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

FCVTAU (scalar, S to X)

Test 1: uops

Code:

  fcvtau x0, s0
  mov x0, 1
  mov x1, 2

(no loop instructions)

1000 unrolls and 1 iteration

Retires: 2.000

Issues: 3.000

Integer unit issues: 1.001

Load/store unit issues: 0.000

SIMD/FP unit issues: 2.000

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)? int retires (ef)
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000
20041037300110012000200011000200020002000100110001000

Test 2: Latency 1->2 roundtrip

Code:

  fcvtau x0, s0
  fmov d0, x0
  mov x0, 1
  mov x1, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 10.0032

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)schedule simd uop (54)schedule ldst uop (55)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 ldst uop inputs (80)map simd uop inputs (81)? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)
3020410016240110101032000410003100200301000030015469672578492301002001000220004200100022000410001100001000010100
3020410003240101101012000010000100200001000030015469112578388301002001000120003200100012000310001100001000010100
3020410007040101101012000010000100200001000030015469752578492301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003840101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100022000410001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100

1000 unrolls and 10 iterations

Result (median cycles for code): 10.0032

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)schedule simd uop (54)schedule ldst uop (55)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 ldst uop inputs (80)map simd uop inputs (81)? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)
300241000364001110011200001000010200001000030154633625782063001020100022000420100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100202004010002100001000010010
300241000324001110011200001000010200001000030154637825782583001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000334001110011200001000010200001001730154650825784833005520100192003820100002000010001100001000010010
300241000354001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154788525806763001020100002000020100002000010001100001000010010

Test 3: throughput

Count: 8

Code:

  fcvtau x0, s8
  fcvtau x1, s8
  fcvtau x2, s8
  fcvtau x3, s8
  fcvtau x4, s8
  fcvtau x5, s8
  fcvtau x6, s8
  fcvtau x7, s8
  mov x8, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 1.0005

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 ldst uop inputs (80)map simd uop inputs (81)? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)
160204800612401038010116000210016000830088004116010820016001220001600128000108000080100
160204800372401038010116000210016000830088004116010820016001220001600128000108000080100
160204800372401038010116000210016000830088004116010820016001220001600128000108000080100
160205800742401558011516004010016005830088029016015820016006820001600128000108000080100
160204800372401038010116000210016000830088004116010820016001220001600128000108000080100
160204800372401038010116000210016000830088004116010820016001220001600128000108000080100
160204800462401038010116000210016000830088004116010820016001220001600128000108000080100
160204800372401038010116000210016000830088004116010820016001220001600128000108000080100
160204800372401038010116000210016000830088004116010820016001220001600128000108000080100
160204800372401038010116000210016000830088004116010820016001220001600128000108000080100

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 1.0005

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)
160024800502400138001116000210160008308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160068800158000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010
160024800372400118001116000010160000308800001600102016000020160000800018000080010