Apple M1 Microarchitecture Research by Dougall Johnson

Firestorm: Overview | Base Instructions | SIMD and FP Instructions
Icestorm:  Overview | Base Instructions | SIMD and FP Instructions

FCVTN (vector, 2D)

Test 1: uops

Code:

  fcvtn v0.2s, v0.2d
  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: 0.000

Load/store unit issues: 0.000

SIMD/FP unit issues: 1.000

retire (01)cycle (02)031e3f4e51inst issue (52)~issue fp/simd (54)~dispatch fp/simd (57)huge thing fp/simd (5b)60696d6edispatch stall (70)scheduler rewind (75)scheduler stall (76)~dispatch op (78)~map op fp/simd (7e)~map lookup fp/simd (81)8283pipeline redirect (84)85inst all (8c)inst neon or fp (9a)a8accfd5d6ddinst fetch restart (de)e0? fp/simd (ee)f5f6f7f8fd
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372406125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116122629100030383038303830383038
1004303723010325472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372308925472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372406125472510001000100039816003018303730372414328951000100010003037303711100110000373116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  fcvtn v0.2s, v0.2d
  movi v0.16b, 1
  movi v1.16b, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)03080b18191e1f3a3f4e51inst issue (52)~issue int (53)~issue fp/simd (54)~dispatch int (56)~dispatch fp/simd (57)huge thing int (59)huge thing fp/simd (5b)5e60696d6edispatch stall (70)scheduler rewind (75)scheduler stall (76)~dispatch op (78)~map op int (7c)~map op fp/simd (7e)~map lookup int (7f)~map lookup fp/simd (81)8283pipeline redirect (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst b.cc (94)inst integer (97)inst neon or fp (9a)9fa1a6a7a8a9acc2c9cfd5d6ddinst fetch restart (de)e0? int output thing (e9)eb? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
1020430037233000000061295472510100100100001001000050042771600030018300373003728264328745101002001000020010000300373003711102011009910010010000100000000009163661129982240100001003051530474304223046930468
1020430463237009412001056067122947498102211301007215310750680428628200301263026330467282884228814105662221116222010655304603021810110201100991001001000010000000000710125112963300100001003003830038300383003830038
1020430037232115466046006240295472510100100100001001000050042771600030018300373003728264328745101002201115620810665304653027591102011009910010010000100421042009500710116112963300100001003003830038300383013430038
102043008423300006006129547251010010010000100100005004277160003001830037300372826432874510100200100002001000030037300371110201100991001001000010000000300710116112963300100001003003830038300383003830038
1020430131235107326744006129547174101001001000013610900729428932800303423041830418282963828872107342261067122910988304683040821102011009910010010000100000000008083561229890230100001003032330135305133022730277
10204304192490100000416829493174101931441004814311200704428527200300183003730037282643287451026820010000200100003003730037111020110099100100100001000000000291710116112963300100001003003830038300863003830038
10204300372410000000822954725101001001000010010000500427716000300183003730037282643287451010020010000200100003003730037111020110099100100100001000121000000710116412963300100001003003830038300383003830038
102043003723200000006129547251010010010000100100005004277160103001830037300372826432874510100200100002001000030037300371110201100991001001000010000000020710116112963300100001003003830038300383003830038
102043003723300000006129547251010010010000100100005004277160003001830037300372826432874510100200100002001000030037300371110201100991001001000010000000000710116112963300100001003003830038300383003830038
102043003723200000006129547251010010010000100100005004277160003001830037300372826432874510100200100002001000030037300371110201100991001001000010000000000710116112963300100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)03091e3f4e51inst issue (52)~issue int (53)~issue fp/simd (54)~dispatch int (56)~dispatch fp/simd (57)huge thing int (59)huge thing fp/simd (5b)60696d6edispatch stall (70)scheduler rewind (75)scheduler stall (76)~dispatch op (78)~map op int (7c)~map op fp/simd (7e)~map lookup int (7f)~map lookup fp/simd (81)8283pipeline redirect (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst b.cc (94)inst integer (97)inst neon or fp (9a)9fa8acbranch mispredict (cb)cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
10024300372330210140429547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038
1002430037232006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300863022730038
1002430037233006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038
1002430037233006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038
1002430037232006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038
1002430037232036129547251001010100001010000504277160130018300373003728286328773100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038
100243003722502076129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300375110021109101010000100006402162229629010000103003830038300383003830038
10024300372250246129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100006402162229629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  fcvtn v0.2s, v8.2d
  fcvtn v1.2s, v8.2d
  fcvtn v2.2s, v8.2d
  fcvtn v3.2s, v8.2d
  fcvtn v4.2s, v8.2d
  fcvtn v5.2s, v8.2d
  fcvtn v6.2s, v8.2d
  fcvtn v7.2s, v8.2d
  movi v8.16b, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.2505

retire (01)cycle (02)030b1e1f3f51inst issue (52)~issue int (53)~issue fp/simd (54)~dispatch int (56)~dispatch fp/simd (57)huge thing int (59)huge thing fp/simd (5b)60696d6edispatch stall (70)scheduler rewind (75)scheduler stall (76)~dispatch op (78)~map op int (7c)~map op fp/simd (7e)~map lookup int (7f)~map lookup fp/simd (81)8283pipeline redirect (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst b.cc (94)inst integer (97)inst neon or fp (9a)9fa8a9acc5branch mispredict (cb)cdcfd5d6ddinst fetch restart (de)e0e2? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
802042003915500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100000111511801600200360800001002004020040200402004020040
8020420039155000116258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100000111511801600200360800001002004920049200502004920049
802042004915510085278011610080016100800285006401961200292004820048997699986801282008003820080038200482004811802011009910010080000100100222512812311200450800001002025320049200492005020050
8020420049155000922780116100800161008002850064019602002920049200489976109986801282008003820080038202732003911802011009910010080000100100111511801600200360800001002004020040200402004020040
802042003915600030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100009111511801600200360800001002004020040200402004020040
802042003915500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100003111511801600200360800001002004020040200402004020040
802042003915500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100000111511801600200360800001002004020040200402004020040
802042003916500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100000111511801600200360800001002004020040200402004020040
802042003915600030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100000111511801600200360800001002004020040200402004020040
8020420039155000302580108100800081008002050064013212009620039200399977699908012020080032200800322003920039118020110099100100800001001063111511801600200360800001002004020040200402004020040

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.2505

retire (01)cycle (02)0308191e3f51inst issue (52)~issue int (53)~issue fp/simd (54)~dispatch int (56)~dispatch fp/simd (57)huge thing int (59)huge thing fp/simd (5b)5f60696d6edispatch stall (70)scheduler rewind (75)scheduler stall (76)~dispatch op (78)~map op int (7c)~map op fp/simd (7e)~map lookup int (7f)~map lookup fp/simd (81)8283pipeline redirect (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst b.cc (94)inst integer (97)inst neon or fp (9a)9fa0a8acc2cfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
8002420050156005740448010710800001080000506400000020020200392003999963100198001020800002080000200392003911800211091010800001000005020116112003680000102004020040200402004020040
80024200391551018828258001010800001080104506408281120020200392003999963100198001020800002080000200392003911800211091010800001000005020116112003680000102004020040200402004020040
800242003915601040258001010800001080212506400000020020200392003999963100198001020800002080000200392003911800211091010800001001005020116112003680000102004020040200402004020040
800242003916100040258001010800001080000506400000120020200392003999963100198001020800002080000200392003911800211091010800001000005020116112003680000102004020040200402004020040
80024200391550005017258001010800001080000506400000120020200392003999963100198001020800002080000200392003911800211091010800001000005020116112003680000102004020040200402004020040
800242003915600040258001010800001080000506400000120020200392003999963100198001020800002080000200392003911800211091010800001000005020116112003680000102004020040200402004020040
800242003915500040258001010800001080000506400000120020200392003999963100198001020800002080000200392003911800211091010800001000005020116112003680000102004020040200402004020040
80024200421560001032580010108000010802115064000001200592009020088100058100458001020800002080000200392003921800211091010800001000005020116112003680000102004020040200402004020040
800242003915500040258001010800001080000506400000120020200392003999963100198001020800002080000200392003911800211091010800001000005020116112003680000102004020040200402004020040
8002420039155000357258001010800001080000506400000120020200392003999963100198001020800002080000200392003911800211091010800001000305020116112003680000102004020040200402004020040