Apple Microarchitecture Research by Dougall Johnson

M1/A14 P-core (Firestorm): Overview | Base Instructions | SIMD and FP Instructions
M1/A14 E-core (Icestorm):  Overview | Base Instructions | SIMD and FP Instructions

FCVTNS (scalar, D to D)

Test 1: uops

Code:

  fcvtns d0, d0

Initialization

  movi v0.16b, 1
  movi v1.16b, 2

(no loop instructions)

1000 unrolls and 1 iteration

Retires: 1.000

Issues: 1.000

Integer unit issues: 0.001

Load/store unit issues: 0.000

SIMD/FP unit issues: 1.000

Recorded non-zero counters (first 10 of 64 runs)

retire uop (01)	cycle (02)	schedule uop (52)	schedule int uop (53)	schedule simd uop (54)	dispatch simd uop (57)	ldst uops in schedulers (5b)	dispatch uop (78)	map simd uop (7e)	map simd uop inputs (81)	? int output thing (e9)	? simd retires (ee)
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000
1004	3033	1001	1	1000	1000	75905	1000	1000	1000	1	1000

Test 2: Latency 1->2

Code:

  fcvtns d0, d0

Initialization

  movi v0.16b, 1
  movi v1.16b, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 3.0033

Recorded non-zero counters (first 10 of 64 runs)

retire uop (01)	cycle (02)	schedule uop (52)	schedule int uop (53)	schedule simd uop (54)	dispatch int uop (56)	dispatch simd uop (57)	int uops in schedulers (59)	ldst uops in schedulers (5b)	dispatch uop (78)	map int uop (7c)	map simd uop (7e)	map int uop inputs (7f)	map simd uop inputs (81)	? int output thing (e9)	? simd retires (ee)	? int retires (ef)
10204	30033	10101	101	10000	100	10000	300	769247	10131	202	10044	200	10004	1	10000	100
10205	30066	10107	101	10006	100	10031	300	768905	10100	200	10006	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100
10204	30033	10101	101	10000	100	10000	300	768905	10100	200	10004	200	10004	1	10000	100

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0033

Recorded non-zero counters (first 10 of 64 runs)

retire uop (01)	cycle (02)	schedule uop (52)	schedule int uop (53)	schedule simd uop (54)	dispatch int uop (56)	dispatch simd uop (57)	int uops in schedulers (59)	ldst uops in schedulers (5b)	dispatch uop (78)	map int uop (7c)	map simd uop (7e)	map int uop inputs (7f)	map simd uop inputs (81)	? int output thing (e9)	? simd retires (ee)	? int retires (ef)
10024	30033	10021	21	10000	20	10000	70	769247	10051	20	10046	20	10004	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10
10024	30033	10021	21	10000	20	10000	70	768905	10020	20	10000	20	10000	11	10000	10

Test 3: throughput

Count: 8

Code:

  fcvtns d0, d8
  fcvtns d1, d8
  fcvtns d2, d8
  fcvtns d3, d8
  fcvtns d4, d8
  fcvtns d5, d8
  fcvtns d6, d8
  fcvtns d7, d8

Initialization

  movi v8.16b, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.5004

Recorded non-zero counters (first 10 of 64 runs)

retire uop (01)	cycle (02)	schedule uop (52)	schedule int uop (53)	schedule simd uop (54)	dispatch int uop (56)	dispatch simd uop (57)	int uops in schedulers (59)	ldst uops in schedulers (5b)	dispatch uop (78)	map int uop (7c)	map simd uop (7e)	map int uop inputs (7f)	map simd uop inputs (81)	? int output thing (e9)	? simd retires (ee)	? int retires (ef)
80204	40047	80107	101	80006	100	80010	300	320036	80108	200	80012	200	80012	1	80000	100
80205	40071	80143	101	80042	100	80054	300	320044	80110	200	80014	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100
80204	40035	80105	101	80004	100	80008	300	320036	80108	200	80012	200	80012	1	80000	100

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.5004

Recorded non-zero counters (first 10 of 64 runs)

retire uop (01)	cycle (02)	schedule uop (52)	schedule int uop (53)	schedule simd uop (54)	dispatch int uop (56)	dispatch simd uop (57)	dispatch ldst uop (58)	int uops in schedulers (59)	simd uops in schedulers (5a)	ldst uops in schedulers (5b)	dispatch uop (78)	map int uop (7c)	map ldst uop (7d)	map simd uop (7e)	map int uop inputs (7f)	map simd uop inputs (81)	? int output thing (e9)	? simd retires (ee)	? int retires (ef)
80024	40174	80027	21	80006	20	80010	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80049	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10
80024	40035	80021	21	80000	20	80000	0	70	0	320000	80020	20	0	80000	20	80000	11	80000	10