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[PATCH] Fix GDB crash with upstream GCC due to memcpy(NULL, ...)

Similar to qsort(), the glibc version of memcpy() also declares its
arguments with __attribute__(__nonnull__(...)).  If NULL is passed
anyway, upstream GCC's new pass '-fisolate-erroneous-paths' typically
causes a trap in such cases.  I've encountered this with GDB in
chain_candidate() when trying to execute the break.exp test case.

2013-11-13  Andreas Arnez  <>

	* dwarf2loc.c (chain_candidate): Prevent invoking memcpy with
 gdb/dwarf2loc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 8242dca..d85370f 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -749,8 +749,9 @@ chain_candidate (struct gdbarch *gdbarch, struct call_site_chain **resultp,
 					   * (length - 1));
       result->length = length;
       result->callers = result->callees = length;
-      memcpy (result->call_site, VEC_address (call_sitep, chain),
-	      sizeof (*result->call_site) * length);
+      if (!VEC_empty (call_sitep, chain))
+	memcpy (result->call_site, VEC_address (call_sitep, chain),
+		sizeof (*result->call_site) * length);
       *resultp = result;
       if (entry_values_debug)

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