Hi! For the VEXTRACT* insns, I can't find anything that would make them special wrt. masking, so I believe they can't accept {%k0}, just no masking or {%k1} through {%k7}.
I've tried to reproduce it with: #include <x86intrin.h> __m128i f1 (__m128i a, __m512i b, __mmask8 c) { register __mmask8 d __asm ("k0"); d = c; asm ("" : "+k" (d)); return _mm512_mask_extracti64x2_epi64 (a, d, b, 3); } but for some reason it still chose k1, still I believe k constraint is wrong in these cases. Ok for trunk? 2016-08-12 Jakub Jelinek <ja...@redhat.com> * config/i386/sse.md (avx512dq_vextract<shuffletype>64x2_1_maskm, vec_extract_hi_<mode>_mask, vec_extract_lo_<mode>_mask, vec_extract_hi_<mode>_mask): Use Yk constraint instead of k. --- gcc/config/i386/sse.md.jj 2016-07-14 20:28:33.000000000 +0200 +++ gcc/config/i386/sse.md 2016-08-12 12:14:19.618486123 +0200 @@ -6957,7 +6957,7 @@ (define_insn "avx512dq_vextract<shufflet (parallel [(match_operand 2 "const_0_to_7_operand") (match_operand 3 "const_0_to_7_operand")])) (match_operand:<ssequartermode> 4 "memory_operand" "0") - (match_operand:QI 5 "register_operand" "k")))] + (match_operand:QI 5 "register_operand" "Yk")))] "TARGET_AVX512DQ && (INTVAL (operands[2]) % 2 == 0) && (INTVAL (operands[2]) == INTVAL (operands[3]) - 1) @@ -7171,7 +7171,7 @@ (define_insn "vec_extract_hi_<mode>_mask (const_int 12) (const_int 13) (const_int 14) (const_int 15)])) (match_operand:<ssehalfvecmode> 2 "memory_operand" "0") - (match_operand:QI 3 "register_operand" "k")))] + (match_operand:QI 3 "register_operand" "Yk")))] "TARGET_AVX512DQ && rtx_equal_p (operands[2], operands[0])" "vextract<shuffletype>32x8\t{$0x1, %1, %0%{%3%}|%0%{%3%}, %1, 0x1}" @@ -7377,7 +7377,7 @@ (define_insn "vec_extract_lo_<mode>_mask (parallel [(const_int 0) (const_int 1) (const_int 2) (const_int 3)])) (match_operand:<ssehalfvecmode> 2 "memory_operand" "0") - (match_operand:QI 3 "register_operand" "k")))] + (match_operand:QI 3 "register_operand" "Yk")))] "TARGET_AVX512VL && TARGET_AVX512F && rtx_equal_p (operands[2], operands[0])" "vextract<shuffletype>32x4\t{$0x0, %1, %0%{%3%}|%0%{%3%}, %1, 0x0}" @@ -7395,7 +7395,7 @@ (define_insn "vec_extract_hi_<mode>_mask (parallel [(const_int 4) (const_int 5) (const_int 6) (const_int 7)])) (match_operand:<ssehalfvecmode> 2 "memory_operand" "0") - (match_operand:<ssehalfvecmode> 3 "register_operand" "k")))] + (match_operand:<ssehalfvecmode> 3 "register_operand" "Yk")))] "TARGET_AVX512F && TARGET_AVX512VL && rtx_equal_p (operands[2], operands[0])" "vextract<shuffletype>32x4\t{$0x1, %1, %0%{%3%}|%0%{%3%}, %1, 0x1}" Jakub