gdb: Change a VEC to std::vector in btrace.{c,h}

Replace a VEC with a std::vector in btrace.h, and update btrace.c to
match.  It is worth noting that this code appears to be currently
untested by the GDB testsuite.  I've tried to do a like for like
replacement when moving to std::vector, with minimal refactoring to
try and avoid introducing any bugs.

As the new vector is inside a union I've currently used a pointer to
vector, which makes the code slightly uglier than it might otherwise
be, but again, due to lack of testing I'm reluctant to start
refactoring the code in a big way.

gdb/ChangeLog:

	* btrace.c (btrace_maint_clear): Update to handle change from VEC
	to std::vector.
	(btrace_maint_decode_pt): Likewise, and move allocation of the
	vector outside of the loop.
	(btrace_maint_update_packets): Update to handle change from VEC to
	std::vector.
	(btrace_maint_print_packets): Likewise.
	(maint_info_btrace_cmd): Likewise.
	* btrace.h: Remove use of DEF_VEC_O.
	(typedef btrace_pt_packet_s): Delete.
	(struct btrace_maint_info) <packets>: Change fromm VEC to
	std::vector.
	* gdbsupport/btrace-common.h: Remove 'vec.h' include.

4 files changed, 38 insertions, 25 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a5a87df..7d18431 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,21 @@
 2019-10-02  Andrew Burgess  <andrew.burgess@embecosm.com>
 
+	* btrace.c (btrace_maint_clear): Update to handle change from VEC
+	to std::vector.
+	(btrace_maint_decode_pt): Likewise, and move allocation of the
+	vector outside of the loop.
+	(btrace_maint_update_packets): Update to handle change from VEC to
+	std::vector.
+	(btrace_maint_print_packets): Likewise.
+	(maint_info_btrace_cmd): Likewise.
+	* btrace.h: Remove use of DEF_VEC_O.
+	(typedef btrace_pt_packet_s): Delete.
+	(struct btrace_maint_info) <packets>: Change fromm VEC to
+	std::vector.
+	* gdbsupport/btrace-common.h: Remove 'vec.h' include.
+
+2019-10-02  Andrew Burgess  <andrew.burgess@embecosm.com>
+
 	* btrace.c (btrace_compute_ftrace_bts): Update for std::vector,
 	make accesses into the vector constant references.
 	(btrace_add_pc): Update for std::vector.
diff --git a/gdb/btrace.c b/gdb/btrace.c
index b6a1113..8bed31cd 100644
--- a/gdb/btrace.c
+++ b/gdb/btrace.c
@@ -1825,7 +1825,7 @@ btrace_maint_clear (struct btrace_thread_info *btinfo)
 
 #if defined (HAVE_LIBIPT)
     case BTRACE_FORMAT_PT:
-      xfree (btinfo->maint.variant.pt.packets);
+      delete btinfo->maint.variant.pt.packets;
 
       btinfo->maint.variant.pt.packets = NULL;
       btinfo->maint.variant.pt.packet_history.begin = 0;
@@ -2962,6 +2962,9 @@ btrace_maint_decode_pt (struct btrace_maint_info *maint,
 {
   int errcode;
 
+  if (maint->variant.pt.packets == NULL)
+    maint->variant.pt.packets = new std::vector <btrace_pt_packet>;
+
   for (;;)
     {
       struct btrace_pt_packet packet;
@@ -2982,8 +2985,7 @@ btrace_maint_decode_pt (struct btrace_maint_info *maint,
 	  if (maint_btrace_pt_skip_pad == 0 || packet.packet.type != ppt_pad)
 	    {
 	      packet.errcode = pt_errcode (errcode);
-	      VEC_safe_push (btrace_pt_packet_s, maint->variant.pt.packets,
-			     &packet);
+	      maint->variant.pt.packets->push_back (packet);
 	    }
 	}
 
@@ -2991,8 +2993,7 @@ btrace_maint_decode_pt (struct btrace_maint_info *maint,
 	break;
 
       packet.errcode = pt_errcode (errcode);
-      VEC_safe_push (btrace_pt_packet_s, maint->variant.pt.packets,
-		     &packet);
+      maint->variant.pt.packets->push_back (packet);
 
       warning (_("Error at trace offset 0x%" PRIx64 ": %s."),
 	       packet.offset, pt_errstr (packet.errcode));
@@ -3093,11 +3094,14 @@ btrace_maint_update_packets (struct btrace_thread_info *btinfo,
 
 #if defined (HAVE_LIBIPT)
     case BTRACE_FORMAT_PT:
-      if (VEC_empty (btrace_pt_packet_s, btinfo->maint.variant.pt.packets))
+      if (btinfo->maint.variant.pt.packets == nullptr)
+	btinfo->maint.variant.pt.packets = new std::vector <btrace_pt_packet>;
+
+      if (btinfo->maint.variant.pt.packets->empty ())
 	btrace_maint_update_pt_packets (btinfo);
 
       *begin = 0;
-      *end = VEC_length (btrace_pt_packet_s, btinfo->maint.variant.pt.packets);
+      *end = btinfo->maint.variant.pt.packets->size ();
       *from = btinfo->maint.variant.pt.packet_history.begin;
       *to = btinfo->maint.variant.pt.packet_history.end;
       break;
@@ -3140,23 +3144,21 @@ btrace_maint_print_packets (struct btrace_thread_info *btinfo,
 #if defined (HAVE_LIBIPT)
     case BTRACE_FORMAT_PT:
       {
-	VEC (btrace_pt_packet_s) *packets;
+	const std::vector <btrace_pt_packet> &packets
+	  = *btinfo->maint.variant.pt.packets;
 	unsigned int pkt;
 
-	packets = btinfo->maint.variant.pt.packets;
 	for (pkt = begin; pkt < end; ++pkt)
 	  {
-	    const struct btrace_pt_packet *packet;
-
-	    packet = VEC_index (btrace_pt_packet_s, packets, pkt);
+	    const struct btrace_pt_packet &packet = packets.at (pkt);
 
 	    printf_unfiltered ("%u\t", pkt);
-	    printf_unfiltered ("0x%" PRIx64 "\t", packet->offset);
+	    printf_unfiltered ("0x%" PRIx64 "\t", packet.offset);
 
-	    if (packet->errcode == pte_ok)
-	      pt_print_packet (&packet->packet);
+	    if (packet.errcode == pte_ok)
+	      pt_print_packet (&packet.packet);
 	    else
-	      printf_unfiltered ("[error: %s]", pt_errstr (packet->errcode));
+	      printf_unfiltered ("[error: %s]", pt_errstr (packet.errcode));
 
 	    printf_unfiltered ("\n");
 	  }
@@ -3447,9 +3449,9 @@ maint_info_btrace_cmd (const char *args, int from_tty)
 			   version.ext != NULL ? version.ext : "");
 
 	btrace_maint_update_pt_packets (btinfo);
-	printf_unfiltered (_("Number of packets: %u.\n"),
-			   VEC_length (btrace_pt_packet_s,
-				       btinfo->maint.variant.pt.packets));
+	printf_unfiltered (_("Number of packets: %zu.\n"),
+			   ((btinfo->maint.variant.pt.packets == nullptr)
+			    ? 0 : btinfo->maint.variant.pt.packets->size ()));
       }
       break;
 #endif /* defined (HAVE_LIBIPT)  */
diff --git a/gdb/btrace.h b/gdb/btrace.h
index ba8d27c..208c089 100644
--- a/gdb/btrace.h
+++ b/gdb/btrace.h
@@ -264,9 +264,6 @@ struct btrace_pt_packet
   struct pt_packet packet;
 };
 
-/* Define functions operating on a vector of packets.  */
-typedef struct btrace_pt_packet btrace_pt_packet_s;
-DEF_VEC_O (btrace_pt_packet_s);
 #endif /* defined (HAVE_LIBIPT)  */
 
 /* Branch trace iteration state for "maintenance btrace packet-history".  */
@@ -300,7 +297,7 @@ struct btrace_maint_info
     struct
     {
       /* A vector of decoded packets.  */
-      VEC (btrace_pt_packet_s) *packets;
+      std::vector <btrace_pt_packet> *packets;
 
       /* The packet history iterator.
 	 We are iterating over the above PACKETS vector.  */
diff --git a/gdb/gdbsupport/btrace-common.h b/gdb/gdbsupport/btrace-common.h
index 9c57645..166d7b1 100644
--- a/gdb/gdbsupport/btrace-common.h
+++ b/gdb/gdbsupport/btrace-common.h
@@ -26,8 +26,6 @@
    inferior.  For presentation purposes, the branch trace is represented as a
    list of sequential control-flow blocks, one such list per thread.  */
 
-#include "vec.h"
-
 /* A branch trace block.
 
    This represents a block of sequential control-flow.  Adjacent blocks will be