[PATCH] Add DIE offsets in error messages to make it easier to find what is wrong.

[PATCH] Add DIE offsets in error messages to make it easier to find what is wrong.

[Mark Wielaard]

With the following patch dwz will give a message like:

libmozjs-78.so: Couldn't find DIE at [bd6b507] referenced by
  DW_AT_abstract_origin from DIE at [bd5bb9b]

Which makes it a easier to figure out what is going on.

In the above case it is easy to find the producer of the CU of those
two DIEs. Which turned out the be is clang LLVM (rustc version 1.49.0)
which seems to have gotten the abstract origin reference wrong.
---
 dwz.c | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/dwz.c b/dwz.c
index 28f0c4d..1db93dd 100644
--- a/dwz.c
+++ b/dwz.c
@@ -2414,8 +2414,10 @@ read_exprloc (DSO *dso, dw_die_ref die, unsigned char *ptr, size_t len,
 	  ref = off_htab_lookup (cu, cu->cu_offset + addr);
 	  if (ref == NULL)
 	    {
-	      error (0, 0, "%s: Couldn't find DIE referenced by %s",
-		     dso->filename, get_DW_OP_str (op));
+	      error (0, 0, "%s: Couldn't find DIE at [%" PRIx64 "] "
+		     "referenced by %s from DIE at [%x]",
+		     dso->filename, cu->cu_offset + addr,
+		     get_DW_OP_str (op), die->die_offset);
 	      return 1;
 	    }
 	  if (op == DW_OP_call2)
@@ -2465,8 +2467,9 @@ read_exprloc (DSO *dso, dw_die_ref die, unsigned char *ptr, size_t len,
 	  ref = off_htab_lookup (NULL, addr);
 	  if (ref == NULL || (unlikely (low_mem) && ref->die_tag == 0))
 	    {
-	      error (0, 0, "%s: Couldn't find DIE referenced by %s",
-		     dso->filename, get_DW_OP_str (op));
+	      error (0, 0, "%s: Couldn't find DIE at [%" PRIx64 "] "
+		     "referenced by %s from DIE at [%x]",
+		     dso->filename, addr, get_DW_OP_str (op), die->die_offset);
 	      return 1;
 	    }
 	  ref->die_no_multifile = 1;
@@ -2551,8 +2554,10 @@ read_exprloc (DSO *dso, dw_die_ref die, unsigned char *ptr, size_t len,
 	  ref = off_htab_lookup (cu, cu->cu_offset + addr);
 	  if (ref == NULL)
 	    {
-	      error (0, 0, "%s: Couldn't find DIE referenced by %s",
-		     dso->filename, get_DW_OP_str (op));
+	      error (0, 0, "%s: Couldn't find DIE at [%" PRIx64 "] "
+			   "referenced by %s from DIE at [%x]",
+		     dso->filename, cu->cu_offset + addr,
+		     get_DW_OP_str (op), die->die_offset);
 	      return 1;
 	    }
 	  if (unlikely (low_mem))
@@ -3537,8 +3542,10 @@ checksum_die (DSO *dso, dw_cu_ref cu, dw_die_ref top_die, dw_die_ref die)
 	      ref = off_htab_lookup (cu, value);
 	      if (ref == NULL)
 		{
-		  error (0, 0, "%s: Couldn't find DIE referenced by %s",
-			 dso->filename, get_DW_AT_str (t->attr[i].attr));
+		  error (0, 0, "%s: Couldn't find DIE at [%" PRIx64 "] "
+			       "referenced by %s from DIE at [%x]",
+			 dso->filename, value,
+			 get_DW_AT_str (t->attr[i].attr), die->die_offset);
 		  return 1;
 		}
 	      if (unlikely (op_multifile) && ref->die_collapsed_child)
@@ -3635,8 +3642,10 @@ checksum_die (DSO *dso, dw_cu_ref cu, dw_die_ref top_die, dw_die_ref die)
 		= off_htab_lookup (cu, cu->cu_offset + value);
 	      if (ref == NULL)
 		{
-		  error (0, 0, "%s: Couldn't find DIE referenced by %s",
-			 dso->filename, get_DW_AT_str (t->attr[i].attr));
+		  error (0, 0, "%s: Couldn't find DIE at [%" PRIx64 "] "
+			 "referenced by %s from DIE at [%x]",
+			 dso->filename, cu->cu_offset + value,
+			 get_DW_AT_str (t->attr[i].attr), die->die_offset);
 		  return 1;
 		}
 	      if (die->die_ck_state != CK_BAD)
@@ -7146,8 +7155,10 @@ read_debug_info (DSO *dso, int kind, unsigned int *die_count)
 	  dw_die_ref ref = off_htab_lookup (cu, cu->cu_offset + type_offset);
 	  if (ref == NULL)
 	    {
-	      error (0, 0, "%s: Couldn't find DIE referenced by type_offset",
-		     dso->filename);
+	      error (0, 0, "%s: Couldn't find DIE at [%x] "
+		     "referenced by type_offset from cu DIE at [%x]",
+		     dso->filename, cu->cu_offset + type_offset,
+		     cu->cu_die->die_offset);
 	      goto fail;
 	    }
 	  if (unlikely (low_mem))
-- 
2.18.4

Re: [PATCH] Add DIE offsets in error messages to make it easier to find what is wrong.

[Jakub Jelinek]

On Tue, Jan 26, 2021 at 09:45:09PM +0100, Mark Wielaard wrote:
> With the following patch dwz will give a message like:
> 
> libmozjs-78.so: Couldn't find DIE at [bd6b507] referenced by
>   DW_AT_abstract_origin from DIE at [bd5bb9b]
> 
> Which makes it a easier to figure out what is going on.
> 
> In the above case it is easy to find the producer of the CU of those
> two DIEs. Which turned out the be is clang LLVM (rustc version 1.49.0)
> which seems to have gotten the abstract origin reference wrong.

LGTM, thanks.

	Jakub