Bug#299188: gcc: -ffreestanding and builtins don't work as expected

[Adrian Bunk <bunk@stusta.de>]

Package: gcc-3.4
Version: 3.4.3-11
Severity: normal


The info file says:


<--  snip  -->

     With the `-fno-builtin-FUNCTION' option only the built-in function
     FUNCTION is disabled.  FUNCTION must not begin with `__builtin_'.
     If a function is named this is not built-in in this version of
     GCC, this option is ignored.  There is no corresponding
     `-fbuiltin-FUNCTION' option; if you wish to enable built-in
     functions selectively when using `-fno-builtin' or
     `-ffreestanding', you may define macros such as:

          #define abs(n)          __builtin_abs ((n))
          #define strcpy(d, s)    __builtin_strcpy ((d), (s))

<--  snip  -->


But:


<--  snip  -->

$ cat test.c 

#define sprintf __builtin_sprintf

int main()
{
  char str[] = "abc";
  char buf[10];

  sprintf(buf,"%s",str);

  return 0;
}

$ gcc-3.4 -S -ffreestanding -Wall test.c
$ cat test.s
        .file   "test.c"
        .section        .rodata
.LC0:
        .string "abc"
        .text
.globl main
        .type   main, @function
main:
        pushl   %ebp
        movl    %esp, %ebp
        subl    $40, %esp
        andl    $-16, %esp
        movl    $0, %eax
        addl    $15, %eax
        addl    $15, %eax
        shrl    $4, %eax
        sall    $4, %eax
        subl    %eax, %esp
        movl    .LC0, %eax
        movl    %eax, -12(%ebp)
        subl    $8, %esp
        leal    -12(%ebp), %eax
        pushl   %eax
        leal    -40(%ebp), %eax
        pushl   %eax
        call    strcpy
        addl    $16, %esp
        movl    $0, %eax
        leave
        ret
        .size   main, .-main
        .section        .note.GNU-stack,"",@progbits
        .ident  "GCC: (GNU) 3.4.4 20050305 (prerelease) (Debian 3.4.3-11)"
$

<--  snip  -->


As far as I understand the documentation, the call to strcpy
shouldn't be emitted since this function is not required in a
freestanding environment.

gcc-3.3 and gcc-4.0 behave similar.

I'm not sure whether this is expected, but if it is, the documentation
should be updated.



-- System Information:
Debian Release: 3.1
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: i386 (i686)
Kernel: Linux 2.6.11-mm2
Locale: LANG=en_US, LC_CTYPE=en_US (charmap=ISO-8859-1)

Versions of packages gcc-3.4 depends on:
ii  binutils                    2.15-5       The GNU assembler, linker and bina
ii  cpp-3.4                     3.4.3-11     The GNU C preprocessor
ii  gcc-3.4-base                3.4.3-11     The GNU Compiler Collection (base 
ii  libc6                       2.3.2.ds1-20 GNU C Library: Shared libraries an
ii  libgcc1                     1:4.0-0pre5  GCC support library

-- no debconf information