Simplify regcache_cpy and remove regcache::cpy_no_passthrough
Commit Message
Nowadays, regcache_cpy is used where src is read-only and dst is not
read-only, so the regcache_cpy can be simplified to handle this case only.
As a result, regcache::cpy_no_passthrough, which is about two read-only
regcache copy, is no longer used, remove it as well.
Regression tested on x86_64-linux, both native and gdbserver.
gdb:
2017-06-27 Yao Qi <yao.qi@linaro.org>
* regcache.c (regcache_cpy): Simplify it.
(regcache::cpy_no_passthrough): Remove it.
* regcache.h (cpy_no_passthrough): Remove it.
---
gdb/regcache.c | 31 ++-----------------------------
gdb/regcache.h | 2 --
2 files changed, 2 insertions(+), 31 deletions(-)
Comments
> On 27 Jun 2017, at 08:37, Yao Qi <qiyaoltc@gmail.com> wrote:
>
> Nowadays, regcache_cpy is used where src is read-only and dst is not
> read-only, so the regcache_cpy can be simplified to handle this case only.
> As a result, regcache::cpy_no_passthrough, which is about two read-only
> regcache copy, is no longer used, remove it as well.
>
I like the simplification.
But, I don’t think it’s clear that regcache_cpy now only handles the single case
of read-only src with !read-only dest. It only becomes clear after reading the
gdb_asserts.
Would it be better to remove regcache_cpy completely?
There are only three places that use it, and they would call (for example)
get_current_regcache ()->restore (scratch) instead.
That would make the caller code clearer, and would remove an outside the class
regcache_ function.
If not, then there should be a comment above regcache_cpy stating the
restrictions.
> Regression tested on x86_64-linux, both native and gdbserver.
>
> gdb:
>
> 2017-06-27 Yao Qi <yao.qi@linaro.org>
>
> * regcache.c (regcache_cpy): Simplify it.
> (regcache::cpy_no_passthrough): Remove it.
> * regcache.h (cpy_no_passthrough): Remove it.
> ---
> gdb/regcache.c | 31 ++-----------------------------
> gdb/regcache.h | 2 --
> 2 files changed, 2 insertions(+), 31 deletions(-)
>
> diff --git a/gdb/regcache.c b/gdb/regcache.c
> index 7eeb737..e8f92d6 100644
> --- a/gdb/regcache.c
> +++ b/gdb/regcache.c
> @@ -388,36 +388,9 @@ regcache_cpy (struct regcache *dst, struct regcache *src)
> gdb_assert (src != NULL && dst != NULL);
> gdb_assert (src->m_descr->gdbarch == dst->m_descr->gdbarch);
> gdb_assert (src != dst);
> - gdb_assert (src->m_readonly_p || dst->m_readonly_p);
> + gdb_assert (src->m_readonly_p && !dst->m_readonly_p);
>
> - if (!src->m_readonly_p)
> - regcache_save (dst, do_cooked_read, src);
> - else if (!dst->m_readonly_p)
> - dst->restore (src);
> - else
> - dst->cpy_no_passthrough (src);
> -}
> -
> -/* Copy/duplicate the contents of a register cache. Unlike regcache_cpy,
> - which is pass-through, this does not go through to the target.
> - Only values values already in the cache are transferred. The SRC and DST
> - buffers must not overlap. */
> -
> -void
> -regcache::cpy_no_passthrough (struct regcache *src)
> -{
> - gdb_assert (src != NULL);
> - gdb_assert (src->m_descr->gdbarch == m_descr->gdbarch);
> - /* NOTE: cagney/2002-05-17: Don't let the caller do a no-passthrough
> - move of data into a thread's regcache. Doing this would be silly
> - - it would mean that regcache->register_status would be
> - completely invalid. */
> - gdb_assert (m_readonly_p && src->m_readonly_p);
> -
> - memcpy (m_registers, src->m_registers,
> - m_descr->sizeof_cooked_registers);
> - memcpy (m_register_status, src->m_register_status,
> - m_descr->sizeof_cooked_register_status);
> + dst->restore (src);
> }
>
> struct regcache *
> diff --git a/gdb/regcache.h b/gdb/regcache.h
> index b416d5e..03c042a 100644
> --- a/gdb/regcache.h
> +++ b/gdb/regcache.h
> @@ -369,8 +369,6 @@ private:
>
> void restore (struct regcache *src);
>
> - void cpy_no_passthrough (struct regcache *src);
> -
> enum register_status xfer_part (int regnum, int offset, int len, void *in,
> const void *out,
> decltype (regcache_raw_read) read,
> --
> 1.9.1
>
Alan.
@@ -388,36 +388,9 @@ regcache_cpy (struct regcache *dst, struct regcache *src)
gdb_assert (src != NULL && dst != NULL);
gdb_assert (src->m_descr->gdbarch == dst->m_descr->gdbarch);
gdb_assert (src != dst);
- gdb_assert (src->m_readonly_p || dst->m_readonly_p);
+ gdb_assert (src->m_readonly_p && !dst->m_readonly_p);
- if (!src->m_readonly_p)
- regcache_save (dst, do_cooked_read, src);
- else if (!dst->m_readonly_p)
- dst->restore (src);
- else
- dst->cpy_no_passthrough (src);
-}
-
-/* Copy/duplicate the contents of a register cache. Unlike regcache_cpy,
- which is pass-through, this does not go through to the target.
- Only values values already in the cache are transferred. The SRC and DST
- buffers must not overlap. */
-
-void
-regcache::cpy_no_passthrough (struct regcache *src)
-{
- gdb_assert (src != NULL);
- gdb_assert (src->m_descr->gdbarch == m_descr->gdbarch);
- /* NOTE: cagney/2002-05-17: Don't let the caller do a no-passthrough
- move of data into a thread's regcache. Doing this would be silly
- - it would mean that regcache->register_status would be
- completely invalid. */
- gdb_assert (m_readonly_p && src->m_readonly_p);
-
- memcpy (m_registers, src->m_registers,
- m_descr->sizeof_cooked_registers);
- memcpy (m_register_status, src->m_register_status,
- m_descr->sizeof_cooked_register_status);
+ dst->restore (src);
}
struct regcache *
@@ -369,8 +369,6 @@ private:
void restore (struct regcache *src);
- void cpy_no_passthrough (struct regcache *src);
-
enum register_status xfer_part (int regnum, int offset, int len, void *in,
const void *out,
decltype (regcache_raw_read) read,