[PATCH v4 1/3] gdb, dwarf: move part of dwarf2_get_pc_bounds into separate function

[Nils-Christian Kempke]

This commit is in preparation of the next commit.  There, we will add
a second variation to retrieve the pc bounds for DIEs tagged with
DW_TAG_entry_point.  Instead of dwarf_get_pc_bounds_ranges_or_highlow_pc
we will call a separate method for entry points.  As the validity checks
at the endo f dwarf2_get_pc_bounds are the same for both variants,
we introduced the new dwarf_get_pc_bounds_ranges_or_highlow_pc method,
outsourcing part of dwarf2_get_pc_bounds.

This commit should have no functional impact on GDB.

Signed-off-by: Nils-Christian Kempke <nils-christian.kempke@intel.com>
---
 gdb/dwarf2/read.c | 71 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 50 insertions(+), 21 deletions(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 5ca787cc095..7ea6c1a7831 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -12978,20 +12978,19 @@ dwarf2_ranges_read_low_addrs (unsigned offset, struct dwarf2_cu *cu,
     });
 }
 
-/* Get low and high pc attributes from a die.  See enum pc_bounds_kind
-   definition for the return value.  *LOWPC and *HIGHPC are set iff
-   neither PC_BOUNDS_NOT_PRESENT nor PC_BOUNDS_INVALID are returned.  */
+/* Determine the low and high pc using the DW_AT_low_pc and DW_AT_high_pc or
+   DW_AT_ranges attributes of a DIE.  */
 
-static enum pc_bounds_kind
-dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
-		      CORE_ADDR *highpc, struct dwarf2_cu *cu,
-		      addrmap *map, void *datum)
+static pc_bounds_kind
+dwarf_get_pc_bounds_ranges_or_highlow_pc (die_info *die, CORE_ADDR *low,
+					  CORE_ADDR *high, dwarf2_cu *cu,
+					  addrmap *map, void *datum)
 {
-  dwarf2_per_objfile *per_objfile = cu->per_objfile;
+  gdb_assert (low != nullptr);
+  gdb_assert (high != nullptr);
+
   struct attribute *attr;
   struct attribute *attr_high;
-  CORE_ADDR low = 0;
-  CORE_ADDR high = 0;
   enum pc_bounds_kind ret;
 
   attr_high = dwarf2_attr (die, DW_AT_high_pc, cu);
@@ -13000,17 +12999,19 @@ dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
       attr = dwarf2_attr (die, DW_AT_low_pc, cu);
       if (attr != nullptr)
 	{
-	  low = attr->as_address ();
-	  high = attr_high->as_address ();
+	  *low = attr->as_address ();
+	  *high = attr_high->as_address ();
 	  if (cu->header.version >= 4 && attr_high->form_is_constant ())
-	    high += low;
+	    *high += *low;
+
+	  /* Found consecutive range of addresses.  */
+	  ret = PC_BOUNDS_HIGH_LOW;
 	}
       else
-	/* Found high w/o low attribute.  */
-	return PC_BOUNDS_INVALID;
-
-      /* Found consecutive range of addresses.  */
-      ret = PC_BOUNDS_HIGH_LOW;
+	{
+	  /* Found high w/o low attribute.  */
+	  ret = PC_BOUNDS_INVALID;
+	}
     }
   else
     {
@@ -13028,16 +13029,44 @@ dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
 
 	  /* Value of the DW_AT_ranges attribute is the offset in the
 	     .debug_ranges section.  */
-	  if (!dwarf2_ranges_read (ranges_offset, &low, &high, cu,
+	  if (!dwarf2_ranges_read (ranges_offset, low, high, cu,
 				   map, datum, die->tag))
 	    return PC_BOUNDS_INVALID;
 	  /* Found discontinuous range of addresses.  */
 	  ret = PC_BOUNDS_RANGES;
 	}
       else
-	return PC_BOUNDS_NOT_PRESENT;
+	{
+	  /* Could not find high_pc or ranges attributed and thus no bounds
+	     pair.  */
+	  ret = PC_BOUNDS_NOT_PRESENT;
+	}
     }
 
+    return ret;
+}
+
+/* Get low and high pc attributes from a die.  See enum pc_bounds_kind
+   definition for the return value.  *LOWPC and *HIGHPC are set iff
+   neither PC_BOUNDS_NOT_PRESENT nor PC_BOUNDS_INVALID are returned.  */
+
+static enum pc_bounds_kind
+dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
+		      CORE_ADDR *highpc, struct dwarf2_cu *cu,
+		      addrmap *map, void *datum)
+{
+  dwarf2_per_objfile *per_objfile = cu->per_objfile;
+
+  CORE_ADDR low = 0;
+  CORE_ADDR high = 0;
+  enum pc_bounds_kind ret;
+
+  ret = dwarf_get_pc_bounds_ranges_or_highlow_pc (die, &low, &high, cu, map,
+						  datum);
+
+  if (ret == PC_BOUNDS_NOT_PRESENT || ret == PC_BOUNDS_INVALID)
+    return ret;
+
   /* partial_die_info::read has also the strict LOW < HIGH requirement.  */
   if (high <= low)
     return PC_BOUNDS_INVALID;
@@ -13054,7 +13083,7 @@ dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
     return PC_BOUNDS_INVALID;
 
   *lowpc = low;
-  if (highpc)
+  if (highpc != nullptr)
     *highpc = high;
   return ret;
 }
-- 
2.25.1

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