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

[Tom Tromey <tom@tromey.com>]

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