Apple M1 Microarchitecture Research by Dougall Johnson

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

URSQRTE (vector, 4S)

Test 1: uops

Code:

  ursqrte v0.4s, v0.4s
  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)031e1f3f4e51inst 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)a1a8accfd5d6ddinst fetch restart (de)e0? fp/simd (ee)f5f6f7f8fd
10043037240061190025100010001000104451130183037303727383289510001000100030373037111001100000073116112919100030383038303830383038
10043037240061190025100010001000104451130183037303727383289510001000100030373037111001100000073116112919100030383038303830383038
10043037230061190025100010001000104451130183037303727383289510001000100030373037111001100000073116112919100030383038308530383038
100430372308861190025100010001000104451130183037303727383289510001056100030373037111001100000073124112919100030383038303830383038
1004303723003091900251008100010001044511301830373037273832895100010001000303730371110011000001873116112919100030383038303830383038
100430372300103190025100010001000104451130183037303727383289510001000100030373037111001100001073116112919100030383038303830383038
10043037230098190025100010001000104451130183037303727383289510001000100030373037111001100000073116112919100030383038303830383038
10043037230061190025100010001000104451130183037303727383289510001000100030373037111001100000073116112919100030383038303830383038
100430372300247190025100010001000104451130183037303727383289510001000100030373037111001100001073116112919100030383038303830383038
10043037230061190025100010001000104451130183037303727383289510001000100030373037111001100000073116112919100030383038303830383038

Test 2: Latency 1->2

Code:

  ursqrte v0.4s, v0.4s
  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)0318191e1f3a3f4e51inst 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)9fa8a9accfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
102043003723300000611990025101001001000010010000500106745113001830037300372858832874510100200100002001000030037300371110201100991001001000010000071011611299190100001003003830038300383003830038
102043003723300000611990025101001001000010010000500106745103001830037300372858832874510100200100002001000030037300371110201100991001001000010000071011611299190100001003003830038300383003830038
102043003723200000611990025101251001000010010000500106745103001830037300372858832874510100200100002001000030037300371110201100991001001000010000071011611299190100001003003830038300383003830038
102043003723300000611990025101001001000010010000500106745113001830037300372858832874510100200100002001000030037300371110201100991001001000010000071011611299190100001003003830038300383003830038
1020430037232000006119900251010010010000100100005001067451030018300373003728588328745101002001000020010000300373003711102011009910010010000100000710116112991925100001003003830038300383003830038
102043003723300000611990025101001251000012510000500106745103001830037300372858832874510100200100002001000030037300371110201100991001001000010000071011611299190100001003003830038300383003830038
102043003723300000611990025101001001000010010000500106745113001830037300372858832874510100200100002001016730037300371110201100991001001000010000071211611299190100001003003830038300383003830038
102043003723300300611990025101251251000010010000500106745113001830037300372858832874410125200100002001000030037300371110201100991001001000010010071241711299190100001003003830038300383003830038
1020430037233000005321990025101001001000012510000500106745103001830037300372858832874510100200100002001000030037300371110201100991001001000010000071051611299190100001003003830038300383003830038
1020430037233000001171990025101001001000010010000626106745113001830037300372858832874510100200100002001000030037300371110201100991001001000010000071441611299190100001003003830038300383003830038

1000 unrolls and 10 iterations

Result (median cycles for code): 3.0037

retire (01)cycle (02)0318191e3f4e51inst 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)9fa0a8accfd5d6ddinst fetch restart (de)e0? int output thing (e9)? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
100243003723300456119900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006563164329919010000103003830038300383003830038
10024300372330006119900251001010100001010000501067451030018300373003728610328767100102010058201005930085301333110021109101010000100236402242229919310000103003830038300383003830038
10024300712332206119900251001010100001110042551067612130090301323013128628628832100532010000201000030037300371110021109101010000100006555244329919110000103003830038300383003830038
100243003723300010319900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006404164429919010000103003830038300383003830038
10024300372330006119900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006402163329919010000103003830038300383003830038
10024300372320006119900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006403164429919010000103003830038300383003830038
10024300372320006119900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006404164329919010000103003830038300383003830038
10024300372330006119900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006404163429919010000103003830038300383003830038
100243003723300072619900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006403164229919010000103003830038300383003830038
10024300372330006119900251001010100001010000501067451030018300373003728610328767100102010000201000030037300371110021109101010000100006403164429919010000103003830038300383003830038

Test 3: throughput

Count: 8

Code:

  ursqrte v0.4s, v8.4s
  ursqrte v1.4s, v8.4s
  ursqrte v2.4s, v8.4s
  ursqrte v3.4s, v8.4s
  ursqrte v4.4s, v8.4s
  ursqrte v5.4s, v8.4s
  ursqrte v6.4s, v8.4s
  ursqrte v7.4s, v8.4s
  movi v8.16b, 9

(fused SUBS/B.cc loop)

100 unrolls and 100 iterations

Result (median cycles for code divided by count): 1.0005

retire (01)cycle (02)030408181e1f3f51inst 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)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)9fa1a6a8a9acc5branch mispredict (cb)cdcfd5d6ddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
802048003960010000392580100100800001008000050064000018002080039800396997106699938010020080008200800088003980039118020110099100100800001000000011151170160080036800001008004080040800408004080040
80204800396000000055292580100100800001008000050064000008002080039800396997106699938010020080008200800088003980039118020110099100100800001000000011151170160080036800001008004080040800408004080040
802048003959900000392580100100800001008000050064000008002080039800396997106699938010020080008200800088003980039118020110099100100800001000000611151170160080036800001008004080040800408004080040
802048003959900000392580100100800001008000050064000008002080039800396997106699938010020080008200800088003980039118020110099100100800001000020011151170160080036800001008004080040800408004080040
8020480039600000003925801001008000010080000500640000080020800398003969971066999380100200800082008000880039800391180202100991001008000010000004811151170160080036800001008004080040800408004080040
802048003960000000392580100100800001008000050064000008002080039800396997106699938010020080008200800088003980039118020110099100100800001000000011151170160080036800001008004080040800408004080040
802048003959900000625625801001008000010080000500640000080020800398003969971066999380100200800082008000880039800391180201100991001008000010000006311151170160080036800001008004080040800408004080040
80204800396000000039258010010080000100800005006400000800208003980039699710669993801002008000820080008800398003911802011009910010080000100000022811151170160080036800001008004080040800408004080040
802048003959900000392580100100800001008000050064000008002080039800396997136699938010020080008200800088003980039118020110099100100800001000067016811151170160080036800001008004080040800408004080040
8020480039600000003925801001008000010080000500640000080020800398003969971066999380100200800082008000880039800391180201100991001008000010000001511151170160080036800001008004080040800408004080040

1000 unrolls and 10 iterations

Result (median cycles for code divided by count): 1.0005

retire (01)cycle (02)031e3a3f51inst 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)5f60696d6edispatch 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)9fa0a6a8accfd5d6dadbddinst fetch restart (de)e0? fp/simd (ee)gpr retires (ef)f5f6f7f8fd
800248003960000502580010108000010800005064000001800208003980039699860370019800102080000208000080039800391180021109101080000100000502061620448003480000108004080040800408004080040
800248003959900502580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100000502041601458003480000108004080040800408004080040
8002480039599007152580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100000502041600348003480000108004080040800408004080040
8002480039600005252580010108000010800005064000001801348003980039699860370019800102080000208000080039800391180021109101080000100000502041600558003480000108004080040800408004080040
8002480039599002402580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100000502071600648003480000108004080040800408004080040
800248003959900502580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100003502031600688003480000108004080040800408004080040
8002480039599007152580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100000502041600678003480000108004080040800408004080040
8002480039600007152580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100000502041600548003480000108004080040800408004080040
800248003960000502580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100010502041600368003480000108004080040800408004080040
8002480039599005252580010108000010800005064000000800208003980039699860370019800102080000208000080039800391180021109101080000100010502071600448003480000108004080040800408004080040