RFC: tracepoints: extend range of ax_trace_quick function

[Jim Blandy]

In order to get Linux kernel tracepoints working, I needed to make a
number of fixes in GDB.  This is one such patch; the code which uses
the function's new range comes a bit later.

Okay to commit?

gdb/ChangeLog:
2007-10-24  Jim Blandy  <jimb@codesourcery.com>

	* ax-general.c (ax_trace_quick): Generate trace16 instructions for
	sizes from 256 to 65535.

diff -r 7625042dd5a0 -r eb635294a14e gdb/ax-general.c
--- a/gdb/ax-general.c	Wed Oct 24 10:17:42 2007 -0700
+++ b/gdb/ax-general.c	Wed Oct 24 18:02:15 2007 -0700
@@ -166,17 +166,29 @@ ax_zero_ext (struct agent_expr *x, int n
 }
 
 
-/* Append a trace_quick instruction to EXPR, to record N bytes.  */
+/* Append a trace_quick or trace16 instruction to EXPR, to record N bytes.  */
 void
 ax_trace_quick (struct agent_expr *x, int n)
 {
-  /* N must fit in a byte.  */
-  if (n < 0 || n > 255)
-    error (_("GDB bug: ax-general.c (ax_trace_quick): size out of range for trace_quick"));
-
-  grow_expr (x, 2);
-  x->buf[x->len++] = aop_trace_quick;
-  x->buf[x->len++] = n;
+  if (n < 0)
+    internal_error (__FILE__, __LINE__,
+                    _("ax_trace_quick: negative size"));
+  else if (n < (1 << 8))
+    {
+      grow_expr (x, 2);
+      x->buf[x->len++] = aop_trace_quick;
+      x->buf[x->len++] = n;
+    }
+  else if (n < (1 << 16))
+    {
+      grow_expr (x, 3);
+      x->buf[x->len++] = aop_trace16;
+      x->buf[x->len++] = n >> 8;
+      x->buf[x->len++] = n;
+    }
+  else
+    internal_error (__FILE__, __LINE__,
+                    _("ax_trace_quick: size out of range"));
 }
 
 
diff -r 7625042dd5a0 -r eb635294a14e gdb/ax.h
--- a/gdb/ax.h	Wed Oct 24 10:17:42 2007 -0700
+++ b/gdb/ax.h	Wed Oct 24 18:02:15 2007 -0700
@@ -157,7 +157,8 @@ extern void ax_ext (struct agent_expr *E
 /* Append a zero-extension instruction to EXPR, to extend an N-bit value.  */
 extern void ax_zero_ext (struct agent_expr *EXPR, int N);
 
-/* Append a trace_quick instruction to EXPR, to record N bytes.  */
+/* Append a trace_quick or trace16 instruction to EXPR, to record N bytes.  
+   N must be less than 65536.  */
 extern void ax_trace_quick (struct agent_expr *EXPR, int N);
 
 /* Append a goto op to EXPR.  OP is the actual op (must be aop_goto or