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, H from H)

Test 1: uops

Code:

  scvtf h0, h0, #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)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
1004303723276125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722309625472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722126125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303723516125472510001000100039816013018303730372414328951000100010003037303711100110001073116112629100030383038303830383038
10043037234810325472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722426125472510001000100039816003018303730372414328951000100010003037303711100110001073116112629100030383038303830383038
1004303722276125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722516125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303723306125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722456125472510001000100039816003018303730372414328951000100010003037303711100110000073116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  scvtf h0, h0, #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)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)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)9fa0a8a9acc2cfd0d5d6ddinst fetch restart (de)e0ea? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
10204300372250012103295472510100100100001001000050042771600300183003730037282643287451010020010000200100003003730037111020110099100100100001000101440710011611296330100001003003830038300383003830038
10204300372250012103295472510100100100001001000050042771600300183003730037282643287451010020010000200100003003730037111020110099100100100001000101680710111611296330100001003003830038300383003830038
10204300372250012103295472510100100100001001000050042771600300183003730037282643287451010020010000200100003003730037111020110099100100100001000101650710011611296330100001003003830038300383003830038
10204300372240001032954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010001030710011611296330100001003003830038300383003830038
1020430037224000103295472510100100100001001000050042771600300183003730084282683287451010020010000200100003003730037111020110099100100100001000101530710011611296330100001003003830038300383003830038
102043003722400121032954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000000710011611296330100001003003830038300383003830038
102043003722500121032954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010000030710011611296330100001003003830038300383003830038
1020430037233001241629547251010010010000100100005004277160030018300373003728264328745101002001000020010000300373003711102011009910010010000100010180710011611296330100001003003830038300383003830038
10204300372250021612954725101001001000010010000500427716003001830037300372826432874510100200100002001000030037300371110201100991001001000010001030710011611296330100001003003830038300383003830038
1020430037225011261295472510100100100001001000050042771600300183003730037282643287451010020010000200100003003730037111020110099100100100001000001530710011611296330100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)031e1f3f4e51inst 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? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000101006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373008428291328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504278512030018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160130018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038
1002430037225006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100006403163329629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  scvtf h0, h8, #3
  scvtf h1, h8, #3
  scvtf h2, h8, #3
  scvtf h3, h8, #3
  scvtf h4, h8, #3
  scvtf h5, h8, #3
  scvtf h6, h8, #3
  scvtf h7, h8, #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)0307081e3f51inst 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)cdcfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80204200581510012302580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001003311151181160020036800001002004020040200402004020040
80204200391500012722580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001001011151180160020036800001002004020040200402004020040
802042003915000124522580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001001611151180160020036800001002004020040200402004020040
8020420039150000722580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001000311151180160020036800001002004020040200402004020040
80204200391500012302580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001001011151180160020036800001002004020040200402004020040
80204200391500012302580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001001311151180160020036800001002004020040200402004020040
80204200391510012722580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001001311151180160020036800001002004020040200402004020040
80204200391500012722580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001000011151180160020036800001002004020040200402004020040
80204200391500012302580108100800081008002050064013202002020039200399977699908012020080032200800322003920039118020110099100100800001001611151180160020036800001002004020040200402004020040
802042003915000124102580108100800081008002050064013212002020039200399977699908012020080032200800322003920039118020110099100100800001001311151180160020036800001002004020040200402004020040

1000 unrolls and 10 iterations

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

retire (01)cycle (02)03080a18191e3f51inst 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)6061696d6edispatch 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 ld/st (80)~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)9fa0a6a8acc2cfd0d2d5d6d9ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80024200711550001184162580010108000010800005064000000200202003920039999631001980010208000020080000200392003911800211091010800001072000502000151607122003680000102004020040200402004020040
8002420039150000004025800101080000108000050640000002002020039200399996310019800102080000200800002003920039118002110910108000010000005020511016012102003680000102004020040200402004020040
80024200391500000018742580010108000010800005064000000200202003920039999631001980010208000020080000200392003911800211091010800001000000502000516011112003680000102004020040200402004020040
800242003915000000402580010108000010800005064000000200202003920039999631001980010208000020080000200392003911800211091010800001000000502000916010102003680000102004020040200402004020040
80024200391500000040258001010800001080000506400000020020200392003999963100198001020800002008000020039200391180021109101080000100000050200061601172003680000102004020040200402004020040
8002420039150000004025800101080000108000050640000002002020039200399996310019800102080000200800002003920039118002110910108000010000005020001016010122003680000102004020040200402004020040
8002420039150000007052580010108000010800005064000000200202003920039999631001980010208000020080000200392003911800211091010800001000000502000141601172003680000102004020040200402004020040
8002420039150000004025800101080000108000050640000102002020039200399996310019800102080000200800002003920039118002110910108000010000159050200071607112003680000102004020040200402004020040
8002420039150000004025800101080000108000050640000102002020039200399996310019800102080000200800002003920039118002110910108000010000005020001016012122003680000102004020040200402004020040
8002420039150000004025800101080000108000050640000052002020039200399996310019800102080000200800002003920039118002110910108000010000005020001116013102003680000102004020040200402004020040