libdw: Support DW_OP_addrx/constx and split DWARF addrx/constx support.

DW_OP_addrx/constx and GNU DebugFission DW_OP_GNU_addr/const_index take
as argument an index into the .debug_addr section for the associated CU.
This index gets resolved through dwarf_getlocation_attr. A new fake addr
CU is created per Dwarf for use with this new attribute. For split DWARF
files, the IDX_debug_addr gets replaced with the skeleton section and the
addr base is resolved immediately when constructing the split DWARF CU.
Move __libdw_cu_addr_base to libdwP.h to share with eu-readelf. Also
make it possible to resolve addrx[1234]/GNU_addr_index also as constant
indexes to (also) show when displaying these attributes in eu-readelf.

A new varlocs tests is added to test the resolving for both the DWARF4
and DWARF5 DW_OP variants. And now that addrx forms are resolved in
split DWARF files add the new DIEs with "single ranges" (those DIEs that
have a lowpc/highpc attribute pair) to run-all-dwarf-ranges.sh.

Signed-off-by: Mark Wielaard <mark@klomp.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/libdw/dwarf_begin_elf.c b/libdw/dwarf_begin_elf.c
index 0e435c57..5d8e79e3 100644
--- a/libdw/dwarf_begin_elf.c
+++ b/libdw/dwarf_begin_elf.c
@@ -246,6 +246,33 @@ valid_p (Dwarf *result)
 	}
     }
 
+  /* For DW_OP_constx/GNU_const_index and DW_OP_addrx/GNU_addr_index
+     the dwarf_location_attr () will need a "fake" address CU to
+     indicate where the attribute data comes from.  This is a just
+     inside the .debug_addr section, if it exists.  */
+  if (result != NULL && result->sectiondata[IDX_debug_addr] != NULL)
+    {
+      result->fake_addr_cu = (Dwarf_CU *) calloc (1, sizeof (Dwarf_CU));
+      if (unlikely (result->fake_addr_cu == NULL))
+	{
+	  Dwarf_Sig8_Hash_free (&result->sig8_hash);
+	  __libdw_seterrno (DWARF_E_NOMEM);
+	  free (result->fake_loc_cu);
+	  free (result);
+	  result = NULL;
+	}
+      else
+	{
+	  result->fake_addr_cu->sec_idx = IDX_debug_addr;
+	  result->fake_addr_cu->dbg = result;
+	  result->fake_addr_cu->startp
+	    = result->sectiondata[IDX_debug_addr]->d_buf;
+	  result->fake_addr_cu->endp
+	    = (result->sectiondata[IDX_debug_addr]->d_buf
+	       + result->sectiondata[IDX_debug_addr]->d_size);
+	}
+    }
+
   if (result != NULL)
     result->debugdir = __libdw_debugdir (result->elf->fildes);