[Bug c/18213] New: New inline heuristic make binary bigger (single call site)

[jt at hpl dot hp dot com]

Hi,

    I was just upgrading from gcc-2.95 to gcc-3.3.4 (yeah, I'm way behind).
While recompiling my favorite package (Wireless Tools for Linux), I noticed that
gcc was giving me many warning of the type "warning: inlining failed". And the
resulting binary were bigger than with the previous version of gcc.
    My package is used in various embedded systems, therefore I compile with -Os
and always watch the size.
    Then, I added "__attribute__((always_inline))" to my code, recompiled with
gcc-3.3.4, and the resulting binary was 150B *smaller* than the default
gcc-3.3.4 compile, which is almost a 1% saving (with no loss of functionality).
So, the new inline behaviour is making the binary bigger.

    I personally prefer to defer optimisations to compiler, and I would prefer
not to tag functions inline, but I've noticed that gcc is not capable of
automatically inlining functions that have a single call site. And the new
heuristic make it even more difficult to happen properly, I don't really like
the idea of adding "__attribute__((always_inline))" everywhere.
    I would actually like gcc to automatically inline static functions with a
single call site, possibly even if they are not marked inline, as keeping track
of all the call sites of all functions is pretty tedious...

    Thanks in advance...

    Jean

-- 
           Summary: New inline heuristic make binary bigger (single call
                    site)
           Product: gcc
           Version: 3.3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jt at hpl dot hp dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386-linux
  GCC host triplet: i386-linux
GCC target triplet: i386-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18213