Hi!
binutils since https://sourceware.org/bugzilla/show_bug.cgi?id=25612
changes from March last year until the
https://sourceware.org/pipermail/binutils/2020-August/112684.html
fix in early August emits incorrect .debug_info when assembling files
with --gdwarf-5. Instead of emitting proper DWARF 5 .debug_info header,
it emits DWARF 4 .debug_info header with 5 as the dwarf version instead of
4. This results e.g. in libgcc.a (morestack.o) having garbage in its
.debug_info sections and e.g. libbacktrace during pretty much all libgo
tests fails miserably.
The following patch adds a workaround for that, don't set
HAVE_AS_GDWARF_5_DEBUG_FLAG if readelf can't read the .debug_info back.
Built tested on x86_64-linux against both binutils 2.35 (buggy ones) and
latest binutils trunk, the former with the patch now has DWARF 3
.debug_line and DWARF 2 .debug_info in morestack.o, while the latter
as before correct DWARF 5 .debug_line and .debug_info.
Ok for trunk?
2021-01-25 Jakub Jelinek <ja...@redhat.com>
PR debug/98811
* configure.ac (HAVE_AS_GDWARF_5_DEBUG_FLAG): Only define if
readelf -wi is able to read the emitted .debug_info back.
* configure: Regenerated.
--- gcc/configure.ac.jj 2021-01-25 12:35:11.034835330 +0100
+++ gcc/configure.ac 2021-01-25 13:04:10.002980861 +0100
@@ -5416,8 +5416,12 @@ if test x"$insn" != x; then
gcc_GAS_CHECK_FEATURE([--gdwarf-5 option],
gcc_cv_as_gdwarf_5_flag,
- [elf,2,36,0], [--gdwarf-5], [$insn],,
- [AC_DEFINE(HAVE_AS_GDWARF_5_DEBUG_FLAG, 1,
+ [elf,2,36,0], [--gdwarf-5], [$insn],
+ [if test x$gcc_cv_readelf != x \
+ && $gcc_cv_readelf -wi conftest.o 2>&1 \
+ | grep DW_TAG_compile_unit > /dev/null 2>&1; then
+ gcc_cv_as_gdwarf_5_flag=yes;
+ fi],[AC_DEFINE(HAVE_AS_GDWARF_5_DEBUG_FLAG, 1,
[Define if your assembler supports the --gdwarf-5 option.])])
dwarf4_debug_info_size=0x46
--- gcc/configure.jj 2021-01-25 12:35:11.012835581 +0100
+++ gcc/configure 2021-01-25 13:04:14.982924030 +0100
@@ -29075,7 +29075,11 @@ fi
$as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
test $ac_status = 0; }; }
then
- gcc_cv_as_gdwarf_5_flag=yes
+ if test x$gcc_cv_readelf != x \
+ && $gcc_cv_readelf -wi conftest.o 2>&1 \
+ | grep DW_TAG_compile_unit > /dev/null 2>&1; then
+ gcc_cv_as_gdwarf_5_flag=yes;
+ fi
else
echo "configure: failed program was" >&5
cat conftest.s >&5
Jakub
