btrace: indicate speculative execution

Indicate speculatively executed instructions with a leading '?'.  We use the
space that is normally used for the PC prefix.  In the case where the
instruction at the current PC had been executed speculatively before, the PC
prefix will be partially overwritten resulting in "?> ".

As a side-effect, the /p modifier to omit the PC prefix in the "record
instruction-history" command now uses a 3-space PC prefix "   " in order to
have enough space for the speculative execution indication.

gdb/
	* btrace.c (btrace_compute_ftrace_bts): Clear insn flags.
	(pt_btrace_insn_flags): New.
	(ftrace_add_pt): Call pt_btrace_insn_flags.
	* btrace.h (btrace_insn_flag): New.
	(btrace_insn) <flags>: New.
	* record-btrace.c (btrace_insn_history): Print insn prefix.
	* NEWS: Announce it.

doc/
	* gdb.texinfo (Process Record and Replay): Document prefixing of
	speculatively executed instructions in the "record instruction-history"
	command.

testsuite/
	* gdb.btrace/instruction_history.exp: Update.
	* gdb.btrace/tsx.exp: New.
	* gdb.btrace/tsx.c: New.
	* lib/gdb.exp (skip_tsx_tests, skip_btrace_pt_tests): New.

1 files changed, 15 insertions, 0 deletions

diff --git a/gdb/btrace.c b/gdb/btrace.c
index 94942f4..abdf639 100644
--- a/gdb/btrace.c
+++ b/gdb/btrace.c
@@ -660,6 +660,7 @@ btrace_compute_ftrace_bts (struct thread_info *tp,
 	  insn.pc = pc;
 	  insn.size = size;
 	  insn.iclass = ftrace_classify_insn (gdbarch, pc);
+	  insn.flags = 0;
 
 	  ftrace_update_insns (end, &insn);
 
@@ -725,6 +726,19 @@ pt_reclassify_insn (enum pt_insn_class iclass)
     }
 }
 
+/* Return the btrace instruction flags for INSN.  */
+
+static enum btrace_insn_flag
+pt_btrace_insn_flags (const struct pt_insn *insn)
+{
+  enum btrace_insn_flag flags = 0;
+
+  if (insn->speculative)
+    flags |= BTRACE_INSN_FLAG_SPECULATIVE;
+
+  return flags;
+}
+
 /* Add function branch trace using DECODER.  */
 
 static void
@@ -792,6 +806,7 @@ ftrace_add_pt (struct pt_insn_decoder *decoder,
 	  btinsn.pc = (CORE_ADDR) insn.ip;
 	  btinsn.size = (gdb_byte) insn.size;
 	  btinsn.iclass = pt_reclassify_insn (insn.iclass);
+	  btinsn.flags = pt_btrace_insn_flags (&insn);
 
 	  ftrace_update_insns (end, &btinsn);
 	}