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

SBC (32-bit)

Test 1: uops

Code:

  sbc w0, w0, w1
  mov x0, 1
  mov x1, 2

(no loop instructions)

1000 unrolls and 1 iteration

Retires: 1.000

Issues: 1.000

Integer unit issues: 1.001

Load/store unit issues: 0.000

SIMD/FP unit issues: 0.000

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000
100410301001100110002560310001000300010011000

Test 2: Latency 1->2

Code:

  sbc w0, w0, w1
  mov x0, 1
  mov x1, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 1.0030

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
10204100301010110101101082594351010710214302361000110100
10204100301010110101101072594151010710214302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100

1000 unrolls and 10 iterations

Result (median cycles for code): 1.0030

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
10024100301002110021100282609411016410180300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10025100601003510035100692595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010

Test 3: Latency 1->3

Code:

  sbc w0, w1, w0
  mov x0, 1
  mov x1, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 1.0030

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
10204100301010110101101082593291010710214302421000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100
10204100301010110101101072595391010710212302361000110100

1000 unrolls and 10 iterations

Result (median cycles for code): 1.0030

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
10024100301002110021100292594901002810034300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10024100301002110021100202595911002010020300201001110010
10025100601003510035100692595911002010020300201001110010

Test 4: Latency 1->4

Chain cycles: 1

Code:

  sbc w0, w1, w2
  tst x0, 1
  mov x0, 1
  mov x1, 2
  mov x2, 3

(non-fused SUB/CBNZ loop)

100 unrolls and 100 iterations

Result (median cycles for code, minus 1 chain cycle): 1.0030

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
20204200302020120201202085192992021120216403282011510100
20204200302020120201202085192512020920216402322010110100
20204200302020120201202085194482020820216402322010110100
20204200302020120201202085194482020820216402322010110100
20204200302020120201202085194482020820216402322010110100
20204200302020120201202085194482020820216402322010110100
20204200302020120201202085194482020820216402322010110100
20204200302020120201202085194482020820216402322010110100
20204200302020120201202085194482020820216402322010110100
20204200302020120201202085194482020820216402322010110100

1000 unrolls and 10 iterations

Result (median cycles for code, minus 1 chain cycle): 1.0030

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
20024200302002120021200295195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010
20024200302002120021200205195912002020020400202001110010

Test 5: throughput

Count: 8

Code:

  sbc w0, w8, w9
  sbc w1, w8, w9
  sbc w2, w8, w9
  sbc w3, w8, w9
  sbc w4, w8, w9
  sbc w5, w8, w9
  sbc w6, w8, w9
  sbc w7, w8, w9
  mov x8, 9
  mov x9, 10

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.3342

retire uop (01)cycle (02)schedule uop (52)schedule int uop (53)dispatch int uop (56)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
802042688580115801158012029163480120802222402668001580100
802052677180158801588017329270280120802222404408005680100
802042673780115801158012029323680120802242402728001580100
802042674580115801158012029323680120802242402728001580100
802042673780115801158012029323680120802242402728001580100
802042673780115801158012029323680120802242402728001580100
802042673780115801158012029323680120802242402728001580100
802042673780115801158012029323680120802242402728001580100
802042673780115801158012029323680120802242402728001580100
802042673780115801158012029323680120802242402728001580100

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.3344

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)int uops in schedulers (59)dispatch uop (78)map int uop (7c)map int uop inputs (7f)? int output thing (e9)? int retires (ef)
800242796480038800380080052029352780046800502400208001180010
800242680180021800210080020038943780020800202400208001180010
800252696580188801880080214033342380020800202400208001180010
800242675180021800210080020038943780020800202400208001180010
800242675180021800210080020042678080020800202400208001180010
800242675680021800210080020042678080020800202400208001180010
800242675180021800210080020042678080020800202400208001180010
800242675180021800210080020042678080020800202400208001180010
800242752480038800380080052038943780020800202400208001180010
800242677080021800210080020035761180052800542400208001180010