Fix bit offset regression

The type-safe attribute patch introduced a regression that can occur
when the DW_AT_bit_offset value is negative.  This can happen with
some Ada programs.

This patch fixes the problem.  It also fixes a minor oddity in the
existing scalar storage test -- this test was intended to assign a
smaller number of bits to the field.

2020-10-09  Tom Tromey  <tromey@adacore.com>

	* dwarf2/read.c (dwarf2_add_field): Handle signed offsets.

gdb/testsuite/ChangeLog
2020-10-09  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/scalar_storage/storage.adb (Another_Range): New type.
	(Rec): Add field.  Fix range.
	* gdb.ada/scalar_storage.exp: Update.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 01bca5c58427981f812f740031f08235265dd642..80a1d28015ad4b5871da56887110c956dae80871 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2020-10-09  Tom Tromey  <tromey@adacore.com>
+
+       * dwarf2/read.c (dwarf2_add_field): Handle signed offsets.
+
 2020-10-09  Tom Tromey  <tromey@adacore.com>
 
        * ada-lang.h (ada_encode): Return std::string.

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index eedfea112d96223d37e13642f67006c5a7d8f5e4..2ec3789135d698f4049052bf3286669d0da61ca9 100644 (file)
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -15050,7 +15050,7 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
       /* Get bit offset of field.  */
       handle_data_member_location (die, cu, fp);
       attr = dwarf2_attr (die, DW_AT_bit_offset, cu);
-      if (attr != nullptr && attr->form_is_unsigned ())
+      if (attr != nullptr && attr->form_is_constant ())
        {
          if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
            {
@@ -15060,7 +15060,7 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
                 have to do anything special since we don't need to
                 know the size of the anonymous object.  */
              SET_FIELD_BITPOS (*fp, (FIELD_BITPOS (*fp)
-                                     + attr->as_unsigned ()));
+                                     + attr->constant_value (0)));
            }
          else
            {
@@ -15071,15 +15071,15 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
                 the field itself.  The result is the bit offset of
                 the LSB of the field.  */
              int anonymous_size;
-             int bit_offset = attr->as_unsigned ();
+             int bit_offset = attr->constant_value (0);
 
              attr = dwarf2_attr (die, DW_AT_byte_size, cu);
-             if (attr != nullptr && attr->form_is_unsigned ())
+             if (attr != nullptr && attr->form_is_constant ())
                {
                  /* The size of the anonymous object containing
                     the bit field is explicit, so use the
                     indicated size (in bytes).  */
-                 anonymous_size = attr->as_unsigned ();
+                 anonymous_size = attr->constant_value (0);
                }
              else
                {

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index e1b623b7fec3c29f632a8901b7d50a87ffab80f1..d7e80954b1d380c8576d505fd22aefce6cfaee23 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2020-10-09  Tom Tromey  <tromey@adacore.com>
+
+       * gdb.ada/scalar_storage/storage.adb (Another_Range): New type.
+       (Rec): Add field.  Fix range.
+       * gdb.ada/scalar_storage.exp: Update.
+
 2020-10-09  Hannes Domani  <ssbssa@yahoo.de>
 
        PR exp/26714

diff --git a/gdb/testsuite/gdb.ada/scalar_storage.exp b/gdb/testsuite/gdb.ada/scalar_storage.exp
index b5e634c615b043edaa398b553caf5dff7a4a3383..952d7fd136eea80a9721bcf2691a0eadd9066716 100644 (file)
--- a/gdb/testsuite/gdb.ada/scalar_storage.exp
+++ b/gdb/testsuite/gdb.ada/scalar_storage.exp
@@ -34,5 +34,5 @@ if ![runto "storage.adb:$bp_location" ] then {
   return
 }
 
-gdb_test "print V_LE" "= \\(value => 126\\)"
-gdb_test "print V_BE" "= \\(value => 126\\)"
+gdb_test "print V_LE" "= \\(value => 126, another_value => 12\\)"
+gdb_test "print V_BE" "= \\(value => 126, another_value => 12\\)"

diff --git a/gdb/testsuite/gdb.ada/scalar_storage/storage.adb b/gdb/testsuite/gdb.ada/scalar_storage/storage.adb
index 608425d9dd1000c349c28225c86619f712e56769..741718e4e511b6b8befde5ede2ed330f3c87f62d 100644 (file)
--- a/gdb/testsuite/gdb.ada/scalar_storage/storage.adb
+++ b/gdb/testsuite/gdb.ada/scalar_storage/storage.adb
@@ -18,13 +18,16 @@ with System.Storage_Elements; use System.Storage_Elements;
 
 procedure Storage is
    subtype Some_Range is Natural range 0..127;
+   subtype Another_Range is Natural range 0..15;
 
    type Rec is record
       Value : Some_Range;
+      Another_Value : Another_Range;
    end record;
    
    for Rec use record
-      Value at 0 range 0..127;
+      Value at 0 range 0..6;
+      Another_Value at 0 range 7..10;
    end record;
 
    type Rec_LE is new Rec;
@@ -39,8 +42,8 @@ procedure Storage is
    V_BE : Rec_BE;
 
 begin
-   V_LE.Value := 126;
-   V_BE.Value := 126;
+   V_LE := (126, 12);
+   V_BE := (126, 12);
 
    Do_Nothing (V_LE'Address);  --  START
    Do_Nothing (V_BE'Address);