[Pixman] Basic infrastructure for MIPS architecture and initial set of SRC routines.

[Matt Turner]

On Tue, Feb 21, 2012 at 1:05 PM, Siarhei Siamashka
<siarhei.siamashka at gmail.com> wrote:
> On Tue, Feb 21, 2012 at 4:59 PM, Nemanja Lukic <nlukic at mips.com> wrote:
>>
>> Per previous code review:
>>
>> Run time detection is still there (per Siarhei's comments), uses /proc/cpuinfo,
>> but now properly detects DSPr2 extensions and 32 byte cache line size (both are
>> true only for MIPS 74Kc cores).
>>  - Currently only 74Kc core is available that supports DSPr2.
>>  - In the future, when M14KE, 1074Kc cores (and others) become available we
>>    can add those also to the search string.
>
> One practical problem is that my MIPS router has the following line in
> /proc/cpuinfo:
>    cpu model           : MIPS 74K V4.0
>
> Yes, unfortunately this router does not run a mainline kernel, but
> searching for "MIPS 74K" instead of "MIPS 74Kc" could be used as a
> workaround. As an additional bonus, it could also match "MIPS 74Kf".
>
>> -mdspr2 compiler flag is automatically enabled for MIPS platforms. It can be
>> disabled at configure time for chips that doesn't support it.
>
> Apparently this is not enough to ensure a successful build:
>
> $ ./autogen.sh && ./configure --disable-shared && make V=99
>
> <snip>
>
> checking whether to use MMX intrinsics... no
> checking whether to use SSE2 intrinsics... no
> checking whether to use VMX/Altivec intrinsics... no
> checking whether to use ARM SIMD assembler... no
> checking whether to use ARM NEON assembler... no
> checking whether to use ARM IWMMXT intrinsics... no
> checking whether to use MIPS DSPr2 assembler... yes
> checking whether to use GNU-style inline assembler... yes
>
> <snip>
>
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -Wall
> -fno-strict-aliasing -fvisibility=hidden -MT pixman-utils.lo -MD -MP
> -MF .deps/pixman-utils.Tpo -c pixman-utils.c -o pixman-utils.o
> mv -f .deps/pixman-utils.Tpo .deps/pixman-utils.Plo
> /bin/sh ../libtool  --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H -I.
> -I..     -mdspr2 -g -O2 -Wall -fno-strict-aliasing -fvisibility=hidden
> -MT libpixman_mips_dspr2_la-pixman-mips-dspr2.lo -MD -MP -MF
> .deps/libpixman_mips_dspr2_la-pixman-mips-dspr2.Tpo -c -o
> libpixman_mips_dspr2_la-pixman-mips-dspr2.lo `test -f
> 'pixman-mips-dspr2.c' || echo './'`pixman-mips-dspr2.c
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -mdspr2 -g -O2 -Wall
> -fno-strict-aliasing -fvisibility=hidden -MT
> libpixman_mips_dspr2_la-pixman-mips-dspr2.lo -MD -MP -MF
> .deps/libpixman_mips_dspr2_la-pixman-mips-dspr2.Tpo -c
> pixman-mips-dspr2.c -o libpixman_mips_dspr2_la-pixman-mips-dspr2.o
> Assembler messages:
> Warning: mips1 ISA does not support DSP ASE
> Warning: mips1 ISA does not support DSP R2 ASE
> mv -f .deps/libpixman_mips_dspr2_la-pixman-mips-dspr2.Tpo
> .deps/libpixman_mips_dspr2_la-pixman-mips-dspr2.Plo
> /bin/sh ../libtool    --mode=compile gcc -DHAVE_CONFIG_H -I. -I..
> -g -O2 -mdspr2 -MT pixman-mips-dspr2-asm.lo -MD -MP -MF
> .deps/pixman-mips-dspr2-asm.Tpo -c -o pixman-mips-dspr2-asm.lo
> pixman-mips-dspr2-asm.S
> libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -mdspr2 -MT
> pixman-mips-dspr2-asm.lo -MD -MP -MF .deps/pixman-mips-dspr2-asm.Tpo
> -c pixman-mips-dspr2-asm.S -o pixman-mips-dspr2-asm.o
> Assembler messages:
> Warning: mips1 ISA does not support DSP ASE
> Warning: mips1 ISA does not support DSP R2 ASE
> pixman-mips-dspr2-asm.S:70: Error: opcode not supported on this
> processor: mips1 (mips1) `ext $9,$8,0x3,0x5'
> pixman-mips-dspr2-asm.S:116: Error: opcode not supported on this
> processor: mips1 (mips1) `ext $10,$8,0x2,0x3'
> pixman-mips-dspr2-asm.S:146: Error: opcode not supported on this
> processor: mips1 (mips1) `pref 0,32($5)'
> pixman-mips-dspr2-asm.S:164: Error: opcode not supported on this
> processor: mips1 (mips1) `pref 30,32($4)'
> make[2]: *** [pixman-mips-dspr2-asm.lo] Error 1
>
>
> This issue can be resolved by adding the following directives to the
> assembly files, so that adding extra compiler flags is not even
> needed:
>
> .set arch=mips32r2
> .set dspr2

How does this affect compiling with -march=mips64{,r2}, assuming that
there are mips64 CPUs with DSPr2?

All this seem like a ton of work to deal with the unsolved problem of
mips runtime testing. Wouldn't it be simpler to just have the
configure test fail if you're not compiling with the needed CFLAGS?
Any distro wanting maximum compatibility is going to compile with
mips1, which is incompatible with DSPr2.