Apple M1 Microarchitecture Research by Dougall Johnson

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

FCVT (S to H)

Test 1: uops

Code:

  fcvt h0, s0
  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)acc2cfd5d6ddinst fetch restart (de)e0? fp/simd (ee)f5f6f7f8fd
100430372206125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303723084254725100010001000398160130183037303724143289510001000100030373037111001100042073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372206125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372206125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  fcvt h0, s0
  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)031e3f4e51inst 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)9fa6a7a8accfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
1020430037225156612954725101001001000010010000500427716003001830037300372827632874510100200100002001000030037300371110201100991001001000010000128707101161129633100001003003830038300383003830038
10204300372240612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000007101161129633100001003003830038300383003830038
10204300372250612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000007101161129633100001003003830038300383003830038
10204300372250612954725101001001000010010000500427716003001830084300372826432874510100200100002001000030037300371110201100991001001000010000007101161129633100001003003830038300383003830038
10204300372250612954725101001001000010010000500427716013001830037300372826432874510100200100002001000030037300371110201100991001001000010000007101161129633100001003003830038300383003830038
10204300372250612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000028017101161129633100001003003830038300383003830038
10204300372250612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000007101161129633100001003003830038300383003830038
102043003722530612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000107101161129633100001003003830038300383003830038
10204300372250612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000007101161129633100001003003830038300383003830038
10204300372250612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000007101161129633100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)030b1e3f4e51inst 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)9fa0a8accdcfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
10024300372250876129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640316222962910000103003830038300383003830038
10024300372250248229547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640316222962910000103003830038300383003830038
10024300372250246129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640216222962910000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640216222962910000103003830038300383003830038
10024300372250276129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100000640216222970110000103003830038300383003830038
10024300372250366129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640216222962910000103003830038300383003830038
10024300372250216129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640224222962910000103003830038300383003830038
100243003722503396129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640216222962910000103003830038300383003830038
10024300372250246129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640216222962910000103003830038300383003830038
10024300372250246129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000640216222962910000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  fcvt h0, s8
  fcvt h1, s8
  fcvt h2, s8
  fcvt h3, s8
  fcvt h4, s8
  fcvt h5, s8
  fcvt h6, s8
  fcvt h7, s8
  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)0308090b18191e1f3f51inst 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)9fa6a7a8a9acc2c5branch mispredict (cb)cdcfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80204200581500000000302580108100800081008002050064013220020200392003999776999080120200801422008003220039200391180201100991001008000010000000011151181161120036800001002004020040200402004020040
80204200391500000000302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010000000011151181161120036800001002004020040200402004020040
802042003915000000003025801081008000810080020500640132200202003920039997715999080120200800322008003220039200391180201100991001008000010000090011151181161120036800001002004020040200402004020040
802042003915000000150302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010000100011151181161120036800001002004020040200402004020040
802042003915000000270302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010000000011151181161120036800001002004020040200402004020040
80204200391500000030302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010000000011151181162120036800001002004020040200402004020040
80204200391500000000302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010000000011151181161120036800001002004020040200402004020040
80204200391500000000302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010000003011151181161120036800001002004020040200402004020040
80204200391500000000302580108100800081008002050064013220020200392003999776999080120200800322008003220039200391180201100991001008000010000000011151181161120036800001002004020040200402004020040
80204200391500000000302580108100800081008002050064013220020200392009999776999080120200800322008003220039200391180201100991001008000010000000011151181161120036800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)031e3a3f51inst 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)9fa8accfd2icache miss (d3)d5d6d9dadbddinst fetch restart (de)e0eaeb? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
800242005015000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200021600011200360080000102004020040200402004020040
800242003915000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040
800242003915000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040
800242003915000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040
800242011215100402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040
800242003915000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040
800242003915000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040
800242003915000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000101050200011600011200360080000102004020040200402004020040
800242003915030402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040
800242003915000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100050200011600011200360080000102004020040200402004020040