[FFmpeg-devel] fft_mmx.asm yasm 64bit build broken
Sat Aug 16 18:41:12 CEST 2008
D <lessen42 at gmail.com> writes:
> On Aug 16, 2008, at 11:59 AM, Robert Swain wrote:
>> 2008/8/16 M?ns Rullg?rd <mans at mansr.com>:
>>> vmrsss <vmrsss at gmail.com> writes:
>>>> On 16 Aug 2008, at 15:49, M?ns Rullg?rd wrote:
>>>>> Ask Apple if they can fix the system. We don't know.
>>>> What do you mean? Doesn't look like a Apple problem at all...
>>>>> error: macho: sorry, cannot apply 32 bit absolute relocations in 64
>>>>> bit mode, consider "[_symbol wrt rip]" for mem access, "qword" and
>>>>> "dq _foo" for pointers.
>>> This is an Apple problem. Since the same code works on the same
>>> hardware under Linux, it follows that it must be an Apple problem if
>>> it doesn't work in MacOS. In fact, code like this used to work just
>>> fine with older versions of the Apple linker. Sorry, but you're
>>> barking up the wrong tree.
>> I don't think this is that linker issue about text relocations. The
>> errors are being spewed by yasm, are they not?
> Indeed, from yasm's macho-objfmt.c:
> 2.2) data referencing in 64 bit mode
> While ELF allows 32 bit absolute relocations in 64 bit mode,
> does not. Therefore code like
> lea rbx,[_foo] ;48 8d 1c 25 00 00 00 00
> mov rcx,[_bar] ;48 8b 0c 25 00 00 00 00
> with a 32 bit address field cannot be relocated into an address
> >= 0x100000000 (OSX actually uses that).
> Actually, the only register where a 64 bit displacement is
> allowed in
> x86-64, is rax as in the example 1).
> A plausible workaround is either classic PIC (like in C),
> which is in turn
> not implemented in this object format. The recommended was is
> PC relative
> code (called RIP-relative in x86-64). So instead of the lines
> above, just write:
> lea rbx,[_foo wrt rip]
> mov rcx,[_bar wrt rip]
> x264 uses -DPIC unconditionally for asm code in the x86_64/macho case.
> Additionally, ffmpeg was using macho rather than macho64 in this case.
> The attached patch the ffmpeg build on x86_64/darwin.
> diff --git a/configure b/configure
> index 479105c..6195d81 100755
> --- a/configure
> +++ b/configure
> @@ -1262,6 +1262,7 @@ case $target_os in
> + enabled x86_64 && objformat="macho64"
> @@ -1561,6 +1562,7 @@ EOF
> enabled_all x86_64 shared && append YASMFLAGS "-DPIC"
> case "$objformat" in
> elf) enabled debug && append YASMFLAGS "-g dwarf2" ;;
> + macho64) append YASMFLAGS "-DPIC -DPREFIX" ;;
> *) append YASMFLAGS "-DPREFIX" ;;
> check_yasm "pabsw xmm0, xmm0" && enable yasm
Can someone confirm that this fixes the problem? If so, patch OK.
mans at mansr.com
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