Re: [PATCH v3 6/6] opts: allow any combination of DWARF, CTF, BTF

[Indu Bhagat]

On 5/30/24 14:32, David Faust wrote:
Previously it was not supported to generate both CTF and BTF debug info
in the same compiler run, as both formats made incompatible changes to
the same internal data structures.
With the structural change in the prior patches, in particular the
guarantee that CTF will always be fully emitted before any BTF
translation occurs, there is no longer anything preventing generation
of both CTF and BTF at the same time.  This patch changes option parsing
to allow any combination of -gdwarf, -gctf, and -gbtf at the same time.


I am not an approver for this change, but I have a comment below.

gcc/
        * opts.cc (set_debug_level): Allow any combination of -gdwarf,
        -gctf and -gbtf at the same time.
---
  gcc/opts.cc | 20 +++++++-------------
  1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/gcc/opts.cc b/gcc/opts.cc
index f80d5d4ba8f9..d58bea096a5f 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -3505,21 +3505,15 @@ set_debug_level (uint32_t dinfo, int extended, const 
char *arg,
      }
    else
      {
-      /* Make and retain the choice if both CTF and DWARF debug info are to
-        be generated.  */
-      if (((dinfo == DWARF2_DEBUG) || (dinfo == CTF_DEBUG))
+      /* Any combination of DWARF, CTF and BTF is allowed together.  */
+      if (((dinfo == DWARF2_DEBUG) || (dinfo == CTF_DEBUG)
+          || (dinfo == BTF_DEBUG))
          && ((opts->x_write_symbols == (DWARF2_DEBUG|CTF_DEBUG))
+             || (opts->x_write_symbols == (DWARF2_DEBUG|BTF_DEBUG))
+             || (opts->x_write_symbols == (CTF_DEBUG|BTF_DEBUG))
              || (opts->x_write_symbols == DWARF2_DEBUG)
-             || (opts->x_write_symbols == CTF_DEBUG)))
-       {
-         opts->x_write_symbols |= dinfo;
-         opts_set->x_write_symbols |= dinfo;
-       }
-      /* However, CTF and BTF are not allowed together at this time.  */
-      else if (((dinfo == DWARF2_DEBUG) || (dinfo == BTF_DEBUG))
-              && ((opts->x_write_symbols == (DWARF2_DEBUG|BTF_DEBUG))
-                  || (opts->x_write_symbols == DWARF2_DEBUG)
-                  || (opts->x_write_symbols == BTF_DEBUG)))
+             || (opts->x_write_symbols == CTF_DEBUG)
+             || (opts->x_write_symbols == BTF_DEBUG)))

I realised that this check will cause failures on double occurrences of 
the command line flags:

$ gcc -c sort.c -g3 -gctf -flto -gbtf -gctf
gcc: error: debug format ‘ctf’ conflicts with prior selection

What do you think about the following check instead ?

if ((dinfo == DWARF2_DEBUG || dinfo == CTF_DEBUG || dinfo == BTF_DEBUG)
    && ((opts->x_write_symbols | (DWARF2_DEBUG|CTF_DEBUG|BTF_DEBUG))
        == (DWARF2_DEBUG|CTF_DEBUG|BTF_DEBUG)))
  {

We have some testcases for checking -gctf -gdwarf (in 
debug/ctf/ctf-debug*), adding something for -gctf -gbtf will be great.

        {
          opts->x_write_symbols |= dinfo;
          opts_set->x_write_symbols |= dinfo;