Apple M1 Microarchitecture Research by Dougall Johnson

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

FCVTN (vector, 4S)

Test 1: uops

Code:

  fcvtn v0.4h, v0.4s
  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)03080918191e1f3f4e51inst 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)a8a9acc2cfd5d6ddinst fetch restart (de)e0? fp/simd (ee)f5f6f7f8fd
1004303724000000612547251000100010003981601301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
10043037230000003692547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
1004303723000100842547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
1004303723000000612547251000100010003981600301830373037241432895100010001000303730371110011000100073116112629100030383038303830383038
1004303723000000612547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
10043037230000003482547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
10043037220000001622547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
10043037220000001442547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
1004303722000000612547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038
10043037230000001242547251000100010003981600301830373037241432895100010001000303730371110011000000073116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  fcvtn v0.4h, v0.4s
  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)03080b1e3f4e51inst 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)9fa8accdcfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
10204300372330006129547251010010010000100100005004277160130018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372330006129547251010010010000100100005004277160030018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372320012199629547251010010010000100100005004277160130018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372321006129547251010010010000100100005004277160130018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372330006129547251010010010000100100005004277160130018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
102043003724100128929547251010010010000100100005004277160130018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372320006129547251010010010000100100005004277160030018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372320006129547251010010010000100100005004277160130018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372330006129547251010010010000100100005004277160130018030037300372826432874510100200100002001000030037300371110201100991001001000010000071021622296330100001003003830038300383003830038
10204300372330006129547251010010010000100100005004277160030018030037300372826432874510100200100002001000030037300371110201100991001001000010010071021622296330100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)03080b0e18191e1f3f4e5051inst 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)9fa0a1a6a7a8a9acc2cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
100243003723300000006129547025100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000000006402162229629010000103003830038300383003830038
100243003723200000006129547025100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000022306402162229667010000103003830038300383003830038
100243003723300000006129547025100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000000306402162229629010000103003830038300383003830038
1002430037233000000010329547025100101010000101000050427716003001830037300372829162876710163201000024100003003730037111002110910101000010000000006612162229629010000103003830038300383003830038
1002430037233000000015629547025100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000000306402162229629010000103003830038300383003830038
100243003723300000006129547025100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000000006402162229629010000103003830038300383003830038
100243003724600000006129547025100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000000006402162229629010000103003830038301323013430038
100243003723300000006129547025100101010000101000050427716003001830037300372828832876710010201016720100003008430084111002110910101000010022000006402162229629010000103003830038300383003830038
100243003723200000006129547025100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000000006402162229629010000103003830038300383003830038
10024300372330000000272629547025100101010000101000050427716003001830037300372828632876710010201065020100003003730037111002110910101000010000002006402162229629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  fcvtn v0.4h, v8.4s
  fcvtn v1.4h, v8.4s
  fcvtn v2.4h, v8.4s
  fcvtn v3.4h, v8.4s
  fcvtn v4.4h, v8.4s
  fcvtn v5.4h, v8.4s
  fcvtn v6.4h, v8.4s
  fcvtn v7.4h, v8.4s
  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)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)9fa8acc5branch mispredict (cb)cdcficache miss (d3)d5d6dde0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391560302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
802042003916003072580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180016020036800001002004020040200402004020040
80204200391550302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180116020036800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)030b18191e1f3f51inst 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)9fa6a8a9acc2cfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
800242005115600000402580010108000010800005064000002002020039200399996281001980010208000020800002003920039118002110910108000010000305020171616162003680000102004020040200402004020040
8002420039156000004025800101080000108000050640000020020200392003999963100198001020800002080000200392003911800211091010800001000000502016166162003680000102004020040200402004020040
8002420039156000004025800101080000108000050640000020020200392003999963100198001020800002080000200392003911800211091010800001000000502061617162003680000102004020040200402004020040
800242003915500000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100000050206166162003680000102004020040200402004020040
800242003915601100402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100000050207161662003680000102004020040200402004020040
8002420039156000004025800101080000108000050640000020020200392003999963100198001020800002080000200392003911800211091010800001000000502016166162003680000102004020040200402004020040
8002420039166000004025800101080000108000050640000020020200392003999963100198001020800002080000200392003911800211091010800001000000502061616162003680000102004020040200402004020040
800242003915500000402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100000050206161662003680000102004020040200402004020040
8002420039155000008225800101080000108000050640000020020200392003999963100198001020800002080000200392003911800211091010800001000000502016166162003680000102004020040200402004020040
8002420039155000120402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000100000050207166162003680000102004020040200402004020040