Re: [PATCH v2 2/8] Use tdesc_reg in gxdbserver tdesc

Philipp Rudo
2018-01-25T13:12:20Z

On Wed, 24 Jan 2018 09:27:21 +0000
Alan Hayward <Alan.Hayward@arm.com> wrote:

> This patch commonises tdesc_reg and makes use of it in gdbserver tdesc.
>
> tdesc_create_reg is changed to create a tdesc_reg and place it in
> tdesc_feature.
>
> After registers have been parsed, init_target_desc is called. I
> have expanded this function so that it now populates the reg_defs
> directly from the tdesc_reg registers.
>
> The long term goal is to change the other files within gdbserver to
> access member functions instead of reg_defs directly. reg_defs can
> then be removed. This is out of the scope of this patch series.
>
> I wanted to make tdesc_create_reg common, but I cannot do that until
> the next patch.
>
> I also had to commonise tdesc_element_visitor and tdesc_element.
>
> The gdbserver makefile change is a little strange. I had to add using
> "..". I think there is a rule that needs changing, but I have no idea
> where it is. Note that this is the first file in arch which is common
> for all builds. I'm also wondering if tdesc.c/h should be in arch/ ?
> Maybe it should be moved to common?

In my opinion arch/ should only hold architecture specific code. So i would
prefer when you move tdesc.c/h to common/.

Philipp

>
> Alan.
>
> 2018-01-24 Alan Hayward <alan.hayward@arm.com>
>
> gdb/
> * Makefile.in: Add arch/tdesc.c
> * arch/tdesc.c: New file.
> * arch/tdesc.h (tdesc_element_visitor): Move to here.
> (tdesc_element): Likewise.
> (tdesc_reg): Likewise.
> (tdesc_reg_up): Likewise.
> * target-descriptions.c: (tdesc_element_visitor): Move from here.
> (tdesc_element): Likewise.
> (tdesc_reg): Likewise.
> (tdesc_reg_up): Likewise.
>
> gdbserver/
> * Makefile.in: Add arch/tdesc.c
> * tdesc.c (init_target_desc): init all reg_defs from register vector.
> (tdesc_create_reg): Create tdesc_reg.
> * tdesc.h (tdesc_feature): Add register vector.
>
>
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 364ea7afc66d00d0be44c4369f3ddc924de7b6aa..05ecf64451de4df3a5593d158404d526a71c0b29 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -911,6 +911,7 @@ COMMON_SFILES = \
> agent.c \
> annotate.c \
> arch-utils.c \
> + arch/tdesc.c \
> auto-load.c \
> auxv.c \
> ax-gdb.c \
> diff --git a/gdb/arch/tdesc.h b/gdb/arch/tdesc.h
> index cc11651dcaa7abe81598b69f509ef34ff0d94dbf..e957822b348182b8cae9809cd21f72974ffe05c5 100644
> --- a/gdb/arch/tdesc.h
> +++ b/gdb/arch/tdesc.h
> @@ -18,6 +18,12 @@
> #ifndef ARCH_TDESC_H
> #define ARCH_TDESC_H 1
>
> +#ifdef GDBSERVER
> +#include "server.h"
> +#else
> +#include "defs.h"
> +#endif
> +
> struct tdesc_feature;
> struct tdesc_type;
> struct tdesc_type_builtin;
> @@ -26,6 +32,99 @@ struct tdesc_type_with_fields;
> struct tdesc_reg;
> struct target_desc;
>
> +/* The interface to visit different elements of target description. */
> +
> +class tdesc_element_visitor
> +{
> +public:
> + virtual void visit_pre (const target_desc *e) = 0;
> + virtual void visit_post (const target_desc *e) = 0;
> +
> + virtual void visit_pre (const tdesc_feature *e) = 0;
> + virtual void visit_post (const tdesc_feature *e) = 0;
> +
> + virtual void visit (const tdesc_type_builtin *e) = 0;
> + virtual void visit (const tdesc_type_vector *e) = 0;
> + virtual void visit (const tdesc_type_with_fields *e) = 0;
> +
> + virtual void visit (const tdesc_reg *e) = 0;
> +};
> +
> +class tdesc_element
> +{
> +public:
> + virtual void accept (tdesc_element_visitor &v) const = 0;
> +};
> +
> +/* An individual register from a target description. */
> +
> +struct tdesc_reg : tdesc_element
> +{
> + tdesc_reg (struct tdesc_feature *feature, const std::string &name_,
> + int regnum, int save_restore_, const char *group_,
> + int bitsize_, const char *type_);
> +
> + virtual ~tdesc_reg () = default;
> +
> + DISABLE_COPY_AND_ASSIGN (tdesc_reg);
> +
> + /* The name of this register. In standard features, it may be
> + recognized by the architecture support code, or it may be purely
> + for the user. */
> + std::string name;
> +
> + /* The register number used by this target to refer to this
> + register. This is used for remote p/P packets and to determine
> + the ordering of registers in the remote g/G packets. */
> + long target_regnum;
> +
> + /* If this flag is set, GDB should save and restore this register
> + around calls to an inferior function. */
> + int save_restore;
> +
> + /* The name of the register group containing this register, or empty
> + if the group should be automatically determined from the
> + register's type. If this is "general", "float", or "vector", the
> + corresponding "info" command should display this register's
> + value. It can be an arbitrary string, but should be limited to
> + alphanumeric characters and internal hyphens. Currently other
> + strings are ignored (treated as empty). */
> + std::string group;
> +
> + /* The size of the register, in bits. */
> + int bitsize;
> +
> + /* The type of the register. This string corresponds to either
> + a named type from the target description or a predefined
> + type from GDB. */
> + std::string type;
> +
> + /* The target-described type corresponding to TYPE, if found. */
> + struct tdesc_type *tdesc_type;
> +
> + void accept (tdesc_element_visitor &v) const override
> + {
> + v.visit (this);
> + }
> +
> + bool operator== (const tdesc_reg &other) const
> + {
> + return (name == other.name
> + && target_regnum == other.target_regnum
> + && save_restore == other.save_restore
> + && bitsize == other.bitsize
> + && group == other.group
> + && type == other.type);
> + }
> +
> + bool operator!= (const tdesc_reg &other) const
> + {
> + return !(*this == other);
> + }
> +};
> +
> +typedef std::unique_ptr<tdesc_reg> tdesc_reg_up;
> +
> /* Allocate a new target_desc. */
> target_desc *allocate_target_description (void);
>
> diff --git a/gdb/arch/tdesc.c b/gdb/arch/tdesc.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..3d84ad8d3fa2e017f4c6f7d137a3be2b58427370
> --- /dev/null
> +++ b/gdb/arch/tdesc.c
> @@ -0,0 +1,40 @@
> +/* Target description support for GDB.
> +
> + 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/>. */
> +
> +#ifdef GDBSERVER
> +#include "server.h"
> +#else
> +#include "defs.h"
> +#endif
> +
> +#include "tdesc.h"
> +
> +tdesc_reg::tdesc_reg (struct tdesc_feature *feature, const std::string &name_,
> + int regnum, int save_restore_, const char *group_,
> + int bitsize_, const char *type_)
> + : name (name_), target_regnum (regnum),
> + save_restore (save_restore_),
> + group (group_ != NULL ? group_ : ""),
> + bitsize (bitsize_),
> + type (type_ != NULL ? type_ : "<unknown>")
> +{
> + /* If the register's type is target-defined, look it up now. We may not
> + have easy access to the containing feature when we want it later. */
> + tdesc_type = tdesc_named_type (feature, type.c_str ());
> +}
> diff --git a/gdb/gdbserver/Makefile.in b/gdb/gdbserver/Makefile.in
> index 3ce086d70f23df445b174c49c489ec8415d7614a..8ae124875dd08f31e8424b18281cb1454ed40edb 100644
> --- a/gdb/gdbserver/Makefile.in
> +++ b/gdb/gdbserver/Makefile.in
> @@ -194,6 +194,7 @@ SFILES = \
> $(srcdir)/arch/arm.c \
> $(srcdir)/arch/arm-get-next-pcs.c \
> $(srcdir)/arch/arm-linux.c \
> + $(srcdir)/../arch/tdesc.c \
> $(srcdir)/common/btrace-common.c \
> $(srcdir)/common/buffer.c \
> $(srcdir)/common/cleanups.c \
> @@ -232,6 +233,7 @@ TAGFILES = $(SOURCES) ${HFILES} ${ALLPARAM} ${POSSLIBS}
>
> OBS = \
> agent.o \
> + arch/tdesc.o \
> ax.o \
> btrace-common.o \
> buffer.o \
> @@ -391,6 +393,7 @@ gdbreplay$(EXEEXT): $(GDBREPLAY_OBS) $(LIBGNU) $(LIBIBERTY)
> $(XM_CLIBS) $(LIBGNU) $(LIBIBERTY)
>
> IPA_OBJS = \
> + arch/tdesc-ipa.o \
> ax-ipa.o \
> common-utils-ipa.o \
> errors-ipa.o \
> diff --git a/gdb/gdbserver/tdesc.h b/gdb/gdbserver/tdesc.h
> index 705b968b98af9405682507acbcfb41356da62857..cfc1a194def019ecf899e9184385be94de39d08c 100644
> --- a/gdb/gdbserver/tdesc.h
> +++ b/gdb/gdbserver/tdesc.h
> @@ -25,7 +25,10 @@
> #include <vector>
>
> struct tdesc_feature
> -{};
> +{
> + /* The registers associated with this feature. */
> + std::vector<tdesc_reg_up> registers;
> +};
>
> /* A target description. Inherit from tdesc_feature so that target_desc
> can be used as tdesc_feature. */
> diff --git a/gdb/gdbserver/tdesc.c b/gdb/gdbserver/tdesc.c
> index 359ab97361c07ff2cbc2c8d5ff392c6233c329ff..5dec636baa6b899490e8c700eea21d363fb79fa3 100644
> --- a/gdb/gdbserver/tdesc.c
> +++ b/gdb/gdbserver/tdesc.c
> @@ -72,9 +72,27 @@ init_target_desc (struct target_desc *tdesc)
> {
> int offset = 0;
>
> - for (reg *reg : tdesc->reg_defs)
> + /* Go through all the features and populate reg_defs. */
> + for (const tdesc_reg_up &treg : tdesc->registers)
> {
> + /* Fill in any blank spaces. */
> + while (tdesc->reg_defs.size () < treg->target_regnum)
> + {
> + struct reg *reg = XCNEW (struct reg);
> + reg->name = "";
> + reg->size = 0;
> + reg->offset = offset;
> + tdesc->reg_defs.push_back (reg);
> + }
> +
> + gdb_assert (treg->target_regnum == 0
> + || treg->target_regnum == tdesc->reg_defs.size ());
> +
> + struct reg *reg = XCNEW (struct reg);
> + reg->name = treg->name.c_str ();
> + reg->size = treg->bitsize;
> reg->offset = offset;
> + tdesc->reg_defs.push_back (reg);
> offset += reg->size;
> }
>
> @@ -241,23 +259,10 @@ tdesc_create_reg (struct tdesc_feature *feature, const char *name,
> {
> struct target_desc *tdesc = (struct target_desc *) feature;
>
> - while (tdesc->reg_defs.size () < regnum)
> - {
> - struct reg *reg = XCNEW (struct reg);
> -
> - reg->name = "";
> - reg->size = 0;
> - tdesc->reg_defs.push_back (reg);
> - }
> -
> - gdb_assert (regnum == 0
> - || regnum == tdesc->reg_defs.size ());
> -
> - struct reg *reg = XCNEW (struct reg);
> + tdesc_reg *reg = new tdesc_reg (feature, name, regnum, save_restore,
> + group, bitsize, type);
>
> - reg->name = name;
> - reg->size = bitsize;
> - tdesc->reg_defs.push_back (reg);
> + tdesc->registers.emplace_back (reg);
> }
>
> /* See arch/tdesc.h. */
> diff --git a/gdb/target-descriptions.c b/gdb/target-descriptions.c
> index 1b20a12d769718e591dea6df8183c2e9ecfac990..881ef78d2e3adde409e8585deb67c96e2f0594ed 100644
> --- a/gdb/target-descriptions.c
> +++ b/gdb/target-descriptions.c
> @@ -38,30 +38,6 @@
> #include "completer.h"
> #include "readline/tilde.h" /* tilde_expand */
>
> -/* The interface to visit different elements of target description. */
> -
> -class tdesc_element_visitor
> -{
> -public:
> - virtual void visit_pre (const target_desc *e) = 0;
> - virtual void visit_post (const target_desc *e) = 0;
> -
> - virtual void visit_pre (const tdesc_feature *e) = 0;
> - virtual void visit_post (const tdesc_feature *e) = 0;
> -
> - virtual void visit (const tdesc_type_builtin *e) = 0;
> - virtual void visit (const tdesc_type_vector *e) = 0;
> - virtual void visit (const tdesc_type_with_fields *e) = 0;
> -
> - virtual void visit (const tdesc_reg *e) = 0;
> -};
> -
> -class tdesc_element
> -{
> -public:
> - virtual void accept (tdesc_element_visitor &v) const = 0;
> -};
> -
> /* Types. */
>
> struct property
> @@ -74,84 +50,6 @@ struct property
> std::string value;
> };
>
> -/* An individual register from a target description. */
> -
> -struct tdesc_reg : tdesc_element
> -{
> - tdesc_reg (struct tdesc_feature *feature, const std::string &name_,
> - int regnum, int save_restore_, const char *group_,
> - int bitsize_, const char *type_)
> - : name (name_), target_regnum (regnum),
> - save_restore (save_restore_),
> - group (group_ != NULL ? group_ : ""),
> - bitsize (bitsize_),
> - type (type_ != NULL ? type_ : "<unknown>")
> - {
> - /* If the register's type is target-defined, look it up now. We may not
> - have easy access to the containing feature when we want it later. */
> - tdesc_type = tdesc_named_type (feature, type.c_str ());
> - }
> -
> - virtual ~tdesc_reg () = default;
> -
> - DISABLE_COPY_AND_ASSIGN (tdesc_reg);
> -
> - /* The name of this register. In standard features, it may be
> - recognized by the architecture support code, or it may be purely
> - for the user. */
> - std::string name;
> -
> - /* The register number used by this target to refer to this
> - register. This is used for remote p/P packets and to determine
> - the ordering of registers in the remote g/G packets. */
> - long target_regnum;
> -
> - /* If this flag is set, GDB should save and restore this register
> - around calls to an inferior function. */
> - int save_restore;
> -
> - /* The name of the register group containing this register, or empty
> - if the group should be automatically determined from the register's
> - type. This is traditionally "general", "float", "vector" but can
> - also be an arbitrary string. If defined the corresponding "info"
> - command should display this register's value. The string should be
> - limited to alphanumeric characters and internal hyphens. */
> - std::string group;
> -
> - /* The size of the register, in bits. */
> - int bitsize;
> -
> - /* The type of the register. This string corresponds to either
> - a named type from the target description or a predefined
> - type from GDB. */
> - std::string type;
> -
> - /* The target-described type corresponding to TYPE, if found. */
> - struct tdesc_type *tdesc_type;
> -
> - void accept (tdesc_element_visitor &v) const override
> - {
> - v.visit (this);
> - }
> -
> - bool operator== (const tdesc_reg &other) const
> - {
> - return (name == other.name
> - && target_regnum == other.target_regnum
> - && save_restore == other.save_restore
> - && bitsize == other.bitsize
> - && group == other.group
> - && type == other.type);
> - }
> -
> - bool operator!= (const tdesc_reg &other) const
> - {
> - return !(*this == other);
> - }
> -};
> -
> -typedef std::unique_ptr<tdesc_reg> tdesc_reg_up;
> -
> /* A named type from a target description. */
>
> struct tdesc_type_field
>