*ping*
Thanks,
James
On Tue, Jun 24, 2014 at 09:45:28AM +0100, James Greenhalgh wrote:
>
> Hi,
>
> vec_concat ( { a, b }, { c, d }) should give a new vector { a, b, c, d }.
>
> On big-endian aarch64 targets, we have to think carefully about what this
> means as we map GCC's view of endian-ness on to ours. GCC (for reasons I have
> yet to understand) likes to describe lane-extracts from a vector as
> endian-ness dependant bit-field extracts. This cause major headaches, and
> means we have to pretend throughout the backend that lane zero is at the
> high bits of a vector register.
>
> When we have a machine instruction which zeroes the high bits of a vector
> register, and we want to describe it in RTL, the natural little-endian view is
> vec_concat ( operand, zeroes ). The reality described above implies that the
> correct description on big-endian systems is vec_concat ( zeroes, operand ).
>
> This also affects arm_neon.h intrinsics. When we say vcombine (a, b) we mean
> that a should occupy the low 64-bits and b the high 64 bits. We therefore
> need to take care to swap the operands to vec_concat when we are targeting
> big-endian.
>
> This patch is messy, but it gives an notable improvement in the PASS
> rates for an internal testsuite for Neon intrinsics.
>
> Tested on aarch64-none-elf and aarch64_be-none-elf with no issues, but no
> improvements either.
>
> OK for trunk?
>
> Thanks,
> James
>
> ---
> gcc/
>
> 2014-06-20 James Greenhalgh <[email protected]>
>
> * config/aarch64/aarch64-simd.md (move_lo_quad_internal_<mode>): New.
> (move_lo_quad_internal_be_<mode>): Likewise.
> (move_lo_quad_<mode>): Convert to define_expand.
> (aarch64_simd_move_hi_quad_<mode>): Gate on BYTES_BIG_ENDIAN.
> (aarch64_simd_move_hi_quad_be_<mode>): New.
> (move_hi_quad_<mode>): Use appropriate insn for BYTES_BIG_ENDIAN.
> (aarch64_combinez<mode>): Gate on BYTES_BIG_ENDIAN.
> (aarch64_combinez_be<mode>): New.
> (aarch64_combine<mode>): Convert to define_expand.
> (aarch64_combine_internal<mode>): New.
> (aarch64_simd_combine<mode>): Remove bogus RTL description.
>
> diff --git a/gcc/config/aarch64/aarch64-simd.md
> b/gcc/config/aarch64/aarch64-simd.md
> index
> 6b81d811b70bd157207f7753027309442ec9e8b5..00e2206b200fd32c6df5987d7317687488e8dadd
> 100644
> --- a/gcc/config/aarch64/aarch64-simd.md
> +++ b/gcc/config/aarch64/aarch64-simd.md
> @@ -942,14 +942,38 @@ (define_insn "<su><maxmin><mode>3"
> [(set_attr "type" "neon_minmax<q>")]
> )
>
> -;; Move into low-half clearing high half to 0.
> +;; vec_concat gives a new vector with the low elements from operand 1, and
> +;; the high elements from operand 2. That is to say, given op1 = { a, b }
> +;; op2 = { c, d }, vec_concat (op1, op2) = { a, b, c, d }.
> +;; What that means, is that the RTL descriptions of the below patterns
> +;; need to change depending on endianness.
> +
> +;; Move to the low architectural bits of the register.
> +;; On little-endian this is { operand, zeroes }
> +;; On big-endian this is { zeroes, operand }
>
> -(define_insn "move_lo_quad_<mode>"
> +(define_insn "move_lo_quad_internal_<mode>"
> [(set (match_operand:VQ 0 "register_operand" "=w,w,w")
> (vec_concat:VQ
> (match_operand:<VHALF> 1 "register_operand" "w,r,r")
> (vec_duplicate:<VHALF> (const_int 0))))]
> - "TARGET_SIMD"
> + "TARGET_SIMD && !BYTES_BIG_ENDIAN"
> + "@
> + dup\\t%d0, %1.d[0]
> + fmov\\t%d0, %1
> + dup\\t%d0, %1"
> + [(set_attr "type" "neon_dup<q>,f_mcr,neon_dup<q>")
> + (set_attr "simd" "yes,*,yes")
> + (set_attr "fp" "*,yes,*")
> + (set_attr "length" "4")]
> +)
> +
> +(define_insn "move_lo_quad_internal_be_<mode>"
> + [(set (match_operand:VQ 0 "register_operand" "=w,w,w")
> + (vec_concat:VQ
> + (vec_duplicate:<VHALF> (const_int 0))
> + (match_operand:<VHALF> 1 "register_operand" "w,r,r")))]
> + "TARGET_SIMD && BYTES_BIG_ENDIAN"
> "@
> dup\\t%d0, %1.d[0]
> fmov\\t%d0, %1
> @@ -960,7 +984,23 @@ (define_insn "move_lo_quad_<mode>"
> (set_attr "length" "4")]
> )
>
> -;; Move into high-half.
> +(define_expand "move_lo_quad_<mode>"
> + [(match_operand:VQ 0 "register_operand")
> + (match_operand:VQ 1 "register_operand")]
> + "TARGET_SIMD"
> +{
> + if (BYTES_BIG_ENDIAN)
> + emit_insn (gen_move_lo_quad_internal_be_<mode> (operands[0],
> operands[1]));
> + else
> + emit_insn (gen_move_lo_quad_internal_<mode> (operands[0], operands[1]));
> + DONE;
> +}
> +)
> +
> +;; Move operand1 to the high architectural bits of the register, keeping
> +;; the low architectural bits of operand2.
> +;; For little-endian this is { operand2, operand1 }
> +;; For big-endian this is { operand1, operand2 }
>
> (define_insn "aarch64_simd_move_hi_quad_<mode>"
> [(set (match_operand:VQ 0 "register_operand" "+w,w")
> @@ -969,12 +1009,25 @@ (define_insn "aarch64_simd_move_hi_quad_
> (match_dup 0)
> (match_operand:VQ 2 "vect_par_cnst_lo_half" ""))
> (match_operand:<VHALF> 1 "register_operand" "w,r")))]
> - "TARGET_SIMD"
> + "TARGET_SIMD && !BYTES_BIG_ENDIAN"
> "@
> ins\\t%0.d[1], %1.d[0]
> ins\\t%0.d[1], %1"
> - [(set_attr "type" "neon_ins")
> - (set_attr "length" "4")]
> + [(set_attr "type" "neon_ins")]
> +)
> +
> +(define_insn "aarch64_simd_move_hi_quad_be_<mode>"
> + [(set (match_operand:VQ 0 "register_operand" "+w,w")
> + (vec_concat:VQ
> + (match_operand:<VHALF> 1 "register_operand" "w,r")
> + (vec_select:<VHALF>
> + (match_dup 0)
> + (match_operand:VQ 2 "vect_par_cnst_hi_half" ""))))]
> + "TARGET_SIMD && BYTES_BIG_ENDIAN"
> + "@
> + ins\\t%0.d[1], %1.d[0]
> + ins\\t%0.d[1], %1"
> + [(set_attr "type" "neon_ins")]
> )
>
> (define_expand "move_hi_quad_<mode>"
> @@ -982,9 +1035,13 @@ (define_expand "move_hi_quad_<mode>"
> (match_operand:<VHALF> 1 "register_operand" "")]
> "TARGET_SIMD"
> {
> - rtx p = aarch64_simd_vect_par_cnst_half (<MODE>mode, false);
> - emit_insn (gen_aarch64_simd_move_hi_quad_<mode> (operands[0],
> - operands[1], p));
> + rtx p = aarch64_simd_vect_par_cnst_half (<MODE>mode, BYTES_BIG_ENDIAN);
> + if (BYTES_BIG_ENDIAN)
> + emit_insn (gen_aarch64_simd_move_hi_quad_be_<mode> (operands[0],
> + operands[1], p));
> + else
> + emit_insn (gen_aarch64_simd_move_hi_quad_<mode> (operands[0],
> + operands[1], p));
> DONE;
> })
>
> @@ -2338,12 +2395,44 @@ (define_insn "*aarch64_combinez<mode>"
> (vec_concat:<VDBL>
> (match_operand:VDIC 1 "register_operand" "w")
> (match_operand:VDIC 2 "aarch64_simd_imm_zero" "Dz")))]
> - "TARGET_SIMD"
> + "TARGET_SIMD && !BYTES_BIG_ENDIAN"
> "mov\\t%0.8b, %1.8b"
> [(set_attr "type" "neon_move<q>")]
> )
>
> -(define_insn_and_split "aarch64_combine<mode>"
> +(define_insn "*aarch64_combinez_be<mode>"
> + [(set (match_operand:<VDBL> 0 "register_operand" "=&w")
> + (vec_concat:<VDBL>
> + (match_operand:VDIC 2 "aarch64_simd_imm_zero" "Dz")
> + (match_operand:VDIC 1 "register_operand" "w")))]
> + "TARGET_SIMD && BYTES_BIG_ENDIAN"
> + "mov\\t%0.8b, %1.8b"
> + [(set_attr "type" "neon_move<q>")]
> +)
> +
> +(define_expand "aarch64_combine<mode>"
> + [(match_operand:<VDBL> 0 "register_operand")
> + (match_operand:VDC 1 "register_operand")
> + (match_operand:VDC 2 "register_operand")]
> + "TARGET_SIMD"
> +{
> + rtx op1, op2;
> + if (BYTES_BIG_ENDIAN)
> + {
> + op1 = operands[2];
> + op2 = operands[1];
> + }
> + else
> + {
> + op1 = operands[1];
> + op2 = operands[2];
> + }
> + emit_insn (gen_aarch64_combine_internal<mode> (operands[0], op1, op2));
> + DONE;
> +}
> +)
> +
> +(define_insn_and_split "aarch64_combine_internal<mode>"
> [(set (match_operand:<VDBL> 0 "register_operand" "=&w")
> (vec_concat:<VDBL> (match_operand:VDC 1 "register_operand" "w")
> (match_operand:VDC 2 "register_operand" "w")))]
> @@ -2352,16 +2441,19 @@ (define_insn_and_split "aarch64_combine<
> "&& reload_completed"
> [(const_int 0)]
> {
> - aarch64_split_simd_combine (operands[0], operands[1], operands[2]);
> + if (BYTES_BIG_ENDIAN)
> + aarch64_split_simd_combine (operands[0], operands[2], operands[1]);
> + else
> + aarch64_split_simd_combine (operands[0], operands[1], operands[2]);
> DONE;
> }
> [(set_attr "type" "multiple")]
> )
>
> (define_expand "aarch64_simd_combine<mode>"
> - [(set (match_operand:<VDBL> 0 "register_operand" "=&w")
> - (vec_concat:<VDBL> (match_operand:VDC 1 "register_operand" "w")
> - (match_operand:VDC 2 "register_operand" "w")))]
> + [(match_operand:<VDBL> 0 "register_operand")
> + (match_operand:VDC 1 "register_operand")
> + (match_operand:VDC 2 "register_operand")]
> "TARGET_SIMD"
> {
> emit_insn (gen_move_lo_quad_<Vdbl> (operands[0], operands[1]));
