Commit 0aad761f authored by Peter Maydell's avatar Peter Maydell
Browse files

target/arm: Convert Neon VEXT to decodetree 



Convert the Neon VEXT insn to decodetree. Rather than keeping the
old implementation which used fixed temporaries cpu_V0 and cpu_V1
and did the extraction with by-hand shift and logic ops, we use
the TCG extract2 insn.

We don't need to special case 0 or 8 immediates any more as the
optimizer is smart enough to throw away the dead code.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent 77e576a9

target/arm/neon-dp.decode

+7 −1
Original line number Diff line number Diff line
@@ -413,7 +413,13 @@ Vimm_1r 1111 001 . 1 . 000 ... .... cmode:4 0 . op:1 1 .... @1reg_imm 
# return false for size==3.

######################################################################

{

  # 0b11 subgroup will go here

  [

    ##################################################################

    # Miscellaneous size=0b11 insns

    ##################################################################

    VEXT         1111 001 0 1 . 11 .... .... imm:4 . q:1 . 0 .... \

                 vm=%vm_dp vn=%vn_dp vd=%vd_dp

  ]



  # Subgroup for size != 0b11

  [

target/arm/translate-neon.inc.c

+76 −0
Original line number Diff line number Diff line
@@ -2812,3 +2812,79 @@ static bool trans_VQDMLSL_2sc(DisasContext *s, arg_2scalar *a) 


    return do_2scalar_long(s, a, opfn[a->size], accfn[a->size]);

}



static bool trans_VEXT(DisasContext *s, arg_VEXT *a)

{

    if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {

        return false;

    }



    /* UNDEF accesses to D16-D31 if they don't exist. */

    if (!dc_isar_feature(aa32_simd_r32, s) &&

        ((a->vd | a->vn | a->vm) & 0x10)) {

        return false;

    }



    if ((a->vn | a->vm | a->vd) & a->q) {

        return false;

    }



    if (a->imm > 7 && !a->q) {

        return false;

    }



    if (!vfp_access_check(s)) {

        return true;

    }



    if (!a->q) {

        /* Extract 64 bits from <Vm:Vn> */

        TCGv_i64 left, right, dest;



        left = tcg_temp_new_i64();

        right = tcg_temp_new_i64();

        dest = tcg_temp_new_i64();



        neon_load_reg64(right, a->vn);

        neon_load_reg64(left, a->vm);

        tcg_gen_extract2_i64(dest, right, left, a->imm * 8);

        neon_store_reg64(dest, a->vd);



        tcg_temp_free_i64(left);

        tcg_temp_free_i64(right);

        tcg_temp_free_i64(dest);

    } else {

        /* Extract 128 bits from <Vm+1:Vm:Vn+1:Vn> */

        TCGv_i64 left, middle, right, destleft, destright;



        left = tcg_temp_new_i64();

        middle = tcg_temp_new_i64();

        right = tcg_temp_new_i64();

        destleft = tcg_temp_new_i64();

        destright = tcg_temp_new_i64();



        if (a->imm < 8) {

            neon_load_reg64(right, a->vn);

            neon_load_reg64(middle, a->vn + 1);

            tcg_gen_extract2_i64(destright, right, middle, a->imm * 8);

            neon_load_reg64(left, a->vm);

            tcg_gen_extract2_i64(destleft, middle, left, a->imm * 8);

        } else {

            neon_load_reg64(right, a->vn + 1);

            neon_load_reg64(middle, a->vm);

            tcg_gen_extract2_i64(destright, right, middle, (a->imm - 8) * 8);

            neon_load_reg64(left, a->vm + 1);

            tcg_gen_extract2_i64(destleft, middle, left, (a->imm - 8) * 8);

        }



        neon_store_reg64(destright, a->vd);

        neon_store_reg64(destleft, a->vd + 1);



        tcg_temp_free_i64(destright);

        tcg_temp_free_i64(destleft);

        tcg_temp_free_i64(right);

        tcg_temp_free_i64(middle);

        tcg_temp_free_i64(left);

    }

    return true;

}

target/arm/translate.c

+2 −56
Original line number Diff line number Diff line
@@ -5030,10 +5030,8 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn) 
    int pass;

    int u;

    int vec_size;

    uint32_t imm;

    TCGv_i32 tmp, tmp2, tmp3, tmp5;

    TCGv_ptr ptr1;

    TCGv_i64 tmp64;



    if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {

        return 1;
@@ -5076,60 +5074,8 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn) 
            return 1;

        } else { /* size == 3 */

            if (!u) {

                /* Extract.  */

                imm = (insn >> 8) & 0xf;



                if (imm > 7 && !q)

                    return 1;



                if (q && ((rd | rn | rm) & 1)) {

                /* Extract: handled by decodetree */

                return 1;

                }



                if (imm == 0) {

                    neon_load_reg64(cpu_V0, rn);

                    if (q) {

                        neon_load_reg64(cpu_V1, rn + 1);

                    }

                } else if (imm == 8) {

                    neon_load_reg64(cpu_V0, rn + 1);

                    if (q) {

                        neon_load_reg64(cpu_V1, rm);

                    }

                } else if (q) {

                    tmp64 = tcg_temp_new_i64();

                    if (imm < 8) {

                        neon_load_reg64(cpu_V0, rn);

                        neon_load_reg64(tmp64, rn + 1);

                    } else {

                        neon_load_reg64(cpu_V0, rn + 1);

                        neon_load_reg64(tmp64, rm);

                    }

                    tcg_gen_shri_i64(cpu_V0, cpu_V0, (imm & 7) * 8);

                    tcg_gen_shli_i64(cpu_V1, tmp64, 64 - ((imm & 7) * 8));

                    tcg_gen_or_i64(cpu_V0, cpu_V0, cpu_V1);

                    if (imm < 8) {

                        neon_load_reg64(cpu_V1, rm);

                    } else {

                        neon_load_reg64(cpu_V1, rm + 1);

                        imm -= 8;

                    }

                    tcg_gen_shli_i64(cpu_V1, cpu_V1, 64 - (imm * 8));

                    tcg_gen_shri_i64(tmp64, tmp64, imm * 8);

                    tcg_gen_or_i64(cpu_V1, cpu_V1, tmp64);

                    tcg_temp_free_i64(tmp64);

                } else {

                    /* BUGFIX */

                    neon_load_reg64(cpu_V0, rn);

                    tcg_gen_shri_i64(cpu_V0, cpu_V0, imm * 8);

                    neon_load_reg64(cpu_V1, rm);

                    tcg_gen_shli_i64(cpu_V1, cpu_V1, 64 - (imm * 8));

                    tcg_gen_or_i64(cpu_V0, cpu_V0, cpu_V1);

                }

                neon_store_reg64(cpu_V0, rd);

                if (q) {

                    neon_store_reg64(cpu_V1, rd + 1);

                }

            } else if ((insn & (1 << 11)) == 0) {

                /* Two register misc.  */

                op = ((insn >> 12) & 0x30) | ((insn >> 7) & 0xf);