Re: [PATCH] Tweak gdb.trace/tfile.c for thumb mode

[Yao Qi <yao at codesourcery dot com>]

On 07/09/2014 10:52 PM, Pedro Alves wrote:
> #if defined(__thumb__) || defined(__thumb2__)
>   /* Although Thumb functions are two-byte aligned, function
>      pointers have the Thumb bit set.  Clear it.  */
>   func_addr &= ~1;
> #endif
> 
> (This bit is widely known as the "Thumb bit", so call it that,
> and remove a few "the"'s that sound odd to me, and say
> "two-byte aligned".)

I often associate "Thumb bit" with the bit in CPSR.  Look into
arm-tdep.c and arm-linux-tdep.c, "Thumb bit" is used for both cases
(LSB of function address and the bit in CPSR).  It shouldn't cause any
confusion.

Patch is updated as you suggested and pushed in.

-- 
Yao (éå)

gdb/testsuite:

2014-07-10  Yao Qi  <yao@codesourcery.com>

	* gdb.trace/tfile.c (write_basic_trace_file)
	[__thumb__||__thumb2__]: Clear the Thumb bit of the function
	address written to trace file.
---
 gdb/testsuite/ChangeLog         |  6 ++++++
 gdb/testsuite/gdb.trace/tfile.c | 11 +++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 19e6232..2278496 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2014-07-10  Yao Qi  <yao@codesourcery.com>
+
+	* gdb.trace/tfile.c (write_basic_trace_file)
+	[__thumb__||__thumb2__]: Clear the Thumb bit of the function
+	address written to trace file.
+
 2014-07-09  Pedro Alves  <palves@redhat.com>
 
 	* gdb.base/attach-wait-input.exp: New file.
diff --git a/gdb/testsuite/gdb.trace/tfile.c b/gdb/testsuite/gdb.trace/tfile.c
index ac65901..bc25b80 100644
--- a/gdb/testsuite/gdb.trace/tfile.c
+++ b/gdb/testsuite/gdb.trace/tfile.c
@@ -91,6 +91,7 @@ write_basic_trace_file (void)
 {
   int fd, int_x;
   short short_x;
+  long func_addr;
 
   fd = start_trace_file (TFILE_DIR "tfile-basic.tf");
 
@@ -109,8 +110,14 @@ write_basic_trace_file (void)
   /* Dump tracepoint definitions, in syntax similar to that used
      for reconnection uploads.  */
   /* FIXME need a portable way to print function address in hex */
-  snprintf (spbuf, sizeof spbuf, "tp T1:%lx:E:0:0\n",
-	    (long) &write_basic_trace_file);
+  func_addr = (long) &write_basic_trace_file;
+#if defined(__thumb__) || defined(__thumb2__)
+  /* Although Thumb functions are two-byte aligned, function
+     pointers have the Thumb bit set.  Clear it.  */
+  func_addr &= ~1;
+#endif
+
+  snprintf (spbuf, sizeof spbuf, "tp T1:%lx:E:0:0\n", func_addr);
   write (fd, spbuf, strlen (spbuf));
   /* (Note that we would only need actions defined if we wanted to
      test tdump.) */
-- 
1.9.0