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Re: [PATCH] gdb.trace: Fix string collection for 64-bit platforms.


On 21/01/16 17:14, Pedro Alves wrote:
On 01/21/2016 04:02 PM, Marcin KoÅcielnicki wrote:
String collection always used ref32 to fetch the string pointer.  Make it
use ref64 when pointeer size is 64-bit.

"pointer".


This appeared to work on x86_64 since it's a little-endian platform, and
malloc (used in gdb.trace/collection.exp) returns addresses in low 4GB.
Noticed and tested on s390x-ibm-linux-gnu, also tested on
i686-unknown-linux-gnu and x86_64-unknown-linux-gnu.

gdb/ChangeLog:

	* ax-gdb.c (gen_traced_pop): Use aop_ref64 when appropriate for
	string collection.
---
OK to push?

  gdb/ChangeLog | 5 +++++
  gdb/ax-gdb.c  | 5 ++++-
  2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 45d8ef9..3f4d152 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2016-01-21  Marcin KoÅcielnicki  <koriakin@0x04.net>
+
+	* ax-gdb.c (gen_traced_pop): Use aop_ref64 when appropriate for
+	string collection.
+
  2016-01-21  Andrew Burgess  <andrew.burgess@embecosm.com>

  	* disasm.c (maybe_add_dis_line_entry): Rename to...
diff --git a/gdb/ax-gdb.c b/gdb/ax-gdb.c
index dd6eee6..d17cb04 100644
--- a/gdb/ax-gdb.c
+++ b/gdb/ax-gdb.c
@@ -410,7 +410,10 @@ gen_traced_pop (struct gdbarch *gdbarch,

  	  if (string_trace)
  	    {
-	      ax_simple (ax, aop_ref32);
+	      if (TYPE_LENGTH(value->type) == 4)

Missing space before parens.

+	        ax_simple (ax, aop_ref32);
+	      else
+	        ax_simple (ax, aop_ref64);

+	      if (TYPE_LENGTH(value->type) == 4)
+	        ax_simple (ax, aop_ref32);
+	      else
+	        ax_simple (ax, aop_ref64);


Missing space before parens.  I was going to say to
check for == 8 instead so that we don't pessimize the
8/16 bits cases, but sounds better even to factor out
the switch in gen_fetch, so that the ref8/ref16 are covered
as well:

       switch (TYPE_LENGTH (type))
	{
	case 8 / TARGET_CHAR_BIT:
	  ax_simple (ax, aop_ref8);
	  break;
	case 16 / TARGET_CHAR_BIT:
	  ax_simple (ax, aop_ref16);
	  break;
	case 32 / TARGET_CHAR_BIT:
	  ax_simple (ax, aop_ref32);
	  break;
	case 64 / TARGET_CHAR_BIT:
	  ax_simple (ax, aop_ref64);
	  break;

	  /* Either our caller shouldn't have asked us to dereference
	     that pointer (other code's fault), or we're not
	     implementing something we should be (this code's fault).
	     In any case, it's a bug the user shouldn't see.  */
	default:
	  internal_error (__FILE__, __LINE__,

WDYT?

Thanks,
Pedro Alves



Fair enough, ref16 may actually be useful on some tiny platforms, and it certainly won't hurt to throw in ref8 as well. I'll do that.


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