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target/arm: Speed up aarch64 TBL/TBX 

Always perform one call instead of two for 16-byte operands.
Use byte loads/stores directly into the vector register file
instead of extractions and deposits to a 64-bit local variable.

In order to easily receive pointers into the vector register file,
convert the helper to the gvec out-of-line signature.  Move the
helper into vec_helper.c, where it can make use of H1 and clear_tail.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20210224230532.276878-1-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2021-02-24 15:05:32 -08:00 committed by Peter Maydell
parent 4565afbbf0
commit 519183d3fe
4 changed files with 56 additions and 84 deletions
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32
target/arm/helper-a64.c
View File

@ -179,38 +179,6 @@ float64 HELPER(vfp_mulxd)(float64 a, float64 b, void *fpstp)
return float64_mul(a, b, fpst);
}
uint64_t HELPER(simd_tbl)(CPUARMState *env, uint64_t result, uint64_t indices,
uint32_t rn, uint32_t numregs)
{
/* Helper function for SIMD TBL and TBX. We have to do the table
* lookup part for the 64 bits worth of indices we're passed in.
* result is the initial results vector (either zeroes for TBL
* or some guest values for TBX), rn the register number where
* the table starts, and numregs the number of registers in the table.
* We return the results of the lookups.
*/
int shift;
for (shift = 0; shift < 64; shift += 8) {
int index = extract64(indices, shift, 8);
if (index < 16 * numregs) {
/* Convert index (a byte offset into the virtual table
* which is a series of 128-bit vectors concatenated)
* into the correct register element plus a bit offset
* into that element, bearing in mind that the table
* can wrap around from V31 to V0.
*/
int elt = (rn * 2 + (index >> 3)) % 64;
int bitidx = (index & 7) * 8;
uint64_t *q = aa64_vfp_qreg(env, elt >> 1);
uint64_t val = extract64(q[elt & 1], bitidx, 8);
result = deposit64(result, shift, 8, val);
}
}
return result;
}
/* 64bit/double versions of the neon float compare functions */
uint64_t HELPER(neon_ceq_f64)(float64 a, float64 b, void *fpstp)
{

2
target/arm/helper-a64.h
View File

@ -28,7 +28,7 @@ DEF_HELPER_3(vfp_cmps_a64, i64, f32, f32, ptr)
DEF_HELPER_3(vfp_cmpes_a64, i64, f32, f32, ptr)
DEF_HELPER_3(vfp_cmpd_a64, i64, f64, f64, ptr)
DEF_HELPER_3(vfp_cmped_a64, i64, f64, f64, ptr)
DEF_HELPER_FLAGS_5(simd_tbl, TCG_CALL_NO_RWG_SE, i64, env, i64, i64, i32, i32)
DEF_HELPER_FLAGS_4(simd_tblx, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, i32)
DEF_HELPER_FLAGS_3(vfp_mulxs, TCG_CALL_NO_RWG, f32, f32, f32, ptr)
DEF_HELPER_FLAGS_3(vfp_mulxd, TCG_CALL_NO_RWG, f64, f64, f64, ptr)
DEF_HELPER_FLAGS_3(neon_ceq_f64, TCG_CALL_NO_RWG, i64, i64, i64, ptr)

58
target/arm/translate-a64.c
View File

@ -7532,10 +7532,8 @@ static void disas_simd_tb(DisasContext *s, uint32_t insn)
int rm = extract32(insn, 16, 5);
int rn = extract32(insn, 5, 5);
int rd = extract32(insn, 0, 5);
int is_tblx = extract32(insn, 12, 1);
int len = extract32(insn, 13, 2);
TCGv_i64 tcg_resl, tcg_resh, tcg_idx;
TCGv_i32 tcg_regno, tcg_numregs;
int is_tbx = extract32(insn, 12, 1);
int len = (extract32(insn, 13, 2) + 1) * 16;
if (op2 != 0) {
unallocated_encoding(s);
@ -7546,53 +7544,11 @@ static void disas_simd_tb(DisasContext *s, uint32_t insn)
return;
}
/* This does a table lookup: for every byte element in the input
* we index into a table formed from up to four vector registers,
* and then the output is the result of the lookups. Our helper
* function does the lookup operation for a single 64 bit part of
* the input.
*/
tcg_resl = tcg_temp_new_i64();
tcg_resh = NULL;
if (is_tblx) {
read_vec_element(s, tcg_resl, rd, 0, MO_64);
} else {
tcg_gen_movi_i64(tcg_resl, 0);
}
if (is_q) {
tcg_resh = tcg_temp_new_i64();
if (is_tblx) {
read_vec_element(s, tcg_resh, rd, 1, MO_64);
} else {
tcg_gen_movi_i64(tcg_resh, 0);
}
}
tcg_idx = tcg_temp_new_i64();
tcg_regno = tcg_const_i32(rn);
tcg_numregs = tcg_const_i32(len + 1);
read_vec_element(s, tcg_idx, rm, 0, MO_64);
gen_helper_simd_tbl(tcg_resl, cpu_env, tcg_resl, tcg_idx,
tcg_regno, tcg_numregs);
if (is_q) {
read_vec_element(s, tcg_idx, rm, 1, MO_64);
gen_helper_simd_tbl(tcg_resh, cpu_env, tcg_resh, tcg_idx,
tcg_regno, tcg_numregs);
}
tcg_temp_free_i64(tcg_idx);
tcg_temp_free_i32(tcg_regno);
tcg_temp_free_i32(tcg_numregs);
write_vec_element(s, tcg_resl, rd, 0, MO_64);
tcg_temp_free_i64(tcg_resl);
if (is_q) {
write_vec_element(s, tcg_resh, rd, 1, MO_64);
tcg_temp_free_i64(tcg_resh);
}
clear_vec_high(s, is_q, rd);
tcg_gen_gvec_2_ptr(vec_full_reg_offset(s, rd),
vec_full_reg_offset(s, rm), cpu_env,
is_q ? 16 : 8, vec_full_reg_size(s),
(len << 6) | (is_tbx << 5) | rn,
gen_helper_simd_tblx);
}
/* ZIP/UZP/TRN

48
target/arm/vec_helper.c
View File

@ -1937,3 +1937,51 @@ DO_VRINT_RMODE(gvec_vrint_rm_h, helper_rinth, uint16_t)
DO_VRINT_RMODE(gvec_vrint_rm_s, helper_rints, uint32_t)
#undef DO_VRINT_RMODE
#ifdef TARGET_AARCH64
void HELPER(simd_tblx)(void *vd, void *vm, void *venv, uint32_t desc)
{
const uint8_t *indices = vm;
CPUARMState *env = venv;
size_t oprsz = simd_oprsz(desc);
uint32_t rn = extract32(desc, SIMD_DATA_SHIFT, 5);
bool is_tbx = extract32(desc, SIMD_DATA_SHIFT + 5, 1);
uint32_t table_len = desc >> (SIMD_DATA_SHIFT + 6);
union {
uint8_t b[16];
uint64_t d[2];
} result;
/*
* We must construct the final result in a temp, lest the output
* overlaps the input table. For TBL, begin with zero; for TBX,
* begin with the original register contents. Note that we always
* copy 16 bytes here to avoid an extra branch; clearing the high
* bits of the register for oprsz == 8 is handled below.
*/
if (is_tbx) {
memcpy(&result, vd, 16);
} else {
memset(&result, 0, 16);
}
for (size_t i = 0; i < oprsz; ++i) {
uint32_t index = indices[H1(i)];
if (index < table_len) {
/*
* Convert index (a byte offset into the virtual table
* which is a series of 128-bit vectors concatenated)
* into the correct register element, bearing in mind
* that the table can wrap around from V31 to V0.
*/
const uint8_t *table = (const uint8_t *)
aa64_vfp_qreg(env, (rn + (index >> 4)) % 32);
result.b[H1(i)] = table[H1(index % 16)];
}
}
memcpy(vd, &result, 16);
clear_tail(vd, oprsz, simd_maxsz(desc));
}
#endif