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gdbserver: define and use regcache::reset

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Define a `reset` method for a regcache and use it for code
simplification.  This patch allows further simplification in the next
patch.

The reset method fills the register data with zeroes.  For the use in
get_thread_regcache, this is added behavior, making the patch not a
pure refactoring, and may look like extra overhead.  However, it is
better to avoid having arbitrary values left in the data buffer.
Hence, it is considered a behavioral improvement.

Approved-By: Simon Marchi <simon.marchi@efficios.com>
This commit is contained in:
Tankut Baris Aktemur
2025-01-29 10:50:31 +01:00
parent b5a42cbfd9
commit fe1b4d6dd9
2 changed files with 21 additions and 14 deletions
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31
gdbserver/regcache.cc
View File

@@ -52,8 +52,7 @@ get_thread_regcache (thread_info *thread, bool fetch)
switch_to_thread (thread);
/* Invalidate all registers, to prevent stale left-overs. */
memset (regcache->register_status, REG_UNKNOWN,
regcache->tdesc->reg_defs.size ());
regcache->reset (REG_UNKNOWN);
fetch_inferior_registers (regcache, -1);
regcache->registers_fetched = true;
}
@@ -130,11 +129,10 @@ regcache::regcache (const target_desc *tdesc)
fetches. This way they'll read as zero instead of
garbage. */
this->registers
= (unsigned char *) xcalloc (1, tdesc->registers_size);
= (unsigned char *) xmalloc (tdesc->registers_size);
this->register_status
= (unsigned char *) xmalloc (tdesc->reg_defs.size ());
memset ((void *) this->register_status, REG_UNKNOWN,
tdesc->reg_defs.size ());
reset (REG_UNKNOWN);
}
regcache::~regcache ()
@@ -146,6 +144,19 @@ regcache::~regcache ()
#endif
void
regcache::reset (enum register_status status)
{
/* Zero-initialize the register cache, in case there are registers
the target never fetches. This way they'll read as zero instead
of garbage. */
memset (this->registers, 0, this->tdesc->registers_size);
#ifndef IN_PROCESS_AGENT
if (this->register_status != nullptr)
memset (this->register_status, status, this->tdesc->reg_defs.size ());
#endif
}
void
regcache::copy_from (regcache *src)
{
@@ -360,15 +371,7 @@ supply_regblock (struct regcache *regcache, const void *buf)
#endif
}
else
{
const struct target_desc *tdesc = regcache->tdesc;
memset (regcache->registers, 0, tdesc->registers_size);
#ifndef IN_PROCESS_AGENT
for (int i = 0; i < tdesc->reg_defs.size (); i++)
regcache->set_register_status (i, REG_UNAVAILABLE);
#endif
}
regcache->reset (REG_UNAVAILABLE);
}
#ifndef IN_PROCESS_AGENT

4
gdbserver/regcache.h
View File

@@ -63,6 +63,10 @@ struct regcache : public reg_buffer_common
DISABLE_COPY_AND_ASSIGN (regcache);
/* Clear the register values to all zeros and set the register
statuses to STATUS. */
void reset (enum register_status status);
/* See gdbsupport/common-regcache.h. */
enum register_status get_register_status (int regnum) const override;