Apple Microarchitecture Research by Dougall Johnson

M1/A14 P-core (Firestorm): Overview | Base Instructions | SIMD and FP Instructions
M1/A14 E-core (Icestorm):  Overview | Base Instructions | SIMD and FP Instructions

SCVTF (scalar, fixed-point, S from X)

Test 1: uops

Code:

  scvtf s0, x0, #3
  mov x0, 1
  mov x1, 2

(no loop instructions)

1000 unrolls and 1 iteration

Retires: 2.000

Issues: 2.000

Integer unit issues: 0.000

Load/store unit issues: 1.000

SIMD/FP unit issues: 1.000

retire uop (01)cycle (02)03191e3f51schedule uop (52)schedule simd uop (54)schedule ldst uop (55)dispatch simd uop (57)dispatch ldst uop (58)simd uops in schedulers (5a)ldst uops in schedulers (5b)60696d6emap stall dispatch (70)map rewind (75)map stall (76)dispatch uop (78)map ldst uop (7d)map simd uop (7e)map ldst uop inputs (80)map simd uop inputs (81)8283flush restart other nonspec (84)85inst all (8c)inst simd alu (9a)ld unit uop (a6)l1d cache writeback (a8)accfd5map dispatch bubble (d6)ddfetch restart (de)e0? ldst retires (ed)? simd retires (ee)f5f6f7f8fd
2004379300361252000100010001000100014075228720357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004376300361252000100010001000100014075228200357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004376300361252000100010001000100014075228200357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004376200369252000100010001000100014075229851357376376723109200010001000100010003763761110011000100000731161137310001000377377377379377
2004376300364252000100010001000100014075228201357376376753109200010001000100010003763761110011000100000731161137310001000377377377377378
2004376400361252000100010001000100014075228201357376379723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004376200372252000100010001000100014075228200357376376723110200010001000100010003763761110011000100000731161137310001000377377377377377
2004376310362252000100010001000100014075228201357376376723112200010001000100010003763761110011000100000731161137310001000377377377377377
2004376300361252000100010001000100014104228200357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377
2004376300361252000100010001000100014225228200357376376723109200010001000100010003763761110011000100000731161137310001000377377377377377

Test 2: Latency 1->2 roundtrip

Code:

  scvtf s0, x0, #3
  fmov x0, d0
  mov x0, 1
  mov x1, 2

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code): 13.0032

retire uop (01)cycle (02)03mmu table walk instruction (07)l2 tlb miss instruction (0a)1e3a3f4f51schedule uop (52)schedule int uop (53)schedule simd uop (54)schedule ldst uop (55)dispatch int uop (56)dispatch simd uop (57)dispatch ldst uop (58)int uops in schedulers (59)simd uops in schedulers (5a)ldst uops in schedulers (5b)60696b6d6emap stall dispatch (70)map rewind (75)map stall (76)dispatch uop (78)map int uop (7c)map ldst uop (7d)map simd uop (7e)map int uop inputs (7f)map ldst uop inputs (80)map simd uop inputs (81)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fld unit uop (a6)l1d cache writeback (a8)acbranch cond mispred nonspec (c5)branch mispred nonspec (cb)cdcfd0d5map dispatch bubble (d6)ddfetch restart (de)e0? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
30204130032974110013001711940825401001010020000100001002000010000500621449714802709113001301300321300321254737126235301002001000320005200100032000513003213003211202011009910010100100001001000200111131702163212952710000100001000010100130033130033130033130033130033
30204130032974100013001711940825401001010020000100001002000010000500621449714802709013001301300321300321254736126236301002001000320005200100032000513003213003211202011009910010100100001001000060111135502162212953210000100001000010100130033130033130033130033130033
30204130032974000113001711940825401001010020000100001002000010000500621449714802709013001301300321300321254737126235301002001000320005200100032000513003213003311202011009910010100100001001000000111131802162212953210000100001000010100130033130034130033130033130033
30204130032974100013001711940825401001010020000100001002000010000500621449714802709113001301300321300321254736126235301002001000320005200100032000513003213004311202011009910010100100001001000000111131702162212953210000100001000010100130033130033130033130033130033
30204130032974110113001711940825401001010020000100001002000010000500621449714802709013001301300321300321254737126236301002001000320005200100032000513003213003211202011009910010100100001001000000111131802162212953210000100001000010100130033130033130033130033130033
30204130032974000013001711940825401001010020000100001002000010000500621449714802709113001301300321300321254737126235301002001000320005200100032000513003213003211202011009910010100100001001000000111131702162212953210000100001000010100130033130033130033130033130033
30204130032974100113001811940825401001010020000100001002000010000500621449714802709013001301300321300321254736126235301002001000320005200100032000513003213003211202011009910010100100001001000000111131702162212952710000100001000010100130033130033130033130033130033
30204130032974100113001711940825401001010020000100001002000010000500621449714802709113001301300321300321254736126235301002001000320005200100032000513003213003211202011009910010100100001001000000111131702162212952710000100001000010100130064130033130033130033130033
30204130032973000013001711940825401001010020000100001002000010000500621449714802709113001301300321300321254737126236301002001000320005200100032000513003213003211202011009910010100100001001000000111131702162212952710000100001000010100130033130033130033130033130033
30204130032974000013001711940825401001010020000100001002000010000500621449714802709113001301300321300321254736126235301002001000320005200100032000513003213003211202011009910010100100001001000000111131702162212953210000100001000010100130033130033130033130033130033

1000 unrolls and 10 iterations

Result (median cycles for code): 13.0032

retire uop (01)cycle (02)031e3f4f51schedule uop (52)schedule int uop (53)schedule simd uop (54)schedule ldst uop (55)dispatch int uop (56)dispatch simd uop (57)dispatch ldst uop (58)int uops in schedulers (59)simd uops in schedulers (5a)ldst uops in schedulers (5b)60696d6emap stall dispatch (70)map rewind (75)map stall (76)dispatch uop (78)map int uop (7c)map ldst uop (7d)map simd uop (7e)map int uop inputs (7f)map ldst uop inputs (80)map simd uop inputs (81)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fl1d tlb access (a0)ld unit uop (a6)l1d cache writeback (a8)accfd5map dispatch bubble (d6)ddfetch restart (de)e0? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
30024130032974013001711940825400101001020000100001020000100005062144971480052811300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100000312702171112951910000100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052811300131300321300321254893126264300102010000200002010000200001300321300321120021109101001010000100100000012702161112951910000100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052811300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100000012701161112951910000100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052801300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100006012701161112951910000100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052801300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100000012701161112973910000100001000010010130033130033130033130033130033
300241300329741213001711940825400101001020000100001020000100005062144971480052801300131300321300321254893126262301792010000200002010000200001300321300321120021109101001010000100100000012701161112951910001100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052801300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100000012701161112951910000100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052801300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100000012701161112951910000100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052801300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100000012701161112951910000100001000010010130033130033130033130033130033
30024130032974013001711940825400101001020000100001020000100005062144971480052801300131300321300321254893126262300102010000200002010000200001300321300321120021109101001010000100100000012701161112951910000100001000010010130033130033130033130033130033

Test 3: throughput

Count: 8

Code:

  scvtf s0, x8, #3
  scvtf s1, x8, #3
  scvtf s2, x8, #3
  scvtf s3, x8, #3
  scvtf s4, x8, #3
  scvtf s5, x8, #3
  scvtf s6, x8, #3
  scvtf s7, x8, #3
  mov x8, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 0.3339

retire uop (01)cycle (02)03l1i tlb fill (04)mmu table walk data (08)0918191e1f3a3f4f51schedule uop (52)schedule int uop (53)schedule simd uop (54)schedule ldst uop (55)dispatch int uop (56)dispatch simd uop (57)dispatch ldst uop (58)int uops in schedulers (59)simd uops in schedulers (5a)ldst uops in schedulers (5b)60696d6emap stall dispatch (70)simd prf full (72)map rewind (75)map stall (76)dispatch uop (78)map int uop (7c)map ldst uop (7d)map simd uop (7e)map int uop inputs (7f)map ldst uop inputs (80)map simd uop inputs (81)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fl1d tlb miss (a1)a5ld unit uop (a6)st unit uop (a7)l1d cache writeback (a8)a9acc2branch cond mispred nonspec (c5)branch mispred nonspec (cb)cdcfd5map dispatch bubble (d6)ddfetch restart (de)e0? int output thing (e9)? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
16020426710200000000022669402516010010080000800001008002080015500116839618841631266902670926709663206665816013520080020800202008002080020267092670911802011009910010080000100008000003303011151193164826706080000800001002671026710267102671026786
1602042670920000000002266940251601001008000080000100800208001550011689511884163126690267092670966320666601601352008002080020200800208002026709267091180201100991001008000010000800000000011151196169826706080000800001002671026710267102671026800
16020426709200000000022669402516010010080000800001008002080015500116895118841631266902670926709663206665816013520080020800202008002080020267092670911802011009910010080000100008000003300011151198169826706080000800001002671026710267102671026839
160204267092000000000226694025160100100800008000010080020800155001168951188416312669026709267096632066658160135200800208002020080020800202670926709118020110099100100800001000080000010865011151198163826706080000800001002671026710267102671026717
1602042671820000000213022669429251601001008000080000100800208001550011689511884163126690267092670966320666581601352008002080020200800208002026709267091180201100991001008000010000800000100011151198168926706080000800001002671026710267102671026714
1602042670920000000002266942251601001008000080000100800208001550011689511884390126690267092670966320666581601352008002080020200800208002026709267091180201100991001008000010000800000000011151198168926706080000800001002671026710267102671026724
1602042670920000000002266948251601001008000080000100800208001550011689511891994126690267092670966320666581601352008002080020200800208002026709267091180201100991001008000010000800000100011151199168826706080000800001002699826719268202671226710
160204267092000000026488226694625160100100800008000010080020800155001168951188416312669026709267096632066658160135200800208002020080020800202670926709118020110099100100800001000080000000002225129933101026707080000800001002671126711267112671126720
160204272162001000300226863092160100100800008000010080023800185001168352188346012669126710267156621096714160141200807818021520280023800232671026710118020110099100100800001000080000000690222519611529926851080000800001002671126711267112671127248
1602042671020001100405882272086725160100100805208013010080023800185001168352188346012669127210272546621010664516014120280783800002008000080573267102671021802011009910010080000100408000002500211151221025101026707080000800001002721126835269542705026869

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 0.3339

retire uop (01)cycle (02)031e3f4f51schedule uop (52)schedule int uop (53)schedule simd uop (54)schedule ldst uop (55)dispatch int uop (56)dispatch simd uop (57)dispatch ldst uop (58)int uops in schedulers (59)simd uops in schedulers (5a)ldst uops in schedulers (5b)60696d6emap stall dispatch (70)map rewind (75)map stall (76)dispatch uop (78)map int uop (7c)map ldst uop (7d)map simd uop (7e)map int uop inputs (7f)map ldst uop inputs (80)map simd uop inputs (81)8283flush restart other nonspec (84)85inst all (8c)inst branch (8d)inst branch taken (90)inst branch cond (94)inst int alu (97)inst simd alu (9a)9fld unit uop (a6)l1d cache writeback (a8)a9accfd5map dispatch bubble (d6)ddfetch restart (de)e0? ldst retires (ed)? simd retires (ee)? int retires (ef)f5f6f7f8fd
16002426709200026694222516001010800008000010800008000050116888018842061266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000100502011621267068000080000102671026710267102671026717
1600242670920002669402516001010800008000010800008000050117025218847751266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000103502011611267068000080000102678126756268372672626710
1600242670920602669402516001010800008000010800008000050116888018840321266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000201748502011611267068000080000102671026710267102671026715
1600242671020102669402516001010800008000010800008000050116960518840320266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000100502011611267068000080000102671026710267102671026719
1600242670920002669402516001010800008000010800008000050116888018840321266902670926709665336689160010208000080000208000080000267092670921800211091010800001080000100502011611267068000080000102671026710267102671026716
1600242670920002669402516001010800008000010800008000050116888018840321266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000103502011611267068000080000102671026710267102671026719
1600242671120002669402516001010800008000010800008000050116888018840321266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000103502011611267068000080000102671026710267102671026719
1600242671520002669402516001010800008000010800008000050116843518840321266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000103502011611267068000080000102671026710267102671026716
1600242670919902669402516001010800008000010800008000050116888018840321266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000100502011611267068000080000102671026710267102671026719
1600242670920002669402516001010800008000010800008000050116888018840321266902670926709665336689160010208000080000208000080000267092670911800211091010800001080000100502011611267068000080000102671026900267742672826710