record-btrace: indicate gaps

Indicate gaps in the trace due to decode errors.  Internally, a gap is
represented as a btrace function segment without instructions and with a
non-zero format-specific error code.

Show the gap when traversing the instruction or function call history.
Also indicate gaps in "info record".

It looks like this:

  (gdb) info record
  Active record target: record-btrace
  Recording format: Branch Trace Store.
  Buffer size: 64KB.
  Recorded 32 instructions in 5 functions (1 gaps) for thread 1 (process 7182).
  (gdb) record function-call-history /cli
  1	fib	inst 1,9	at src/fib.c:9,14
  2	  fib	inst 10,20	at src/fib.c:6,14
  3	[decode error (1): instruction overflow]
  4	fib	inst 21,28	at src/fib.c:11,14
  5	  fib	inst 29,33	at src/fib.c:6,9
  (gdb) record instruction-history 20,22
  20	   0x000000000040062f <fib+47>:	sub    $0x1,%rax
  [decode error (1): instruction overflow]
  21	   0x0000000000400613 <fib+19>:	add    $0x1,%rax
  22	   0x0000000000400617 <fib+23>:	mov    %rax,0x200a3a(%rip)
  (gdb)

Gaps are ignored during reverse execution and replay.

2015-02-09  Markus Metzger  <markus.t.metzger@intel.com>

	* btrace.c (ftrace_find_call): Skip gaps.
	(ftrace_new_function): Initialize level.
	(ftrace_new_call, ftrace_new_tailcall, ftrace_new_return)
	(ftrace_new_switch): Update
	level computation.
	(ftrace_new_gap): New.
	(ftrace_update_function): Create new function after gap.
	(btrace_compute_ftrace_bts): Create gap on error.
	(btrace_stitch_bts): Update parameters.  Clear trace if it
	becomes empty.
	(btrace_stitch_trace): Update parameters.  Update callers.
	(btrace_clear): Reset the number of gaps.
	(btrace_insn_get): Return NULL if the iterator points to a gap.
	(btrace_insn_number): Return zero if the iterator points to a gap.
	(btrace_insn_end): Allow gaps at the end.
	(btrace_insn_next, btrace_insn_prev, btrace_insn_cmp): Handle gaps.
	(btrace_find_insn_by_number): Assert that the found iterator does
	not point to a gap.
	(btrace_call_next, btrace_call_prev): Assert that the last function
	is not a gap.
	* btrace.h (btrace_bts_error): New.
	(btrace_function): Update comment.
	(btrace_function) <insn, insn_offset, number>: Update comment.
	(btrace_function) <errcode>: New.
	(btrace_thread_info) <ngaps>: New.
	(btrace_thread_info) <replay>: Update comment.
	(btrace_insn_get): Update comment.
	* record-btrace.c (btrace_ui_out_decode_error): New.
	(record_btrace_info): Print number of gaps.
	(btrace_insn_history, btrace_call_history): Call
	btrace_ui_out_decode_error for gaps.
	(record_btrace_step_thread, record_btrace_start_replaying): Skip gaps.

testsuite/
	* gdb.btrace/buffer-size.exp: Update "info record" output.
	* gdb.btrace/delta.exp: Update "info record" output.
	* gdb.btrace/enable.exp: Update "info record" output.
	* gdb.btrace/finish.exp: Update "info record" output.
	* gdb.btrace/instruction_history.exp: Update "info record" output.
	* gdb.btrace/next.exp: Update "info record" output.
	* gdb.btrace/nexti.exp: Update "info record" output.
	* gdb.btrace/step.exp: Update "info record" output.
	* gdb.btrace/stepi.exp: Update "info record" output.
	* gdb.btrace/nohist.exp: Update "info record" output.

11 files changed, 31 insertions, 18 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index f4c5ed0..4df5ba9 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,18 @@
 2015-02-09  Markus Metzger  <markus.t.metzger@intel.com>
 
+	* gdb.btrace/buffer-size.exp: Update "info record" output.
+	* gdb.btrace/delta.exp: Update "info record" output.
+	* gdb.btrace/enable.exp: Update "info record" output.
+	* gdb.btrace/finish.exp: Update "info record" output.
+	* gdb.btrace/instruction_history.exp: Update "info record" output.
+	* gdb.btrace/next.exp: Update "info record" output.
+	* gdb.btrace/nexti.exp: Update "info record" output.
+	* gdb.btrace/step.exp: Update "info record" output.
+	* gdb.btrace/stepi.exp: Update "info record" output.
+	* gdb.btrace/nohist.exp: Update "info record" output.
+
+2015-02-09  Markus Metzger  <markus.t.metzger@intel.com>
+
 	* gdb.btrace/buffer-size: New.
 
 2015-02-09  Markus Metzger  <markus.t.metzger@intel.com>
diff --git a/gdb/testsuite/gdb.btrace/buffer-size.exp b/gdb/testsuite/gdb.btrace/buffer-size.exp
index 0381cc2..1f10668 100644
--- a/gdb/testsuite/gdb.btrace/buffer-size.exp
+++ b/gdb/testsuite/gdb.btrace/buffer-size.exp
@@ -39,7 +39,7 @@ gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: Branch Trace Store\." \
   "Buffer size: 4kB\." \
-  "Recorded 0 instructions in 0 functions for \[^\\\r\\\n\]*" \
+  "Recorded 0 instructions in 0 functions \\\(0 gaps\\\) for \[^\\\r\\\n\]*" \
   ] "\r\n"] "info record with small bts buffer"
 gdb_test "record stop" ".*" "stop recording with small bts buffer"
 
@@ -52,6 +52,6 @@ gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: Branch Trace Store\." \
   "Buffer size: .*\." \
-  "Recorded 0 instructions in 0 functions for \[^\\\r\\\n\]*" \
+  "Recorded 0 instructions in 0 functions \\\(0 gaps\\\) for \[^\\\r\\\n\]*" \
   ] "\r\n"] "info record with unlimited bts buffer"
 gdb_test "record stop" ".*" "stop recording with unlimited bts buffer"
diff --git a/gdb/testsuite/gdb.btrace/delta.exp b/gdb/testsuite/gdb.btrace/delta.exp
index 59959bc..38b6e26 100644
--- a/gdb/testsuite/gdb.btrace/delta.exp
+++ b/gdb/testsuite/gdb.btrace/delta.exp
@@ -40,7 +40,7 @@ with_test_prefix "no trace" {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-    "Recorded 0 instructions in 0 functions for .*" \
+    "Recorded 0 instructions in 0 functions \\\(0 gaps\\\) for .*" \
     ] "\r\n"]
   gdb_test "record instruction-history" "No trace\."
   gdb_test "record function-call-history" "No trace\."
@@ -53,7 +53,7 @@ proc check_trace {} {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-    "Recorded 1 instructions in 1 functions for .*" \
+    "Recorded 1 instructions in 1 functions \\\(0 gaps\\\) for .*" \
     ] "\r\n"]
   gdb_test "record instruction-history /f 1" \
     "1\t   0x\[0-9a-f\]+ <\\+\[0-9\]+>:\tmov *\\\$0x0,%eax\r"
@@ -74,7 +74,7 @@ gdb_test "reverse-stepi"
 gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: .*" \
-  "Recorded 1 instructions in 1 functions for .*" \
+  "Recorded 1 instructions in 1 functions \\\(0 gaps\\\) for .*" \
   "Replay in progress\.  At instruction 1\." \
   ] "\r\n"] "reverse-stepi"
 
@@ -83,5 +83,5 @@ gdb_test "stepi"
 gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: .*" \
-  "Recorded 1 instructions in 1 functions for .*" \
+  "Recorded 1 instructions in 1 functions \\\(0 gaps\\\) for .*" \
   ] "\r\n"] "and back"
diff --git a/gdb/testsuite/gdb.btrace/enable.exp b/gdb/testsuite/gdb.btrace/enable.exp
index 1122884..d447bd9 100644
--- a/gdb/testsuite/gdb.btrace/enable.exp
+++ b/gdb/testsuite/gdb.btrace/enable.exp
@@ -58,7 +58,7 @@ gdb_test "record full" "The process is already being recorded\\.  Use \"record s
 # no trace recorded yet
 gdb_test "info record" "Active record target: record-btrace\r
 .*\r
-Recorded 0 instructions in 0 functions for thread 1.*\\." "info record without trace"
+Recorded 0 instructions in 0 functions \\\(0 gaps\\\) for thread 1.*\\." "info record without trace"
 
 # stop btrace record
 gdb_test "record stop" "Process record is stopped and all execution logs are deleted\\." "record stop"
diff --git a/gdb/testsuite/gdb.btrace/finish.exp b/gdb/testsuite/gdb.btrace/finish.exp
index 3857c10..6881e3b 100644
--- a/gdb/testsuite/gdb.btrace/finish.exp
+++ b/gdb/testsuite/gdb.btrace/finish.exp
@@ -38,7 +38,7 @@ proc check_replay_at { insn } {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-    "Recorded 40 instructions in 16 functions for .*" \
+    "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for .*" \
     "Replay in progress\.  At instruction $insn\." \
     ] "\r\n"]
 }
diff --git a/gdb/testsuite/gdb.btrace/instruction_history.exp b/gdb/testsuite/gdb.btrace/instruction_history.exp
index 63d902b..a7b57e5 100644
--- a/gdb/testsuite/gdb.btrace/instruction_history.exp
+++ b/gdb/testsuite/gdb.btrace/instruction_history.exp
@@ -50,7 +50,7 @@ gdb_continue_to_breakpoint "cont to $bp_location" ".*$srcfile2:$bp_location.*"
 set traced {}
 set testname "determine number of recorded instructions"
 gdb_test_multiple "info record" $testname {
-    -re "Active record target: record-btrace\r\n.*\r\nRecorded \(\[0-9\]*\) instructions in \(\[0-9\]*\) functions for thread 1 .*\\.\r\n$gdb_prompt $" {
+    -re "Active record target: record-btrace\r\n.*\r\nRecorded \(\[0-9\]*\) instructions in \(\[0-9\]*\) functions \\\(0 gaps\\\) for thread 1 .*\\.\r\n$gdb_prompt $" {
         set traced $expect_out(1,string)
         pass $testname
     }
diff --git a/gdb/testsuite/gdb.btrace/next.exp b/gdb/testsuite/gdb.btrace/next.exp
index 88bd8af..3d2fa10 100644
--- a/gdb/testsuite/gdb.btrace/next.exp
+++ b/gdb/testsuite/gdb.btrace/next.exp
@@ -38,7 +38,7 @@ proc check_replay_at { insn } {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-    "Recorded 40 instructions in 16 functions for .*" \
+    "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for .*" \
     "Replay in progress\.  At instruction $insn\." \
     ] "\r\n"]
 }
@@ -57,7 +57,7 @@ gdb_test "next" ".*main\.3.*"
 gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: .*" \
-  "Recorded 40 instructions in 16 functions for \[^\\\r\\\n\]*" \
+  "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for \[^\\\r\\\n\]*" \
   ] "\r\n"] "next back"
 
 # let's go somewhere where we can step some more
diff --git a/gdb/testsuite/gdb.btrace/nexti.exp b/gdb/testsuite/gdb.btrace/nexti.exp
index 76ca0a6..911ad86 100644
--- a/gdb/testsuite/gdb.btrace/nexti.exp
+++ b/gdb/testsuite/gdb.btrace/nexti.exp
@@ -38,7 +38,7 @@ proc check_replay_at { insn } {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-    "Recorded 40 instructions in 16 functions for .*" \
+    "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for .*" \
     "Replay in progress\.  At instruction $insn\." \
     ] "\r\n"]
 }
@@ -57,7 +57,7 @@ gdb_test "nexti" ".*main\.3.*" "next, 1.5"
 gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: .*" \
-  "Recorded 40 instructions in 16 functions for \[^\\\r\\\n\]*" \
+  "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for \[^\\\r\\\n\]*" \
   ] "\r\n"] "nexti back"
 
 # let's go somewhere where we can step some more
diff --git a/gdb/testsuite/gdb.btrace/nohist.exp b/gdb/testsuite/gdb.btrace/nohist.exp
index f53870b..f267250 100644
--- a/gdb/testsuite/gdb.btrace/nohist.exp
+++ b/gdb/testsuite/gdb.btrace/nohist.exp
@@ -34,7 +34,7 @@ proc check_not_replaying {} {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-	"Recorded 0 instructions in 0 functions for \[^\\\r\\\n\]*" \
+	"Recorded 0 instructions in 0 functions \\\(0 gaps\\\) for \[^\\\r\\\n\]*" \
     ] "\r\n"]
 }
 
diff --git a/gdb/testsuite/gdb.btrace/step.exp b/gdb/testsuite/gdb.btrace/step.exp
index e3febe1..22aded8 100644
--- a/gdb/testsuite/gdb.btrace/step.exp
+++ b/gdb/testsuite/gdb.btrace/step.exp
@@ -38,7 +38,7 @@ proc check_replay_at { insn } {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-    "Recorded 40 instructions in 16 functions for .*" \
+    "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for .*" \
     "Replay in progress\.  At instruction $insn\." \
     ] "\r\n"]
 }
@@ -87,5 +87,5 @@ gdb_test "step" ".*main\.3.*"
 gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: .*" \
-  "Recorded 40 instructions in 16 functions for \[^\\\r\\\n\]*" \
+  "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for \[^\\\r\\\n\]*" \
   ] "\r\n"] "step to live"
diff --git a/gdb/testsuite/gdb.btrace/stepi.exp b/gdb/testsuite/gdb.btrace/stepi.exp
index 0276f72..a663f87 100644
--- a/gdb/testsuite/gdb.btrace/stepi.exp
+++ b/gdb/testsuite/gdb.btrace/stepi.exp
@@ -36,7 +36,7 @@ proc check_replay_at { insn } {
   gdb_test "info record" [join [list \
     "Active record target: record-btrace" \
     "Recording format: .*" \
-    "Recorded 40 instructions in 16 functions for .*" \
+    "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for .*" \
     "Replay in progress\.  At instruction $insn\." \
     ] "\r\n"]
 }
@@ -61,7 +61,7 @@ gdb_test "stepi" ".*main\.3.*"
 gdb_test "info record" [join [list \
   "Active record target: record-btrace" \
   "Recording format: .*" \
-  "Recorded 40 instructions in 16 functions for \[^\\\r\\\n\]*" \
+  "Recorded 40 instructions in 16 functions \\\(0 gaps\\\) for \[^\\\r\\\n\]*" \
   ] "\r\n"] "stepi to live"
 
 # let's step from a goto position somewhere in the middle