OV - exec - Loop 102

	Loop Id: 102	Module: exec	Source: timestep.c:88-94	Coverage: 0.10%

0x41a4cc LDR	W5, [X18, X14,LSL #2]

0x41a4d0 CMP	W5, #0

0x41a4d4 B.LE	41a630

0x41a4d8 LDP	X10, X13, [X17, #32]

0x41a4dc SUB	W9, W5, #1

0x41a4e0 UBFM	X7, X14, #56, #55

0x41a4e4 ADD	X8, X9, X14,LSL #6

0x41a4e8 ORR	X0, XZR, X15

0x41a4ec LDP	X6, X30, [X10, #16]

0x41a4f0 LDR	X20, [X10, #32]

0x41a4f4 ADD	X11, X6, #4

0x41a4f8 ADD	X3, X6, X7

0x41a4fc ADD	X21, X11, X8,LSL #2

0x41a500 ADD	X19, X30, #8

0x41a504 ADD	X2, X30, #16

0x41a508 SUB	X1, X21, X3

0x41a50c ADD	X12, X20, #8

0x41a510 ADD	X4, X20, #16

0x41a514 TBZ	W1, #2, 41a580

0x41a518 LDRSW	X5, [X6, X7]

0x41a51c ADD	X3, X3, #4

0x41a520 ADD	X0, X15, #24

0x41a524 LDR	D3, [X20, X15]

0x41a528 LDR	D2, [X30, X15]

0x41a52c ADD	X9, X13, X5,LSL #4

0x41a530 LDR	D1, [X9, #8]

0x41a534 FMUL	D5, D0, D3

0x41a538 FDIV	D6, D4, D1

0x41a53c FMADD	D7, D6, D5, D2

0x41a540 STR	D7, [X30, X15]

0x41a544 LDR	D16, [X12, X15]

0x41a548 LDR	D17, [X19, X15]

0x41a54c FMUL	D18, D0, D16

0x41a550 FMADD	D19, D6, D18, D17

0x41a554 STR	D19, [X19, X15]

0x41a558 LDR	D20, [X4, X15]

0x41a55c LDR	D21, [X2, X15]

0x41a560 FMUL	D22, D0, D20

0x41a564 FMADD	D23, D6, D22, D21

0x41a568 STR	D23, [X2, X15]

0x41a56c CMP	X3, X21

0x41a570 B.EQ	41a630

0x41a574 HINT	#0

0x41a578 HINT	#0

0x41a57c HINT	#0

  (103) 0x41a580 ORR	X8, XZR, X3

  (103) 0x41a584 LDR	D24, [X20, X0]

  (103) 0x41a588 ADD	X10, X0, #24

  (103) 0x41a58c LDRSW	X7, [X8], #4

  (103) 0x41a590 LDR	D25, [X30, X0]

  (103) 0x41a594 FMUL	D26, D0, D24

  (103) 0x41a598 LDRSW	X6, [X3, #4]

  (103) 0x41a59c ADD	X11, X13, X7,LSL #4

  (103) 0x41a5a0 ADD	X3, X8, #4

  (103) 0x41a5a4 LDR	D27, [X11, #8]

  (103) 0x41a5a8 ADD	X1, X13, X6,LSL #4

  (103) 0x41a5ac FDIV	D28, D4, D27

  (103) 0x41a5b0 FMADD	D29, D28, D26, D25

  (103) 0x41a5b4 STR	D29, [X30, X0]

  (103) 0x41a5b8 LDR	D30, [X12, X0]

  (103) 0x41a5bc LDR	D31, [X19, X0]

  (103) 0x41a5c0 FMUL	D3, D0, D30

  (103) 0x41a5c4 FMADD	D2, D28, D3, D31

  (103) 0x41a5c8 STR	D2, [X19, X0]

  (103) 0x41a5cc LDR	D5, [X4, X0]

  (103) 0x41a5d0 LDR	D1, [X2, X0]

  (103) 0x41a5d4 FMUL	D6, D0, D5

  (103) 0x41a5d8 FMADD	D7, D28, D6, D1

  (103) 0x41a5dc STR	D7, [X2, X0]

  (103) 0x41a5e0 ADD	X0, X0, #48

  (103) 0x41a5e4 LDR	D19, [X1, #8]

  (103) 0x41a5e8 LDR	D16, [X20, X10]

  (103) 0x41a5ec LDR	D17, [X30, X10]

  (103) 0x41a5f0 FDIV	D20, D4, D19

  (103) 0x41a5f4 FMUL	D18, D0, D16

  (103) 0x41a5f8 FMADD	D21, D20, D18, D17

  (103) 0x41a5fc STR	D21, [X30, X10]

  (103) 0x41a600 LDR	D22, [X12, X10]

  (103) 0x41a604 LDR	D23, [X19, X10]

  (103) 0x41a608 FMUL	D24, D0, D22

  (103) 0x41a60c FMADD	D25, D20, D24, D23

  (103) 0x41a610 STR	D25, [X19, X10]

  (103) 0x41a614 LDR	D26, [X4, X10]

  (103) 0x41a618 LDR	D27, [X2, X10]

  (103) 0x41a61c FMUL	D28, D0, D26

  (103) 0x41a620 FMADD	D29, D20, D28, D27

  (103) 0x41a624 STR	D29, [X2, X10]

  (103) 0x41a628 CMP	X3, X21

  (103) 0x41a62c B.NE	41a580

0x41a630 ADD	X14, X14, #1

0x41a634 ADD	X15, X15, #1536

0x41a638 CMP	W16, W14

0x41a63c B.GT	41a4cc

/home/eoseret/qaas/qaas_runs/178-176-0594/intel/CoMD/build/CoMD/CoMD/src-openmp/timestep.c: 88 - 94

--------------------------------------------------------------------------------

88:       for (int iOff=MAXATOMS*iBox,ii=0; ii<s->boxes->nAtoms[iBox]; ii++,iOff++)

89:       {

90:          int iSpecies = s->atoms->iSpecies[iOff];

91:          real_t invMass = 1.0/s->species[iSpecies].mass;

92:          s->atoms->r[iOff][0] += dt*s->atoms->p[iOff][0]*invMass;

93:          s->atoms->r[iOff][1] += dt*s->atoms->p[iOff][1]*invMass;

94:          s->atoms->r[iOff][2] += dt*s->atoms->p[iOff][2]*invMass;

Coverage (%)	Name	Module
►99.27+	omp_fulfill_event	libgomp.so.1.0.0
○	start_thread	libc.so.6
○	thread_start	libc.so.6

min	med	avg	max

Percentile Index	10	20	30	40	50	60	70	80	90	100
Value

min	med	avg	max

Percentile Index	10	20	30	40	50	60	70	80	90	100
Value

Path /

Metric	Value
CQA speedup if no scalar integer	1.38
CQA speedup if FP arith vectorized	1.22
CQA speedup if fully vectorized	5.07 - 3.64
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	1.17
Bottlenecks
Function	advancePosition._omp_fn.0
Source	timestep.c:88-88,timestep.c:91-94
Source loop unroll info	NA
Source loop unroll confidence level	NA
Unroll/vectorization loop type	NA
Unroll factor	NA
CQA cycles	4.13
CQA cycles if no scalar integer	3.00
CQA cycles if FP arith vectorized	3.38
CQA cycles if fully vectorized	0.81 - 1.13
Front-end cycles	3.81
P0 cycles	1.63
P1 cycles	1.63
P2 cycles	3.75
P3 cycles	3.75
P4 cycles	3.75
P5 cycles	3.75
P6 cycles	1.25
P7 cycles	1.25
P8 cycles	1.25
P9 cycles	1.25
P10 cycles	3.00
P11 cycles	2.83
P12 cycles	2.92
P13 cycles	0.00
P14 cycles	0.00
DIV/SQRT cycles	0.88 - 1.75
Inter-iter dependencies cycles	1
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	31.25
Nb uops	30.50
Nb loads	NA
Nb stores	1.50
Nb stack references	0.00
FLOP/cycle	1.21
Nb FLOP add-sub	0.00
Nb FLOP mul	1.50
Nb FLOP fma	1.50
Nb FLOP div	0.50
Nb FLOP rcp	0.00
Nb FLOP sqrt	0.00
Nb FLOP rsqrt	0.00
Bytes/cycle	1.46
Bytes prefetched	0.00
Bytes loaded	4.50
Bytes stored	0.00
Stride 0	NA
Stride 1	NA
Stride n	NA
Stride unknown	NA
Stride indirect	NA
Vectorization ratio all	0.00
Vectorization ratio load	0.00
Vectorization ratio store	0.00
Vectorization ratio mul	0.00
Vectorization ratio add_sub	0.00
Vectorization ratio fma	0.00
Vectorization ratio div_sqrt	0.00
Vectorization ratio other	0.00
Vector-efficiency ratio all	22.09
Vector-efficiency ratio load	21.53
Vector-efficiency ratio store	25.00
Vector-efficiency ratio mul	25.00
Vector-efficiency ratio add_sub	24.72
Vector-efficiency ratio fma	25.00
Vector-efficiency ratio div_sqrt	25.00
Vector-efficiency ratio other	18.75

Metric	Value
CQA speedup if no scalar integer	1.00
CQA speedup if FP arith vectorized	1.00
CQA speedup if fully vectorized	6.40
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	1.14
Bottlenecks	P0, P1, P2, P3, P4, P5,
Function	advancePosition._omp_fn.0
Source	timestep.c:88-88,timestep.c:91-94
Source loop unroll info	NA
Source loop unroll confidence level	NA
Unroll/vectorization loop type	NA
Unroll factor	NA
CQA cycles	1.00
CQA cycles if no scalar integer	1.00
CQA cycles if FP arith vectorized	1.00
CQA cycles if fully vectorized	0.16
Front-end cycles	0.88
P0 cycles	1.00
P1 cycles	1.00
P2 cycles	1.00
P3 cycles	1.00
P4 cycles	1.00
P5 cycles	1.00
P6 cycles	0.00
P7 cycles	0.00
P8 cycles	0.00
P9 cycles	0.00
P10 cycles	0.33
P11 cycles	0.33
P12 cycles	0.33
P13 cycles	0.00
P14 cycles	0.00
DIV/SQRT cycles	0.00
Inter-iter dependencies cycles	1
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	7.00
Nb uops	7.00
Nb loads	NA
Nb stores	0.00
Nb stack references	0.00
FLOP/cycle	0.00
Nb FLOP add-sub	0.00
Nb FLOP mul	0.00
Nb FLOP fma	0.00
Nb FLOP div	0.00
Nb FLOP rcp	0.00
Nb FLOP sqrt	0.00
Nb FLOP rsqrt	0.00
Bytes/cycle	3.00
Bytes prefetched	0.00
Bytes loaded	3.00
Bytes stored	0.00
Stride 0	NA
Stride 1	NA
Stride n	NA
Stride unknown	NA
Stride indirect	NA
Vectorization ratio all	0.00
Vectorization ratio load	0.00
Vectorization ratio store	NA
Vectorization ratio mul	NA
Vectorization ratio add_sub	0.00
Vectorization ratio fma	NA
Vectorization ratio div_sqrt	NA
Vectorization ratio other	0.00
Vector-efficiency ratio all	16.67
Vector-efficiency ratio load	12.50
Vector-efficiency ratio store	NA
Vector-efficiency ratio mul	NA
Vector-efficiency ratio add_sub	25.00
Vector-efficiency ratio fma	NA
Vector-efficiency ratio div_sqrt	NA
Vector-efficiency ratio other	12.50

Metric	Value
CQA speedup if no scalar integer	1.00
CQA speedup if FP arith vectorized	1.00
CQA speedup if fully vectorized	4.57
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	1.39
Bottlenecks	P2, P3, P4, P5,
Function	advancePosition._omp_fn.0
Source	timestep.c:88-88,timestep.c:91-94
Source loop unroll info	NA
Source loop unroll confidence level	NA
Unroll/vectorization loop type	NA
Unroll factor	NA
CQA cycles	4.00
CQA cycles if no scalar integer	4.00
CQA cycles if FP arith vectorized	4.00
CQA cycles if fully vectorized	0.88
Front-end cycles	2.88
P0 cycles	1.50
P1 cycles	1.50
P2 cycles	4.00
P3 cycles	4.00
P4 cycles	4.00
P5 cycles	4.00
P6 cycles	0.00
P7 cycles	0.00
P8 cycles	0.00
P9 cycles	0.00
P10 cycles	1.33
P11 cycles	1.33
P12 cycles	1.33
P13 cycles	0.00
P14 cycles	0.00
DIV/SQRT cycles	0.00
Inter-iter dependencies cycles	1
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	23.00
Nb uops	23.00
Nb loads	NA
Nb stores	0.00
Nb stack references	0.00
FLOP/cycle	0.00
Nb FLOP add-sub	0.00
Nb FLOP mul	0.00
Nb FLOP fma	0.00
Nb FLOP div	0.00
Nb FLOP rcp	0.00
Nb FLOP sqrt	0.00
Nb FLOP rsqrt	0.00
Bytes/cycle	0.75
Bytes prefetched	0.00
Bytes loaded	3.00
Bytes stored	0.00
Stride 0	0.00
Stride 1	0.00
Stride n	0.00
Stride unknown	10.00
Stride indirect	0.00
Vectorization ratio all	0.00
Vectorization ratio load	0.00
Vectorization ratio store	NA
Vectorization ratio mul	NA
Vectorization ratio add_sub	0.00
Vectorization ratio fma	NA
Vectorization ratio div_sqrt	NA
Vectorization ratio other	0.00
Vector-efficiency ratio all	24.26
Vector-efficiency ratio load	29.17
Vector-efficiency ratio store	NA
Vector-efficiency ratio mul	NA
Vector-efficiency ratio add_sub	23.86
Vector-efficiency ratio fma	NA
Vector-efficiency ratio div_sqrt	NA
Vector-efficiency ratio other	20.83

Metric	Value
CQA speedup if no scalar integer	1.64
CQA speedup if FP arith vectorized	1.35
CQA speedup if fully vectorized	5.23 - 3.29
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	1.11
Bottlenecks	micro-operation queue,
Function	advancePosition._omp_fn.0
Source	timestep.c:88-88,timestep.c:91-94
Source loop unroll info	NA
Source loop unroll confidence level	NA
Unroll/vectorization loop type	NA
Unroll factor	NA
CQA cycles	5.75
CQA cycles if no scalar integer	3.50
CQA cycles if FP arith vectorized	4.25
CQA cycles if fully vectorized	1.10 - 1.75
Front-end cycles	5.75
P0 cycles	2.00
P1 cycles	2.00
P2 cycles	5.00
P3 cycles	5.00
P4 cycles	5.00
P5 cycles	5.00
P6 cycles	2.50
P7 cycles	2.50
P8 cycles	2.50
P9 cycles	2.50
P10 cycles	5.17
P11 cycles	4.83
P12 cycles	5.00
P13 cycles	0.00
P14 cycles	0.00
DIV/SQRT cycles	1.75 - 3.50
Inter-iter dependencies cycles	1
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	49.00
Nb uops	46.00
Nb loads	NA
Nb stores	3.00
Nb stack references	0.00
FLOP/cycle	1.74
Nb FLOP add-sub	0.00
Nb FLOP mul	3.00
Nb FLOP fma	3.00
Nb FLOP div	1.00
Nb FLOP rcp	0.00
Nb FLOP sqrt	0.00
Nb FLOP rsqrt	0.00
Bytes/cycle	1.04
Bytes prefetched	0.00
Bytes loaded	6.00
Bytes stored	0.00
Stride 0	0.00
Stride 1	0.00
Stride n	0.00
Stride unknown	10.00
Stride indirect	0.00
Vectorization ratio all	0.00
Vectorization ratio load	0.00
Vectorization ratio store	0.00
Vectorization ratio mul	0.00
Vectorization ratio add_sub	0.00
Vectorization ratio fma	0.00
Vectorization ratio div_sqrt	0.00
Vectorization ratio other	0.00
Vector-efficiency ratio all	23.71
Vector-efficiency ratio load	22.22
Vector-efficiency ratio store	25.00
Vector-efficiency ratio mul	25.00
Vector-efficiency ratio add_sub	25.00
Vector-efficiency ratio fma	25.00
Vector-efficiency ratio div_sqrt	25.00
Vector-efficiency ratio other	20.83

Metric	Value
CQA speedup if no scalar integer	1.64
CQA speedup if FP arith vectorized	1.35
CQA speedup if fully vectorized	5.11 - 3.29
CQA speedup if no inter-iteration dependency	NA
CQA speedup if next bottleneck killed	1.11
Bottlenecks	micro-operation queue,
Function	advancePosition._omp_fn.0
Source	timestep.c:88-88,timestep.c:91-94
Source loop unroll info	NA
Source loop unroll confidence level	NA
Unroll/vectorization loop type	NA
Unroll factor	NA
CQA cycles	5.75
CQA cycles if no scalar integer	3.50
CQA cycles if FP arith vectorized	4.25
CQA cycles if fully vectorized	1.13 - 1.75
Front-end cycles	5.75
P0 cycles	2.00
P1 cycles	2.00
P2 cycles	5.00
P3 cycles	5.00
P4 cycles	5.00
P5 cycles	5.00
P6 cycles	2.50
P7 cycles	2.50
P8 cycles	2.50
P9 cycles	2.50
P10 cycles	5.17
P11 cycles	4.83
P12 cycles	5.00
P13 cycles	0.00
P14 cycles	0.00
DIV/SQRT cycles	1.75 - 3.50
Inter-iter dependencies cycles	1
FE+BE cycles (UFS)	NA
Stall cycles (UFS)	NA
Nb insns	46.00
Nb uops	46.00
Nb loads	NA
Nb stores	3.00
Nb stack references	0.00
FLOP/cycle	1.74
Nb FLOP add-sub	0.00
Nb FLOP mul	3.00
Nb FLOP fma	3.00
Nb FLOP div	1.00
Nb FLOP rcp	0.00
Nb FLOP sqrt	0.00
Nb FLOP rsqrt	0.00
Bytes/cycle	1.04
Bytes prefetched	0.00
Bytes loaded	6.00
Bytes stored	0.00
Stride 0	NA
Stride 1	NA
Stride n	NA
Stride unknown	NA
Stride indirect	NA
Vectorization ratio all	0.00
Vectorization ratio load	0.00
Vectorization ratio store	0.00
Vectorization ratio mul	0.00
Vectorization ratio add_sub	0.00
Vectorization ratio fma	0.00
Vectorization ratio div_sqrt	0.00
Vectorization ratio other	0.00
Vector-efficiency ratio all	23.71
Vector-efficiency ratio load	22.22
Vector-efficiency ratio store	25.00
Vector-efficiency ratio mul	25.00
Vector-efficiency ratio add_sub	25.00
Vector-efficiency ratio fma	25.00
Vector-efficiency ratio div_sqrt	25.00
Vector-efficiency ratio other	20.83

Path /

Average path: Display a virtual path defined by average values of all real paths

Function	advancePosition._omp_fn.0
Source file and lines	timestep.c:88-94
Module	exec

The loop is defined in /home/eoseret/qaas/qaas_runs/178-176-0594/intel/CoMD/build/CoMD/CoMD/src-openmp/timestep.c:88-94.

Analyzed code is defined in /home/eoseret/qaas/qaas_runs/178-176-0594/intel/CoMD/build/CoMD/CoMD/src-openmp/timestep.c:88,91-94.

Warnings:
Non-innermost loop: analyzing only self part (ignoring child loops).
This loop has 4 execution paths.

The presence of multiple execution paths is typically the main/first bottleneck.
Try to simplify control inside loop: ideally, try to remove all conditional expressions, for example by (if applicable):

hoisting them (moving them outside the loop)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Vectorization

Your loop is not vectorized. Only 22% of vector register length is used (average across all VPU instructions). By vectorizing your loop, you can lower the cost of an iteration from 4.13 to 1.13 cycles (3.64x speedup).

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized loop can use their full power.

Workaround

Try another compiler or update/tune your current one:
- recompile with fassociative-math (included in Ofast or ffast-math) to extend loop vectorization to FP reductions.
Remove inter-iterations dependences from your loop and make it unit-stride:
- If your arrays have 2 or more dimensions, check whether elements are accessed contiguously and, otherwise, try to permute loops accordingly: C storage order is row-major: for(i) for(j) a[j][i] = b[j][i]; (slow, non stride 1) => for(i) for(j) a[i][j] = b[i][j]; (fast, stride 1)
- If your loop streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

FMA

Detected 1.50 FMA (fused multiply-add) operations.

Matching between your loop (in the source code) and the binary loop

The binary loop is composed of 5 FP arithmetical operations:

1.50: addition or subtraction (all inside FMA instructions)
3: multiply (1 inside FMA instructions)
0.50: divide

The binary loop is loading 4 bytes.

Arithmetic intensity

Arithmetic intensity is 1.11 FP operations per loaded or stored byte.

General properties

nb instructions	31.25
nb uops	30.50
loop length	125
used w registers	4.50
used x registers	17.75
used b registers	0
used h registers	0
used s registers	0
used d registers	8
used q registers	0
used v registers	0
used z registers	0
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE

micro-operation queue	3.81 cycles
front end	3.81 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	1.63	1.63	3.75	3.75	3.75	3.75	1.25	1.25	1.25	1.25	3.00	2.83	2.92	0.00	0.00
cycles	1.63	1.63	3.75	3.75	3.75	3.75	1.25	1.25	1.25	1.25	3.00	2.83	2.92	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions	0.88-1.75
Longest recurrence chain latency (RecMII)	1.00

Cycles summary

Front-end	3.81
Dispatch	3.83
DIV/SQRT	0.88-1.75
Data deps.	1.00
Overall L1	4.13

Vectorization ratios

INT

all	0%
load	0%
store	0%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
other	0%

all	0%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	0%
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	0%
div/sqrt	0%
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	0%
load	0%
store	0%
mul	0%
add-sub	0%
fma	0%
div/sqrt	0%
other	0%

Vector efficiency ratios

INT

all	21%
load	21%
store	25%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	24%
fma	NA (no fma vectorizable/vectorized instructions)
other	18%

all	25%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	25%
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	25%
div/sqrt	25%
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	22%
load	21%
store	25%
mul	25%
add-sub	24%
fma	25%
div/sqrt	25%
other	18%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 4.13 cycles. At this rate:

1% of peak load performance is reached (1.46 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

Function	advancePosition._omp_fn.0
Source file and lines	timestep.c:88-94
Module	exec

hoisting them (moving them outside the loop)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Vectorization

Your loop is not vectorized. Only 16% of vector register length is used (average across all VPU instructions). By vectorizing your loop, you can lower the cost of an iteration from 1.00 to 0.16 cycles (6.40x speedup).

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized loop can use their full power.

Workaround

Try another compiler or update/tune your current one:
- recompile with fassociative-math (included in Ofast or ffast-math) to extend loop vectorization to FP reductions.
Remove inter-iterations dependences from your loop and make it unit-stride:
- If your arrays have 2 or more dimensions, check whether elements are accessed contiguously and, otherwise, try to permute loops accordingly: C storage order is row-major: for(i) for(j) a[j][i] = b[j][i]; (slow, non stride 1) => for(i) for(j) a[i][j] = b[i][j]; (fast, stride 1)
- If your loop streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

No data for this section

Matching between your loop (in the source code) and the binary loop

The binary loop does not contain any FP arithmetical operations. The binary loop is loading 3 bytes.

General properties

nb instructions	7
nb uops	7
loop length	28
used w registers	3
used x registers	3
used b registers	0
used h registers	0
used s registers	0
used d registers	0
used q registers	0
used v registers	0
used z registers	0
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	0.88 cycles
front end	0.88 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	1.00	1.00	1.00	1.00	1.00	1.00	0.00	0.00	0.00	0.00	0.33	0.33	0.33	0.00	0.00
cycles	1.00	1.00	1.00	1.00	1.00	1.00	0.00	0.00	0.00	0.00	0.33	0.33	0.33	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions	NA
Longest recurrence chain latency (RecMII)	1.00

Cycles summary

Front-end	0.88
Dispatch	1.00
Data deps.	1.00
Overall L1	1.00

Vectorization ratios

all	0%
load	0%
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

Vector efficiency ratios

all	16%
load	12%
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	25%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	12%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 1.00 cycles. At this rate:

3% of peak load performance is reached (3.00 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

Front-end bottlenecks

Found no such bottlenecks.

ASM code

In the binary file, the address of the loop is: 41a4cc

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P10	P11	P12	Latency	Recip. throughput	Vectorization
LDR W5, [X18, X14,LSL #2]	1	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	scal (12.5%)
CMP W5, #0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.33	scal (12.5%)
B.LE 41a630 <advancePosition._omp_fn.0+0x1d0>	1	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A
ADD X14, X14, #1	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	N/A
ADD X15, X15, #1536	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
CMP W16, W14	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.33	N/A
B.GT 41a4cc <advancePosition._omp_fn.0+0x6c>	1	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A

Function	advancePosition._omp_fn.0
Source file and lines	timestep.c:88-94
Module	exec

hoisting them (moving them outside the loop)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Vectorization

Your loop is not vectorized. Only 24% of vector register length is used (average across all VPU instructions). By vectorizing your loop, you can lower the cost of an iteration from 4.00 to 0.87 cycles (4.57x speedup).

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized loop can use their full power.

Workaround

Try another compiler or update/tune your current one:
- recompile with fassociative-math (included in Ofast or ffast-math) to extend loop vectorization to FP reductions.
Remove inter-iterations dependences from your loop and make it unit-stride:
- If your arrays have 2 or more dimensions, check whether elements are accessed contiguously and, otherwise, try to permute loops accordingly: C storage order is row-major: for(i) for(j) a[j][i] = b[j][i]; (slow, non stride 1) => for(i) for(j) a[i][j] = b[i][j]; (fast, stride 1)
- If your loop streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

No data for this section

Slow data structures access

Detected data structures (typically arrays) that cannot be efficiently read/written

Details

Constant unknown stride: 10 occurrence(s)

Non-unit stride (uncontiguous) accesses are not efficiently using data caches

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)

Matching between your loop (in the source code) and the binary loop

The binary loop does not contain any FP arithmetical operations. The binary loop is loading 3 bytes.

General properties

nb instructions	23
nb uops	23
loop length	92
used w registers	5
used x registers	22
used b registers	0
used h registers	0
used s registers	0
used d registers	0
used q registers	0
used v registers	0
used z registers	0
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	2.88 cycles
front end	2.88 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	1.50	1.50	4.00	4.00	4.00	4.00	0.00	0.00	0.00	0.00	1.33	1.33	1.33	0.00	0.00
cycles	1.50	1.50	4.00	4.00	4.00	4.00	0.00	0.00	0.00	0.00	1.33	1.33	1.33	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions	NA
Longest recurrence chain latency (RecMII)	1.00

Cycles summary

Front-end	2.88
Dispatch	4.00
Data deps.	1.00
Overall L1	4.00

Vectorization ratios

all	0%
load	0%
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	0%

Vector efficiency ratios

all	24%
load	29%
store	NA (no store vectorizable/vectorized instructions)
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	23%
fma	NA (no fma vectorizable/vectorized instructions)
div/sqrt	NA (no div/sqrt vectorizable/vectorized instructions)
other	20%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 4.00 cycles. At this rate:

0% of peak load performance is reached (0.75 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

Front-end bottlenecks

Found no such bottlenecks.

ASM code

In the binary file, the address of the loop is: 41a4cc

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P10	P11	P12	Latency	Recip. throughput	Vectorization
LDR W5, [X18, X14,LSL #2]	1	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	scal (12.5%)
CMP W5, #0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.33	scal (12.5%)
B.LE 41a630 <advancePosition._omp_fn.0+0x1d0>	1	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A
LDP X10, X13, [X17, #32]	1	0	0	0	0	0	0	0.33	0.33	0.33	4	1	N/A
SUB W9, W5, #1	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (12.5%)
UBFM X7, X14, #56, #55	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
ADD X8, X9, X14,LSL #6	1	0	0	0	0	0.50	0.50	0	0	0	2	0.50	scal (25.0%)
ORR X0, XZR, X15	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
LDP X6, X30, [X10, #16]	1	0	0	0	0	0	0	0.33	0.33	0.33	4	1	scal (50.0%)
LDR X20, [X10, #32]	1	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	scal (25.0%)
ADD X11, X6, #4	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
ADD X3, X6, X7	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
ADD X21, X11, X8,LSL #2	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
ADD X19, X30, #8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
ADD X2, X30, #16	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
SUB X1, X21, X3	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
ADD X12, X20, #8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
ADD X4, X20, #16	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
TBZ W1, #2, 41a580 <advancePosition._omp_fn.0+0x120>	1	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A
ADD X14, X14, #1	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	N/A
ADD X15, X15, #1536	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.25	scal (25.0%)
CMP W16, W14	1	0	0	0.25	0.25	0.25	0.25	0	0	0	1	0.33	N/A
B.GT 41a4cc <advancePosition._omp_fn.0+0x6c>	1	0.50	0.50	0	0	0	0	0	0	0	1	0.50	N/A

Function	advancePosition._omp_fn.0
Source file and lines	timestep.c:88-94
Module	exec

hoisting them (moving them outside the loop)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Code clean check

Detected a slowdown caused by scalar integer instructions (typically used for address computation). By removing them, you can lower the cost of an iteration from 5.75 to 3.50 cycles (1.64x speedup).

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)

Vectorization

Your loop is not vectorized. Only 23% of vector register length is used (average across all VPU instructions). By vectorizing your loop, you can lower the cost of an iteration from 5.75 to 1.75 cycles (3.29x speedup).

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized loop can use their full power.

Workaround

Try another compiler or update/tune your current one:
- recompile with fassociative-math (included in Ofast or ffast-math) to extend loop vectorization to FP reductions.
Remove inter-iterations dependences from your loop and make it unit-stride:
- If your arrays have 2 or more dimensions, check whether elements are accessed contiguously and, otherwise, try to permute loops accordingly: C storage order is row-major: for(i) for(j) a[j][i] = b[j][i]; (slow, non stride 1) => for(i) for(j) a[i][j] = b[i][j]; (fast, stride 1)
- If your loop streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

FMA

Detected 3 FMA (fused multiply-add) operations.

Slow data structures access

Detected data structures (typically arrays) that cannot be efficiently read/written

Details

Constant unknown stride: 10 occurrence(s)

Non-unit stride (uncontiguous) accesses are not efficiently using data caches

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)

Matching between your loop (in the source code) and the binary loop

The binary loop is composed of 10 FP arithmetical operations:

3: addition or subtraction (all inside FMA instructions)
6: multiply (3 inside FMA instructions)
1: divide

The binary loop is loading 6 bytes.

Arithmetic intensity

Arithmetic intensity is 1.67 FP operations per loaded or stored byte.

General properties

nb instructions	49
nb uops	46
loop length	196
used w registers	5
used x registers	23
used b registers	0
used h registers	0
used s registers	0
used d registers	16
used q registers	0
used v registers	0
used z registers	0
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	5.75 cycles
front end	5.75 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	2.00	2.00	5.00	5.00	5.00	5.00	2.50	2.50	2.50	2.50	5.17	4.83	5.00	0.00	0.00
cycles	2.00	2.00	5.00	5.00	5.00	5.00	2.50	2.50	2.50	2.50	5.17	4.83	5.00	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions	1.75-3.50
Longest recurrence chain latency (RecMII)	1.00

Cycles summary

Front-end	5.75
Dispatch	5.17
DIV/SQRT	1.75-3.50
Data deps.	1.00
Overall L1	5.75

Vectorization ratios

INT

all	0%
load	0%
store	0%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
other	0%

all	0%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	0%
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	0%
div/sqrt	0%
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	0%
load	0%
store	0%
mul	0%
add-sub	0%
fma	0%
div/sqrt	0%
other	0%

Vector efficiency ratios

INT

all	23%
load	22%
store	25%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	25%
fma	NA (no fma vectorizable/vectorized instructions)
other	20%

all	25%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	25%
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	25%
div/sqrt	25%
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	23%
load	22%
store	25%
mul	25%
add-sub	25%
fma	25%
div/sqrt	25%
other	20%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 5.75 cycles. At this rate:

1% of peak load performance is reached (1.04 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

Front-end bottlenecks

Performance is limited by instruction throughput (loading/decoding program instructions to execution core) (front-end is a bottleneck). By removing all these bottlenecks, you can lower the cost of an iteration from 5.75 to 5.17 cycles (1.11x speedup).

ASM code

In the binary file, the address of the loop is: 41a4cc

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14	Latency	Recip. throughput	Vectorization
LDR W5, [X18, X14,LSL #2]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (12.5%)
CMP W5, #0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.33	scal (12.5%)
B.LE 41a630 <advancePosition._omp_fn.0+0x1d0>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDP X10, X13, [X17, #32]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	1	N/A
SUB W9, W5, #1	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
UBFM X7, X14, #56, #55	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
ADD X8, X9, X14,LSL #6	1	0	0	0	0	0.50	0.50	0	0	0	0	0	0	0	0	0	2	0.50	scal (25.0%)
ORR X0, XZR, X15	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
LDP X6, X30, [X10, #16]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	1	N/A
LDR X20, [X10, #32]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	N/A
ADD X11, X6, #4	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X3, X6, X7	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X21, X11, X8,LSL #2	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X19, X30, #8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
ADD X2, X30, #16	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
SUB X1, X21, X3	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X12, X20, #8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
ADD X4, X20, #16	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
TBZ W1, #2, 41a580 <advancePosition._omp_fn.0+0x120>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDRSW X5, [X6, X7]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	4	0.33	scal (12.5%)
ADD X3, X3, #4	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X0, X15, #24	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
LDR D3, [X20, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (25.0%)
LDR D2, [X30, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (25.0%)
ADD X9, X13, X5,LSL #4	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
LDR D1, [X9, #8]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (25.0%)
FMUL D5, D0, D3	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	3	0.25	scal (25.0%)
FDIV D6, D4, D1	1	0	0	0	0	0	0	0.50	0	0.50	0	0	0	0	0	0	7-15	1.75-3.50	scal (25.0%)
FMADD D7, D6, D5, D2	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	4	0.25	scal (25.0%)
STR D7, [X30, X15]	1	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	scal (25.0%)
LDR D16, [X12, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (25.0%)
LDR D17, [X19, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (25.0%)
FMUL D18, D0, D16	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	3	0.25	scal (25.0%)
FMADD D19, D6, D18, D17	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	4	0.25	scal (25.0%)
STR D19, [X19, X15]	1	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	scal (25.0%)
LDR D20, [X4, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (25.0%)
LDR D21, [X2, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	0	0	6	0.33	scal (25.0%)
FMUL D22, D0, D20	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	3	0.25	scal (25.0%)
FMADD D23, D6, D22, D21	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	4	0.25	scal (25.0%)
STR D23, [X2, X15]	1	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	0	0	2	0.50	scal (25.0%)
CMP X3, X21	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.33	scal (25.0%)
B.EQ 41a630 <advancePosition._omp_fn.0+0x1d0>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
HINT #0																			N/A
HINT #0																			N/A
HINT #0																			N/A
ADD X14, X14, #1	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
ADD X15, X15, #1536	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.25	N/A
CMP W16, W14	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	0	0	1	0.33	N/A
B.GT 41a4cc <advancePosition._omp_fn.0+0x6c>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A

Function	advancePosition._omp_fn.0
Source file and lines	timestep.c:88-94
Module	exec

hoisting them (moving them outside the loop)
turning them into conditional moves, MIN or MAX

Ex: if (x<0) x=0 => x = (x<0 ? 0 : x) (or MAX(0,x) after defining the corresponding macro)

gain
potential
hint
expert

Code clean check

Detected a slowdown caused by scalar integer instructions (typically used for address computation). By removing them, you can lower the cost of an iteration from 5.75 to 3.50 cycles (1.64x speedup).

Workaround

Try to reorganize arrays of structures to structures of arrays
Consider to permute loops (see vectorization gain report)

Vectorization

Details

All VPU instructions are used in scalar version (process only one data element in vector registers). Since your execution units are vector units, only a vectorized loop can use their full power.

Workaround

Try another compiler or update/tune your current one:
- recompile with fassociative-math (included in Ofast or ffast-math) to extend loop vectorization to FP reductions.
Remove inter-iterations dependences from your loop and make it unit-stride:
- If your arrays have 2 or more dimensions, check whether elements are accessed contiguously and, otherwise, try to permute loops accordingly: C storage order is row-major: for(i) for(j) a[j][i] = b[j][i]; (slow, non stride 1) => for(i) for(j) a[i][j] = b[i][j]; (fast, stride 1)
- If your loop streams arrays of structures (AoS), try to use structures of arrays instead (SoA): for(i) a[i].x = b[i].x; (slow, non stride 1) => for(i) a.x[i] = b.x[i]; (fast, stride 1)

FMA

Detected 3 FMA (fused multiply-add) operations.

Matching between your loop (in the source code) and the binary loop

The binary loop is composed of 10 FP arithmetical operations:

3: addition or subtraction (all inside FMA instructions)
6: multiply (3 inside FMA instructions)
1: divide

The binary loop is loading 6 bytes.

Arithmetic intensity

Arithmetic intensity is 1.67 FP operations per loaded or stored byte.

General properties

nb instructions	46
nb uops	46
loop length	184
used w registers	5
used x registers	23
used b registers	0
used h registers	0
used s registers	0
used d registers	16
used q registers	0
used v registers	0
used z registers	0
nb stack references	0

Front-end

MACRO FUSION NOT POSSIBLE FIT IN UOP CACHE

micro-operation queue	5.75 cycles
front end	5.75 cycles

Back-end

	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	P13	P14
uops	2.00	2.00	5.00	5.00	5.00	5.00	2.50	2.50	2.50	2.50	5.17	4.83	5.00	0.00	0.00
cycles	2.00	2.00	5.00	5.00	5.00	5.00	2.50	2.50	2.50	2.50	5.17	4.83	5.00	0.00	0.00

Execution ports to units layout:

P0: BRU
P1: BRU
P2: ALU
P3: ALU
P4: ALU
P5: ALU
P6 (128 bits): VPU, FP store data, ALU, DIV/SQRT
P7 (128 bits): VPU, ALU, FP store data
P8 (128 bits): VPU, ALU, DIV/SQRT
P9 (128 bits): ALU, VPU
P10 (256 bits): store address, load
P11 (256 bits): store address, load
P12 (256 bits): load
P13 (64 bits): store data
P14 (64 bits): store data

Cycles executing div or sqrt instructions	1.75-3.50
Longest recurrence chain latency (RecMII)	1.00

Cycles summary

Front-end	5.75
Dispatch	5.17
DIV/SQRT	1.75-3.50
Data deps.	1.00
Overall L1	5.75

Vectorization ratios

INT

all	0%
load	0%
store	0%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	0%
fma	NA (no fma vectorizable/vectorized instructions)
other	0%

all	0%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	0%
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	0%
div/sqrt	0%
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	0%
load	0%
store	0%
mul	0%
add-sub	0%
fma	0%
div/sqrt	0%
other	0%

Vector efficiency ratios

INT

all	23%
load	22%
store	25%
mul	NA (no mul vectorizable/vectorized instructions)
add-sub	25%
fma	NA (no fma vectorizable/vectorized instructions)
other	20%

all	25%
load	NA (no load vectorizable/vectorized instructions)
store	NA (no store vectorizable/vectorized instructions)
mul	25%
add-sub	NA (no add-sub vectorizable/vectorized instructions)
fma	25%
div/sqrt	25%
other	NA (no other vectorizable/vectorized instructions)

INT+FP

all	23%
load	22%
store	25%
mul	25%
add-sub	25%
fma	25%
div/sqrt	25%
other	20%

Cycles and memory resources usage

Assuming all data fit into the L1 cache, each iteration of the binary loop takes 5.75 cycles. At this rate:

1% of peak load performance is reached (1.04 out of 96.00 bytes loaded per cycle (GB/s @ 1GHz))

Front-end bottlenecks

ASM code

In the binary file, the address of the loop is: 41a4cc

Instruction	Nb FU	P0	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10	P11	P12	Latency	Recip. throughput	Vectorization
LDR W5, [X18, X14,LSL #2]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	scal (12.5%)
CMP W5, #0	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.33	scal (12.5%)
B.LE 41a630 <advancePosition._omp_fn.0+0x1d0>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDP X10, X13, [X17, #32]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	4	1	N/A
SUB W9, W5, #1	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
UBFM X7, X14, #56, #55	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
ADD X8, X9, X14,LSL #6	1	0	0	0	0	0.50	0.50	0	0	0	0	0	0	0	2	0.50	scal (25.0%)
ORR X0, XZR, X15	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
LDP X6, X30, [X10, #16]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	4	1	N/A
LDR X20, [X10, #32]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	N/A
ADD X11, X6, #4	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X3, X6, X7	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X21, X11, X8,LSL #2	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X19, X30, #8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
ADD X2, X30, #16	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
SUB X1, X21, X3	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X12, X20, #8	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
ADD X4, X20, #16	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
TBZ W1, #2, 41a580 <advancePosition._omp_fn.0+0x120>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
LDRSW X5, [X6, X7]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	4	0.33	scal (12.5%)
ADD X3, X3, #4	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
ADD X0, X15, #24	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	scal (25.0%)
LDR D3, [X20, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	6	0.33	scal (25.0%)
LDR D2, [X30, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	6	0.33	scal (25.0%)
ADD X9, X13, X5,LSL #4	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
LDR D1, [X9, #8]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	6	0.33	scal (25.0%)
FMUL D5, D0, D3	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	3	0.25	scal (25.0%)
FDIV D6, D4, D1	1	0	0	0	0	0	0	0.50	0	0.50	0	0	0	0	7-15	1.75-3.50	scal (25.0%)
FMADD D7, D6, D5, D2	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	4	0.25	scal (25.0%)
STR D7, [X30, X15]	1	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	2	0.50	scal (25.0%)
LDR D16, [X12, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	6	0.33	scal (25.0%)
LDR D17, [X19, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	6	0.33	scal (25.0%)
FMUL D18, D0, D16	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	3	0.25	scal (25.0%)
FMADD D19, D6, D18, D17	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	4	0.25	scal (25.0%)
STR D19, [X19, X15]	1	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	2	0.50	scal (25.0%)
LDR D20, [X4, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	6	0.33	scal (25.0%)
LDR D21, [X2, X15]	1	0	0	0	0	0	0	0	0	0	0	0.33	0.33	0.33	6	0.33	scal (25.0%)
FMUL D22, D0, D20	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	3	0.25	scal (25.0%)
FMADD D23, D6, D22, D21	1	0	0	0	0	0	0	0.25	0.25	0.25	0.25	0	0	0	4	0.25	scal (25.0%)
STR D23, [X2, X15]	1	0	0	0	0	0	0	0.50	0.50	0	0	0.50	0.50	0	2	0.50	scal (25.0%)
CMP X3, X21	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.33	scal (25.0%)
B.EQ 41a630 <advancePosition._omp_fn.0+0x1d0>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A
ADD X14, X14, #1	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
ADD X15, X15, #1536	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.25	N/A
CMP W16, W14	1	0	0	0.25	0.25	0.25	0.25	0	0	0	0	0	0	0	1	0.33	N/A
B.GT 41a4cc <advancePosition._omp_fn.0+0x6c>	1	0.50	0.50	0	0	0	0	0	0	0	0	0	0	0	1	0.50	N/A

Report Configuration

Vectorization

Details

Workaround

FMA

Matching between your loop (in the source code) and the binary loop

Arithmetic intensity

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Vectorization

Details

Workaround

Matching between your loop (in the source code) and the binary loop

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code

Vectorization

Details

Workaround

Slow data structures access

Details

Workaround

Matching between your loop (in the source code) and the binary loop

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code

Code clean check

Workaround

Vectorization

Details

Workaround

FMA

Slow data structures access

Details

Workaround

Matching between your loop (in the source code) and the binary loop

Arithmetic intensity

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code

Code clean check

Workaround

Vectorization

Details

Workaround

FMA

Matching between your loop (in the source code) and the binary loop

Arithmetic intensity

General properties

Front-end

Back-end

Cycles summary

Vectorization ratios

Vector efficiency ratios

Cycles and memory resources usage

Front-end bottlenecks

ASM code