Apple M1 Microarchitecture Research by Dougall Johnson

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

FCVTNU (scalar, S to X)

Test 1: uops

Code:

  fcvtnu x0, s0
  mov x0, 1
  mov x1, 2

(no loop instructions)

1000 unrolls and 1 iteration

Retires: 2.000

Issues: 3.000

Integer unit issues: 1.000

Load/store unit issues: 0.000

SIMD/FP unit issues: 2.000

retire (01)cycle (02)031e3f51inst issue (52)~issue int (53)~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 integer (97)a8accfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
2004541405125300010002000200018000052254154124832742000200020005415411110011000007341622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542
2004541404325300010002000200018000052254154124832742000200020005415411110011000007321622538100010001000542542542542542

Test 2: Latency 1->2 roundtrip

Code:

  fcvtnu x0, s0
  fmov d0, x0
  mov x0, 1
  mov x1, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 13.0038

retire (01)cycle (02)03080918191e1f3a3f4f51inst issue (52)~issue int (53)~issue fp/simd (54)~issue ld/st (55)~dispatch int (56)~dispatch fp/simd (57)~dispatch ld/st (58)huge thing int (59)huge thing ld/st (5a)huge thing fp/simd (5b)60696b6d6edispatch stall (70)scheduler rewind (75)scheduler stall (76)~dispatch op (78)~map op int (7c)~map op ld/st (7d)~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)9fa0a1a6a7a8a9acc2c5cdcfd0d5d6ddinst fetch restart (de)e0? int output thing (e9)ld/st retires (ed)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
302041300389740000000130023119417254010010100200001000010020000100005006214979148010341130013013003813003812547631262463010020010000200002001000020000130038130038112020110099100101001000010000100000000000131002162212952510000100001000010100130039130039130039130039130039
30204130038974000021001300231194172540100101002000010000100200001000050062149791480103411300130130038130038125476151262333010020010000200002001000020000130040130038112020110099100101001000010000100000000000131003162312952510000100001000010100130039130039130039130039130039
302041300389740000000130023119423254010010100200001000010020000100005006214979148010341130013013003813007412547631262463010020010000200002001000020000130038130038112020110099100101001000010000100000000010131001163312952510000100001000010100130039130039130039130039130039
3020413003810080100000130023119417254010010100200001000010020000100005006214979148010340130013013003813003812547631262473010020010000200002001000020000130038130038112020110099100101001000010000100000000000131002162312952510000100001000010100130039130039130039130039130039
3020413003897400001200130023119417254010010100200001000010020000100005006214979148010341130013013003813003812547631262463010020010000200002001000020000130038130038112020110099100101001000010002100040103400131003163312952510000100001000010100130041130039130039130039130039
302041300389740000000130023119417254010010100200001000010020000100005006214979148010341130013013003813003812547831262463010020010000200002001000020000130040130038112020110099100101001000010000100000103000131003163312952510000100001000010100130039130039130039130039130039
302041300709740040000130023119417384010010100200001000010020000100005006214979148011460130013013003813003812547631262463010020010000200002001000020000130038130038112020110099100101001000010000100000000000131003163312952510000100001000010100130039130039130039130039130039
3020413003897400003000130023119417254010010100200001000010020000100005006214979148010341130013013003813003812547631262463010020010000200002001000020000130038130038112020110099100101001000010000100000000000131002163212952510000100001000010100130039130039130039130039130039
302041300389740000000130065119417254010010100200001000010020000100005006215445148041041130013013003813003812547631262463010020010000200002001000020000130038130038112020110099100101001000010000100000003000131003163312952510000100001000010100130039130039130039130039130039
302041300389740000000130023119417254010010100200001000010020000100005006214979148010340130013013003813003812547631262463010020010000200002001000020000130038130038112020110099100101001000010000100000000000131002163312952510000100001000010100130039130039130039130039130039

1000 unrolls and 10 iterations

Result (median cycles for code): 13.0038

retire (01)cycle (02)03071e3f4f51inst issue (52)~issue int (53)~issue fp/simd (54)~issue ld/st (55)~dispatch int (56)~dispatch fp/simd (57)~dispatch ld/st (58)huge thing int (59)huge thing ld/st (5a)huge thing fp/simd (5b)60696b6d6edispatch stall (70)scheduler rewind (75)scheduler stall (76)~dispatch op (78)~map op int (7c)~map op ld/st (7d)~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)9fa6a8a9acbranch mispredict (cb)cfd5d6ddinst fetch restart (de)e0? int output thing (e9)ld/st retires (ed)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
30024130038974001300231194172540010100102000010000102000010000506214979148000250130013013007413006212549831262683001020100002000020100002013213003913004011200211091010010100001010000000012705161112952510000100001000010010130039130039130039130039130039
30024130038974001301041194192540010100102000010000102000010000506214979148000250130013013003813003812549831262683001020100002000020100002000013003813003811200211091010010100001010000000012701162112952510000100001000010010130077130039130039130039130039
30024130038974001300231194172540010100102000410000102000010000506214979148001370130013013003813003812549831262683001020100002012320100002000013003813003811200211091010010100001010000000012701161212952510000100001000010010130039130039130039130039130039
300241300389740013002311941725400101001020000100001020000100005062149791480002501300130130038130038125498191263163001020100002000020100002000013003813003811200211091010010100001010000000012701161112952510000100001000010010130039130039130039130039130039
30024130038974001300231194172540010100102000010000102000010000506214979148000250130013013003813003812549831262683001020100002000020100002000013003813003811200211091010010100001010000000012701161112952510000100001000010010130039130039130039130039130039
30024130038974091300231194172540010100102000010000102000010000506214979148000250130019013003813003812549831262683001020100002000020100002000013003913003811200211091010010100001010000000012701161112952510000100001000010010130039130039130039130070130039
30024130038974091300231194172540010100102000010000102000010000506214979148000251130013013003813003812549831262683001020100002000020100002000013003813006011200211091010010100001010000000012701161112952510000100001000010010130039130039130039130039130039
30024130038974001300231194172540010100102000010000102000010000506214979148000250130013013003813003812549831262683001020100002000020100002000013003813003811200211091010010100001010000000112701161112952510000100001000010010130039130039130039130041130039
300241300389740691300231194172540010100102000010000102000010000506214979148000250130013013003813003812549831262683001020100002000020100002000013003813003811200211091010010100001010000000012701161112952510000100001000010010130039130039130039130039130039
30024130038974001300231194172540010100102000010000102000010000506214979148000250130013013003813003812549831262683001020100002000020100002000013003813003811200211091010010100001010000000012703161112952510000100001000010010130039130039130039130039130039

Test 3: throughput

Count: 8

Code:

  fcvtnu x0, s8
  fcvtnu x1, s8
  fcvtnu x2, s8
  fcvtnu x3, s8
  fcvtnu x4, s8
  fcvtnu x5, s8
  fcvtnu x6, s8
  fcvtnu x7, s8
  mov x8, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.5005

retire (01)cycle (02)03181e3f5051inst 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)9fa0a1a8acc2c5branch mispredict (cb)cdcfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
160204400643000032400252524010480100160004100160020500144013204002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511721612400388000080000801004004240042400424004240042
16020440041300303202524010480100160004100160020500144013204002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511711622400388000080000801004004240042400424004240042
16020440041300003202524010480100160004100160020500144013214002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511711612400388000080000801004004240042400424004240042
16020440041300003202524010480100160004100160020500144013214002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511721622400388000080000801004004240042400424004240042
16020440041299003202524010480100160004100160020500144013204002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511721621400388000080000801004004240042400424004240042
16020440041299005302524010480100160004100160020500144013214002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511721621400388000080000801004004240042400424004240042
16020440041300003202524010480100160004100160020500144013204002240041400411997761999216012020016003220016003240041400411180201100991008010010000090111511721622400388000080000801004004240042400424004240042
16020440041299003202524010480100160004100160020500144013204002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511711612400388000080000801004004240042400424004240042
16020440041300003202524010480100160004100160020500144013204002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511721621400388000080000801004004240042400424004240042
16020440041300003202524010480100160004100160020500144013214002240041400411997761999216012020016003220016003240041400411180201100991008010010000000111511721622400388000080000801004004240042400424004240042

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.5005

retire (01)cycle (02)03080a0b18191e1f3f51inst 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 fp/simd (81)8283pipeline redirect (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst b.cc (94)inst integer (97)9fa0a1a8a9accfd2d5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
16002440042299000000042252400108001016000010160000501440000004002240041400411999632002116001020160000201600004004140041118002110910800101000006502001416106400388000080000800104004240042400424004240042
160024400413000000000422524001080010160000101600005014400000040022400414004119996320021160010201600002016000040041400411180021109108001010000005020014161213400388000080000800104004240042400424004240042
16002440041300000000042252400108001016000010160000501440000004002240041400411999632002116001020160000201600004004140041118002110910800101000000502007351411400388000080000800104004240042400424004240042
1600244004130000000004225240010800101600001016000050144000000400224004140041199963200211600102016000020160000400414004111800211091080010100000216502001016107400388000080000800104004240042400424004240042
1600244004130000000004225240010800101600001016000050144000000400224004140041199963200211600102016000020160000400414004111800211091080010100000335020012161010400388000080000800104004240042400424004240042
16002440041300000000042252400108001016000010160000501440000004002240041400411999632002116001020160000201600004004140041118002110910800101000000502011216117400388000080000800104004240042400424004240042
160024400412990000000422524001080010160000101600005014400000040022400414004119996320021160646201600002016000040041400411180021109108001010000005020010161211400388000080000800104004240042400424004240042
1600244004130000000001912524001080010160000101600005014400000040022400414004119996320021160010201600002016000040041400411180021109108001010000005020010161010400388000080000800104004240042400424004240042
160024400413000000000422524001080010160000101600005014400000040022400414010719996320021160226201600002016000040041400411180021109108001010000005020011161010400388000080000800104004240042400424004240042
1600244004130000000008425240010800101600001016000050144000000400224004140041199963200211600102016000020160000400414004111800211091080010100000050200616711400388000080000800104004240042400424004240042