Re: Patch to allow strlen expander to fail

["Martin v. Loewis" <martin at loewis dot home dot cs dot tu-berlin dot de>]

> I probably should go to sleep - flag_hosted == 0 implies flag_no_builtin
> - so it should work correctly.  The Linux makefile(s) simply have to
> specify -ffreestanding to get this to work correctly.

Not quite:

loewis 37 ( ~/tmp ) > cat a.c
struct X{
  long foo[16];
};

void docopy(struct X* a,struct X* b)
{
  *b=*a;
}

loewis 38 ( ~/tmp ) > gcc -v
Reading specs from gnu/lib/gcc-lib/sparc-sun-solaris2.5.1/2.96/specs
gcc version 2.96 20000228 (experimental)

loewis 39 ( ~/tmp ) > gcc -S -O2 -ffreestanding a.c

loewis 40 ( ~/tmp ) > cat a.s
        .file   "a.c"
gcc2_compiled.:
.section        ".text"
        .align 4
        .global docopy
        .type    docopy,#function
        .proc   020
docopy:
        !#PROLOGUE# 0
        save    %sp, -112, %sp
        !#PROLOGUE# 1
        mov     %i1, %o0
        mov     %i0, %o1
        call    memcpy, 0
        mov     64, %o2
        ret
        restore
.LLfe1:
        .size    docopy,.LLfe1-docopy
        .ident  "GCC: (GNU) 2.96 20000228 (experimental)"

so it generated a memcpy call even with -ffreestanding. This is
because of (what I consider) a bug in gcc, which emits a call to
memcpy even when asked not to. The technical reason is that
-fno-builtin only disables availability of inline-optimizations for
user memcpy calls - the memcpy call generated by the block mover is
hard-coded, and does not care about freestanding or not.

Regards,
Martin