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

FCVTN2 (vector, 4S)

Test 1: uops

Code:

  fcvtn2 v0.8h, v1.4s
  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

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)
1004303310011100010007590510001000200011000
1004303310011100010007590510001000200011000
1004303310011100010007590510001000207611000
1004308510091100810337590510001000200011000
1004303310011100010007590510001000200011000
1004303310011100010007590510001000200011000
1004303310011100010007590510001000200011000
1004303310011100010007590510001000200011000
1004303310011100010007590510001000200011000
1004303310011100010007590510001000200011000

Test 2: Latency 1->1

Code:

  fcvtn2 v0.8h, v1.4s
  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

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)
1020430033101011011000010010000300768905101002001000620020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0033

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)
1002430033100212110000201000070768905100202010004200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010
1002430033100212110000201000070768905100202010000200200001101000010

Test 3: Latency 1->2

Code:

  fcvtn2 v0.8h, v0.4s
  movi v0.16b, 1

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 3.0033

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)
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300768905101002001000420020008110000100
1020430033101011011000010010000300769247101312001004420020008110000100

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0033

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)
10024300331002121100002010000707689051002020100042020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010
10024300331002121100002010000707689051002020100002020000111000010

Test 4: throughput

Count: 8

Code:

  movi v0.16b, 0
  fcvtn2 v0.8h, v8.4s
  movi v1.16b, 0
  fcvtn2 v1.8h, v8.4s
  movi v2.16b, 0
  fcvtn2 v2.8h, v8.4s
  movi v3.16b, 0
  fcvtn2 v3.8h, v8.4s
  movi v4.16b, 0
  fcvtn2 v4.8h, v8.4s
  movi v5.16b, 0
  fcvtn2 v5.8h, v8.4s
  movi v6.16b, 0
  fcvtn2 v6.8h, v8.4s
  movi v7.16b, 0
  fcvtn2 v7.8h, v8.4s
  movi v8.16b, 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)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)
1602044047680109101800081008001230032020080149200800492001600261160000100
1602044010880110101800091008001330032005280112200800122001600241160000100
1602044008680109101800081008001230032005680113200800132001600241160000100
1602044008680109101800081008001230032005280112200800122001600241160000100
1602044008680109101800081008001230032005280112200800122001600241160000100
1602044008680109101800081008001230032005280112200800122001600241160000100
1602044008680109101800081008001230032005280112200800122001600241160000100
1602044008680109101800081008001230032005280112200800122001600241160000100
1602044008680109101800081008001230032005280112200800122001600241160000100
1602044008680109101800081008001230032005280112200800122001600241160000100

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.5053

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)
1600244393380019118000810800123032005280022208001220160000116000010
1600244123280011118000010800003032000080010208000020160000116000010
1600244041780011118000010800003032000080010208000020160000116000010
1600244042680011118000010800003032000080010208000020160000116000010
1600244041780011118000010800003032000080010208000020160000116000010
1600244041780011118000010800003032000080010208000020160000116000010
1600244042680011118000010800003032000080010208000020160000116000010
1600244041780011118000010800003032000080010208000020160000116000010
1600244041780011118000010800003032000080010208000020160000116000010
1600244041780011118000010800003032000080010208000020160000116000010

Test 5: throughput

Count: 16

Code:

  fcvtn2 v0.8h, v16.4s
  fcvtn2 v1.8h, v16.4s
  fcvtn2 v2.8h, v16.4s
  fcvtn2 v3.8h, v16.4s
  fcvtn2 v4.8h, v16.4s
  fcvtn2 v5.8h, v16.4s
  fcvtn2 v6.8h, v16.4s
  fcvtn2 v7.8h, v16.4s
  fcvtn2 v8.8h, v16.4s
  fcvtn2 v9.8h, v16.4s
  fcvtn2 v10.8h, v16.4s
  fcvtn2 v11.8h, v16.4s
  fcvtn2 v12.8h, v16.4s
  fcvtn2 v13.8h, v16.4s
  fcvtn2 v14.8h, v16.4s
  fcvtn2 v15.8h, v16.4s
  movi v16.16b, 17

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.5002

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)
160204800971601051011600041001600083006400361601082001600122003200281160000100
160204800461601071011600061001600103006400361601082001600122003200241160000100
160204800351601051011600041001600083006400361601082001600122003200241160000100
160204800351601051011600041001600083006400361601082001600122003200241160000100
160204800351601051011600041001600083006400361601082001600122003200241160000100
160204800351601051011600041001600083006400361601082001600122003200241160000100
160204800351601051011600041001600083006400361601082001600122003200241160000100
160204800441601051011600041001600083006400361601082001600122003200281160000100
160204800351601051011600041001600083006400361601082001600122003200241160000100
160204800351601051011600041001600083006402081601542001600632003200241160000100

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.5002

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)
160024800971600171116000610160010030064000016001020016000020320000116000010
160024800401600111116000010160000030064000016001020016000020320000116000010
160024800351600111116000010160000030064000016001020016000020320000116000010
160024800351600111116000010160000030064000016001020016000020320000116000010
160024800351600111116000010160000030064000016001020016000020320000116000010
160024800641600111116000010160000030064000016001020016000020320000116000010
160024800361600111116000010160000030064000016001020016000020320000116000010
160025800751600481116003710160045030064000016001020016000020320000116000010
160024800351600111116000010160000030064000016001020016000020320000116000010
160024800351600111116000010160000030064000016001020016000020320000116000010