-mstackrealign causes stack corruption on MinGW. And without it the ability
to use SSE instrinsics goes down the drain. Even if we use
__attribute__((force_align_arg_pointer)) for the functions we explicitly
use SSE instrinsics, the SSE code automatically generated by gcc will
cause assertion failures. What a nightmare.
Thankfully LLVM gets this right, so all runtime generated SSE code just
works. rtasm code doesn't assume 16byte alignment. Therefore the bulk of
our performance sensitive code is not affected by this.
Still, intrinsics can be convenient, and it would be nice
to get this working again some day, sp will try to get a reduced test
case.
gprof is useful for shared libraries, hence our drivers. Nevertheless
profilers like oprofile can benefit from disabling some relatively
minor optimizations for more accurate / complete results.
gcc-4.2's optimizer has a strange bug where it looses code from inner
loops in certain situations. For example, if the appearently innocent
looking code below is compiled with gcc-4.2 -S -O1, the inner loop's
code is missing from the outputed assembly.
struct Size {
unsigned width;
};
struct Command {
unsigned length;
struct Size sizes[32];
};
extern void emit_command(void *command, unsigned length);
void
create_surface( struct Size size, unsigned faces, unsigned levels)
{
struct Command cmd;
unsigned face;
unsigned level;
cmd.length = faces*levels*sizeof(cmd.sizes[0]);
for(face = 0; face < faces; ++face) {
for(level = 0; level < levels; ++level) {
cmd.sizes[face*levels + level] = size;
// This should generate a shrl statement, but the whole for body
// disappears in gcc-4.2 -O1/-O2/-O3!
size.width >>= 1;
}
}
emit(&cmd, sizeof cmd.length + cmd.length);
}
Note that this is not specific to MinGW's gcc-4.2 crosscompiler (the
version typically found in debian/ubuntu's mingw32 packages). gcc-4.2 on
Linux also displays the same error. gcc-4.3 and above gets this
correctly though.
Updated MinGW debian packages with gcc-4.3 are available from
http://people.freedesktop.org/~jrfonseca/debian/pool/main/m/
This prevents the error
relocation R_X86_64_PC32 against symbol `_gl_DispatchTSD' can not be used when making a shared object; recompile with -fPIC
when building on x86_64 architecture.
It a scary world out there: people use all sort of non standard C stuff,
and we must enable support for that in here in order to build.
-pedantic still warn us when we use that nonstandard though.
MSVC may not support full C99, but supports more than plain C90. And
-pedantic without -std=c99 generates too many spurious warnings
(specially C++ style comments) to be of any use.
Note that using certain C99 features in the cross-platform parts of Gallium
is still not possible; namely mid-of-scope variable declarations and named
structure initializers will break MSVC builds.
MSVC may not support full C99, but supports more than plain C90. And
-pedantic without -std=c99 generates too many spurious warnings
(specially C++ style comments) to be of any use.
Note that using certain C99 features in the cross-platform parts of Gallium
is still not possible; namely mid-of-scope variable declarations and named
structure initializers will break MSVC builds.
To build an alternative opengl32.dll with Gallium's software-rasterizer from a
debian-based distribution run:
sudo apt-get install mingw32
scons platform=windows toolchain=crossmingw machine=x86 winsys=gdi dri=no
To build an alternative opengl32.dll with Gallium's software-rasterizer from a
debian-based distribution run:
sudo apt-get install mingw32
scons platform=windows toolchain=crossmingw machine=x86 winsys=gdi dri=no
