Apple M1 Microarchitecture Research by Dougall Johnson

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

SCVTF (vector, fixed-point, 4H from 4H)

Test 1: uops

Code:

  scvtf v0.4h, v0.4h, #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)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)cfd5d6ddinst fetch restart (de)e0? fp/simd (ee)f5f6f7f8fd
1004303722061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
1004303723061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
1004303722061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
1004303723061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
1004303723061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
1004303723061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
1004303723061254725100010001000398160130183037303724143289510001000100030373037111001100073316112629100030383038303830383038
1004303722061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
10043037231261254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038
1004303722061254725100010001000398160130183037303724143289510001000100030373037111001100073116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  scvtf v0.4h, v0.4h, #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)03080b18191e1f3f4e51inst 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)9fa0a1a8a9accfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
102043003722500000061295382510100100100081051000050042771601300543003730131282758287621010020010166200100003008530037111020110099100100100001000000071031611296330100001003003830038300383003830038
1020430037225000000266295472510100100100001001000050042771601300183003730037282643287451010020010000204100003003730037111020110099100100100001000000071011611296330100001003003830038300383003830038
102043003722400000061295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000000071011611296330100001003003830038300383003830038
1020430037225000087061295472510111126100001001000050042771601300183003730037282643287821010020210000204100003008530037111020110099100100100001000000071011621296330100001003003830038300383003830038
102043003722501000061295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000000071011611296330100001003003830038300383003830038
102043003722500000061295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000000071011611296930100001003003830038300383003830038
102043003722500004200103295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000000071011611296330100001003003830038300383003830038
102043003722500000061295472510100100100001001000050042771601300183003730037282643287451010020010000204100003003730037111020110099100100100001000000071011611296330100001003003830038300383003830038
102043003722500000061295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000000071011611296330100001003003830038300383003830038
10204300372240000171061295472510100100100001001000050042771601300183003730070282643287451010020010000200100003003730037111020110099100100100001000000071011611296330100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)030b18191e1f3f4e51inst 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)9fa0a1a6a7a8a9acc2cdcfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
100243003722500012019829547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000003006403162229629010000103003830038300383003830038
100243003722500012010329547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000100006402162229629010000103003830038300383003830038
100243003722500012010329547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000103006402162229629010000103003830038300383003830038
100243003722500012010329547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000003006402162229629010000103003830038300383003830038
10024300372250001206129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000100006402162229629010000103003830038300383003830038
100243003722400000103295472510010101000010100005042771600300183003730037282863287671001020100002010000300373003711100211091010100001020211019233207686644429878310000103035730320303683036730321
1002430360227077924528487829493150100711410056131105060428679803023430367303672832029289031106320111462210989303703036971100211091010100001044202418461006402162229629010000103003830038300853003830038
100243003722518794817640222948415710069161004814110507042866240303063036930413283091828897110632411135221132930371303669110021109101010000100200208548207932644229916510000103037030367300383037130369
100243035722501794870470942945720810094161006418115006642893280303423050830500283134028957115112411482221164630508305141011002110910101000010002004167212085321222330024410000103055830545302753055830084
10024300372250001201530294461731008611100801611500824287976030378305583055828323452897011534261177024111623051030560141100211091010100001004001022383006402164429845310000103036930371305573032130370

Test 3: throughput

Count: 8

Code:

  scvtf v0.4h, v8.4h, #3
  scvtf v1.4h, v8.4h, #3
  scvtf v2.4h, v8.4h, #3
  scvtf v3.4h, v8.4h, #3
  scvtf v4.4h, v8.4h, #3
  scvtf v5.4h, v8.4h, #3
  scvtf v6.4h, v8.4h, #3
  scvtf v7.4h, v8.4h, #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)0308090b191e1f3f51inst 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)9fa0a8acc5branch mispredict (cb)cdcfd5d6inst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80204200391500000120722580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000101115118116020036800001002004020040200402004020040
8020420039150000013813230258010810080008100800205006401320200202003920039997769990801202008003220080032200392003911802011009910010080000100012251115118016020036800001002004020040200402004020040
8020420039150000000722580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000001115118016020036800001002004020040200402004020040
8020420039150000012030258010810080008100800205006401320200202003920039997769990801202008003220080032200392003911802011009910010080000100011351115118016020036800001002004020040200402004020040
80204200391500000120722580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000001115118016020036800001002004020040200402004020040
80204200391500000120302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000101115118016020036800001002004020040200402004020040
80204200391500000360722580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000131115118016020036800001002004020040200402004020040
802042003915000001206212580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000001115118016020036800001002004020040200402004020040
80204200391500000120302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000231115118016020036800001002004020040200402004020040
80204200391500000120722580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000101115118016020036800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)030b1e1f3a3f51inst 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)9fa8accfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80024200391500120245258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010105024151616152003680000102004020040200402004020040
80024200391500120287258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010035024181617162003680000102004020040200402004020040
80024200391500120245258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010105024151617142003680000102004020040200402004020040
80024200391510120287258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010135024171617182003680000102004020040200402004020040
80024200391500120245258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010135024131614122003680000102004020040200402004020040
800242003915001202351258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010035024181619182003680000102004020040200402004020040
8002420039150012028725800101080000108000050640000120020200392003999963100198001020800002080000200392003911800211091010800001000502417161792003680000102004020040200402004020040
8002420039150000287258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010135024161617142003680000102004020040200402004020040
8002420039150000245258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010135024171717142003680000102004020040200402004020040
8002420039150000245258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010005024161619162003680000102004020040200402004020040