[Bug rtl-optimization/38854] New: missed optimization with -m32: empty functions shouldn't contain push/mov/pop

[edwintorok at gmail dot com]

Testcase:
void noop(char* foo) {}

For 64-bit it does the right thing:
$ gcc -O2 foo.c -S

Output is:
noop:
.LFB2:
        rep
        ret

However for 32-bit it has useless extra instructions:
$ gcc -m32 -O2 foo.c -S

noop:
        pushl   %ebp
        movl    %esp, %ebp
        popl    %ebp
        ret

The push/mov/pop should be removed.

I tested this with gcc-4.2, 4.3, and 4.4(trunk revision 143382), all produce
same code.


-- 
           Summary: missed optimization with -m32: empty functions shouldn't
                    contain push/mov/pop
           Product: gcc
           Version: 4.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: edwintorok at gmail dot com
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38854