMBLER_TEST_VERBOSE)
> +	{
> +	  fprintf_unfiltered (stream (), "%s ",
> +			      gdbarch_bfd_arch_info (arch ())->arch_name);
> +	}
> +
> +      int len = gdb_disassembler::print_insn (memaddr);
> +
> +      if (DISASSEMBLER_TEST_VERBOSE)
> +	fprintf_unfiltered (stream (), "\n");
> +
> +      return len;
> +    }
> +
> +  private:
> +    /* A buffer contain one instruction.  */
> +    const gdb_byte *m_insn;
> +
> +    /* Length of the buffer.  */
> +    size_t m_len;
> +
> +    static int read_memory (bfd_vma memaddr, gdb_byte *myaddr,
> +			    unsigned int len, struct disassemble_info *info)
> +    {
> +      gdb_disassembler_test *self
> +	= static_cast<gdb_disassembler_test *>(info->application_data);
> +
> +      /* The disassembler in opcodes may read more data than one
> +	 instruction.  */

I suggest:

      /* The opcodes disassembler may read more data than one
         instruction.  Supply infinite consecutive copies
         of the same instruction.

> +      for (unsigned int i = 0; i < len; i++)

size_t.

> +	myaddr[i] = self->m_insn[(memaddr + i) % self->m_len];

Clever.  :-)

> +
> +      return 0;
> +    }
> +  };
> +
> +  gdb_disassembler_test di (gdbarch, insn, len);
> +
> +  SELF_CHECK (di.print_insn (0) == len);
> +}
> +
> +} // namespace selftests
> +#endif /* GDB_SELF_TEST */
> +
> +/* Suppress warning from -Wmissing-prototypes.  */
> +extern initialize_file_ftype _initialize_disasm_test;
> +
> +void
> +_initialize_disasm_test (void)

The standard is to name the _initialize_foo function after
the file/module name:

 _initialize_disasm_selftests

> +
> +static void
> +tests_with_arch (void)

We longer need the "void" in C++.

> +{
> +  int failed = 0;
> +
> +  for (const auto &f : gdbarch_tests)
> +    {
> +      const char **arches = gdbarch_printable_names ();
> +      int i;
> +
> +      for (i = 0; arches[i] != NULL; i++)

Can be "for (int i ..." now.


> +/* Suppress warning from -Wmissing-prototypes.  */
> +extern initialize_file_ftype _initialize_selftests_with_arch;
> +
> +void
> +_initialize_selftests_with_arch (void)

Likewise (naming / void).

> +#ifndef SELFTEST_ARCH_H
> +#define SELFTEST_ARCH_H
> +
> +typedef void self_test_function_with_gdbarch (struct gdbarch *);
> +
> +extern void register_self_test (self_test_function_with_gdbarch *function);

IMO, overloading the "register_self_test" function is confusing.
This function and the register_self_test() function in selftest.c
are semantically different, not two ways to do the same
thing (like e.g. const char * vs std::string).

If nothing else, it makes it a bit harder to grep for / find
arch self tests (only) in the future.

I'd prefer calling this something else that indicates more clearly
what the selftest being registered is about.  That's why I had
suggested before the distinct:

  register_arch_self_test

Perhaps better would be:

  register_self_test_foreach_arch

And then self_test_function_with_gdbarch -> self_test_foreach_arch_function.

WDYT?

Thanks,
Pedro Alves
  

On 17-01-20 00:03:48, Pedro Alves wrote:
> > +  /* Test gdb_disassembler for a given gdbarch by reading data from a
> > +     pre-allocated buffer.  If you want to see the disassembled
> > +     instruction printed to gdb_stdout, set DISASSEMBLER_TEST_VERBOSE
> > +     to true.  */
> > +
> > +  class gdb_disassembler_test : public gdb_disassembler
> > +  {
> > +  public:
> > +
> > +    const bool DISASSEMBLER_TEST_VERBOSE = false;
> 
> static.  We give macros long unique names in order to
> avoid naming conflicts, but if this is no longer a macro,
> the name could be shortened, to e.g., just:
> 
>  static const bool verbose = false;
> 

gdb_disassembler_test is a local class, so it can't have a static data
member.

I'll update patch to address your other comments.