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* [binutils-gdb] gas/Dwarf: properly skip zero-size functions
@ 2022-08-10 8:31 Jan Beulich
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From: Jan Beulich @ 2022-08-10 8:31 UTC (permalink / raw)
To: bfd-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d7abcbcea5ddd40a3bf28758b62f35933c59f996
commit d7abcbcea5ddd40a3bf28758b62f35933c59f996
Author: Jan Beulich <jbeulich@suse.com>
Date: Wed Aug 10 10:30:46 2022 +0200
gas/Dwarf: properly skip zero-size functions
PR gas/29451
While out_debug_abbrev() properly skips such functions, out_debug_info()
mistakenly didn't. It needs to calculate the high_pc expression ahead of
time, in order to skip emitting any data for the function if the value
is zero.
The one case which would still leave a zero-size entry is when
symbol_get_obj(symp)->size ends up evaluating to zero. I hope we can
expect that to not be the case, otherwise we'd need to have a way to
post-process .debug_info contents between resolving expressions and
actually writing the data out to the file. Even then it wouldn't be
entirely obvious in which way to alter the data.
Diff:
---
gas/dwarf2dbg.c | 39 ++++++++++++++++++++-------------------
1 file changed, 20 insertions(+), 19 deletions(-)
diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c
index 868ec79ee2c..f346bd6a412 100644
--- a/gas/dwarf2dbg.c
+++ b/gas/dwarf2dbg.c
@@ -2882,6 +2882,7 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT str_seg,
{
const char *name;
size_t len;
+ expressionS size = { .X_op = O_constant };
/* Skip warning constructs (see above). */
if (symbol_get_bfdsym (symp)->flags & BSF_WARNING)
@@ -2895,6 +2896,18 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT str_seg,
if (!S_IS_DEFINED (symp) || !S_IS_FUNCTION (symp))
continue;
+#if defined (OBJ_ELF) /* || defined (OBJ_MAYBE_ELF) */
+ size.X_add_number = S_GET_SIZE (symp);
+ if (size.X_add_number == 0 && IS_ELF
+ && symbol_get_obj (symp)->size != NULL)
+ {
+ size.X_op = O_add;
+ size.X_op_symbol = make_expr_symbol (symbol_get_obj (symp)->size);
+ }
+#endif
+ if (size.X_op == O_constant && size.X_add_number == 0)
+ continue;
+
subseg_set (str_seg, 0);
name_sym = symbol_temp_new_now_octets ();
name = S_GET_NAME (symp);
@@ -2920,29 +2933,17 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT str_seg,
emit_expr (&exp, sizeof_address);
/* DW_AT_high_pc */
- exp.X_op = O_constant;
-#if defined (OBJ_ELF) /* || defined (OBJ_MAYBE_ELF) */
- exp.X_add_number = S_GET_SIZE (symp);
- if (exp.X_add_number == 0 && IS_ELF
- && symbol_get_obj (symp)->size != NULL)
- {
- exp.X_op = O_add;
- exp.X_op_symbol = make_expr_symbol (symbol_get_obj (symp)->size);
- }
-#else
- exp.X_add_number = 0;
-#endif
if (DWARF2_VERSION < 4)
{
- if (exp.X_op == O_constant)
- exp.X_op = O_symbol;
- exp.X_add_symbol = symp;
- emit_expr (&exp, sizeof_address);
+ if (size.X_op == O_constant)
+ size.X_op = O_symbol;
+ size.X_add_symbol = symp;
+ emit_expr (&size, sizeof_address);
}
- else if (exp.X_op == O_constant)
- out_uleb128 (exp.X_add_number);
+ else if (size.X_op == O_constant)
+ out_uleb128 (size.X_add_number);
else
- emit_leb128_expr (symbol_get_value_expression (exp.X_op_symbol), 0);
+ emit_leb128_expr (symbol_get_value_expression (size.X_op_symbol), 0);
}
/* End of children. */
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