This patch fixes three of the four unexpected failures that I'm seeing
in the gcc testsuite on x86_64-pc-linux-gnu. The three FAILs are:
FAIL: gcc.c-torture/execute/fprintf-2.c -O3 -g (test for excess errors)
FAIL: gcc.c-torture/execute/printf-2.c -O3 -g (test for excess errors)
FAIL: gcc.c-torture/execute/user-printf.c -O3 -g (test for excess errors)
and are caused by the linker/toolchain (GNU ld 2.27 on RedHat 7) issuing
a link-time warning:
/usr/bin/ld: Dwarf Error: found dwarf version '5', this reader only handles
version 2, 3 and 4 information.
This also explains why these c-torture tests only fail with -g.
One solution might be to tweak/improve GCC's testsuite to ignore
these warnings. However, ideally it should also be possible to
configure gcc not to generate dwarf5 debugging information on
systems that don't/can't support it. This patch supplements the
current --with-dwarf2 configure option with the addition of a
--with-dwarf4 option that adds a tm-dwarf4.h to $tm_file (using
the same mechanism as --with-dwarf2) that changes/redefines
DWARF_VERSION_DEFAULT to 4 (overriding the current default of 5),
This patch has been tested on x86_64-pc-linux-gnu, with a full
make bootstrap, both with and without --with-dwarf4. This is
fixes the three failures above, and causes no new failures outside
of the gcc.dg/guality directory. Unfortunately, the guality
testsuite contains a large number of tests that assume support
for dwarf5 and don't (yet) check check_effective_target_dwarf5.
Hopefully, adding --with-dwarf4 will help improve/test the
portability of the guality testsuite.
Ok for mainline? An alternative implementation might be to
allow integer values for $with_dwarf such that --with-dwarf5,
--with-dwarf3 etc. do the right thing. In fact, I'd originally
misread the documentation and assumed --with-dwarf4 was already
supported.
2024-01-14 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
* configure.ac: Add a with --with dwarf4 option.
* configure: Regenerate.
* config/tm-dwarf4.h: New target file to define
DWARF_VERSION_DEFAULT to 4.
Thanks in advance,
Roger
--
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 596e5f2..2ce9093 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -1036,6 +1036,11 @@ AC_ARG_WITH(dwarf2,
dwarf2="$with_dwarf2",
dwarf2=no)
+AC_ARG_WITH(dwarf4,
+[AS_HELP_STRING([--with-dwarf4], [force the default debug format to be DWARF
4])],
+dwarf4="$with_dwarf4",
+dwarf4=no)
+
AC_ARG_ENABLE(shared,
[AS_HELP_STRING([--disable-shared], [don't provide a shared libgcc])],
[
@@ -1916,6 +1921,10 @@ if test x"$dwarf2" = xyes
then tm_file="$tm_file tm-dwarf2.h"
fi
+if test x"$dwarf4" = xyes
+then tm_file="$tm_file tm-dwarf4.h"
+fi
+
# Say what files are being used for the output code and MD file.
echo "Using \`$srcdir/config/$out_file' for machine-specific logic."
echo "Using \`$srcdir/config/$md_file' as machine description file."
diff --git a/gcc/config/tm-dwarf4.h b/gcc/config/tm-dwarf4.h
new file mode 100644
index 0000000..9557b40
--- /dev/null
+++ b/gcc/config/tm-dwarf4.h
@@ -0,0 +1,3 @@
+/* Make Dwarf4 debugging info the default */
+#undef DWARF_VERSION_DEFAULT
+#define DWARF_VERSION_DEFAULT 4
