[4/9] Avoid undefined behavior in read_subrange_type
Commit Message
-fsanitize=undefined pointed out an undefined shift of a negative
value in read_subrange_type. The fix is to do the work in an unsigned
type, where this is defined.
ChangeLog
2018-08-27 Tom Tromey <tom@tromey.com>
* dwarf2read.c (read_subrange_type): Make "negative_mask"
unsigned.
---
gdb/ChangeLog | 5 +++++
gdb/dwarf2read.c | 4 ++--
2 files changed, 7 insertions(+), 2 deletions(-)
@@ -17682,7 +17682,7 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
int low_default_is_valid;
int high_bound_is_count = 0;
const char *name;
- LONGEST negative_mask;
+ ULONGEST negative_mask;
orig_base_type = die_type (die, cu);
/* If ORIG_BASE_TYPE is a typedef, it will not be TYPE_UNSIGNED,
@@ -17815,7 +17815,7 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
the bounds as signed, and thus sign-extend their values, when
the base type is signed. */
negative_mask =
- -((LONGEST) 1 << (TYPE_LENGTH (base_type) * TARGET_CHAR_BIT - 1));
+ -((ULONGEST) 1 << (TYPE_LENGTH (base_type) * TARGET_CHAR_BIT - 1));
if (low.kind == PROP_CONST
&& !TYPE_UNSIGNED (base_type) && (low.data.const_val & negative_mask))
low.data.const_val |= negative_mask;