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, S from W)

Test 1: uops

Code:

  scvtf s0, w0, #3
  mov x0, 1
  mov x1, 2

(no loop instructions)

1000 unrolls and 1 iteration

Retires: 2.000

Issues: 2.000

Integer unit issues: 0.000

Load/store unit issues: 1.000

SIMD/FP unit issues: 1.000

retire uop (01)cycle (02)031e3f4f51schedule uop (52)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)60696d6emap stall dispatch (70)map rewind (75)map stall (76)dispatch uop (78)map ldst uop (7d)map simd uop (7e)map ldst uop inputs (80)map simd uop inputs (81)8283flush restart other nonspec (84)85inst all (8c)inst simd alu (9a)ld unit uop (a6)l1d cache writeback (a8)accfd5map dispatch bubble (d6)ddfetch restart (de)e0? ldst retires (ed)? simd retires (ee)f5f6f7f8fd
2004376303610252000100010001000100014075228201357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004377303610252000100011301000100014075228201357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004376233610252000100010001000100014075228201357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004376303610252000100010001000100014075228201357376376723109200010001000100010003763761110011000100000731161137310001000377378377377377
2004376203610252000100010001000100014075228201357376376723109200010001000100010003763761110011000100000731161137310001000377377377378377
2004376303610252000100010001000100014075228201357376376723109200010001000100010003763761110011000100000731161237310001000377377377377377
2004376303610252000100010001000100014075228201357376376733109200010001000100010003763761110011000100030731161237310001000377377377377377
2004376303610252000100010001000100014075228201357376376723109200010001000100010003763761110011000100000731161237310001000377377377377377
2004376303614252000100010001000100014075228201357376376723109200010001000100010003763791110011000100000731161237310001000377377377377377
2004376303612252000100010001000100014075228201357376376723109200010001000100010003763761110011000100000731161237310001000377377377377377

Test 2: Latency 1->2 roundtrip

Code:

  scvtf s0, w0, #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): 13.0032

retire uop (01)cycle (02)03mmu table walk data (08)l2 tlb miss data (0b)18191e1f3f4f51schedule 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)696d6emap stall dispatch (70)map rewind (75)map stall (76)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)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fl1d tlb miss (a1)ld unit uop (a6)l1d cache writeback (a8)accfd0d5map dispatch bubble (d6)ddfetch restart (de)e0? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
30204130032974001130601300211194092540100101002000010000100200001000050062144971480270913001313003213003212546631262403010020010000200002001000020000130032130032112020110099100101001000010001000013131012162212952110000100001000010100130038130035130033130033130033
3020413003297400000013001711955411240100101002000010000100200001000050062147851480270913001313003213003312546631262413010020010000200002001000020000130032130054112020110099100101001000010001000013131013163212952110000100001000010100130033130036130033130033130033
3020413003297400003001300171194082540100101002000010000100200001000050062144971480282513001313003213003212546631262403010020010000200002001000020000130032130032112020110099100101001000010001000013131013163312951910000100001000010100130033130033130033130037130033
3020413003297400001201300171194082540100101002000010000100200001000050062144971480270913001313003213003212549531262423010020010000200002001000020000130032130083112020110099100101001000010001000013131013163312951910000100001000010100130033130033130033130033130033
3020413003297400001201300171194082540100101002000010000100200001000050062144971480294113001313003213003212546631262403010020010000200002001000020000130032130032112020110099100101001000010001000010131012162212952010000100001000010100130033130033130033130034130033
3020413003297400001201300171194082540100101002000010000100200001000050062144971480270913001313003413003512546631262403010020010000200002001000020000130032130032112020110099100101001000010001000013131012162212951910000100001000010100130033130034130033130035130033
302041300329730000001300171194102540100101002000010000100200001000050062145451480270913001313003213003212546631262433010020010000200002001000020000130036130032112020110099100101001000010001000013131013162212952010000100001000010100130033130033130033130033130033
3020413003297400001201300171194082540100101002000010000100200001000050062144971480270913001313003213003212546731262403010020010000200002001000020000130032130052112020110099100101001000010001000013131012162212951910000100001000010100130035130033130033130033130062
3020413003297300001201300171194082540100101002000010000100200001000050062145451480304813001313003213003212546831262403010020010000200002001000020000130032130032112020110099100101001000010001000013131013163312951910000100001000010100130033130033130033130033130033
3020413003297400001201300171194102540100101002000010000100200001000050062144971480270913001313003213003312546631262403010020010000200002001000020000130032130032112020110099100101001000010001000010133612163212951910000100001000010100130034130036130033130033130033

1000 unrolls and 10 iterations

Result (median cycles for code): 13.0032

retire uop (01)cycle (02)0318191e1f3f4f51schedule 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)60696d6emap stall dispatch (70)map rewind (75)map stall (76)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)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fl1d tlb access (a0)l1d tlb miss (a1)ld unit uop (a6)l1d cache writeback (a8)acc2branch mispred nonspec (cb)cdcfd5map dispatch bubble (d6)ddfetch restart (de)e0? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
300241300329740000130017119408254001010010200001000010200001000050621449714800528013001313003213003212548931262623001020100002000020100002000013003213003211200211091010010100001000100000000012702161112952010000100001000010010130033130033130033130033130033
300241300329740000130017119408254001010010200001000010200001000050621449714800528013001313003213003212548931262623001020100002000020100002000013003213003211200211091010010100001000100000000012701161112952210000100001000010010130033130033130033130033130033
300241300329740000130017119408464001010010200001000010200001000050621449714800528013001313003213003212548931262623001020100002000020100002000013003213003211200211091010010100001000100000000012701161112955410000100001000010010130033130033130033130033130033
300241300329740000130017119408254001010010200001000010200001000050621449714800528013001313003213003212548931262623001020100002000020100002000013003213003211200211091010010100001000100000000012701161312953910000100001000010010130033130033130033130036130033
3002413003297400120130017119408254001010010200001000010200001000050621454514800528013001313003213003212548931262623001020100002000020100002000013003213003211200211091010010100001000100001300012701161112952110000100001000010010130033130034130033130033130033
3002413003297400120130017119408254001010010200001000010200001000050621449714800528013001313003213003412548931262623001020100002000020100002000013003513003211200211091010010100001000100001300012701161112955410000100001000010010130033130033130033130033130033
3002413003297400120130018119409254001010010200001000010200001000050621449714800642113001313003513003212548931262623001020100002000020100002000013003213003611200211091010010100001000100001300012701161112954510000100001000010010130033130033130036130033130033
300241300359740000130019119408254001010010200001000010200001000050621464114808070113001313003213003212548931262653001020100002000020100002000013003213003211200211091010010100001000100000000013951793312996310000100001000010010130033130033130033130367130373
300241303689740090988130017119408254001010010200001000010200001000050621449714800528013001313003213003212548931262623001020100002000020100002000013003213003211200211091010010100001000100001300012701161112954010000100001000010010130033130033130033130033130033
3002413003297400120130017119410254001010010200001000010200001000050621449714800864113001313003213003512549231262623001020100002000020100002000013003313003311200211091010010100001000100001300012701161112955810000100001000010010130033130033130033130035130033

Test 3: throughput

Count: 8

Code:

  scvtf s0, w8, #3
  scvtf s1, w8, #3
  scvtf s2, w8, #3
  scvtf s3, w8, #3
  scvtf s4, w8, #3
  scvtf s5, w8, #3
  scvtf s6, w8, #3
  scvtf s7, w8, #3
  mov x8, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.3339

retire uop (01)cycle (02)033f4f51schedule 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)60696d6emap stall dispatch (70)map rewind (75)map stall (76)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)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fld unit uop (a6)l1d cache writeback (a8)acbranch cond mispred nonspec (c5)branch mispred nonspec (cb)cdcfd5map dispatch bubble (d6)ddfetch restart (de)e0? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
1602042671020026700025160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080020200800208002026917270551180201100991001008000010080000001115117016002670680000800001002671026710267102671026710
1602042670920026694625160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080024200800208002426725267211180201100991001008000010080000001115117016002670680000800001002671026710267102671026710
1602042670920026694025160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080020200800208002026709267091180201100991001008000010080000001115117016002670680000800001002671026710267102671026710
1602042670920026694025160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080020200800208002026709267091180201100991001008000010080000001115117016002670680000800001002671826710267102671026710
1602042670920026694025160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080020200800208002026709267091180201100991001008000010080000001115117016002670680000800001002671026710267102671026710
1602042670920026694025160100100800008000010080020800155001168951188534812669026709267096632666581601352008002080020200800208002026709267091180201100991001008000010080000001115117016002670680000800001002671026710267102671026710
1602042670920026694025160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080020200800208002026709267091180201100991001008000010080000001115117016002670680000800001002671026710267102671026710
1602042670920026694025160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080020200800208002026709267091180201100991001008000010080000001115117016002671080000800001002671026710267102671026710
1602042670920026694025160100100800008000010080020800155001168951188416312669026709267096632666581601352008002080020200800208002026709267091180201100991001008000010080000001115117016002670680000800001002671026710267102671026710
1602042670920026694025160100100800008000010080020800155001174360188419812669026709267096632666581601352008002080020200800208002026715267101180201100991001008000010080000001115117016002670680000800001002671026710267102671026710

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.3339

retire uop (01)cycle (02)03mmu table walk data (08)1e3f4f51schedule 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)60696d6emap stall dispatch (70)map rewind (75)map stall (76)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)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fl1d tlb miss (a1)a5ld unit uop (a6)l1d cache writeback (a8)a9accfl1i cache miss demand (d3)d5map dispatch bubble (d6)ddfetch restart (de)e0? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
160024267152000122670132516001010800008000010800008000050118212518841061266902671426709665736693160010208000080000208000080000267132671311800211091010800001000800001035020031633268748000080000102671426714267102671426714
16002426713200012266992251600101080000800001080000800005011687011885392126694267132671466573669416001020800008000020800008000026713267131180021109101080000100111800002035020021633267128000080000102671426714267102671426714
160024267132000122669802516001010800008000010800008000050117066218807821266942671326713665336693160010208000080000208000080000267092674011800211091010800001000800000005020031633267168000080000102671426714267142671426714
160024267102000122669832516001010800008000010800008000050117541518838471266902671326713665436693160010208000080000208000080000268632674011800211091010800001000800001035020031663267178000080000102671526710267142671426714
1600242671320000266982251600101080130801301080000800005011683881883204126690267132671366573669316001020800008000020800008000026711267091180021109101080000100080000148815020181623267108000080000102671426710267142671426710
160024267132000122669832516001010800008000010800008000050116876418901941266952671326709665636693160010208000080000208000080000267132671411800211091010800001000800000035020041666267188000080000102671526714267102671426714
160024267092050122669822516001010800008000010800008000050116945518853221266952671426714665336693160010208000080000208000080000267132671311800211091010800001000800001035020031632267368000080000102671426714267152671426715
160024267092000122669422516001010800008000010800008000050116860018835111266952671026713665736694160010208000080000208000080000267132671411800211091010800001000800000035020061632267188000080000102671426714267142671426714
160024267092000122669832516001010800008000010800008000050116888018840321266902671326714665736690160010208000080000208000080000267142671311800211091010800001000800000035020031653267188000080000102671526714267152671026714
16002426709200002669822516001010800008000010800008000050116888018840321266902671426713665336693160010208000080000208000080000267132671311800211091010800001040800000035020031636267148000080000102671026710267142671426710