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

FCVTZU (scalar, fixed-point, S to X)

Test 1: uops

Code:

  fcvtzu x0, s0, #3
  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:

  fcvtzu x0, s0, #3
  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)
3020410003240101101012000010000100200001000030015467862578206301002001000220004200100202004010002100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001001830015469642578483301462001002020040200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
3020410003240101101012000010000100200001000030015467962578206301002001000120003200100012000310001100001000010100
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)
300241000324001110011200001000010200001000030154633625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001001630154652925785273005620100172003620100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010
300241000324001110011200001000010200001000030154634625782063001020100002000020100002000010001100001000010010

Test 3: throughput

Count: 8

Code:

  fcvtzu x0, s8, #3
  fcvtzu x1, s8, #3
  fcvtzu x2, s8, #3
  fcvtzu x3, s8, #3
  fcvtzu x4, s8, #3
  fcvtzu x5, s8, #3
  fcvtzu x6, s8, #3
  fcvtzu x7, s8, #3
  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 simd uop inputs (81)? int output thing (e9)? simd retires (ee)? int retires (ef)
1602048004724010480101160003100160010300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100
1602058007424015580115160040100160058300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100
1602048003724010380101160002100160008300880041160108200160012200160012800018000080100

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)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)
160024800572400138001116000210160008030088004116001820016001220160000800018000080010
160024800372400118001116000010160000030088000016001020016000020160000800018000080010
160024800472400148001116000310160010030088000016001020016000020160000800018000080010
160024800372400118001116000010160000030088000016001020016000020160000800018000080010
160024800372400118001116000010160000030088000016001020016000020160000800018000080010
160024800372400118001116000010160000030088000016001020016000020160068800158000080010
160024800372400118001116000010160000030088000016001020016000020160000800018000080010
160024800372400118001116000010160000030088000016001020016000020160000800018000080010
160024800372400118001116000010160000030088029016006820016006820160000800018000080010
160024800372400118001116000010160000030088000016001020016000020160000800018000080010