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, S from S)

Test 1: uops

Code:

  scvtf s0, s0, #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)0318191e1f3f4e51inst 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
100430372300006125472510001000100039816003018303730372414328951000100010003037303711100110004073216222629100030383038303830383038
100430372300006125472510001000100039816003018303730372414328951000100010003037303711100110002073216222629100030383038303830383038
100430372200006125472510001000100039816003018303730372414328951000100010003037303711100110004073216222629100030383038303830383038
1004303723000061254725100010001000398160030183037303724143289510001000100030373037111001100083973216222629100030383038303830383038
100430372200006125472510001000100039816003018303730372414328951000100010003037303711100110002073216222629100030383038303830383038
100430372300006125472510001000100039816003018303730372414328951000100010003037303711100110003073216222629100030383038303830383038
100430372200006125472510001000100039816003018303730372414328951000100010003037303711100110000073216222629100030383038303830383038
100430372300306125472510001000100039816003018303730372414328951000100010003037303711100110000673216222629100030383038303830383038
100430372300006125472510001000100039816003018303730372414328951000100010003037303711100110006373216222629100030383038303830383038
1004303724000015625472510001000100039816013018303730372414328951000100010003037303711100110000073216222629100030383038303830383038

Test 2: Latency 1->2

Code:

  scvtf s0, s0, #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)033f4e51inst 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)9fa8accdcfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
102043003722561295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000007101161129633100001003003830038300383003830038
102043003722561295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000007101161129633100001003003830038300383003830038
1020430037225128295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001001007101161129633100001003003830038300383003830038
102043003722561295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000007101161129633100001003003830038300383003830038
102043003722561295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000007101161129633100001003003830038300383003830038
102043003722561295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001001007101161129633100001003003830038300383003830038
102043003722561295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000007101161129633100001003003830038300383003830038
102043003722561295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001001007101161129633100001003003830038300383003830038
1020430037281217295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001001007101161129633100001003003830038300383003830038
1020430037225943295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001000007101161129633100001003003830038300383003830038

1000 unrolls and 10 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 fp/simd load (98)inst neon or fp (9a)9fa0a1a7a8a9acc2cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
100243003722400001201032954725100101010000101000050427716013001830037300372828632876710010201000020100003003730037111002110910100100001000040606402162229629010000103003830038300383003830038
100243003722500001206129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101001000010000106287451133430131310000103045530651306073064330686
1002430415246101313184811449013294392421011418100961311800894292063030594305923050928336612899111815261196224121473065330651141100211091010010000102441236692081451363330094510000103065030654306843065230606
1002430037232007017161232396629457243101021410096121195060429338403045030698306402833159289861136528113242812061306953063810110021109101001000010001003906506404942429940710000103055630641305573055530556
10024305072371112131728105691122943026610111191010414113509442948460304503073630499283395729007121182210000201000030037300371110021109101001000010000106285031283429788210000103036730554306053060330511
10024303662370100601032954725100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910100100001000010306402162229629010000103003830038300383003830038
10024300372250000120103295472510010101000010100005042771601300183003730037282863287671001020100002010000300373003711100211091010010000100001012606402162229629010000103003830038300383003830038
10024300372240000120612954725100101010000101000050427716013001830037300372828632876710010201000020100003003730037111002110910100100001000080606402162229629010000103003830038300383003830038
1002430037225000012010329547251001010100001010000504277160130018300373003728286328767100102010000201016130037300371110021109101001000010000101206402162229629010000103003830038300383003830038
10024300372250000006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101001000010000109006402162229629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  scvtf s0, s8, #3
  scvtf s1, s8, #3
  scvtf s2, s8, #3
  scvtf s3, s8, #3
  scvtf s4, s8, #3
  scvtf s5, s8, #3
  scvtf s6, s8, #3
  scvtf s7, s8, #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)0318191e1f3f51inst 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)9fa1a6a8a9acc5branch mispredict (cb)cdcfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80204200601510000512580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151182161120036800001002004020040200402014820040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000030011151181161120036800001002004020040200402004020040
802042003918800001982580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151181161120036800001002004020040200402004020040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151181161220036800001002004020040200402004020040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151181161120036800001002004020040200402004020040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151181161120036800001002004020040200402004020040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000020011151181161120036800001002004020040200402004020040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151181161120036800001002004020040200402004020040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151181161120036800001002004020040200402004020040
80204200391500000302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000000011151181161120036800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)03080918191e1f3f51inst 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)9fa0a1a7a8accfd5d6dadbddinst fetch restart (de)e0eb? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
8002420039150000012082258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010000105020316003220036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010000135020216003220036080000102004020040200402004020040
800242003915000000082258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010000235020316003320036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010000135020416003320036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010000195020316003320036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400000200202003920039999631001980010208000020801042003920100118002110910108000010000235020216003420036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010000135020216003320036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010000105020316002320036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010000305020316003220036080000102004020040200402004020040
8002420039150000012082258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010000005020216002320036080000102004020040200402004020145