re PR sanitizer/65479 (sanitizer stack trace missing frames past #0 on powerpc64)

2015-06-11  Martin Sebor  <msebor@redhat.com>

	PR sanitizer/65479
	* dwarf.c (struct line): Add new field idx.
	(line_compare): Use it.
	(add_line): Set it.
	(read_line_info): Reset it.

From-SVN: r224402

diff --git a/libbacktrace/ChangeLog b/libbacktrace/ChangeLog
index e105e38ee957ee710f52175ca5c92a0bd372f2e9..d043761bbe7732c4adf303e29190f174bbb159ed 100644 (file)
--- a/libbacktrace/ChangeLog
+++ b/libbacktrace/ChangeLog
@@ -1,3 +1,11 @@
+2015-06-11  Martin Sebor  <msebor@redhat.com>
+
+       PR sanitizer/65479
+       * dwarf.c (struct line): Add new field idx.
+       (line_compare): Use it.
+       (add_line): Set it.
+       (read_line_info): Reset it.
+
 2015-05-29  Tristan Gingold  <gingold@adacore.com>
 
        * pecoff.c: New file.

diff --git a/libbacktrace/dwarf.c b/libbacktrace/dwarf.c
index 919b568c786ce264971d7aa4db807d12ab8d624c..e32c46885735d6baed838e791a03fba649efb6eb 100644 (file)
--- a/libbacktrace/dwarf.c
+++ b/libbacktrace/dwarf.c
@@ -211,6 +211,10 @@ struct line
   const char *filename;
   /* Line number.  */
   int lineno;
+  /* Index of the object in the original array read from the DWARF
+     section, before it has been sorted.  The index makes it possible
+     to use Quicksort and maintain stability.  */
+  int idx;
 };
 
 /* A growable vector of line number information.  This is used while
@@ -940,9 +944,10 @@ unit_addrs_search (const void *vkey, const void *ventry)
     return 0;
 }
 
-/* Sort the line vector by PC.  We want a stable sort here.  We know
-   that the pointers are into the same array, so it is safe to compare
-   them directly.  */
+/* Sort the line vector by PC.  We want a stable sort here to maintain
+   the order of lines for the same PC values.  Since the sequence is
+   being sorted in place, their addresses cannot be relied on to
+   maintain stability.  That is the purpose of the index member.  */
 
 static int
 line_compare (const void *v1, const void *v2)
@@ -954,9 +959,9 @@ line_compare (const void *v1, const void *v2)
     return -1;
   else if (ln1->pc > ln2->pc)
     return 1;
-  else if (ln1 < ln2)
+  else if (ln1->idx < ln2->idx)
     return -1;
-  else if (ln1 > ln2)
+  else if (ln1->idx > ln2->idx)
     return 1;
   else
     return 0;
@@ -1551,6 +1556,7 @@ add_line (struct backtrace_state *state, struct dwarf_data *ddata,
 
   ln->filename = filename;
   ln->lineno = lineno;
+  ln->idx = vec->count;
 
   ++vec->count;
 
@@ -2011,6 +2017,7 @@ read_line_info (struct backtrace_state *state, struct dwarf_data *ddata,
   ln->pc = (uintptr_t) -1;
   ln->filename = NULL;
   ln->lineno = 0;
+  ln->idx = 0;
 
   if (!backtrace_vector_release (state, &vec.vec, error_callback, data))
     goto fail;