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, integer, 8H from 8H)

Test 1: uops

Code:

  scvtf v0.8h, v0.8h
  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)a8accfd5d6ddinst fetch restart (de)e0? fp/simd (ee)f5f6f7f8fd
1004303722126125472510001000100039816003018303730372414328951000100010003037303711100110000073116112699100030383038303830383038
100430372312612547251000100010003981600301830373037241432895100010001000303730371110011000116873116112629100030383038303830383038
1004303723126125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110001073116112629100030383038303830383038
1004303723061254725100010001000398160030183037303724143289510001000100030373037111001100011273116112629100030383038303830383038
100430372306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000373116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722126125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303723061254725100010001000398160130183037303724143289510001000100030373037111001100003373116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  scvtf v0.8h, v0.8h
  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)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)9fa0a6a8a9acc2c5cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
102043003722501210329547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100001030071011611296330100001003003830038300383008230038
102043003722501210329547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100001030071011611296330100001003003830038300383003830038
102043003722401210329547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100001000071011611296330100001003003830038300383003830038
102043003722501210329547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100001000071011611296330100001003003830038300383003830038
10204300372250126129547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100001000071011611296330100001003003830038300383003830038
102043003722401210329547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100001030071011611296330100001003003830038300383003830038
102043003722501210329547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100001030071011611296330100001003003830038300383003830038
102043003722501210329547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100001000071011611296330100001003003830038300383003830038
1020430037225006129547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100000030073511611296330100001003003830038300383003830038
102043003722501210329547251010010010000100100005004277160130018300373003728264328745101002001000020010000300373003711102011009910010010000100004000071011611296330100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)030818191e1f3a3f4e51inst 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)9fa1a6a7a8a9acbcc2cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
1002430037225000000612954725100101010000101000050427716013001830037300372828632876710010201000020100003003730037111002110910101000010000000006402162229629010000103003830038300383003830038
1002430037224000000612954725100101010000161000050427851213001830037300372828632876710010201000020100003003730037111002110910101000010000000006402162229629010000103003830038300383003830038
10024300372250000006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100003506006402162229629010000103003830038300383003830038
1002430037225000000612954725100101010000101000050427716013001830037300372828632876710010201000020100003003730037111002110910101000010000409006402162229629010000103003830038300383003830038
1002430037225000000612954725100101010000101000050427716013001830037300372828632876710010201000020100003003730037111002110910101000010000300006402162229629010000103003830038300383003830038
10024300372250000006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100002106006402162229629010000103003830038300383003830038
1002430037224000000612954725100101010000101000050427716013001830037300372828632876710010201000020100003003730037111002110910101000010000000006402162229629010000103003830038300383003830038
1002430037225000000612954725100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000406006402162229629010000103003830038300383003830038
10024300372250000006129547251001010100001010000504277160030018300373003728286328767101602010000201000030037300371110021109101010000100004103006402162229629010000103003830038300383003830038
1002430037225000000612954725100101010000101000050427716013001830037300372828632876710010201000020100003003730037111002110910101000010000003006402272229629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  scvtf v0.8h, v8.8h
  scvtf v1.8h, v8.8h
  scvtf v2.8h, v8.8h
  scvtf v3.8h, v8.8h
  scvtf v4.8h, v8.8h
  scvtf v5.8h, v8.8h
  scvtf v6.8h, v8.8h
  scvtf v7.8h, v8.8h
  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)03091e3f51inst 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)cdcfd5d6inst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80204200611500030618010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118016020036800001002004020040200402004020040
80204200391500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100101115118016020036800001002004020040200402004020040
80204200391500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118016020036800001002004020040200402004020040
80204200391500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118016020036800001002004020040200402004020040
80204200391500030808010810080008100800205006401321200202003920039997769990801202008003220080032200922003921802011009910010080000100001115118016020036800001002004020040200402004020040
80204200391490030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118016020036800001002004020040200402004020040
80204200391500030258010810080008100800205006401320200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118016020036800001002004020040200402004020040
80204200391500030258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118016020036800001002004020040200402004020040
80204200391500030258010810080008100800205006401320200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118116020036800001002004020040200402004020040
802042003915000220258010810080008100800205006401321200202003920039997769990801202008003220080032200392003911802011009910010080000100001115118016020036800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)0308181e3f51inst 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)5f60696b6d6edispatch 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)9fa0a8a9accfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
8002420051150000822580010108000010800005064000000200200200392003999963100198001020800002080000200392003911800211091010800001001035020416662003680000102004020040200402004020040
80024200391500012822580010108000010800005064000011200200200392003999963100198001020800002080000200392003911800211091010800001005035020516542003680000102004020040200402004020040
80024200391500012822580010108000010800005064000000200200200392003999963100198001020800002080000200392003911800211091010800001001005020516662003680000102004020040200402004020040
80024200391500012822580010108000010800005064000001200200200392003999963100198001020800002080000200392003911800211091010800001001005020316562003680000102004020040200402004020040
800242003915000129642580010108000010800005064000001200200200392003999963100198001020800002080000200392003911800211091010800001001035020516552003680000102004020040200402004020040
8002420039150000822580010108000010800005064000000200200200392003999963100198001020800002080000200392003911800211091010800001002035020416552003680000102004020040200402004020040
800242003915000122722580010108000010800005064000001200200200392003999963100198001020800002080000200392003911800211091010800001001035020616662003680000102004020040200402004020040
80024200391500012822580010108000010800005064000000200200200392003999963100198001020800002080000200392003911800211091010800001001005020516552003680000102004020040200402004020040
80024200391500012822580010108000010800005064000000200200200392003999963100198001020800002080000200392003911800211091010800001000035020416642003680000102004020040200402004020040
8002420039150000402580010108000010800005064000000200200200392003999963100198001020800002080000200392003911800211091010800001001035020516662003680000102004020040200402004020040