Re: [PATCH 6/8] const-fy regcache::m_aspace

Yao Qi
2017-11-01T09:43:02Z

Simon Marchi <simon.marchi@ericsson.com> writes:

> I don't really understand what this patch tries to achieve. From the
> description above, I thought you wanted to make the m_aspace field const,
> not the pointed object.
>

I want to achieve both, the field m_aspace is a const, and the pointed
object is const too.

/* The address space of this register cache (for registers where it
makes sense, like PC or SP). */
- struct address_space *m_aspace;
+ const address_space * const m_aspace;

> If constifying the pointed address_space object is really what you meant to
> do, I find having the const_cast more confusing than anything else. I think
> we should constify all the way (removing const_casts, putting more consts
> where needed) or not at all.

OK, const_cast is removed in the updated patch, what do you think?

--
Yao (齐尧)

From 9e7e0560bafbb736a7a7fda79fd99fa37bd4c701 Mon Sep 17 00:00:00 2001
From: Yao Qi <yao.qi@linaro.org>
Date: Mon, 23 Oct 2017 10:42:54 +0100
Subject: [PATCH] const-fy regcache::m_aspace

regcache::m_aspace is a const, never changed during the lifetime of
regcache object. The address_space object is a const object too.

gdb:

2017-10-23 Yao Qi <yao.qi@linaro.org>

* breakpoint.c (insert_single_step_breakpoints): Update.
* frame.c (struct frame_info) <aspace>: Add const.
(frame_save_as_regcache): Add const.
(get_frame_address_space): Return const address_space *.
* frame.h (get_frame_address_space): Update declaration.
* infrun.c (struct step_over_info) <aspace>: Add const.
(set_step_over_info): Make aspace const.
(displaced_step_prepare_throw): Change variable const.
(resume): Likewise.
(proceed): Likewise.
(adjust_pc_after_break): Likewise.
(save_waitstatus): Likewise.
(handle_signal_stop): Likewise.
(keep_going_pass_signal): Likewise.
* jit.c (jit_frame_sniffer): Add const.
* mips-tdep.c (mips_single_step_through_delay): Likewise.
* ppc-linux-tdep.c (ppu2spu_sniffer): Likewise.
* record-full.c (record_full_wait_1): Likewise.
* regcache.c (regcache::regcache): Change parameter to const.
* regcache.h (regcache::regcache): Likewise.
(regcache::aspace): Return const address_space *.
(regcache) <m_aspace>: Add const.

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index ada72e0..98cedb4 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -14572,7 +14572,7 @@ insert_single_step_breakpoints (struct gdbarch *gdbarch)
if (!next_pcs.empty ())
{
struct frame_info *frame = get_current_frame ();
- struct address_space *aspace = get_frame_address_space (frame);
+ const address_space *aspace = get_frame_address_space (frame);

for (CORE_ADDR pc : next_pcs)
insert_single_step_breakpoint (gdbarch, aspace, pc);
diff --git a/gdb/frame.c b/gdb/frame.c
index 5380c7d..e40685f 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -99,7 +99,7 @@ struct frame_info
struct program_space *pspace;

/* The frame's address space. */
- struct address_space *aspace;
+ const address_space *aspace;

/* The frame's low-level unwinder and corresponding cache. The
low-level unwinder is responsible for unwinding register values
@@ -1020,7 +1020,7 @@ do_frame_register_read (void *src, int regnum, gdb_byte *buf)
std::unique_ptr<struct regcache>
frame_save_as_regcache (struct frame_info *this_frame)
{
- struct address_space *aspace = get_frame_address_space (this_frame);
+ const address_space *aspace = get_frame_address_space (this_frame);
std::unique_ptr<struct regcache> regcache
(new struct regcache (get_frame_arch (this_frame), aspace));

@@ -2643,7 +2643,7 @@ frame_unwind_program_space (struct frame_info *this_frame)
return this_frame->pspace;
}

-struct address_space *
+const address_space *
get_frame_address_space (struct frame_info *frame)
{
return frame->aspace;
diff --git a/gdb/frame.h b/gdb/frame.h
index 190ce76..c751002 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -494,8 +494,10 @@ extern struct program_space *get_frame_program_space (struct frame_info *);
/* Unwind THIS frame's program space from the NEXT frame. */
extern struct program_space *frame_unwind_program_space (struct frame_info *);

+class address_space;
+
/* Return the frame's address space. */
-extern struct address_space *get_frame_address_space (struct frame_info *);
+extern const address_space *get_frame_address_space (struct frame_info *);

/* For frames where we can not unwind further, describe why. */

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 0e31dbc..ef5a505 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -1289,7 +1289,7 @@ struct step_over_info
and address of the instruction the breakpoint is set at. We'll
skip inserting all breakpoints here. Valid iff ASPACE is
non-NULL. */
- struct address_space *aspace;
+ const address_space *aspace;
CORE_ADDR address;

/* The instruction being stepped over triggers a nonsteppable
@@ -1332,7 +1332,7 @@ static struct step_over_info step_over_info;
because when we need the info later the thread may be running. */

static void
-set_step_over_info (struct address_space *aspace, CORE_ADDR address,
+set_step_over_info (const address_space *aspace, CORE_ADDR address,
int nonsteppable_watchpoint_p,
int thread)
{
@@ -1760,7 +1760,7 @@ displaced_step_prepare_throw (ptid_t ptid)
struct thread_info *tp = find_thread_ptid (ptid);
struct regcache *regcache = get_thread_regcache (ptid);
struct gdbarch *gdbarch = regcache->arch ();
- struct address_space *aspace = regcache->aspace ();
+ const address_space *aspace = regcache->aspace ();
CORE_ADDR original, copy;
ULONGEST len;
struct displaced_step_closure *closure;
@@ -2388,7 +2388,7 @@ resume (enum gdb_signal sig)
struct gdbarch *gdbarch = regcache->arch ();
struct thread_info *tp = inferior_thread ();
CORE_ADDR pc = regcache_read_pc (regcache);
- struct address_space *aspace = regcache->aspace ();
+ const address_space *aspace = regcache->aspace ();
ptid_t resume_ptid;
/* This represents the user's step vs continue request. When
deciding whether "set scheduler-locking step" applies, it's the
@@ -2983,7 +2983,6 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
struct gdbarch *gdbarch;
struct thread_info *tp;
CORE_ADDR pc;
- struct address_space *aspace;
ptid_t resume_ptid;
struct execution_control_state ecss;
struct execution_control_state *ecs = &ecss;
@@ -3007,7 +3006,8 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)

regcache = get_current_regcache ();
gdbarch = regcache->arch ();
- aspace = regcache->aspace ();
+ const address_space *aspace = regcache->aspace ();
+
pc = regcache_read_pc (regcache);
tp = inferior_thread ();

@@ -4070,7 +4070,6 @@ adjust_pc_after_break (struct thread_info *thread,
{
struct regcache *regcache;
struct gdbarch *gdbarch;
- struct address_space *aspace;
CORE_ADDR breakpoint_pc, decr_pc;

/* If we've hit a breakpoint, we'll normally be stopped with SIGTRAP. If
@@ -4150,7 +4149,7 @@ adjust_pc_after_break (struct thread_info *thread,
if (decr_pc == 0)
return;

- aspace = regcache->aspace ();
+ const address_space *aspace = regcache->aspace ();

/* Find the location where (if we've hit a breakpoint) the
breakpoint would be. */
@@ -4385,7 +4384,6 @@ static void
save_waitstatus (struct thread_info *tp, struct target_waitstatus *ws)
{
struct regcache *regcache;
- struct address_space *aspace;

if (debug_infrun)
{
@@ -4404,7 +4402,7 @@ save_waitstatus (struct thread_info *tp, struct target_waitstatus *ws)
tp->suspend.waitstatus_pending_p = 1;

regcache = get_thread_regcache (tp->ptid);
- aspace = regcache->aspace ();
+ const address_space *aspace = regcache->aspace ();

if (ws->kind == TARGET_WAITKIND_STOPPED
&& ws->value.sig == GDB_SIGNAL_TRAP)
@@ -5776,11 +5774,11 @@ handle_signal_stop (struct execution_control_state *ecs)
if (ecs->event_thread->suspend.stop_signal == GDB_SIGNAL_TRAP)
{
struct regcache *regcache;
- struct address_space *aspace;
CORE_ADDR pc;

regcache = get_thread_regcache (ecs->ptid);
- aspace = regcache->aspace ();
+ const address_space *aspace = regcache->aspace ();
+
pc = regcache_read_pc (regcache);

/* However, before doing so, if this single-step breakpoint was
@@ -5871,7 +5869,7 @@ handle_signal_stop (struct execution_control_state *ecs)
inline function call sites). */
if (ecs->event_thread->control.step_range_end != 1)
{
- struct address_space *aspace =
+ const address_space *aspace =
get_thread_regcache (ecs->ptid)->aspace ();

/* skip_inline_frames is expensive, so we avoid it if we can
diff --git a/gdb/jit.c b/gdb/jit.c
index a2d1f6d..b70f87c 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -1186,7 +1186,6 @@ jit_frame_sniffer (const struct frame_unwind *self,
struct jit_unwind_private *priv_data;
struct gdb_unwind_callbacks callbacks;
struct gdb_reader_funcs *funcs;
- struct address_space *aspace;
struct gdbarch *gdbarch;

callbacks.reg_get = jit_unwind_reg_get_impl;
@@ -1200,7 +1199,8 @@ jit_frame_sniffer (const struct frame_unwind *self,

gdb_assert (!*cache);

- aspace = get_frame_address_space (this_frame);
+ const address_space *aspace = get_frame_address_space (this_frame);
+
gdbarch = get_frame_arch (this_frame);

*cache = XCNEW (struct jit_unwind_private);
diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index 4b19896..20bd5d3 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -6598,7 +6598,6 @@ mips_single_step_through_delay (struct gdbarch *gdbarch,
{
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
CORE_ADDR pc = get_frame_pc (frame);
- struct address_space *aspace;
enum mips_isa isa;
ULONGEST insn;
int status;
@@ -6616,7 +6615,9 @@ mips_single_step_through_delay (struct gdbarch *gdbarch,
/* _has_delay_slot above will have validated the read. */
insn = mips_fetch_instruction (gdbarch, isa, pc, NULL);
size = mips_insn_size (isa, insn);
- aspace = get_frame_address_space (frame);
+
+ const address_space *aspace = get_frame_address_space (frame);
+
return breakpoint_here_p (aspace, pc + size) != no_breakpoint_here;
}

diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index 67d8305..d01cff8 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -1362,7 +1362,7 @@ ppu2spu_sniffer (const struct frame_unwind *self,
struct ppu2spu_cache *cache
= FRAME_OBSTACK_CALLOC (1, struct ppu2spu_cache);

- struct address_space *aspace = get_frame_address_space (this_frame);
+ const address_space *aspace = get_frame_address_space (this_frame);
std::unique_ptr<struct regcache> regcache
(new struct regcache (data.gdbarch, aspace));
regcache_save (regcache.get (), ppu2spu_unwind_register, &data);
diff --git a/gdb/record-full.c b/gdb/record-full.c
index 0488b71..6fc29d6 100644
--- a/gdb/record-full.c
+++ b/gdb/record-full.c
@@ -1098,7 +1098,6 @@ record_full_wait_1 (struct target_ops *ops,
&& status->value.sig == GDB_SIGNAL_TRAP)
{
struct regcache *regcache;
- struct address_space *aspace;
enum target_stop_reason *stop_reason_p
= &record_full_stop_reason;

@@ -1109,7 +1108,7 @@ record_full_wait_1 (struct target_ops *ops,
registers_changed ();
regcache = get_current_regcache ();
tmp_pc = regcache_read_pc (regcache);
- aspace = regcache->aspace ();
+ const struct address_space *aspace = regcache->aspace ();

if (target_stopped_by_watchpoint ())
{
@@ -1172,7 +1171,7 @@ record_full_wait_1 (struct target_ops *ops,
{
struct regcache *regcache = get_current_regcache ();
struct gdbarch *gdbarch = regcache->arch ();
- struct address_space *aspace = regcache->aspace ();
+ const struct address_space *aspace = regcache->aspace ();
int continue_flag = 1;
int first_record_full_end = 1;
struct cleanup *old_cleanups
diff --git a/gdb/regcache.c b/gdb/regcache.c
index 6985dc9..2cffb70 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -181,7 +181,7 @@ regcache_register_size (const struct regcache *regcache, int n)
return register_size (regcache->arch (), n);
}

-regcache::regcache (gdbarch *gdbarch, address_space *aspace_,
+regcache::regcache (gdbarch *gdbarch, const address_space *aspace_,
bool readonly_p_)
: m_aspace (aspace_), m_readonly_p (readonly_p_)
{
diff --git a/gdb/regcache.h b/gdb/regcache.h
index 2360e27..cea76fb 100644
--- a/gdb/regcache.h
+++ b/gdb/regcache.h
@@ -232,7 +232,7 @@ typedef struct cached_reg
class regcache
{
public:
- regcache (gdbarch *gdbarch, address_space *aspace_)
+ regcache (gdbarch *gdbarch, const address_space *aspace_)
: regcache (gdbarch, aspace_, true)
{}

@@ -254,7 +254,7 @@ public:
gdbarch *arch () const;

/* Return REGCACHE's address space. */
- address_space *aspace () const
+ const address_space *aspace () const
{
return m_aspace;
}
@@ -338,7 +338,7 @@ public:

static void regcache_thread_ptid_changed (ptid_t old_ptid, ptid_t new_ptid);
protected:
- regcache (gdbarch *gdbarch, address_space *aspace_, bool readonly_p_);
+ regcache (gdbarch *gdbarch, const address_space *aspace_, bool readonly_p_);

static std::forward_list<regcache *> current_regcache;

@@ -362,7 +362,7 @@ private:

/* The address space of this register cache (for registers where it
makes sense, like PC or SP). */
- struct address_space *m_aspace;
+ const address_space * const m_aspace;

/* The register buffers. A read-only register cache can hold the
full [0 .. gdbarch_num_regs + gdbarch_num_pseudo_regs) while a read/write