>> 2012-12-04  Marc Glisse  <marc.glisse@inria.fr>
>>
>>         PR target/54855
>> gcc/
>>         * simplify-rtx.c (simplify_binary_operation_1) <VEC_CONCAT>: Replace
>>         with VEC_MERGE.
>>
>>         * config/i386/sse.md (<sse>_vm<plusminus_insn><mode>3): Rewrite
>>         pattern.
>>         * config/i386/i386-builtin-types.def: New function types.
>>         * config/i386/i386.c (ix86_expand_args_builtin): Likewise.
>>         (bdesc_args) <__builtin_ia32_addss, __builtin_ia32_subss,
>>         __builtin_ia32_addsd, __builtin_ia32_subsd>: Change prototype.
>>         * config/i386/xmmintrin.h: Adapt to new builtin prototype.
>>         * config/i386/emmintrin.h: Likewise.
>>         * doc/extend.texi (X86 Built-in Functions): Document changed
>> prototype.
>>
>>
>> testsuite/
>>         * gcc.target/i386/pr54855-1.c: New testcase.
>>         * gcc.target/i386/pr54855-2.c: New testcase.

Hello Eric,

could you take a look at the small simplify-rtx bit of this patch to see 
if the general approach makes sense to you?

(this targets 4.9 and passes bootstrap+testsuite on x86_64-linux)

The point of this transformation is to avoid writing a second define_insn 
in config/i386/sse.md as in the older patch:
http://gcc.gnu.org/ml/gcc-patches/2012-12/msg00028.html

(similar patches for multiplication, division, etc will follow, and this 
will avoid an extra entry in sse.md for each of these operations)

Thanks,

-- 
Marc Glisse