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

SCVTF (scalar, fixed-point, D from X)

Test 1: uops

Code:

  scvtf d0, x0, #3
  mov x0, 1
  mov x1, 2

(no loop instructions)

1000 unrolls and 1 iteration

Retires: 2.000

Issues: 2.000

Integer unit issues: 0.001

Load/store unit issues: 1.000

SIMD/FP unit issues: 1.000

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)schedule simd uop (54)schedule ldst uop (55)dispatch simd uop (57)dispatch ldst uop (58)simd uops in schedulers (5a)ldst uops in schedulers (5b)dispatch uop (78)map ldst uop (7d)map simd uop (7e)map ldst uop inputs (80)map simd uop inputs (81)? int output thing (e9)? ldst retires (ed)? simd retires (ee)
20046452001110001000100010003000800020001000100010001000110001000
20045422001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000
20045372001110001000100010003000800020001000100010001000110001000

Test 2: Latency 1->2 roundtrip

Code:

  scvtf d0, x0, #3
  fmov x0, d0
  mov x0, 1
  mov x1, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 10.0030

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)
3020410003040101101012000010000100200001000130015461722578264301012001000220004200100022000410001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100
3020510006340108101032000310002100200291000030015463382578524301002001000220002200100022000210001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100
3020410003040101101012000010000100200001000030015461742578264301002001000220002200100022000210001100001000010100

1000 unrolls and 10 iterations

Result (median cycles for code): 10.0030

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)
300241000314001110011200001000010200001000030154616825782643001020100002000020100002000010001100001000010010
300251001814001710012200031000210200281007030154987525845203019820100742014420100002000010001100001000010010
300241003034004010019200141000710200881005130154908025829883014820100572011120100002000010001100001000010010
300241002054003010016200091000510200591000030154617425782643001020100002000020100372007210006100001000010010
300241000304001110011200001000010200001005130154813925815413014820100592011320100382007510007100001000010010
300241000304001110011200001000010200001003430154843825820723010220100382007420102822055210043100001000010010
300241018234019510062200891004410205571015930155539025936413043120101702033620100002000010001100001000010010
300241000304001110011200001000010200001000030154617425782643001020100002000020100002000010001100001000010010
300241000304001110011200001000010200001000030154617425782643001020100002000020100002000010001100001000010010
300241000304001110011200001000010200001000030154617425782643001020100002000020100002000010001100001000010010

Test 3: throughput

Count: 8

Code:

  scvtf d0, x8, #3
  scvtf d1, x8, #3
  scvtf d2, x8, #3
  scvtf d3, x8, #3
  scvtf d4, x8, #3
  scvtf d5, x8, #3
  scvtf d6, x8, #3
  scvtf d7, x8, #3
  mov x8, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.5011

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)
16020440171160115101800068000810080012800543002402706404641602082008005480054200800128001218000080000100
16020440101160115101800068000810080012800123002400366400801601242008001280012200800128001218000080000100
16020440090160115101800068000810080012800123002400366400801601242008001280012200800128001218000080000100
16020440090160115101800068000810080012800123002951137095901601242008001280012200800128001218000080000100
16020440142160115101800068000810080012800123002470336516781601242008001280012200800128001218000080000100
16020440090160115101800068000810080012800123002400366400801601242008001280012200800128001218000080000100
16020440090160115101800068000810080012800123002400366400801601242008001280012200800128001218000080000100
16020440090160115101800068000810080012800123002400366400801601242008001280012200800128001218000080000100
16020440090160115101800068000810080012800123002400366400801601242008001280012200800128001218000080000100
16020440090160115101800068000810080012800123002400366400801601242008001280012200800128001218000080000100

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.5006

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)
16002440436160027118000780009108001380012302400366400801600342080012800122080000800001800008000010
16002440058160011118000080000108000080000302400006400001600102080000800002080000800001800008000010
16002440046160011118000080000108000080000302400006400001600102080000800002080000800001800008000010
16002440046160011118000080000108000080000302401386401381600102080000800002080000800001800008000010
16002440046160011118000080000108000080000302426246426241600102080000800002080000800001800008000010
16002440046160011118000080000108000080000302400006400001600102080000800002080000800001800008000010
16002440046160011118000080000108000080000302400006400001600102080000800002080000800001800008000010
16002440046160011118000080000108000080000302400006400001600102080000800002080000800001800008000010
16002440046160011118000080000108000080000302400006400001600102080000800002080000800001800008000010
16002540103160087118003780039108005580000302400006400001600102080000800002080000800001800008000010