Hi,

Due to there being no multilib mapping for Armv8-R, default multilib
targeting -march=armv4t with softfloat floating-point arithmetic is
being used. This patch maps it instead to the existing Armv7 multilibs.
Note that since there is no single-precision multilib compatible with
R profile, -march=armv8-r+fp.sp is mapped to -march=armv7 ie. Armv7
with softfloat floating-point.

Changelog entry is as follows:

*** gcc/ChangeLog ***

2018-02-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* config/arm/t-multilib: Map Armv8-R to Armv7 multilibs.

Testing:

Ran -print-multi-directory for all combinations of extensions one can
pass to -march=armv8-r (including no extension but only considering a
single ordering of extension). All gave the expected result. Details in
appendix.

Is this ok for stage4?

Best regards,

Thomas

Appendix: output of -print-multi-directory for all extensions available
to -march=armv8-r

% for ext in "" +crc +fp.sp +simd +crypto +crc+fp.sp +crc+simd +crc+crypto 
+fp.sp+simd +fp.sp+crypto +simd+crypto +crc+fp.sp+simd +crc+fp.sp+crypto 
+crc+simd+crypto +fp.sp+simd+crypto +crc+fp.sp+simd+crypto ; do 
cmd="arm-none-eabi-gcc -march=armv8-r${ext} -mfloat-abi=soft 
-print-multi-directory" ; echo -n "$cmd: " ; eval $cmd ; done
arm-none-eabi-gcc -march=armv8-r -mfloat-abi=soft -print-multi-directory: 
thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc -mfloat-abi=soft -print-multi-directory: 
thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+fp.sp -mfloat-abi=soft -print-multi-directory: 
thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+simd -mfloat-abi=soft -print-multi-directory: 
thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crypto -mfloat-abi=soft -print-multi-directory: 
thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+simd -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+crypto -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+fp.sp+simd -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+fp.sp+crypto -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+simd+crypto -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+simd -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+crypto -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+simd+crypto -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+fp.sp+simd+crypto -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+simd+crypto -mfloat-abi=soft 
-print-multi-directory: thumb/v7/nofp

% for ext in "" +crc +fp.sp +simd +crypto +crc+fp.sp +crc+simd +crc+crypto 
+fp.sp+simd +fp.sp+crypto +simd+crypto +crc+fp.sp+simd +crc+fp.sp+crypto 
+crc+simd+crypto +fp.sp+simd+crypto +crc+fp.sp+simd+crypto ; do 
cmd="arm-none-eabi-gcc -march=armv8-r${ext} -mfloat-abi=softfp 
-print-multi-directory" ; echo -n "$cmd: " ; eval $cmd ; done
arm-none-eabi-gcc -march=armv8-r -mfloat-abi=softfp -print-multi-directory: 
thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc -mfloat-abi=softfp -print-multi-directory: 
thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+fp.sp -mfloat-abi=softfp 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+simd -mfloat-abi=softfp -print-multi-directory: 
thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp -mfloat-abi=softfp 
-print-multi-directory: thumb/v7/nofp
arm-none-eabi-gcc -march=armv8-r+crc+simd -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+crc+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+fp.sp+simd -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+fp.sp+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+simd+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+simd -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+crc+simd+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+fp.sp+simd+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+simd+crypto -mfloat-abi=softfp 
-print-multi-directory: thumb/v7+fp/softfp

% for ext in "" +crc +fp.sp +simd +crypto +crc+fp.sp +crc+simd +crc+crypto 
+fp.sp+simd +fp.sp+crypto +simd+crypto +crc+fp.sp+simd +crc+fp.sp+crypto 
+crc+simd+crypto +fp.sp+simd+crypto +crc+fp.sp+simd+crypto ; do 
cmd="arm-none-eabi-gcc -march=armv8-r${ext} -mfloat-abi=hard 
-print-multi-directory" ; echo -n "$cmd: " ; eval $cmd ; done
arm-none-eabi-gcc -march=armv8-r -mfloat-abi=hard -print-multi-directory: .
arm-none-eabi-gcc -march=armv8-r+crc -mfloat-abi=hard -print-multi-directory: .
arm-none-eabi-gcc -march=armv8-r+fp.sp -mfloat-abi=hard -print-multi-directory: .
arm-none-eabi-gcc -march=armv8-r+simd -mfloat-abi=hard -print-multi-directory: 
thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+crypto -mfloat-abi=hard -print-multi-directory: 
thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp -mfloat-abi=hard 
-print-multi-directory: .
arm-none-eabi-gcc -march=armv8-r+crc+simd -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+crc+crypto -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+fp.sp+simd -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+fp.sp+crypto -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+simd+crypto -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+simd -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+crypto -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+crc+simd+crypto -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+fp.sp+simd+crypto -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard
arm-none-eabi-gcc -march=armv8-r+crc+fp.sp+simd+crypto -mfloat-abi=hard 
-print-multi-directory: thumb/v7+fp/hard