[gdb/symtab] Trust epilogue unwind info for unknown producer (-g0 case)

For a -g0 -fasynchronous-unwind-tables exec (without .debug_info but with
.eh_frame section), start using the dwarf2 unwinder instead of the
"amd64 epilogue override" unwinder, by returning true in
compunit_epilogue_unwind_valid for cust == nullptr.

This has effect both on the amd64 and i386 targets, but only add amd64
test-case gdb.base/unwind-on-each-insn-amd64-2.exp.

1 files changed, 2 insertions, 2 deletions

diff --git a/gdb/symtab.h b/gdb/symtab.h
index cd6b5f722fd..17d2746fd48 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -1924,9 +1924,9 @@ static inline bool
 compunit_epilogue_unwind_valid (struct compunit_symtab *cust)
 {
   /* In absence of producer information, assume epilogue unwind info is
-     invalid.  */
+     valid.  */
   if (cust == nullptr)
-    return false;
+    return true;
 
   return cust->epilogue_unwind_valid ();
 }