Fix up some stack trace inconsistencies:

- When printing suppressions, never print more entries than there are in the
  stack.  This avoids bogus suppressions in some cases!  (I haven't seen
  them on Linux, but I have seen them on Darwin.)

- When getting a stack trace, stop if we get an IP of zero or one;  that
  means we've hit the end of the stack.  And don't include that entry in the
  stack trace, because it's a guaranteed "???" if it's ever printed which is
  useless.

- In VG_(apply_StackTrace), we can now rely entirely on the n_ip parameter
  rather than looking for 0 or -1, because that check is done when the stack
  trace is first obtained.  In other words, stack traces all use an n_ip
  parameter to record their size, whereas previously they used an odd
  mixture of n_ip and null-termination.

- Rename 'n_ips' variables as 'max_n_ips' where appropriate;  those left as
  'n_ips' truly describe how many IPs there are in the stack trace.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@9793 a5019735-40e9-0310-863c-91ae7b9d1cf9

1 files changed, 7 insertions, 4 deletions

diff --git a/helgrind/libhb_core.c b/helgrind/libhb_core.c
index b2142ec32..1a600ac50 100644
--- a/helgrind/libhb_core.c
+++ b/helgrind/libhb_core.c
@@ -3184,15 +3184,18 @@ Bool libhb_event_map_lookup ( /*OUT*/ExeContext** resEC,
       tl_assert(i >= 0 && i <= N_OLDREF_ACCS);
 
       if (i < N_OLDREF_ACCS) {
+         Int n, maxNFrames;
          /* return with success */
          tl_assert(cand_thr);
          tl_assert(cand_rcec);
          tl_assert(cand_rcec->magic == RCEC_MAGIC);
          tl_assert(cand_szB >= 1);
-         *resEC  = VG_(make_ExeContext_from_StackTrace)(
-                      &cand_rcec->frames[0],
-                      min_UInt(N_FRAMES, VG_(clo_backtrace_size))
-                   );
+         /* Count how many non-zero frames we have. */
+         maxNFrames = min_UInt(N_FRAMES, VG_(clo_backtrace_size));
+         for (n = 0; n < maxNFrames; n++) {
+            if (0 == cand_rcec->frames[n]) break;
+         }
+         *resEC  = VG_(make_ExeContext_from_StackTrace)(cand_rcec->frames, n);
          *resThr = cand_thr;
          *resSzB = cand_szB;
          *resIsW = cand_isW;