[patch] Defer adding cu to read_in_chain until successfully read in

[dje at google dot com (Doug Evans)]

Hi.

I don't have a testcase that shows a problem, but this patch feels
self-evidently cleaner.

I will check it in in a few days if there are no objections.

2012-03-07  Doug Evans  <dje@google.com>

	* dwarf2read.c (load_partial_comp_unit): Defer adding cu to
	read_in_chain until we have successfully read it in.
	(load_full_comp_unit): Ditto.
	(read_signatured_type): Add comment.

Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.619
diff -u -p -r1.619 dwarf2read.c
--- dwarf2read.c	6 Mar 2012 23:41:50 -0000	1.619
+++ dwarf2read.c	7 Mar 2012 19:52:13 -0000
@@ -3679,10 +3679,6 @@ load_partial_comp_unit (struct dwarf2_pe
 	  do_cleanups (free_cu_cleanup);
 	  return;
 	}
-
-      /* Link this CU into read_in_chain.  */
-      this_cu->cu->read_in_chain = dwarf2_per_objfile->read_in_chain;
-      dwarf2_per_objfile->read_in_chain = this_cu;
     }
   else
     {
@@ -3715,6 +3711,10 @@ load_partial_comp_unit (struct dwarf2_pe
       /* We've successfully allocated this compilation unit.  Let our
 	 caller clean it up when finished with it.  */
       discard_cleanups (free_cu_cleanup);
+
+      /* Link this CU into read_in_chain.  */
+      this_cu->cu->read_in_chain = dwarf2_per_objfile->read_in_chain;
+      dwarf2_per_objfile->read_in_chain = this_cu;
     }
 }
 
@@ -4693,10 +4693,6 @@ load_full_comp_unit (struct dwarf2_per_c
       /* Complete the cu_header.  */
       cu->header.offset = offset;
       cu->header.first_die_offset = info_ptr - beg_of_comp_unit;
-
-      /* Link this CU into read_in_chain.  */
-      per_cu->cu->read_in_chain = dwarf2_per_objfile->read_in_chain;
-      dwarf2_per_objfile->read_in_chain = per_cu;
     }
   else
     {
@@ -4723,6 +4719,10 @@ load_full_comp_unit (struct dwarf2_per_c
       /* We've successfully allocated this compilation unit.  Let our
 	 caller clean it up when finished with it.  */
       discard_cleanups (free_cu_cleanup);
+
+      /* Link this CU into read_in_chain.  */
+      per_cu->cu->read_in_chain = dwarf2_per_objfile->read_in_chain;
+      dwarf2_per_objfile->read_in_chain = per_cu;
     }
 }
 
@@ -14426,6 +14426,7 @@ read_signatured_type (struct signatured_
      clean it up when finished with it.	 */
   discard_cleanups (free_cu_cleanup);
 
+  /* Link this TU into read_in_chain.  */
   type_sig->per_cu.cu->read_in_chain = dwarf2_per_objfile->read_in_chain;
   dwarf2_per_objfile->read_in_chain = &type_sig->per_cu;
 }