[Bug c/16355] New: Duplicate function epilog

["anton at samba dot org" <gcc-bugzilla at gcc dot gnu dot org>]

A 3.5 powerpc64 toolchain from cvs (20040703) was used to compile a linux
kernel. I noticed some functions had more than one function epilog. A cut down
testcase is:

int foo(a)
{
        if (a)
                return 1;
#if 1
        bar();
#endif
        return 0;
}

When the call to bar() is present we get 2 function epilogs:

.foo:
        cmpdi 7,3,0
        mflr 0
        li 3,1
        std 0,16(1)
        stdu 1,-112(1)
        beq- 7,.L6
        addi 1,1,112
        ld 0,16(1)
        mtlr 0
        blr
.L6:
        bl .bar
        nop
        addi 1,1,112
        li 3,0
        ld 0,16(1)
        mtlr 0
        blr

We only duplicate 4 instructions here, but on functions which spill a large
number of registers the duplication is worse.

-- 
           Summary: Duplicate function epilog
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: anton at samba dot org
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: powerpc64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16355