Apple M1 Microarchitecture Research by Dougall Johnson

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

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

Test 1: uops

Code:

  scvtf d0, d0, #3
  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)03181e3f4e51inst 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
1004303723006125472510001000100039816013018303730372414328951000100010003037303711100110000373216332629100030383038303830383038
1004303723039525472510001000100039816013018303730372414328951000100010003037303711100110000373416332629100030383038303830383038
1004303723006125472510001000100039816003018303730372414328951000100010003037303711100110000075316332629100030383038303830383038
1004303722006125472510001000100039816003018303730372414328951000100010003037303711100110000373316332629100030383038303830383038
10043037230010325472510001000100039816003018303730372414328951000100010003037303711100110000373416332626100030383038303830383038
100430372301210325472510001000100039816003018303730372414328951000100010003037303711100110000673316332626100030383038303830383038
1004303722006125472510001000100039816013018303730372414328951000100010003037303711100110001373316332629100030383038303830383038
10043037230126125472510001000100039816013018303730372414328951000100010003037303711100110000373416332629100030383038303830383038
1004303723006125472510001000100039816013018303730372414328951000100010003037303711100110001373316332629100030383038303830383038
100430372301210325472510001000100039816013018303730372414328951000100010003037303711100110000373316442626100030383038303830383038

Test 2: Latency 1->2

Code:

  scvtf d0, d0, #3
  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)0308090b1e3f4e51inst 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)696d6edispatch 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)9fa1a8a9acc2cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
10204300372330003310329547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038
10204300372250001210329547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038
1020430037225000010329547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038
10204300372250001210329547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038
1020430037225000126129547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000100071011611296330100001003003830038300383003830038
1020430037224000012429547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000100071011611296330100001003003830038300383003830038
1020430037224000010329547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038
1020430037225000010329547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038
1020430037225000010329547251010010010000100100005004277160300183003730037282643287451010020010000200100003003730037111020110099100100100001000103071011611296330100001003003830038300383003830038

1000 unrolls and 10 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)60696b6d6edispatch 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)9fa0a1a6a8a9acc2cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
10024300372250000000612954725100101010000101000050427716013001803003730037282863287671001020100002010000300373003711100211091010100001000000006402162229629010000103003830038300383003830038
10024300372250000000612954725100101010000101000050427716013001803003730037282863287671001020100002010000300373003711100211091010100001000000006402162229629010000103003830038300383003830038
100243003722500000003402954725100101010000101000050427716013001803003730037282863287671001020100002010000300373003711100211091010100001000000006402162229629010000103003830038300383003830038
100243003722500000001662953825100101010000101000050427716013001803003730037282863287671001020100002010000300373003711100211091010100001000000006402163429924410000103041730424304643045330371
100243041622711881068704049942947516910080161006412112005542866241303060304523046128309222889611214241119224111453041330452911002110910101000010002042234307933813329629010000103003830038300383003830038
1002430037225000014647921530729475171100791410072131120065428932813034203046130463283214028936103692211326261081530448304179110021109101010000100021225160280931012329977310000103046330369303243041530455
10024304182280199118879203105294661591008512100691911350714287976130378030607306052832548289591151724116362011812305573055412110021109101010000104220030518087441054330102010000103003830038300383003830038
1002430037233000012005949294571701006313100001010000504277160130018030273305092828632876710162241147222113133036830560101100211091010100001020310028083953229917410000103041830558304133003830038
1002430037233010214196804100295472510010101000010100005542920321301620304643041728332442897011213201115024113163031930556711002110910101000010003101670506402562230006510000103032330321306053027530469
100243045123711139119179204252952061100281410016141060071427716013001803003730037282863287671001020100002010000300373003711100211091010100001000000006402162229629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  scvtf d0, d8, #3
  scvtf d1, d8, #3
  scvtf d2, d8, #3
  scvtf d3, d8, #3
  scvtf d4, d8, #3
  scvtf d5, d8, #3
  scvtf d6, d8, #3
  scvtf d7, d8, #3
  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)031e1f3f51inst 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)9fa8acc2c5branch mispredict (cb)cdcfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80204200581503072258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100030111511801600200360800001002004020040200402004020040
80204200391502410872258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100030111511801600200360800001002004020040200402004020040
802042003915027072258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100130111511801600200360800001002004020040200402004020040
8020420039150120722580108100800081008002050064013212002020039200399977610068801202008003220080032200392003911802011009910010080000100100111511801600200360800001002004020040200402004020040
80204200391500072258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100130111511801600200360800001002004020040200402004020040
802042003915012030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100132111511801600200360800001002004020040200402004020040
802042003915024030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100130111511801600200360800001002004020040200402004020040
802042003915030357258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100030111511801600200360800001002004020040200402004020040
802042003915012030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100130111511801600200360800001002004020040200402004020040
802042003915012072258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100000111511801600200360800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)030a1e3f51inst 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)9fa8accficache miss (d3)d5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80024200391500102402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050201111611122003680000102004020040200402004020040
800242003915000402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200121614122003680000102004020040200402004020040
800242003915000402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200131612112003680000102004020040200402004020040
800242003915001540258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010005020012161292003680000102004020040200402004020040
8002420039150027402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200111613112003680000102004020040200402004020040
8002420039150001142580010108009710803175064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200131614122003680000102004020040200402004020040
800242003915000402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200151613112003680000102004020040200402004020040
8002420039150015402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200131612122003680000102004020040200402004020040
8002420039150015402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200111611112003680000102004020040200402004020040
800242003915600402580010108000010800005064000012002020039200399996310019800102080000208000020039200391180021109101080000100050200111611122003680000102004020040200402004020040