diff mbox series

[RFC] Allow means for targets to out out of CTF/BTF support

Message ID 1625782952-13143-1-git-send-email-indu.bhagat@oracle.com
State New
Headers show
Series [RFC] Allow means for targets to out out of CTF/BTF support | expand

Commit Message

Indu Bhagat July 8, 2021, 10:22 p.m. UTC 
Hello,

It was brought up when discussing PR debug/101283 (Several tests fail on
Darwin with -gctf/gbtf) that it will be good to provide means for targets to
opt out of CTF/BTF support.

By and large, it seems to me that CTF/BTF debug formats can be safely enabled
for all ELF-based targets by default in GCC.

So, at a high level:
  - By default, CTF/BTF formats can be enabled for all ELF-based targets.
  - By default, CTF/BTF formats can be disabled for all non ELF-based targets.
  - If the user passed a -gctf but CTF is not enabled for the target, GCC
  issues an error to the user (as is done currently with other debug formats) -
  "target system does not support the 'ctf' debug format".

This is a makeshift patch which fulfills the above requirements and is based on
the approach taken for DWARF via DWARF2_DEBUGGING_INFO (I still have to see if
I need some specific handling in common_handle_option in opts.c). On minimal
testing, the patch works as desired on x86_64-pc-linux-gnu and a darwin-based
target.

My question is - Looking around in config.gcc etc., it seems defining in elfos.h
gives targets/platforms means to override it by virtue of the recommended order
of # includes in $tm_file. What I cannot say for certain is if this is true in
practice ? On first look, I believe this could work fine. What do you think ? 

If you think this approach could work, I will continue on this track and
test/refine the patch.

Thanks
Indu

-------------

gcc/ChangeLog:

	* config/elfos.h (CTF_DEBUGGING_INFO): New definition.
	(BTF_DEBUGGING_INFO): Likewise.
	* toplev.c: Guard initialization of debug hooks.

gcc/testsuite/ChangeLog:

	* gcc.dg/debug/btf/btf.exp: Do not run BTF testsuite if target does not
	support BTF format.
	* gcc.dg/debug/ctf/ctf.exp: Do not run CTF testsuite if target does not
	support CTF format.
---
 gcc/config/elfos.h                     |  8 ++++++++
 gcc/testsuite/gcc.dg/debug/btf/btf.exp | 11 +++++++++--
 gcc/testsuite/gcc.dg/debug/ctf/ctf.exp | 11 +++++++++--
 gcc/toplev.c                           | 11 +++++++++--
 4 files changed, 35 insertions(+), 6 deletions(-)

Comments

Richard Biener July 12, 2021, 11:04 a.m. UTC | #1 
On Fri, Jul 9, 2021 at 12:23 AM Indu Bhagat via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hello,
>
> It was brought up when discussing PR debug/101283 (Several tests fail on
> Darwin with -gctf/gbtf) that it will be good to provide means for targets to
> opt out of CTF/BTF support.
>
> By and large, it seems to me that CTF/BTF debug formats can be safely enabled
> for all ELF-based targets by default in GCC.
>
> So, at a high level:
>   - By default, CTF/BTF formats can be enabled for all ELF-based targets.
>   - By default, CTF/BTF formats can be disabled for all non ELF-based targets.
>   - If the user passed a -gctf but CTF is not enabled for the target, GCC
>   issues an error to the user (as is done currently with other debug formats) -
>   "target system does not support the 'ctf' debug format".
>
> This is a makeshift patch which fulfills the above requirements and is based on
> the approach taken for DWARF via DWARF2_DEBUGGING_INFO (I still have to see if
> I need some specific handling in common_handle_option in opts.c). On minimal
> testing, the patch works as desired on x86_64-pc-linux-gnu and a darwin-based
> target.
>
> My question is - Looking around in config.gcc etc., it seems defining in elfos.h
> gives targets/platforms means to override it by virtue of the recommended order
> of # includes in $tm_file. What I cannot say for certain is if this is true in
> practice ? On first look, I believe this could work fine. What do you think ?
>
> If you think this approach could work, I will continue on this track and
> test/refine the patch.

I think it looks reasonable.  Note that target macros need to be documented
in tm.texi - I think while we generally do not want new target macros but
hooks this case can be an exception for consistency purposes (unless
somebody else strongly disagrees).

Thanks,
Richard.

> Thanks
> Indu
>
> -------------
>
> gcc/ChangeLog:
>
>         * config/elfos.h (CTF_DEBUGGING_INFO): New definition.
>         (BTF_DEBUGGING_INFO): Likewise.
>         * toplev.c: Guard initialization of debug hooks.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/debug/btf/btf.exp: Do not run BTF testsuite if target does not
>         support BTF format.
>         * gcc.dg/debug/ctf/ctf.exp: Do not run CTF testsuite if target does not
>         support CTF format.
> ---
>  gcc/config/elfos.h                     |  8 ++++++++
>  gcc/testsuite/gcc.dg/debug/btf/btf.exp | 11 +++++++++--
>  gcc/testsuite/gcc.dg/debug/ctf/ctf.exp | 11 +++++++++--
>  gcc/toplev.c                           | 11 +++++++++--
>  4 files changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/config/elfos.h b/gcc/config/elfos.h
> index 7a736cc..e5cb487 100644
> --- a/gcc/config/elfos.h
> +++ b/gcc/config/elfos.h
> @@ -68,6 +68,14 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>
>  #define DWARF2_DEBUGGING_INFO 1
>
> +/* All ELF targets can support CTF.  */
> +
> +#define CTF_DEBUGGING_INFO 1
> +
> +/* All ELF targets can support BTF.  */
> +
> +#define BTF_DEBUGGING_INFO 1
> +
>  /* The GNU tools operate better with dwarf2, and it is required by some
>     psABI's.  Since we don't have any native tools to be compatible with,
>     default to dwarf2.  */
> diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf.exp b/gcc/testsuite/gcc.dg/debug/btf/btf.exp
> index e173515..a3e680c 100644
> --- a/gcc/testsuite/gcc.dg/debug/btf/btf.exp
> +++ b/gcc/testsuite/gcc.dg/debug/btf/btf.exp
> @@ -39,8 +39,15 @@ if ![info exists DEFAULT_CFLAGS] then {
>  dg-init
>
>  # Main loop.
> -dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
> -       "" $DEFAULT_CFLAGS
> +set comp_output [gcc_target_compile \
> +    "$srcdir/$subdir/../trivial.c" "trivial.S" assembly \
> +    "additional_flags=-gbtf"]
> +if { ! [string match "*: target system does not support the * debug format*" \
> +    $comp_output] } {
> +    remove-build-file "trivial.S"
> +    dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
> +           "" $DEFAULT_CFLAGS
> +}
>
>  # All done.
>  dg-finish
> diff --git a/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp b/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp
> index 0b650ed..c53cd8b 100644
> --- a/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp
> +++ b/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp
> @@ -39,8 +39,15 @@ if ![info exists DEFAULT_CFLAGS] then {
>  dg-init
>
>  # Main loop.
> -dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
> -       "" $DEFAULT_CFLAGS
> +set comp_output [gcc_target_compile \
> +    "$srcdir/$subdir/../trivial.c" "trivial.S" assembly \
> +    "additional_flags=-gctf"]
> +if { ! [string match "*: target system does not support the * debug format*" \
> +    $comp_output] } {
> +    remove-build-file "trivial.S"
> +    dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
> +           "" $DEFAULT_CFLAGS
> +}
>
>  # All done.
>  dg-finish
> diff --git a/gcc/toplev.c b/gcc/toplev.c
> index 43f1f7d..8103812 100644
> --- a/gcc/toplev.c
> +++ b/gcc/toplev.c
> @@ -1463,8 +1463,15 @@ process_options (void)
>      debug_hooks = &xcoff_debug_hooks;
>  #endif
>  #ifdef DWARF2_DEBUGGING_INFO
> -  else if (dwarf_debuginfo_p ()
> -          || dwarf_based_debuginfo_p ())
> +  else if (dwarf_debuginfo_p ())
> +    debug_hooks = &dwarf2_debug_hooks;
> +#endif
> +#ifdef CTF_DEBUGGING_INFO
> +  else if (write_symbols & CTF_DEBUG)
> +    debug_hooks = &dwarf2_debug_hooks;
> +#endif
> +#ifdef BTF_DEBUGGING_INFO
> +  else if (btf_debuginfo_p ())
>      debug_hooks = &dwarf2_debug_hooks;
>  #endif
>  #ifdef VMS_DEBUGGING_INFO
> --
> 1.8.3.1
>
diff mbox series

Patch

diff --git a/gcc/config/elfos.h b/gcc/config/elfos.h
index 7a736cc..e5cb487 100644
--- a/gcc/config/elfos.h
+++ b/gcc/config/elfos.h
@@ -68,6 +68,14 @@  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 
 #define DWARF2_DEBUGGING_INFO 1
 
+/* All ELF targets can support CTF.  */
+
+#define CTF_DEBUGGING_INFO 1
+
+/* All ELF targets can support BTF.  */
+
+#define BTF_DEBUGGING_INFO 1
+
 /* The GNU tools operate better with dwarf2, and it is required by some
    psABI's.  Since we don't have any native tools to be compatible with,
    default to dwarf2.  */
diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf.exp b/gcc/testsuite/gcc.dg/debug/btf/btf.exp
index e173515..a3e680c 100644
--- a/gcc/testsuite/gcc.dg/debug/btf/btf.exp
+++ b/gcc/testsuite/gcc.dg/debug/btf/btf.exp
@@ -39,8 +39,15 @@  if ![info exists DEFAULT_CFLAGS] then {
 dg-init
 
 # Main loop.
-dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
-	"" $DEFAULT_CFLAGS
+set comp_output [gcc_target_compile \
+    "$srcdir/$subdir/../trivial.c" "trivial.S" assembly \
+    "additional_flags=-gbtf"]
+if { ! [string match "*: target system does not support the * debug format*" \
+    $comp_output] } {
+    remove-build-file "trivial.S"
+    dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
+	    "" $DEFAULT_CFLAGS
+}
 
 # All done.
 dg-finish
diff --git a/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp b/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp
index 0b650ed..c53cd8b 100644
--- a/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp
+++ b/gcc/testsuite/gcc.dg/debug/ctf/ctf.exp
@@ -39,8 +39,15 @@  if ![info exists DEFAULT_CFLAGS] then {
 dg-init
 
 # Main loop.
-dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
-	"" $DEFAULT_CFLAGS
+set comp_output [gcc_target_compile \
+    "$srcdir/$subdir/../trivial.c" "trivial.S" assembly \
+    "additional_flags=-gctf"]
+if { ! [string match "*: target system does not support the * debug format*" \
+    $comp_output] } {
+    remove-build-file "trivial.S"
+    dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.\[cS\] ]] \
+	    "" $DEFAULT_CFLAGS
+}
 
 # All done.
 dg-finish
diff --git a/gcc/toplev.c b/gcc/toplev.c
index 43f1f7d..8103812 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1463,8 +1463,15 @@  process_options (void)
     debug_hooks = &xcoff_debug_hooks;
 #endif
 #ifdef DWARF2_DEBUGGING_INFO
-  else if (dwarf_debuginfo_p ()
-	   || dwarf_based_debuginfo_p ())
+  else if (dwarf_debuginfo_p ())
+    debug_hooks = &dwarf2_debug_hooks;
+#endif
+#ifdef CTF_DEBUGGING_INFO
+  else if (write_symbols & CTF_DEBUG)
+    debug_hooks = &dwarf2_debug_hooks;
+#endif
+#ifdef BTF_DEBUGGING_INFO
+  else if (btf_debuginfo_p ())
     debug_hooks = &dwarf2_debug_hooks;
 #endif
 #ifdef VMS_DEBUGGING_INFO