| Message ID | 00f401da4720$64e86b90$2eb942b0$@nextmovesoftware.com |
|---|---|
| State | New |
| Headers | show |
| Series | [PATCH/RFC] Add --with-dwarf4 configure option. | expand |
On Sun, Jan 14, 2024 at 8:32 PM Roger Sayle <roger@nextmovesoftware.com> wrote: > > > 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. We're patching GCC on old systems to avoid this (and fallout from tools not supporting DWARF5). > 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 $with_dwarf such that --with-dwarf5, > --with-dwarf3 etc. do the right thing. In fact, I'd originally > misread the documentation and assumed --with-dwarf4 was already > supported. The only thing to watch out for is ordering of tm_file since there's ./config/vxworks.h:#undef DWARF_VERSION_DEFAULT ./config/vxworks.h:#define DWARF_VERSION_DEFAULT (TARGET_VXWORKS7 ? 3 : 2) it looks like the --with-dwarf4 adjustment is before the vxworks handling so the vxworks handling will prevail even with --with-dwarf4. Not sure if that's intended? I think this also needs documenting in install.texi (and mention whether target specific defaults will prevail or not) Richard. > > 2024-01-14 Roger Sayle <roger@nextmovesoftware.com> > > gcc/ChangeLog > * configure.ac: Add a with --with dwarf4 option. > * configure: Regenerate. > * config/tm-dwarf4.h: New target file to define > DWARF_VERSION_DEFAULT to 4. > > > Thanks in advance, > Roger > -- >
diff --git a/gcc/configure.ac b/gcc/configure.ac index 596e5f2..2ce9093 100644 --- a/gcc/configure.ac +++ b/gcc/configure.ac @@ -1036,6 +1036,11 @@ AC_ARG_WITH(dwarf2, dwarf2="$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
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 <roger@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 --