[RFC 2/2] Test entry values in trace frame

[Yao Qi <yao@codesourcery.com>]

Hi,
This is the test for "entry-values" when GDB is examining trace
frames.  In test, tracepoint action collects arguments i and j and
global variable global1.  Variable global2 is not collected.

The GNU_call_site_parameter is faked that i's entry value is from
global1, j's entry value is from global2.  When GDB is examining trace
frame, value of i, j and i@entry should be available, but value of
j@entry is not.

However, when I run this test, I find j@entry is something like,
j@entry=<error reading variable: Cannot access memory at address 0x8049788>
instead of unavailable.

I don't emit a fail for it because I am not very sure it is expected
to be "unavailable".  I am fine to kfail it.

I looked into a little, and looks reading entry value doesn't use
value availability-aware API.  It is not an easy fix to me.

gdb/testsuite:

2013-08-13  Yao Qi  <yao@codesourcery.com>

	* gdb.trace/entry-values.c (end): New
	(main): Call end.
	* gdb.trace/entry-values.exp: Load trace-support.exp.  Set
	tracepoint and collect data.  Test entry value is unavailable.
---
 gdb/testsuite/gdb.trace/entry-values.c   |    5 +++
 gdb/testsuite/gdb.trace/entry-values.exp |   49 ++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 0 deletions(-)

diff --git a/gdb/testsuite/gdb.trace/entry-values.c b/gdb/testsuite/gdb.trace/entry-values.c
index 3f98615..e287203 100644
--- a/gdb/testsuite/gdb.trace/entry-values.c
+++ b/gdb/testsuite/gdb.trace/entry-values.c
@@ -32,6 +32,10 @@ bar (int i)
 int global1 = 1;
 int global2 = 2;
 
+static void
+end (void)
+{}
+
 int
 main (void)
 {
@@ -41,5 +45,6 @@ main (void)
   global2++;
   ret = bar (0);
 
+  end ();
   return ret;
 }
diff --git a/gdb/testsuite/gdb.trace/entry-values.exp b/gdb/testsuite/gdb.trace/entry-values.exp
index ba95e4f..bf946c3 100644
--- a/gdb/testsuite/gdb.trace/entry-values.exp
+++ b/gdb/testsuite/gdb.trace/entry-values.exp
@@ -221,3 +221,52 @@ gdb_test_sequence "bt" "bt" {
     "\[\r\n\]#1 .* bar \\(i=<optimized out>, i@entry=<optimized out>\\)"
     "\[\r\n\]#2 .* main \\(\\)"
 }
+
+# Restart GDB and trace.
+
+clean_restart $binfile
+
+load_lib "trace-support.exp"
+
+if ![runto_main] {
+    fail "Can't run to main to check for trace support"
+    return -1
+}
+
+if ![gdb_target_supports_trace] {
+    unsupported "target does not support trace"
+    return -1
+}
+
+gdb_test "trace foo" "Tracepoint $decimal at .*"
+
+if [is_amd64_regs_target] {
+    set spreg "\$rsp"
+} elseif [is_x86_like_target] {
+    set spreg "\$esp"
+} else {
+    set spreg "\$sp"
+}
+
+# Collect arguments i and j.  Collect 'global1' which is entry value
+# of argument i.  Don't collect 'global2' to test the entry value of
+# argument j.
+
+gdb_trace_setactions "set action for tracepoint 1" "" \
+    "collect i, j, global1, \(\*\(void \*\*\) \($spreg\)\) @ 64" "^$"
+
+gdb_test_no_output "tstart"
+
+gdb_breakpoint "end"
+gdb_continue_to_breakpoint "end"
+
+gdb_test_no_output "tstop"
+
+gdb_test "tfind" "Found trace frame 0, .*" "tfind start"
+
+# Since 'global2' is not collected, j@entry is expected to be 'unavailable',
+# however, the current output is like:
+# j@entry=<error reading variable: Cannot access memory at address 0x8049788>
+gdb_test "bt 1" "#0 .* foo \\(i=\[-\]?$decimal, i@entry=2, j=\[-\]?$decimal, j@entry=.*\\).*"
+
+gdb_test "tfind" "Target failed to find requested trace frame\..*"
-- 
1.7.7.6