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 D)

Test 1: uops

Code:

  fcvt d0, 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
100430372206125472510001000100039816013018303730372414328951000100010003037303711100110000073216112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372396125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
1004303722025125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372396125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372206125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372206125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013018303730372414328951000100010003037303711100110000073116112629100030383038303830383038
100430372306125472510001000100039816013022303730372414328951000100010003037303711100110000073116112629100030383038303830383038

Test 2: Latency 1->2

Code:

  fcvt d0, 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)03090b1e3a3f4e51inst 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)72scheduler 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)9fa1a8a9accfd2d5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373008411102011009910010010000100000071001161129633100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002041000020010000300373003711102011009910010010000100000071001161129633100001003003830038300383003830038
102043003722400006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003711102011009910010010000100000071001161129633100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003711102011009910010010000100000071001161129633100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003711102011009910010010000100000071001161129633100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003711102011009910010010000100000071011161129633100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003711102011009910010010000100000071001161129703100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003711102011009910010010000100000071001161129633100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003721102011009910010010000100000071001161129701100001003003830038300383003830038
102043003722500006129547251010010010000100100005004277160300183003730037282640328745101002001000020010000300373003711102011009910010010000100000071001161129633100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)03080b18191e1f3f4e51inst 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)9fa0a1a6a7a8acc2cfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
100243003722400000061295472510010101000010100005042771601300183003730037282863287671001020100002010000300373003711100211091010100001000000326403162229629010000103003830038300383003830038
10024300372250000906129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300372110021109101010000100000203606402162229629010000103003830038300383003830038
10024300372240000006129547251001010100001010000504277160030018300373003728286328767100102010000201000030037300371110021109101010000100000010506402162229629010000103003830038300383003830038
100243003722500000061295472510010101000010100005042771600300183003730037282863287671001020100002010000300373003711100211091010100001000000306402162229629010000103003830038300383003830038
100243003722500000061295472510010101000010100005042771600300183003730037282863287671001020100002010000300373003711100211091010100001000000606402162229629010000103003830038300383003830038
100243003722500000061295472510010101000010100005542771601300183003730037282863287671001020100002010000300373003711100211091010100001000000006682162229629010000103003830038300383003830038
100243003722500000061295472510010101000010100005042771600300183003730037282863287671001020100002010000300373003711100211091010100001000000006402162229629010000103003830038300383003830038
100243003722400000061295472510010101000010100005042771600300183003730037282863287671001020100002010000300373003711100211091010100001000000606402162229629010000103003830038300383003830038
100243003722500000061295472510010101000010100005042771601300183003730037282863287671001020100002010000300373003711100211091010100001000000306402162229629010000103003830038300383003830038
1002430037225000000612954725100101010000101000050427716003001830037300372828632876710010201000020100003003730037111002110910101000010000017006402162229629010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  fcvt d0, s8
  fcvt d1, s8
  fcvt d2, s8
  fcvt d3, s8
  fcvt d4, s8
  fcvt d5, s8
  fcvt d6, s8
  fcvt d7, 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)033f51inst 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)72scheduler 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
8020420059151302580108100800081008002050064013220020200392003999770699908012020080032200800322003920039118020110099100100800001000611151181160020036800001002004020040200402004020040
8020420039150302580108100800081008002050064013220020201402003999770699908012020080032200800322003920039118020110099100100800001000011151180160020036800001002004020040200402004020040
8020420039150302580108100800081008002050064013220020200392003999770699908012020080032200800322003920039118020110099100100800001000011151180160020036800001002004020040200402004020040
802042003915010425801081008000810080020500640132200202003920039997776999080120200800322008003220039200391180201100991001008000010001811151180160020036800001002004020040200402004020040
80204200391503025801081008000810080020500640132200202003920039997706999080120200800322008003220039200391180201100991001008000010002411151180160020036800001002004020040200402004020040
802042003915030258010810080008100800205006401322002020039200399977069990801202008003220080032200392003911802011009910010080000100025511151180160020036800001002004020040200402004020040
8020420039150302580108100800081008002050064342820020200392003999770699908012020080032200800322003920039118020110099100100800001000011151180160020036800001002004020040200402004020040
8020420039150302580108100800081008002050064013220020200392003999770699908012020080032200800322003920039118020110099100100800001000011151180160020036800001002004020040200402004020040
80204200391503025801081008000810080020500640132200202003920039997706999080120200800322008003220039200391180201100991001008000010001211151180160020036800001002004020040200402004020040
8020420039150302580108100800081008002050064013220020200392003999770699908012020080032200800322003920039118020110099100100800001000011151180160120036800001002004020040200402004020040

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)9faccfd2d5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
80024200511510402580010108000010800005064000002002020039200399996310019800102080000208000020039200391180021109101080000101250200141614142003680000102004020040200402004020040
8002420039150040258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010050205121612102003680000102004020040200402004020040
800242003915054344192580010108000010800005064000002002420039200391000631001980010208000020800002003920039118002110910108000010050200131611142003680000102011420040201122010020040
8002420039150244025800101080000108000050640000020020200392003999963100198001020800002080000200392003911800211091010800001011150200161614122003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010050200131613152003680000102004020040200402004020040
800242003915004025800101080000108000050640000020020200392003999963100198001020800002080000200392003911800211091010800001035020091617132003680000102004020040200402004020040
8002420039150040258001010800001080000506400001200202003920039999631001980010208000020800002003920039118002110910108000010050200131614142003680000102004020040200402004020040
8002420039150040258001010800001080000506416561200202003920039999631001980010208000020800002003920039118002110910108000010050200131615162003680000102004020040200402004020040
8002420039150940258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010050200161616132003680000102004020040200402004020040
8002420039150040258001010800001080000506400000200202003920039999631001980010208000020800002003920039118002110910108000010050200151614122003680000102004020040200402004020040