Apple M1 Microarchitecture Research by Dougall Johnson

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

FCVT (H to S)

Test 1: uops

Code:

  fcvt s0, h0
  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)031e3f4e5051inst 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
10043037231261254730212510001000100039816013018303730372414328951000100010003037303711100110000073316112629100030383038303830383038
10043037223361254702510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
10043037233361254702510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722061254702510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722061254702510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722061254702510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303723061254702510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722061254702510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
10043037230612547025100010001000398160130183037303724143289510001000100030373037111001100018073116112629100030383038303830383038
1004303723061254702510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  fcvt s0, h0
  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)030f1e3f4e51inst 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)9fa8acc5cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
102043003722500612954725101001001000010010000500427716013001830037300372826432874510100200100002001000030037300371110201100991001001000010080071011611296330100001003003830038300383003830038
1020430037225006129547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100100071011611296330100001003003830038300383003830038
10204300372250061295472510100100100001001000050042771601300183003730037282643287451010020010000200100003003730037111020110099100100100001002624071011611296330100001003003830038300383003830038
102043003722500612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010093071011611296330100001003003830038300383003830038
1020430037225006129547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100715071011611296330100001003003830038300383003830038
102043003722500612954725101001001000010010000500427716003001830037300372828632874510100200100002001000030037300371110201100991001001000010060071011611296330100001003003830038300383003830038
1020430037233002392954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010070071011611296330100001003003830038300383003830038
1020430037225006129547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100313071011611296330100001003003830038300383003830038
1020430037224006129547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100313071011611296330100001003003830038300383003830038
1020430037225006129547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100253071011611296330100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)0318191e3f4e51inst 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)9fa6a7a8accfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
100243003722500018929547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
100243003722500061295472510010101000010100005042771603001830037300372828632876710010201000020100003003730037111002110910101000010003806402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038
10024300372250006129547251001010100001010000504277160300183003730037282863287671001020100002010000300373003711100211091010100001000006402162229629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  fcvt s0, h8
  fcvt s1, h8
  fcvt s2, h8
  fcvt s3, h8
  fcvt s4, h8
  fcvt s5, h8
  fcvt s6, h8
  fcvt s7, h8
  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)031e3f51inst 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)9fa1a8a9acc5branch mispredict (cb)cdcfd5d6e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
802042006115002202580108100800081008002050064013220020200902003999776999080120200800322008003220039200391180201100991001008000010003800111511811620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000100111511801620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000026111511801620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000000111511801620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000000111511801620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000000111511801620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000000111511801620036800001002004020040200402004020040
80204200391500302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010001075111511801620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000000111511801620036800001002004020040200402004020040
8020420039150030258010810080008100800205006401322002020039200399977699908012020080032200800322003920039118020110099100100800001000000111511801620036800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)031e3f51inst 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
8002420051150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020191618232003680000102004020040200402004020040
80024200391501240258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020181623132003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020231618232003680000102004020040200402004020040
80024200391500230258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010035020181622182003680000102004020040200902004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020171623182003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020231618232003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020231623232003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020221624242003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002009020039118002110910108000010105020131623182003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010005020141623182003680000102004020040200402004020040