Opened 10 years ago
Last modified 9 years ago
#4474 open defect
Some inline asm code does not compile on Haiku 32-bit with GCC 4
Reported by: | Timothy Gu | Owned by: | |
---|---|---|---|
Priority: | normal | Component: | build system |
Version: | git-master | Keywords: | haiku |
Cc: | Michael Niedermayer | Blocked By: | |
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description
Summary of the bug
FFmpeg does not compile on Haiku 32-bit out-of-the-box.
How to reproduce
Clone FFmpeg.
Configure with --enable-gpl
(but that shouldn't matter).
Make.
CC libavfilter/x86/vf_noise.o libavfilter/x86/vf_noise.c: In function 'line_noise_avg_mmx': libavfilter/x86/vf_noise.c:62:5: error: 'asm' operand has impossible constraints __asm__ volatile( ^ make: *** [libavfilter/x86/vf_noise.o] Error 1
Workarounds
- Configure with
--disable-inline-asm
- Manually define
HAVE_6REGS
orHAVE_EBP_AVAILABLE
to 0. - Manually set
CFLAGS
to-fno-PIC
(Haiku uses PIC by default so to disable it one has to explicitly add-fno-PIC
)
Interesting parts in config.log
check_ld cc check_cc BEGIN /tmp/ffconf.uJdXoo5E.c 1 #include <signal.h> 2 static void sighandler(int sig){ 3 raise(SIGTERM); 4 } 5 int foo(void){ 6 volatile int i=0; 7 __asm__ volatile ("xorl %%ebp, %%ebp" ::: "%ebp"); 8 return i; 9 } 10 int (*func_ptr)(void) = foo; 11 int main(void){ 12 signal(SIGILL, sighandler); 13 signal(SIGFPE, sighandler); 14 signal(SIGSEGV, sighandler); 15 #ifdef SIGBUS 16 signal(SIGBUS, sighandler); 17 #endif 18 return func_ptr(); 19 } END /tmp/ffconf.uJdXoo5E.c gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DPIC -std=c99 -fomit-frame-pointer -fPIC -c -o /tmp/ffconf.47o9YaJR.o /tmp/ffconf.uJdXoo5E.c gcc -o /tmp/ffconf.L9dLDbtf /tmp/ffconf.47o9YaJR.o check_inline_asm ebx_available ""::"b"(0) check_cc BEGIN /tmp/ffconf.uJdXoo5E.c 1 void foo(void){ __asm__ volatile(""::"b"(0)); } END /tmp/ffconf.uJdXoo5E.c gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DPIC -std=c99 -fomit-frame-pointer -fPIC -c -o /tmp/ffconf.47o9YaJR.o /tmp/ffconf.uJdXoo5E.c /tmp/ffconf.uJdXoo5E.c: In function 'foo': /tmp/ffconf.uJdXoo5E.c:1:17: error: inconsistent operand constraints in an 'asm' void foo(void){ __asm__ volatile(""::"b"(0)); } ^
Compiler version
gcc (2014_12_21) 4.8.4 Copyright (C) 2013 Free Software Foundation, Inc.
Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.
I know.
Change History (12)
follow-up: 4 comment:1 by , 10 years ago
follow-up: 3 comment:2 by , 10 years ago
Is libavfilter/x86/vf_noise.c the only failing file or are there others?
Even gcc 2.95.3 succeeds in compiling this file here on Linux without ebx (with --enable-pic).
Do the functions under HAVE_7REGS succeed compilation when you disable pic?
follow-up: 6 comment:3 by , 10 years ago
Replying to cehoyos:
Is libavfilter/x86/vf_noise.c the only failing file or are there others?
If I use make -k
libpostproc/postprocess.o errors out as well. I'm not sure about others.
Even gcc 2.95.3 succeeds in compiling this file here on Linux without ebx (with --enable-pic).
In my Haiku nightly gcc 2.95.3 crashes multiple times during the compilation.
Do the functions under HAVE_7REGS succeed compilation when you disable pic?
They are not compiled as EBX is detected as not available. (Which is correct.)
comment:4 by , 10 years ago
Replying to michael:
Is there a disadvantange in fno-PIC on haiku for 32bit x86 ?
I don't know, but Haiku's official build use -fno-PIC
with shared library it seems. (Not sure how that's supposed to work but…)
if no then nopic could be forced fr 32bit x86. I assume shared libs still work then ?
I don't know. I'll try.
comment:5 by , 10 years ago
Configuration | shared | static |
---|---|---|
--extra-cflags='-fno-PIC' | compiles correctly links correctly EBP available EBX available | compiles correctly EBP available EBX available |
vanilla | fails to compile EBP available according to configure EBX not available |
I'll have FATE running soon so that should be the final say on whether to enable -fno-PIC
by default on Haiku 32-bit.
follow-up: 7 comment:6 by , 10 years ago
Replying to Timothy_Gu:
Do the functions under HAVE_7REGS succeed compilation when you disable pic?
They are not compiled as EBX is detected as not available. (Which is correct.)
I thought EBX is not available because pic gets enabled and gets available if pic is disabled? Is that not true for Haiku?
Another question is if the test for EBP works on Haiku (it does not work for icc): How does the asm look like?
comment:7 by , 10 years ago
Replying to cehoyos:
Replying to Timothy_Gu:
Do the functions under HAVE_7REGS succeed compilation when you disable pic?
They are not compiled as EBX is detected as not available. (Which is correct.)
I thought EBX is not available because pic gets enabled and gets available if pic is disabled? Is that not true for Haiku?
It is true. Haiku enables PIC for all objects by default, including those for static libraries.
Another question is if the test for EBP works on Haiku (it does not work for icc): How does the asm look like?
Getting it right now.
comment:8 by , 10 years ago
Update: -fno-PIC
does NOT fix the problem when it is used in configure, but when it is used with make
. This is because when it is used in configure HAVE_7REGS
is defined, which doesn't work.
For the EBP test, it does not compile with gcc
:
bp cannot be used in asm here
But FFmpeg automatically adds -fomit-frame-pointer
, which allows it to compile, and generate the following asm:
foo: pushl %ebp subl $16, %esp movl $0, 12(%esp) /APP # 7 "test.c" 1 xorl %ebp, %ebp # 0 "" 2 /NO_APP movl 12(%esp), %eax addl $16, %esp popl %ebp
comment:9 by , 10 years ago
I can only guess that Haiku manages to clobber one more register apart from ebp and ebx.
comment:10 by , 10 years ago
But back to vf_noise.c
. If I comment out this part compilation succeeds. But if I even call any function (including a noop function I created) with a variable as argument compilation fails.
A reduced test case is below:
// gcc -m32 -fPIC -fomit-frame-pointer void noop() {} void line_noise_avg_mmx(int src) { int var = 0; __asm__ volatile( "addl #2, %0" :: "r" (src+1), "r" (src+2), "r" (src+3), "r" (src+4), "r" (src+5), "g" (src+6) : "%eax" ); // Doesn't compile on Haiku. // noop(var); noop(); // this compiles }
The odd thing is that GCC on Ubuntu (4.8.2) and on haiku (4.8.4) generates the exact same assembly with noop()
, but Haiku errors out on noop(var)
.
GCC on Ubuntu seems to add these two instructions right after the exit of inline asm:
movl 28(%esp), %eax # 28(%esp) seems to be `var` movl %eax , (%esp)
and Haiku GCC for some reason is simply too dumb to figure this out of everything, out.
comment:11 by , 10 years ago
Cc: | added |
---|---|
Status: | new → open |
You could disable the functions which fail to build on haiku with some #if !HAIKU, iam not sure how to detect haiku ...
or something like this could be added:
--- a/configure +++ b/configure @@ -5622,6 +5622,7 @@ enabled threads && ! enabled pthreads && ! enabled atomics_native && die "non pt if test $target_os = "haiku"; then disable memalign disable posix_memalign + disable ebp_available # gcc 4.8.4 (2014_12_21) on haiku at least fails if ebp is used fi enabled_all d3d11va d3d11_cobj CoTaskMemFree &&
I can apply this but i suspect the problem is between the compiler and the individual functions and its more a coincidence that ebp_available = 0 catches all
the "g" (-mmx_len)
looks suspicous as a potential cause, the compiler here must be capable to put the intermediate negated variable in memory to avoid the need for another register
Is there a disadvantange in fno-PIC on haiku for 32bit x86 ?
if no then nopic could be forced fr 32bit x86. I assume shared libs still work then ?