[PATCH v2 3/8] Use std::vector for agent_expr::reg_mask

Tom Tromey
2023-06-20T17:37:15Z

agent_expr::reg_mask implements its own packed boolean vector. This
patch replaces it with a std::vector<bool>, simplifying the code.
---
gdb/ax-general.c | 33 +++++++++------------------------
gdb/ax.h | 15 +++++----------
gdb/tracepoint.c | 16 +++++-----------
3 files changed, 19 insertions(+), 45 deletions(-)

diff --git a/gdb/ax-general.c b/gdb/ax-general.c
index d5f4c51e65d..e2a3c31e7f4 100644
--- a/gdb/ax-general.c
+++ b/gdb/ax-general.c
@@ -41,17 +41,12 @@ agent_expr::agent_expr (struct gdbarch *gdbarch, CORE_ADDR scope)
this->gdbarch = gdbarch;
this->scope = scope;

- /* Bit vector for registers used. */
- this->reg_mask_len = 1;
- this->reg_mask = XCNEWVEC (unsigned char, this->reg_mask_len);
-
this->tracing = 0;
this->trace_string = 0;
}

agent_expr::~agent_expr ()
{
- xfree (this->reg_mask);
}

/* Append the low N bytes of VAL as an N-byte integer to the
@@ -330,8 +325,12 @@ ax_print (struct ui_file *f, struct agent_expr *x)

gdb_printf (f, _("Scope: %s\n"), paddress (x->gdbarch, x->scope));
gdb_printf (f, _("Reg mask:"));
- for (i = 0; i < x->reg_mask_len; ++i)
- gdb_printf (f, _(" %02x"), x->reg_mask[i]);
+ for (i = 0; i < x->reg_mask.size (); ++i)
+ {
+ if ((i % 8) == 0)
+ gdb_printf (f, " ");
+ gdb_printf (f, _("%d"), (int) x->reg_mask[i]);
+ }
gdb_printf (f, _("\n"));

/* Check the size of the name array against the number of entries in
@@ -401,28 +400,14 @@ ax_reg_mask (struct agent_expr *ax, int reg)
}
else
{
- int byte;
-
/* Get the remote register number. */
reg = gdbarch_remote_register_number (ax->gdbarch, reg);
- byte = reg / 8;

/* Grow the bit mask if necessary. */
- if (byte >= ax->reg_mask_len)
- {
- /* It's not appropriate to double here. This isn't a
- string buffer. */
- int new_len = byte + 1;
- unsigned char *new_reg_mask
- = XRESIZEVEC (unsigned char, ax->reg_mask, new_len);
-
- memset (new_reg_mask + ax->reg_mask_len, 0,
- (new_len - ax->reg_mask_len) * sizeof (ax->reg_mask[0]));
- ax->reg_mask_len = new_len;
- ax->reg_mask = new_reg_mask;
- }
+ if (reg >= ax->reg_mask.size ())
+ ax->reg_mask.resize (reg);

- ax->reg_mask[byte] |= 1 << (reg % 8);
+ ax->reg_mask[reg] = true;
}
}

diff --git a/gdb/ax.h b/gdb/ax.h
index 608af4c8c68..b0eb20daf75 100644
--- a/gdb/ax.h
+++ b/gdb/ax.h
@@ -110,14 +110,10 @@ struct agent_expr
int max_data_size;

/* Bit vector of registers needed. Register R is needed iff
-
- reg_mask[R / 8] & (1 << (R % 8))
-
- is non-zero. Note! You may not assume that this bitmask is long
- enough to hold bits for all the registers of the machine; the
- agent expression code has no idea how many registers the machine
- has. However, the bitmask is reg_mask_len bytes long, so the
- valid register numbers run from 0 to reg_mask_len * 8 - 1.
+ reg_mask[R] is non-zero. Note! You may not assume that this
+ bitmask is long enough to hold bits for all the registers of
+ the machine; the agent expression code has no idea how many
+ registers the machine has.

Also note that this mask may contain registers that are needed
for the original collection expression to work, but that are
@@ -126,8 +122,7 @@ struct agent_expr
compiler sets the mask bit and skips generating a bytecode whose
result is going to be discarded anyway.
*/
- int reg_mask_len;
- unsigned char *reg_mask;
+ std::vector<bool> reg_mask;

/* For the data tracing facility, we need to insert `trace' bytecodes
before each data fetch; this records all the memory that the
diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index 335df997c05..205380476b3 100644
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -835,19 +835,13 @@ collection_list::add_remote_register (unsigned int regno)
void
collection_list::add_ax_registers (struct agent_expr *aexpr)
{
- if (aexpr->reg_mask_len > 0)
+ for (int ndx1 = 0; ndx1 < aexpr->reg_mask.size (); ndx1++)
{
- for (int ndx1 = 0; ndx1 < aexpr->reg_mask_len; ndx1++)
+ QUIT; /* Allow user to bail out with ^C. */
+ if (aexpr->reg_mask[ndx1])
{
- QUIT; /* Allow user to bail out with ^C. */
- if (aexpr->reg_mask[ndx1] != 0)
- {
- /* Assume chars have 8 bits. */
- for (int ndx2 = 0; ndx2 < 8; ndx2++)
- if (aexpr->reg_mask[ndx1] & (1 << ndx2))
- /* It's used -- record it. */
- add_remote_register (ndx1 * 8 + ndx2);
- }
+ /* It's used -- record it. */
+ add_remote_register (ndx1);
}
}
}

--
2.39.2