[PATCH] Set entryval_error to NULL if entryval is set

[Yao Qi <yao@codesourcery.com>]

Hi,
I get an internal error when 'set print entry-values' to 'both' and
then type command 'tfind 0', shown as below,

(gdb) target remote :1234
Remote debugging using :1234
(gdb) b main
Breakpoint 1 at 0x80483eb: file ../../../../git/gdb/testsuite/gdb.trace/trace-unavailable.c, line 41.
(gdb) c
Continuing.

Breakpoint 1,
main () at ../../../../git/gdb/testsuite/gdb.trace/trace-unavailable.c:41
41        bar (4, s);

(gdb) trace bar
Tracepoint 3 at 0x80483ca: file ../../../../git/gdb/testsuite/gdb.trace/trace-unavailable.c, line 22.
(gdb) actions
Enter actions for tracepoint 3, one per line.
End with a line saying just "end".
 >collect array
 >collect j
 >end
(gdb) tstart
(gdb) b marker
Breakpoint 4 at 0x80483e3: file ../../../../git/gdb/testsuite/gdb.trace/trace-unavailable.c, line 34.
(gdb) c
Continuing.
Breakpoint 4, marker () at ../../../../git/gdb/testsuite/gdb.trace/trace-unavailable.c:34
34      {}
(gdb) tstop
(gdb) set print entry-values both
(gdb) tfind 0
../../../git/gdb/stack.c:223: internal-error: print_frame_arg: Assertion `!arg->val || !arg->error' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? "

In print_frame_arg, this assert indicates that either arg->val or
arg->error should be NULL.  It looks right to me.  This patch is to
set 'entryval_error' NULL when 'entryval' is set (non-NULL).

The test case is modified to expose this internal error, and without
fix in read_frame_arg, we can get the internal error when running
gdb.trace/collection.exp

(gdb) PASS: gdb.trace/collection.exp: collect args collectively: tfind test frame
tfind -1^M
No longer looking at any trace frame^M
79      }^M
(gdb) set print entry-values only^M
(gdb) tfind 0^M
Found trace frame 0, tracepoint 4^M
A problem internal to GDB has been detected,^M
further debugging may prove unreliable.^M
Quit this debugging session? (y or n) FAIL: gdb.trace/collection.exp: collect args collectively: tfind 0 with entry-values only (GDB internal error)

This internal error is fixed when the patch is applied.  The patch is
tested on x86_64-linux with board file unix.exp and
native-gdbserver.exp respectively.

gdb:

2013-08-05  Yao Qi  <yao@codesourcery.com>

	* stack.c (read_frame_arg): Set 'entryval_error' to NULL if
	'entryval' is set.

gdb/testsuite:

2013-08-05  Yao Qi  <yao@codesourcery.com>

	* gdb.trace/collection.exp (gdb_collect_args_test): Set
	"only" and "both" to 'print entry-values' before selecting
	trace frame.
---
 gdb/stack.c                            |    5 ++++-
 gdb/testsuite/gdb.trace/collection.exp |   16 ++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/gdb/stack.c b/gdb/stack.c
index 3177877..9e9ebc1 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -475,7 +475,10 @@ read_frame_arg (struct symbol *sym, struct frame_info *frame,
 	  || print_entry_values == print_entry_values_both
 	  || (print_entry_values == print_entry_values_preferred
 	      && (!val || value_optimized_out (val))))
-	entryval = allocate_optimized_out_value (SYMBOL_TYPE (sym));
+	{
+	  entryval = allocate_optimized_out_value (SYMBOL_TYPE (sym));
+	  entryval_error = NULL;
+	}
     }
   if ((print_entry_values == print_entry_values_compact
        || print_entry_values == print_entry_values_if_needed
diff --git a/gdb/testsuite/gdb.trace/collection.exp b/gdb/testsuite/gdb.trace/collection.exp
index f6d44ce..844cbb5 100644
--- a/gdb/testsuite/gdb.trace/collection.exp
+++ b/gdb/testsuite/gdb.trace/collection.exp
@@ -128,6 +128,22 @@ proc gdb_collect_args_test { myargs msg } {
     # Begin the test.
     run_trace_experiment $msg args_test_func
 
+    # Frame arguments and their entry values are displaced correctly with
+    # various values of "print entry-values" when a trace frame is
+    # selected.
+
+    gdb_test "tfind -1" ".*" ""
+    gdb_test_no_output "set print entry-values only" ""
+    gdb_test "tfind 0" \
+	" \\(argc@entry=\[^,\]*, argi@entry=\[^,\]*, argf@entry=\[^,\]*, argd@entry=\[^,\]*, argstruct@entry=\[^,\]*, argarray@entry=\[^,\]*\\) .*" \
+	"collect $msg: tfind 0 with entry-values only"
+
+    gdb_test "tfind -1" ".*" ""
+    gdb_test_no_output "set print entry-values both" ""
+    gdb_test "tfind 0" \
+	" \\(argc=\[^,\]*, argc@entry=\[^,\]*, argi=\[^,\]*, argi@entry=\[^,\]*, argf=\[^,\]*, argf@entry=\[^,\]*, argd=\[^,\]*, argd@entry=\[^,\]*, argstruct=\[^,\]*, argstruct@entry=\[^,\]*, argarray=\[^,\]*, argarray@entry=\[^,\]*\\) .*" \
+	"collect $msg: tfind 0 with entry-values both"
+
     gdb_test "print argc" \
 	    "\\$\[0-9\]+ = 1 '.001'$cr" \
 	    "collect $msg: collected arg char"
-- 
1.7.7.6