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target-arm: A64: Saturating and narrowing shift ops
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This implements the remaining [US][Q][R]SHR[U][N][2] opcodes, which are
saturating and narrowing shift right operations. These are used in
things like libav. Note signed shifts can have an "unsigned" saturating
narrow operation which will floor negative values.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1394822294-14837-7-git-send-email-peter.maydell@linaro.org
[PMM: Added the scalar encodings, style tweaks]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@stsquad @pm215
stsquad authored and pm215 committed Mar 17, 2014
1 parent b05c306 commit c1b876b
Showing 1 changed file with 178 additions and 3 deletions.
181 changes: 178 additions & 3 deletions target-arm/translate-a64.c
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Expand Up @@ -5907,6 +5907,94 @@ static void handle_scalar_simd_shli(DisasContext *s, bool insert,
tcg_temp_free_i64(tcg_rd);
}

/* SQSHRN/SQSHRUN - Saturating (signed/unsigned) shift right with
* (signed/unsigned) narrowing */
static void handle_vec_simd_sqshrn(DisasContext *s, bool is_scalar, bool is_q,
bool is_u_shift, bool is_u_narrow,
int immh, int immb, int opcode,
int rn, int rd)
{
int immhb = immh << 3 | immb;
int size = 32 - clz32(immh) - 1;
int esize = 8 << size;
int shift = (2 * esize) - immhb;
int elements = is_scalar ? 1 : (64 / esize);
bool round = extract32(opcode, 0, 1);
TCGMemOp ldop = (size + 1) | (is_u_shift ? 0 : MO_SIGN);
TCGv_i64 tcg_rn, tcg_rd, tcg_round;
TCGv_i32 tcg_rd_narrowed;
TCGv_i64 tcg_final;

static NeonGenNarrowEnvFn * const signed_narrow_fns[4][2] = {
{ gen_helper_neon_narrow_sat_s8,
gen_helper_neon_unarrow_sat8 },
{ gen_helper_neon_narrow_sat_s16,
gen_helper_neon_unarrow_sat16 },
{ gen_helper_neon_narrow_sat_s32,
gen_helper_neon_unarrow_sat32 },
{ NULL, NULL },
};
static NeonGenNarrowEnvFn * const unsigned_narrow_fns[4] = {
gen_helper_neon_narrow_sat_u8,
gen_helper_neon_narrow_sat_u16,
gen_helper_neon_narrow_sat_u32,
NULL
};
NeonGenNarrowEnvFn *narrowfn;

int i;

assert(size < 4);

if (extract32(immh, 3, 1)) {
unallocated_encoding(s);
return;
}

if (is_u_shift) {
narrowfn = unsigned_narrow_fns[size];
} else {
narrowfn = signed_narrow_fns[size][is_u_narrow ? 1 : 0];
}

tcg_rn = tcg_temp_new_i64();
tcg_rd = tcg_temp_new_i64();
tcg_rd_narrowed = tcg_temp_new_i32();
tcg_final = tcg_const_i64(0);

if (round) {
uint64_t round_const = 1ULL << (shift - 1);
tcg_round = tcg_const_i64(round_const);
} else {
TCGV_UNUSED_I64(tcg_round);
}

for (i = 0; i < elements; i++) {
read_vec_element(s, tcg_rn, rn, i, ldop);
handle_shri_with_rndacc(tcg_rd, tcg_rn, tcg_round,
false, is_u_shift, size+1, shift);
narrowfn(tcg_rd_narrowed, cpu_env, tcg_rd);
tcg_gen_extu_i32_i64(tcg_rd, tcg_rd_narrowed);
tcg_gen_deposit_i64(tcg_final, tcg_final, tcg_rd, esize * i, esize);
}

if (!is_q) {
clear_vec_high(s, rd);
write_vec_element(s, tcg_final, rd, 0, MO_64);
} else {
write_vec_element(s, tcg_final, rd, 1, MO_64);
}

if (round) {
tcg_temp_free_i64(tcg_round);
}
tcg_temp_free_i64(tcg_rn);
tcg_temp_free_i64(tcg_rd);
tcg_temp_free_i32(tcg_rd_narrowed);
tcg_temp_free_i64(tcg_final);
return;
}

/* Common vector code for handling integer to FP conversion */
static void handle_simd_intfp_conv(DisasContext *s, int rd, int rn,
int elements, int is_signed,
Expand Down Expand Up @@ -6013,6 +6101,11 @@ static void disas_simd_scalar_shift_imm(DisasContext *s, uint32_t insn)
int immh = extract32(insn, 19, 4);
bool is_u = extract32(insn, 29, 1);

if (immh == 0) {
unallocated_encoding(s);
return;
}

switch (opcode) {
case 0x00: /* SSHR / USHR */
case 0x02: /* SSRA / USRA */
Expand All @@ -6027,6 +6120,20 @@ static void disas_simd_scalar_shift_imm(DisasContext *s, uint32_t insn)
handle_simd_shift_intfp_conv(s, true, false, is_u, immh, immb,
opcode, rn, rd);
break;
case 0x10: /* SQSHRUN, SQSHRUN2 */
case 0x11: /* SQRSHRUN, SQRSHRUN2 */
if (!is_u) {
unallocated_encoding(s);
return;
}
handle_vec_simd_sqshrn(s, true, false, false, true,
immh, immb, opcode, rn, rd);
break;
case 0x12: /* SQSHRN, SQSHRN2, UQSHRN */
case 0x13: /* SQRSHRN, SQRSHRN2, UQRSHRN, UQRSHRN2 */
handle_vec_simd_sqshrn(s, true, false, is_u, is_u,
immh, immb, opcode, rn, rd);
break;
default:
unsupported_encoding(s, insn);
break;
Expand Down Expand Up @@ -6985,6 +7092,63 @@ static void handle_vec_simd_wshli(DisasContext *s, bool is_q, bool is_u,
}
}

/* SHRN/RSHRN - Shift right with narrowing (and potential rounding) */
static void handle_vec_simd_shrn(DisasContext *s, bool is_q,
int immh, int immb, int opcode, int rn, int rd)
{
int immhb = immh << 3 | immb;
int size = 32 - clz32(immh) - 1;
int dsize = 64;
int esize = 8 << size;
int elements = dsize/esize;
int shift = (2 * esize) - immhb;
bool round = extract32(opcode, 0, 1);
TCGv_i64 tcg_rn, tcg_rd, tcg_final;
TCGv_i64 tcg_round;
int i;

if (extract32(immh, 3, 1)) {
unallocated_encoding(s);
return;
}

tcg_rn = tcg_temp_new_i64();
tcg_rd = tcg_temp_new_i64();
tcg_final = tcg_temp_new_i64();
read_vec_element(s, tcg_final, rd, is_q ? 1 : 0, MO_64);

if (round) {
uint64_t round_const = 1ULL << (shift - 1);
tcg_round = tcg_const_i64(round_const);
} else {
TCGV_UNUSED_I64(tcg_round);
}

for (i = 0; i < elements; i++) {
read_vec_element(s, tcg_rn, rn, i, size+1);
handle_shri_with_rndacc(tcg_rd, tcg_rn, tcg_round,
false, true, size+1, shift);

tcg_gen_deposit_i64(tcg_final, tcg_final, tcg_rd, esize * i, esize);
}

if (!is_q) {
clear_vec_high(s, rd);
write_vec_element(s, tcg_final, rd, 0, MO_64);
} else {
write_vec_element(s, tcg_final, rd, 1, MO_64);
}

if (round) {
tcg_temp_free_i64(tcg_round);
}
tcg_temp_free_i64(tcg_rn);
tcg_temp_free_i64(tcg_rd);
tcg_temp_free_i64(tcg_final);
return;
}


/* C3.6.14 AdvSIMD shift by immediate
* 31 30 29 28 23 22 19 18 16 15 11 10 9 5 4 0
* +---+---+---+-------------+------+------+--------+---+------+------+
Expand All @@ -7011,6 +7175,20 @@ static void disas_simd_shift_imm(DisasContext *s, uint32_t insn)
case 0x0a: /* SHL / SLI */
handle_vec_simd_shli(s, is_q, is_u, immh, immb, opcode, rn, rd);
break;
case 0x10: /* SHRN */
case 0x11: /* RSHRN / SQRSHRUN */
if (is_u) {
handle_vec_simd_sqshrn(s, false, is_q, false, true, immh, immb,
opcode, rn, rd);
} else {
handle_vec_simd_shrn(s, is_q, immh, immb, opcode, rn, rd);
}
break;
case 0x12: /* SQSHRN / UQSHRN */
case 0x13: /* SQRSHRN / UQRSHRN */
handle_vec_simd_sqshrn(s, false, is_q, is_u, is_u, immh, immb,
opcode, rn, rd);
break;
case 0x14: /* SSHLL / USHLL */
handle_vec_simd_wshli(s, is_q, is_u, immh, immb, opcode, rn, rd);
break;
Expand All @@ -7022,9 +7200,6 @@ static void disas_simd_shift_imm(DisasContext *s, uint32_t insn)
unsupported_encoding(s, insn);
return;
default:
/* We don't currently implement any of the Narrow or
* saturating shifts.
*/
unsupported_encoding(s, insn);
return;
}
Expand Down

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